AGRO 111 Fundamentals of Agronomy PDF

1 MAHATMA PHULE KRISHI VIDYAPEETH, AGRONOMY SECTION, COLLEGE OF AGRICULTURE, KOLHAPUR COURSE NO.: - AGRO-111 CREDITS: -2= 1 + 1 SEMESTER: - I (NEW) TITLE: - FUNDAMENTALS OF AGRONOMY Teaching schedule...

1 MAHATMA PHULE KRISHI VIDYAPEETH, AGRONOMY SECTION, COLLEGE OF AGRICULTURE, KOLHAPUR COURSE NO.: - AGRO-111 CREDITS: -2= 1 + 1 SEMESTER: - I (NEW) TITLE: - FUNDAMENTALS OF AGRONOMY Teaching schedule THEORY: Lect. Topic Weightage No. (%) 1. Agronomy, its definition, scope, role of Agronomist and relationship of 4 Agronomy with other sciences. 2. Tillage, its definition, objects of tillage, types of tillage, tillage 8 implements and factors affecting tillage, Effect of tillage on soil and crop growth. 3. Tilth: its definition, characteristics and ideal tilth, Modern concepts of 6 tillage, minimum, zero and stubble mulch tillage, importance of puddling. 4. Seed, its definition, characteristics of quality seed, seed treatment and 8 its objectives, seed dormancy, causes of seed dormancy and multiplication stages of seed. 5. Methods of sowing seed and sowing implements 4 6. Effect of plant population on growth and yield, Planting geometry: 6 solid, paired and skipped row planting. 7. Role of plant nutrients in crop production, Importance of manures & 6 fertilizers and its classification. 8. Methods and time of application of manures, fertilizers and green 6 manuring. 9. Nutrient use efficiency, meaning and factors affecting nutrient use 6 efficiency. 10. Growth and development, its definition, growth curve and factors 6 affecting growth and development. 11. Plant ideotypes, its definition and types of ideotypes 6 12. Crop rotation, its definition, principles and advantages of crop rotation. 6 13. Study of crop adaptation and its distribution 4 14. Weeds, its definition, characteristics of weeds, merits and demerits of 6 weeds, classification of weeds, meaning of crop weed competition and its period in different crops. 15. Principles and methods of weed management viz., cultural, 6 mechanical, chemical, biological weed control methods and integrated weed management. 16. Classification of herbicides, its selectivity and resistance, allelopathic 6 effect of weed. 17. Crop harvesting, signs of maturity in different field crops, 6 physiological and crop maturity, methods of threshing crops, Cleaning, Drying and storage of field crops. Suggested Reading: 1. Chhidda Singh, Modern techniques of raising field crops. Oxford and IBH publishing Co. Ltd. Bangalore. 2. Gopal Chandra De. 1980, Fundamentals of Agronomy, Oxford and IBH publishing Co. Ltd. Bangalore. 3. Handbook of Agriculture, ICAR publication. 4. Palaniappan, S.P., Cropping Systems in the tropics – Principles and Practices. Willey Eastern Ltd., New Delhi. 5. Panda, S. C., 2006. Agronomy Agribios Publication, New Delhi.  2 6. Reddy, S. R. Principles of Agronomy, Kalyani Publishers. Ludhiana, India. 7. Sankaran, S. and Subbiah Mudliyar, V. T., 1991. Principles of Agronomy. The Bangalore Printing and Publishing Co. Ltd., Bangalore. 8. Vaidya, V. G., Sahastrabudhe, K. R and Khuspe, V. S. Crop production and field experimentation by Continental Prakashan, Vijaynagar, Pune. 9. Rao, V. S. 2006. Principles of Weed science. Oxford and IBH publishing Co., New Delhi, India. 10. Gupta, O.P. 2008, Modern Weed Management. Agribios India publication.  3 Lecture No. 1: - Agronomy, its definition, scope, role of Agronomist and relationship of Agronomy with other sciences. Agronomy:-It is the study of plants in relation to soil and climate. Agronomy is the branch of agriculture, which deals with the principles of crop production and field management. Agronomy is the branch of agricultural science, which deals with principles and practices of soil, water and crop management. In recent times, Agronomy has assumed newer dimensions and can be defined as a branch of agricultural science that deals with the methods, which provide favourable environment to the crop for higher productivity. While, environment is defined as the aggregate of all the external conditions and influences affecting life and development of organism. Norman (1980) has defined agronomy as the science of manipulating the crop environment complex with dual aims of improving agricultural productivity and gaining a degree of understanding of the process involved. Meaning of term Agronomy: The term Agronomy is derived from the Greek words "agros" meaning the field and "nomos" meaning to manage. So Agronomy means the study of plant, soil and related sciences for improvement, production and use of field crops. Agronomy is mainly divided into Crops Agronomy (crop production) and Soils Agronomy (soil and water management) depending upon the stress laid out on plant (crop) or soil aspect. Principles of Agronomy deal with the scientific facts in relation to environment in which the crops are produced. Knowledge of such basic principles aid in modifying the controllable environment factors of crop production for realizing the production potentials of cultivars. The crop environment constitutes both i. e. Soil and Aerial environment and influences the growth and development of crop. i) Soil- Plant is inside the soil (root system). ii) Aerial- Plant parts exposed to an aerial atmosphere. Soil environment: - Soil environment is amenable for modification through tillage, irrigation, fertilizers etc. The soil management deals with manipulation of soil environment for better crop growth. Aerial environment: - Aerial environment, which includes climatic elements viz., solar radiation, rainfall, temperature, humidity and wind velocity, have grate impact on crop growth. Aerial environment cannot be altered easily. Therefore, season for growing for each crop has to be selected for higher production from available climate. Scope of Agronomy: - Agronomy is a dynamic discipline and scope of Agronomy is very vast. It includes methods of tilling the land, suitable period of its cultivation, right time and method of sowing seed, keeping farm implements and farm machinery in good shape and managing field crops in an efficient manner as an experienced farmer. Agronomy is also concerned with the management of livestock, including their feeding, care and disposal of farm and animal products like milk, eggs and meat as well as proper maintenance of farm accounts. Agronomy also involves agronomic research on crops under different environmental conditions like varying soil, climate, irrigation, fertilizers etc. by conducting well laid-out experiments in field, pots and laboratories. It is also concerned with the application of results of research in field and forming suitable package of practices for the particular crop under given set of soil and climatic conditions and transfer of these agro-techniques to the farmers for boosting the crop yields. With the advancement of knowledge and better understanding of plant and environment, agricultural practices are modified or new practices developed for high productivity. For example, availability of chemical fertilizers has necessitated the generation of knowledge on the method, quantity and time of application of fertilizers. Similarly availability of herbicides for control of weeds has led to development of a vast knowledge about selectivity, time and method of application of  4 herbicides. Gigantic irrigation projects are constructed to provide irrigation facilities. However these projects are created side effects like water logging and salinity. To overcome these problems, appropriate water management practices are developed. Population pressure is increasing, but area under cultivation is static or slowly declining. More number of crops has, therefore, to be grown on the same piece of land in a year. As result, intensive cropping has come into vogue. Similarly, no tillage practices have come in place of clean cultivation as a result of increase in cost of energy. Likewise, new technology has to be developed to over come the effect of moisture stress under dry- land conditions. As new varieties of crops with high yield potential become available, package of practices has to be developed to exploit their potential. The factors restricting increased agricultural production are low soil fertility, crop varieties of low genetic yield potential, poor agronomic practices, inadequate or non-availability of production inputs, government economic policies affecting agriculture and weak research and extension programmes. Restoration of soil fertility, preparation of good seed bed, use of proper seed rates, correct dates of sowing for each improved variety, proper conservation and management of soil moisture and proper control of weeds are agronomic practices to make our finite land, water resources more productive. Role of agronomist in agriculture: A person who is expert in Agronomy is known as Agronomist. Agronomist aims at obtaining maximum production at minimum cost. The role of Agronomist in Agriculture is very important because whatever may be the research findings of other specialists, he has to test their suitability under field conditions and accept them finally and also to judge the reaction of farming community. He is therefore a coordinator of different subject matter specialists in the field of agriculture. His role can be compared with physician who gives medicines to the patients suffering from various diseases, but whenever necessity arises, consults the other specialists or directs the patients to them. In the similar type agronomist carries out scientific cultivation of crops and also takes help of other specialists whenever necessary. Agronomist exploits the knowledge developed by basic and allied applied sciences for higher production. In a large sense, agronomist is concerned with the production of food and fiber to meet the needs of growing population. Agronomist carried out research in scientific cultivation of crops taking into account the effects of factors soil, climate, and variety of crop and adjusts production techniques suitably depending on the situation. Finally on the basis of results of research he prepares the package of practices for different field crops and also takes effort for transfer of agro-techniques to the farmers for increasing crop yields. Agronomist is the key person in agriculture and coordinator of different subject matter specialists. Relationship of Agronomy with other allied sciences: Agronomy is an applied science and it is closely related and largely dependent on basic and other applied sciences. Basic Science: - It is the science, which reveals the facts or secrets of nature. e.g. Chemistry, Physics, Mathematics, Botany, Zoology, Economics etc. the knowledge of these sciences is necessary to learn the basic facts. Applied Science: - It is the Science in which the theories and laws propounded in basic sciences are applied for problems in agriculture and other fields e.g. Agronomy, Agricultural Chemistry, Agricultural Entomology, Agricultural Botany, Agricultural Economics, Plant Pathology. etc. Agronomy is synthesis of several disciplines like soil science, agricultural chemistry, crop physiology, plant ecology, biochemistry and economics. The soil physical, chemical and biological properties have to be understood thoroughly to effect modification of the soil environment. Similarly, it is necessary to understand the physiology of crops to meet their requirements. Development in these subjects' help in developing new practices which are simpler and economical to provide favourable environment to crop. Development of potential herbicides made evolutionary changes in weed control. Advances in economic analysis help in production of crops economically. For efficient utilization of resources, system approach is better than individualistic approach. Instead of taking individual crop into consideration for taking decisions, cropping system as a whole is considered.  5 Fertilizer recommendations for an entire cropping system saves considerable amount of fertilizer nutrients compared to recommending fertilizers for individual crops. Agricultural Chemistry:- Agricultural Chemistry consists up soil; water, plant, fertilizer and dairy chemistry has been developed from basic science of chemistry. Agronomy would need the help of fertilizer chemistry when there is question of fertilizer application to crop, as one should know the chemistry of fertilizer and soil analysis. The soil science knowledge is helpful for management of acidic, saline and alkali soils. Plant pathology and Agricultural Entomology: - Developed from botany and zoology. Plant pathology is related with Agronomy for management of diseases of crops and knowledge of Microbiology is essential for use of bio-fertilizers. Agricultural Entomology is related with Agronomy for management of pests (harmful insects) on the crops. Agricultural Economics: - Developed from economics and useful for maintaining farm records, farm accounts and marketing of various farm products. Economic analysis also determines benefit cost ratio, net profit fetched. Agricultural Extension:- Developed from sociology, psychology and anthropology and mainly related with different methods techniques for transfer of the advanced agro-techniques to the farmers. Extension worker act as a bridge between farmers’ problems and scientists as farmers problems are brought to scientists and new advanced technologies are given to farmers by extension workers. Agricultural Botany:- Developed from Botany and Zoology and includes plant morphology, plant physiology and plant breeding. This science is useful for evolving varieties / hybrids of the crops suitable for particular region. Agricultural Engineering:- It is concerned with care and use of improved tools implements and farm machinery required for carrying out various field operations and also use of micro-irrigation system for different crops. Animal Science and Dairy Science: Mainly concerned with Agronomy for management of livestock maintained on the farm including their feeding and care. These enterprises are combined with cropping systems to form farming system. Horticulture: - It is concerned with vegetables, flowers and fruit production. These crops can be introduced in the cropping scheme of the form for proper land utilization and increasing receipts or production. Agroecology:- is the management of agricultural systems with an emphasis on ecological and environmental perspectives. This area is closely associated with work in areas of sustainable agriculture, organic farming, alternative food systems and development of alternative cropping systems. Agro-forestry- Mainly concerned with selection of suitable multipurpose and economic tree species and agro-forestry systems for different eco-units. All these applied sciences are closely related to each other and no branch can progress without help of other allied branches. Agronomy deals with principles and practices of crop production and field management and it would need to help of all these agricultural branches for successful growing of crops and proper working of other enterprises on the farm for getting maximum benefit from farm business.  6 Lecture No. 2:- Tillage, its definition, objects of tillage, types of tillage, tillage implements and factors affecting tillage, Effect of tillage on soil and crop growth. Tillage is as old as agriculture. Primitive man used to disturb the soil for placing seeds. Jethro Tull, who is considered as father of tillage, proposed a theory that plants absorb minute particles of soils. So he suggested that thorough ploughing and subsequent operations were necessary so as to make soil into fine particles. Though his theory is not correct tillage operation are carried out to prepare a fine seedbed for sowing crops. The world tillage is derived from Anglo- saxon words tilian means to plough and teolian meaning to prepare soil for seed to sow. Tillage of soil is the most difficult and time-consuming operation accounting nearly 30% of cost of cultivation of crops. Soil is the medium for growing crops, but in its natural state, it is not an ideal condition to grow the crops satisfactorily. Similarly, after harvest of the crop, soil becomes hard and compact. Beating action of rain drops, irrigation and subsequent drying, movement of inter cultivation implements and labour cause soil compaction. Field also contains weeds and stubbles after harvest of crops. Therefore, the surface soil in which seeds are to be sown, should not be hard and compact but soft and friable, so that tender shoots of germinating seed can push above the soil surface without any difficulty and young roots penetrate easily into the lower layers of soil in search of food, water and air. So seeds need loose, friable soil with sufficient air and water for good germination. It should also be free from weeds and stubble’s to facilitate easy and smooth movement of tillage implements. Such an ideal condition can be achieved by caring out various tillage operations. Soil is to be managed for the crop. Soil conditions must be made favorable for crop growth and development from seeding to harvesting. Definition of tillage: 1) It is the mechanical manipulation of soil with tools and implements for loosening the surface crust and bringing about conditions favorable for germination of seed and the growth of crops. 2) Tillage of the soil consists of breaking the hard compact surface to a certain depth and other operations that are followed for bringing the soil in a good physical condition (fine tilth) for proper crop growth. Manipulation of soil for crop production modifies the natural state of upper 10-20 cm. This manipulated part of the soil is referred to as surface soil or topsoil, which is the major zone of root development for crop production. It is the reservoir of nutrients and water necessary for plant growth. The soil, which is not seen from the surface and not commonly disturbed by tillage, is the subsoil. It is influences root penetration besides serving as a reservoir for moisture and nutrients for crop production. OBJECTS OF TILLAGE: 1) To make the soil loose and porous: This will enable rain or irrigation water to enter the soil easily and less loss of rainwater and soil due to runoff and erosion. Due to adequate proportion of micro–pores the sufficient amount of water will be retained in the soil for crop growth and less losses of water due to percolation 2) To aerate the soil: It enables the metabolic process of living plants, microorganisms to continue properly. Due to adequate air and moisture, desirable chemical and biological activities would go on at greater speed. This would result in rapid decomposition of organic matter and making plant nutrients available to crops. 3) To have repeated exchange of atmospheric air with the soil air: There should be an exchange of atmospheric air with the soil air during the growing period of crop. Such an exchange is necessary for supply of oxygen (O2) in several biological activities taking place in the soil. At the same time CO2 that is released should be removed and not allowed to accumulate extensively in the soil air. The soil air and atmospheric air have more or less the same amount of oxygen i.e. about 20-21%, but the CO2 in atmospheric air is hardly about 0.03% whereas, the soil air contains 0.2 to 0.3% CO2 i.e. about 8 to 10 times more than the atmospheric air. Therefore, it is necessary to introduce fresh air in the soil to keep the CO2 concentration under check by suitable tillage operations. 4) To increase the soil temperature: This can be achieved by maintaining proper amount of air water in the soil and also by exposing the soil to the heat of sun. The optimum soil temperature in  7 active root zone of crop is necessary for proper functioning of plant roots and useful microorganisms in the soil. 5) To control weeds: This is one of the major functions of tillage or an important object of tillage. Weeds are enemies of crops as they compete with the crops for plant nutrients, moisture, space and sunlight, which will result in poor crop yields. Therefore, management of weeds with suitable tools and implements is the definite advantage of tillage. 1) To remove stubbles of previous crops: The deep tillage helps in removing stubbles of previous crop and other sprouting materials like bulbs, stolons etc. and in making clean seedbed. 7) To destroy insects: Insects are either exposed to the sun’s heat or to birds that would pick them up. Many of the insect’s pests remain in dormant conditions in the form of pupae in the top soil during off-season and when the host crop is again sown or planted, they (pest) reappear on the crop. Therefore clean cultivation is useful for control of pests like sorghum and paddy stem borer, cotton bollworm etc. Similarly, some harmful grubs or cutworms can be destroyed by proper tillage operations. Thus, clean cultivation means a pest and pathogen free environment. 8) To break hardpan: Tillage with specially designed implement such as sub-soil plough (chisel plough) is often useful to break hardpan if any, formed just below the ploughing depth. This is helpful for better penetration of roots in deeper layers and also for maintaining proper drainage in soil. It also increases soil depth for water absorption. Tillage at improper moisture also damages soil structure add leads to development of hard pans. 9) To incorporate organic manures and fertilizers in the soil: Organic manures such as F.Y.M. or compost and fertilizers should not be only spread on surface of soil, but properly incorporated (mix thoroughly) into the soil for minimizing the loss of plant nutrients. Sometimes, bacterial cultures or pesticides also required to be drilled into the soil for control of pests like white ants, termites, white grubs, cut worms etc. and this purpose can be served by using proper tillage implements. 10) To invert the soil to improve fertility: By occasional deep tillage the lower layer of soil which is less fertile comes to top while upper layer rich in organic matter and plant nutrients goes down, thus plant roots can get benefit of rich layer. 11) To prepare seedbed for germination of seeds and growth of crop: Finally it is necessary to prepare the suitable seedbed as per requirement of crop and soil for good germination and emergence of the crop and also for proper growth and development of the crop achieving higher crop yields. The most important objects of tillage are seedbed preparation, weed control and soil and water conservation. The other objectives are improvement of soil structure, soil permeability, soil aeration, root penetration, destruction of pests, soil inversion etc. TYPES OF TIILAGE OPERATIONS: They can be broadly classified into two based on the time during which they are carried out. I) On season tillage: Tillage for a crop from start of crop season to the crop harvest is known as on season tillage operations. It includes: A) Preparatory tillage (i. Primary tillage, ii. secondary tillage & iii. Layout of seedbed & sowing), B) Seedbed preparation & C) Inter tillage or Inter culture or after tillage. II) Off season tillage: Tillage operations during uncropped season for special purposes other than that for immediately raising the crop in the season are said to be off season tillage. In dry land agriculture, tillage initiated with onset of summer showers is continued periodically until sowing, during crop growth period and even after crop harvest for control of weeds, soil and water conservation. They are called year round tillage. A) Preparatory tillage or cultivation: - Tillage operations, which are carried out before the land is made ready for sowing or before sowing of the crop is called preparatory tillage. Tillage operations that are carried out from time of harvest of a crop to the sowing of the next crop are known a preparatory tillage or operations carried out in any cultivable land to prepare seedbed for sowing of crops are known as preparatory cultivation. It consists of a number of costly and time consuming operations, which are carried out by using suitable implements at proper moisture content of soil. The following are the preparatory tillage operations, which are carried out in a sequence are: i) Ploughing ii) Clod crushing iii) Leveling of land iv) Harrowing v) Manure mixing vi) Compacting the soil.  8 Generally, the terms preparatory tillage and seedbed preparation are used synonymously. Preparatory tillage consists of three district operations viz; 1) Primary tillage, 2) Secondary tillage 3) Layout of seedbed. 1. Primary tillage or ploughing: - It is opening of the compacted soil with the help of different ploughs. During the primary tillage, the soil is inverted, weeds are uprooted and stubbles incorporated into the soil. Depending on purpose or necessity, different types of tillage are carried out. They are deep ploughing, sub soiling and year-round tillage. 2. Secondary tillage: - Lighter or finer operations performed on the soil after primary tillage are known as secondary tillage. After ploughing, the fields are left with large clods with some weeds and stubbles partially uprooted. Harrowing is done to a shallow depth to crush the clods and to uproot the remaining weeds and stubbles. Disc harrows, Cultivators, Blade harrows etc. are used for this purpose, planking is done to smoothen soil surface and to compact the soil lightly. So field is ready for sowing after ploughing by harrowing and planking. Generally sowing operations are also includes in secondary tillage. 3. Layout of seedbed and sowing: After the seedbed preparation, field is laid out properly for irrigation and sowing or planting seedlings. These operations are crop specific. For sugarcane and maize the ridges and furrows are prepared while flat leveled seedbed is used for wheat, soybean, pearl millet etc. The crops like Tobacco, Tomato, Chilies planted with equal inter and intra row spacing for two ways inter cultivation. Ploughing: It is done mainly to open the hard soil and to separate the top soil from lower layers. Similarly, it is the most essential operation for making the soil loose and porous to desired depth as per the crop requirement. Ploughing should ensure inversion (whenever necessary) of soil, uprooting of weeds and stubbles and less cloddy soil surface. It is useful for the management of weeds, diseases and insect pests. The most common implement used for ploughing since olden times is country or wooden plough or deshi plough, which is made of wood with an iron share point. It cuts a V shaped furrow and opens soil, but there is no inversion. Ploughing operation is also not perfect because some unploughed strip is always left between furrows. This is reduced by cross ploughing, but even then small squares remain unploughed. A deshi wooden plough is still popular with the farmers because it is a multipurpose implement and can be used for opening ridges and furrows, sowing, earthling up of crops, inter cultivation, harvesting of crops like potato etc. They are light in weight. In recent times the soil inversion (reversible) ploughs are in use, which are made of iron and drawn by bullock or tractor. Soil Turning Ploughs: - These are made of iron drawn by a pair of bullocks or two depending on the type of soil. These are also drawn by tractors. 1. Mould board plough- The mould board plough is an improved tillage implement over deshi plough. Its parts are frog or body, mould board or wing, share, landside, connecting rod, bracket and handle. This type of plough leaves no unploughed land as the furrow slices are cut and inverted to one side resulting in better pulverization. The animal drawn mould board ploughs are small, ploughs to a depth of 15 cm, while two mould board ploughs, which are bigger in size and attached to the tractor with ploughing depth of 25 to 30 cm. Mould board ploughs are used where soil inversion is necessary. 2. Disc Plough – A large, revolving, concave steel disc replaces the share and mould board. The disc turns the furrow slice to one side with a scooping action. Usual size of disc is 60-09 cm. in diameter and this turn’s 35 to 30 cm furrow slice. It is more suitable for land in which there is much fibrous growth of weeds as the disc cuts and incorporates the weeds. It works well in soils free from stones. No harrowing is necessary to break the clods of the upturned soil as in a mould board plough. They are basically tractor drawn because of their weight and size. 3. Reversible or one-way plough- The plough bottom in this plough is hinged to the beam such that the mould board and the share can be reversed to the left or the right side of the beam. This adjustment saves the trouble of turning the plough in hilly tracts, but yet facilitates inversion of the furrow slice to one side only.  9 Suitable plough for different situations: Plough Situation or purpose Mould board plough (Tractor drawn) - Deep ploughing and inversion. Mould board plough (Animal drawn) - Incorporation of manures, fertilizers and plant residue. Disc plough - Cutting of creeping or spreading grass and inversion. Country plough – Multipurpose. Optimum or Right time of ploughing: - The correct time of ploughing depends on soil moisture. When soil is dry, it is difficult to open the soil, more energy is used and large sized clouds result. When the soil is ploughed under wet conditions, the soil sticks to the plough, the soil below plough sole becomes compacted and on drying becomes very hard and soil structure is destroyed. Therefore, the optimum range of soil moisture for effective ploughing is 25 to 50 % depletion of available soil moisture. To get maximum benefit from ploughing, it should be done just after harvest of the previous crop, the field under kharif crop may be ploughed in the month of Oct / Nov or Dec depending upon harvest of kharif crop. The light soil get hard immediately after harvest of the crop and should be ploughed in the month of April or May when thunder showers are received or after receiving the first monsoon showers. Number of ploughing: - The number of ploughing necessary to obtain a good tilth depends on soil type, intensity of weed and crop residues on soil surface. In heavy soils, more number of ploughing is necessary (3-5 ploughing). While light soils require 1-3 ploughing. When weed growth and plant residues are higher, more number of ploughing is necessary. Depth of ploughing: - It mainly depends on the effective root zone depth of the crops. Crops with tap root system require greater depth of ploughing e. g,. Tur and cotton while fibrous, shallow rooted crops require shallow ploughing e.g. sorghum, pearl millet, maize, rice and wheat. Similarly, one centimeter of surface soils over one hectare of land weigh about 150 ton. Therefore to plough deeper, enormous amount of energy is required. In western countries, deep ploughing of 50 cm depth for rainfed and 70 cm for irrigated conditions. Central Research Institute for Dry land Agriculture (CRIDA), Hyderabad classified ploughing of 5-6 cm depth as shallow, 15-20 cm depth as medium deep, and 25-30 cm depth as deep ploughing. Generally, the ploughing depth depends on the soil compaction, weed growth and crops to be grown. If the soil surface is hard or compact then it needs deep ploughing for improving aeration and infiltration of rain and irrigation water. The deep ploughing is required (more than 20 cm depth) for crops like sugar cane, turmeric, ginger, and potato. While shallow ploughihg is required (12-15 cm depth) for sorghum, pearl millet, rice, wheat etc. Similarly field infested with perennial weeds like (Cynodon ductylon) Hariali, (Cyperaus rotundus) Nut grass etc, which required deep ploughing. Fall ploughing: - The deep tillage operations have to be carried out when upper soil surface is dry, but lower layer is moist. This condition is usually observed after cessation of South –West monsoon in the months of November-December in India, which is also known as fall ploughing. Or The ploughing operation carried out immediately after harvest of the previous kharif crops in the month of November-December or January is knows as fall ploughing. This time of ploughing the land in winter season coincides with that of show fall in European countries and hence it is called fall ploughing. Advantages of ploughing in right time or Benefits of fall ploughing: - -1) Ploughing goes easy or less power (draft) is required due to proper moisture content in the soil and few clods formed in the field. 2) The plant residues such as straws and leaves of previous crops are buried into the soil, which adds the organic matter to the soil. 3) It destroys weeds 4) It destroys insect pests and disease bearing organisms by exposing the soil to heat of sun and some insects are eaten by birds. Clod Crushing: - This operation is not always necessary. If ploughing is done at right time i.e. when the moisture condition is optimum, then very few clods are formed. While if ploughing is done after drying the soil, then big clods are formed. These clods are crushed with the help of implements known as clod crushers. In case, rain fed crops are to be taken, fields are ploughed and left undisturbed until a shower of rain is received which does a good job softening and breaking clods. It is necessary when crop is taken in rabi or summer season under irrigated conditions where intensive cropping is adopted. Norwegian harrow is the best implement for crushing big and hard clods. Disc  10 harrow, big log of wood called maind, and blade harrow is used for clod crushing. Maind is commonly used in sugarcane tract for clod crushing though it is not a very efficient implement Leveling of land:- This is done occasionally and is not an operation, which requires to be done every year. It is required for even distribution of rain and irrigation water, to avoid yellowing of plants due to water stagnation in low lying areas and also to reduce soil erosion caused by rain water and breaking of bunds. The implements used for leveling such as Iron keni, American petari, maind, and deccan blade harrow and heavy power machinery like bulldozer. Under normal field conditions harrowing are sufficient for leveling of land. Harrowing:- This is one of the most common operations, which is done invariably for preparing a good seedbed. The implement blade harrow or Bakhar is worked once, twice or thrice and serves the purpose of clod crushing, leveling, collecting stubbles, destroying germination weeds, manure mixing and compacting the soil. The deccan blade harrow is known as multipurpose implement as it performs above mentioned operations. A bakhar heavier in weight than normal is used in dry farming regions. The deccan blade harrow is 45 to 60 cm wide and worked by pair of bullocks. If it is desired to work it slightly deeper, the farmer’s presses handle or he stands on it or keeps a big stone. Tying bullocks a bit further also helps in deeper penetration of blade into the soil. Disc harrow cuts soil and pulverized it very efficiently and it works deep or shallow. Manure mixing: - Before the land is finally prepared for sowing, bulky organic manures (FYM or compost) and fertilizer (basal dose of fertilizers) has to be applied and mixed with the soil to avoid loss of nitrogen through volatilization. Manure mixing is done by disc harrow, blade harrow or some times by deshi wooden plough. Compacting the soil or planking: - Sometimes the soil may be loosen more than necessary, which is not desirable for small seeded crops like mustard or sesamum or crops with adventitious roots like sorghum or pearl milled which are liable to lodge. So soil may need compacting and working an inverted harrow or wooden plank can do this. B) Seedbed preparation: After preparatory tillage the land is to be laid out properly for irrigation of crops, if water, available for irrigation and for sowing seeds, planting or transpiration seedling. These operation are known as seedbed preparation and consists of 1) Harrowing, 2) Preparation of irrigation layouts, 3) Sowing and 4) Covering seeds. 1) Harrowing: - If irrigation layouts are prepared immediately after completion of preparatory tillage, then harrowing is not necessary, while sometimes there may be long gap or period between preparatory tillage and preparation of irrigation layouts. So for removing newly germinates weeds or existing young weeds harrowing is essential 2) Preparation of irrigation layouts: - The irrigation layouts are crop specific for e.g. 1) Opening ridges and furrows for crops like sugarcane, irrigated cotton, potato, rabi maize, fruit and vegetables 2) Border strips or saras for cereals like jowar, wheat etc 3) Flat beds for leafy vegetables and forage crops 4) Broad bed furrows (BBF) or raised bed for turmeric, ginger, Bunch/ erect groundnut. So the irrigation layout should be prepared as per crop requirement by using suitable implement. 3) Sowing: - Process of placing seeds in seedbed. The majority of rain fed crops is sown with the help of indigenous seed drill, two-bowl seed drill or mechanical seed drill or by dibbling seeds. Transplanting is followed in transplanted rice, tobacco, chilies etc. by using seedlings. Vegetative plant parts are used in sugarcane, potato, turmeric, ginger etc and sowing method is called as planting. Generally, the rain fed crops are sown at optimum soil moisture after receipt monsoon showers or under dry conditions as dry seeding in case of paddy (Dhul per). While, the irrigated crops are sown after preparation of irrigation layouts. The seeds are dropped by hand in furrow formed by the country plough e.g. sowing of chickpea. 4) Covering seeds: - After sowing seeds in the soil, the seeds may dry up or attacked by birds and insects if not covered with soil. It also affects germination and plant stand in field. The light blade harrow or a plank is used for covering seeds, which results into proper germination of crop. B) Inter tillage or inter culture: - The tillage operations which are carried out in standing crop or in between crop rows are called as inter tillage. Also called after tillage. Inter culturing operations decreases the bulk density of soil and increases the total porosity and as it maintain high porosity at soil surface and so high infiltration rate.  11 Objects of inter tillage: - 1. To destroy/control weeds: - As weeds complete with crop plant for sunlight, space, nutrient and moisture. So management of weeds by hoeing or weeding reduces the competition, which results into normal growth and yield of crop. 2. Conservation of soil moisture by i) Frequent hoeing the capillaries at soil surface breaks and loosen soil act as soil mulch or dust mulch, which reduces water loss due to evaporation and ii) Mulching useful for avoiding direct heating of soil due to sun heat, which reduce evaporation and conserve soil moisture, 3. To destroy pests, 4. To improve aeration of the soil for proper functioning of plant roots and micro-organism, 5. Pruning of non- functional roots. This can be done during weeding or hoeing, 6. To increase the infiltration rate for the irrigation or rain water in the soil. 7. For providing optimum space and plant population of crop, 8. Earthing up/ for drilling or side dressing of fertilizers, Inter tillage includes the operations like Gap filling, Thinning, Hoeing, Weeding, Top dressing of fertilizers, Earthing up and Mulching. 1.Gap filling: - After sowing sometimes there may not be emergence of crop plants at some places in crop rows and these gaps (spots without crops) are filled either by dibbling seeds or transplanting seedlings depending upon crop type and is known as gap filling. It is necessary for maintaining the optimum plant population of crop. It is done 8-10 days after sowing of the crop. 2. Thinning: - It is the process of removing excess plants from the field for maintaining optimum plant population of the crop and for providing uniform space for normal growth and development of crop plant for getting higher crop yields. It is carried out about 2 to 3 weeks after sowing of crop, depending upon type of crop 3. Hoeing: - It is useful for management of weeds, conservation of soil moisture, mixing fertilizers with the soil and improving aeration in top layer of the soil. The different types of hoes like entire blade hoe, slit blade hoe, Akola hoe (cotton), Japanese hoe (paddy) and peg tooth cultivator are used for hoeing depending upon type of crop and soil. Generally 2 to 3 hoeings are carried out from 2 weeks to 5 or 6 weeks after sowing the crop depending upon the weed intensity and type of crop. 4. Weeding: - Removal of weeds in the crops with the help of weeding hook (Khurpi) by manual laborers is called weeding. It is necessary for management of weeds. Recently, herbicides are used for control of weeds. Generally, one to three weddings are carried out depending upon type of crop. 5. Top dressing of fertilizers: - The application of fertilizers in standing crop is known as top dressing. It is necessary for supplying plant nutrients essentials for normal growth, development and yield of crop. The fertilizers should be applied after weeding or hoeing and they should be mixed with soil by hoeing to avoid loss of plant nutrients. There should be sufficient soil moisture in soil at the time of applying fertilizers or irrigation should be given after application of fertilizes 6. Earthing up: - Supporting basal portion of the crop plant with soil for proper development of underground commercial plant parts is known as earthing up. It is done in crops like turmeric, ginger, potato and erect type of gr-nut. In sugarcane it is useful for even distribution of irrigation water and for minimizing lodging of the crop at maturity stage. It can be done by hand labour by kudali or using suitable implement viz, deshi plough, ridger, or a light mould board plough or specially design implement. 7. Mulching: - Covering surface soil in between the crop rows with the help of organic mulch such as plant residues (wheat straw, sugarcane trash) or inorganic material like polythene sheet for conservation of soil moisture, weed management, maintaining soil temperature etc. is known as mulching. Or A mulch is natural or artificially applied layer of plant residues or other materials on the surface of the soil with the object of moisture conservation, temperature control, prevention of surface compaction, or crust formation, reduction of runoff and erosion, improvement in soil structure and weed control. The organic mulch such as plant residues i.e. wheat straw, sugarcane trash, stubbles of crop etc are spread in between crop rows @ 5 tones per hectare. The black polythene sheet is more effective than white polythene sheet. The polythene mulching is more costly than plant residues and used in case of high value crops only.  12 Tillage implements and tools: Tillage implements: Based on the operations for which they are designed, implements classified into different groups. A. Implements for preparatory tillage: a) Primary tillage implements: I) Ploughing: Various types of wooden and iron plough used. 1. Wooden plough or Indigenous plough. a) Black Soil Plough – Use for deep ploughing and is drawn by 3 to 4 Paris of cattle. It is heavier. b) Dry land plough: It is smaller than heavy black soil plough. c) Wetland plough: It is the smallest of the wooden ploughs. 2. Soil turning ploughs: They are made of iron and drawn by a pair of bullocks or two depending on the types of soil. These are also drawn by tractors. a) Mould Board plough: Animal drawn mould board plough is small, plough to a depth of 15 cm. e.g. Victory plough. The advantage of using mould board plough is that a layer of soil is separated from the underlying sub soil and is inverted. b) Reversible or one way plough: c) Disc plough: It works well in conditions where mould board plough does not work satisfactorily, particularly in sticky soils. 3. Special Plough: a) Sub soil plough: The sub soil plough is designed to break up hard layers or pans without bringing them to the surface. The body of sub soil plough is wedge shaped and narrow while the share is wide so as to shatter the hard pan and making only a slot on the top layers. e. g. chisels plough used for breaking hard pans. b) Ridge plough: It has two mould boards, one for turning soil to right and other to left. It is used for preparing ridges & furrows and earthing up of crops. For making broad bed and furrows, two ridge ploughs is fixed on a frame at 150 cm spacing between them. c) Rotary plough or rotavator: It cuts soil & pulverizes it. They perform primary and secondary tillage operations simultaneously so as to prepare fine seeded in a single pass. It is suitable for light soil and depth of cut 12-15 cm. a) Deep Ploughing (20-30 cm): Kirloskar No. 8 & 9 Ploughs, Tractor drawn plough. b) Shallow Ploughing (12-15 cm): Kirloskar No. 100 Ploughs &Victory Ploughs c) Sub Soiling ploughing (30 cm or more):Sub soiler or sub soil plough e. g. Chisel Plough Methods or Ploughing i) To and fro method: Only reversible mould board ploughs are used. ii) In and in method: Dead furrow is formed. ii) Out and Out method: Back furrow is formed. b) Secondary tillage implements: II) Cold crushing: i) Norwegian harrow: The best implement for cold crushing. Clods are crushed by striking and piercing action. ii) Disc harrow: Discs are smaller in size than disc plough, but more number of discs is arranged on a frame clods are crushed by slicing action. iii) Cultivators: It is also known tiller or tooth harrow. Tractor drawn cultivators have two types. 1. Cultivator with spring loaded tynes (Spring tooth cultivator) and 2. Cultivator with rigid tynes (peg tooth cultivator). A cultivator has two rows of tynes attached to its frame in staggered form. iv) Deccan blade harrow: Useful crushing small clods. v) Maind: Clods are crushed by pressing action. III) Levelling of land:  13 Iron keni, Alwat or plank leveler, When soil slope is less than 3 % American Petari, Blade harrow Bulldozer – When soil is hard and slope of field is more than 3 % IV) Harrowing: Harrows are two types 1 disc harrow and 2. blade harrow. Deccan blade harrow or different type of harrows according to types of soil. V) Manure Mixing: Disc harrow, blade harrow, disc plough, Deshi wooden plough. VI) Compacting of soil: Maind, wooden plank, blade harrow by removing prongs & blade, rollers like T bar roller. VII) Pudding or implements for wet land operations: Rice puddle, helical blade puddler, and Cage wheel. B. Seed bed preparation: 1. Ridges and furrows: Different types of ridger are used e.g. Jeeven, Jagat & Jamboo ridger. 2. Preparation of border strips and saras: Sara former is used for preparing bunds at required distance. For mending irrigation layouts, hand tool like spade is used. 3. Sowing: Indigenous seed drill, for sowing seeds and fertilizers application at a time or simultaneously – Two-bowl seed drill (ferti. cum seed drill) and mechanical seed drill are used. The seeds are dropped by hand in the furrow formed by country or wooden plough. Sometime Moghan is attached to the Deshi plough. Planting sugarcane – Sugarcane planter. 4. Covering seeds: Blade harrow and wooden plank. C. Inter-culturing or Inter tillage: 1. Weeding: Hand tool like weeding hook (Khurapi) is used. 2. Hoes: Various types of hoes are used. i) Entire blade hoe: Works in between two crops rows and useful at early stage as well as latter stage of crop growth. ii) Slit blade hoe: It works over crop line and useful at early crop growth stage only. iii) Akola hoe: Useful for hoeing in cotton. iv) Japanese hand hoe & karjat hoe: for hoeing in rice crop. Works in 10 cm height of standing water in field. v) Peg tooth cultivator and spring tooth cultivator: Useful for wide space row crops and fruit crops. 3. Earthing up: Sugarcane – sabul plough & ridger is used. Bunch type groundnut: Entire blade hoe is used Hand tool like kudali is also used for carrying out earthing up. D. Harvesting implements: 1. Groundnut: Groundnut digger or harvester & blade harrow is used. 2. Potato: Potato digger or Deshi wooden plough is used. 3. Cereals, oilseeds & pulses: Combine harvesters are used for harvesting, threshing & winnowing as well as bagging at a time in developed countries. 4. Wheat & Rice: Wheat & Rice harvester is used. 5. Safflower: Safflower combine harvester Hand tool – Sickle is used for harvesting cereals, pulses, some of oilseeds & fodder crops. Chopper – is used for sugarcane harvesting. Hand kuadli – Harvesting of Ginger, turmeric & potato Vaibhav sickle: is used for paddy harvesting. E. Threshing implements: 1. Jower, bajara, wheat, rice – Vicon thresher or various types of power operated thresher. 2. Wheat – Olpad wheat thresher.  14 3. Paddy – Paddy foot thresher. 4. Shelling of maize cobs – Hand driven maize Sheller or power operated. 5. Shelling of Groundnut pods – Groundnut Sheller. 6. Sunflower – Sunflower thresher or Sheller is used. Hand tool like wooden thresher is used for threshing cereals, pulses & some of oil seeds. F. Winnowing: Winnowing fan is used for creating artificial wind for carrying out winnowing operation. Factors affecting tillage or deciding the need for ploughing OR why ploughing is necessary? There are different school of thoughts regarding the need for ploughing some says it is necessary once in two or three years, while others believe that ploughing especially with mould board plough, is not necessary. Black cotton soils in India crack deeply and are supposed to be self–ploughed. Since the land is to be prepared for growing crops and the question of including ploughing with other preliminary operations will have to depend on following factors. i) Previous crops: New and fallow lands cannot be brought in satisfactory condition without ploughing. If the land is under crops like sugarcane, sorghum, maize etc. which forms stubbles or a crop grows very thick and compact the soil, it would need ploughing and the subsequent tillage operations like clod crushing, harrowing and collection of stubble for preparing clean seedbed. Ploughing may not be necessary after crops like cotton or pulses as they receive fair number of inter culturing operations and keep soil open. Similarly, soil under potato, gr-nut turmeric and ginger may not require ploughing, as soil has to be dug while harvesting these crops. So lands under these crops can be prepared by 2 to 3 harrowing or power tiller will bring such soil in right condition. ii) Crops to grown: - The crops like turmeric, ginger, potato and gr-nut require loose and fine seedbed for proper development of underground commercial parts. So deep ploughing with sub- sequent tillage operations is necessary. Crops like sugarcane and vegetables occupy land for longer period and require irrigation. So the deep ploughing is essential. While cereals like, sorghum, pearl millet wheat, rice, oat etc are shallow rooted crops and require firm and compact seedbed. So, one ploughing (shallow) with 2 to 3 harrowing is sufficient for bringing soil in satisfactory condition. iii) Weeds: - The deep ploughing is necessary in the fields infested with perennial weeds like Hariali (Cynodon dactylon), Nut grass Or lavala (Cyperus rotundus) and kans (Saccharum spotaneum) which grows and difficult to eradicate. The deep ploughing by inversion plough will expose the roots to sun’s heat and they are killed. iv) Soil: - The fine textured soil such as clay soils with poor drainage need deep ploughing for improving aeration and drainage. While coarse sandy soils or loamy soils may not need ploughing every year and these soils can be prepared by 2 to 3 harrowing. The black cotton soils, which crack deeply on drying, do not need ploughing unless they are infested with weeds. The deep cracking in black cotton soils serves the purpose of ploughing and can be brought under satisfactory conditions with 2 to 3 harrowings. v) Climate: - Soils in low rain fall areas (in dry farming) may need ploughing and frequent harrowing for conservation of soil moisture. vi) Type of farming: - The frequency of tillage operations is more in irrigated farming due to adoption of multiple cropping or growing more than two crops on the same land in year. Where as, the frequency of tillage of operations is less in dry farming due to less cropping intensity vii) System of culture or type of crop cultivation: - The land preparation of upland rice (drilled rice) differs from low land rice (transplanted rice). The lowland rice needs puddling operation, which is not necessary for upland rice. Effect of tillage on soil and crop growth: The tillage operations carried out at optimum soil moisture content by using suitable tillage implements have beneficial effects on the physical, chemical and biological properties of the soil resulting in proper seed germination, seeding emergence, growth and yield of the crop. While, the tillage operations carried out at low soil moisture content as well as when soil is too wet (excessive moisture content) by using heavy tillage implements or heavy machinery have bad (adverse) effects  15 on physical properties of the soil, seed germination, emergence of seedling, growth and yield of the crop. A) Beneficial effects of tillage: - I] Effects on physical properties of the soil: - Tillage has considerable influence on soil physical properties like pore space, structure, bulk density, water content and colour. 1. Pore space: - The volume of soil not occupied by soil particles is known as pore space. It is occupied by air or water or both. Plant root exist and grow in pore space. It directly controls the amount of water and air in the soil and thus, indirectly controls plant growth and crop production. When a field is ploughed, the soil particles are loosely stacked in a random manner and pore space is increased. So the tillage operations like ploughing, clod crushing and harrowing are useful for making soil, loose and porous to a desired depth, which improve the pore space content of the soil resulting into maintaining about equal proportion of capillary and non-capillary pores. This facilitates free movement of air and water in the soil and increases infiltration and free movement of water up to ground water. 2. Soil structure: - The structure denotes the way in which sand, slit and clay particles are grouped or arranged to form aggregates or arrangements of soil particles is called soil structure. The sand, silt and clay are the primary particles, but when they get aggregated together with some kind of binding / cementing material (organic matter on decomposition humus act binding material, soil micro- organic synthesize sticky material or salts of calcium helps in aggregation), granules are formed. They are called as secondary particles. When proportion of secondary particles is much more than the primary particles, the soil looks granulated and when soil having such small sized granules is very porous, the structure is called crumb structure, which is ideal one. When the tillage operations are carried out carried out at optimum moisture content of the soil, the crumb structure is developed so that the loss of soil due to erosion is reduced. The water is held in the large spaces between the aggregates and also in the microspores of the aggregates. It is considered that the formation of crumb structure of soil with size of soil aggregates from 1 to 6 mm is favourable for growth of crops. Similarly, the crumb structure helps in good drainage or aeration, spread of plant roots, resistance to erosion and removal of excess water. So soil having crumb structure is a highly productive soil. 3) Bulk Density: - It indicates the oven dry weight of a unit volume of soil inclusive of pore space and is expressed as grams per cubic centimeter. When the soil made loose (with tillage operations), the soil volume increases without any effect on weight. Therefore, bulk density of tilled soil is less than untilled soil. In general, the soils with low bulk density have better physical properties and can store more moisture for the crop growth. 4) Soil Water: - The amount of available water depends on soil porosity, soil depth and random roughness (it is elevations and depressions in field). All these above characters increased by tillage. Similarly, tillage is useful for increasing infiltration and moisture retention capacity of soil (water holding capacity) due to increase in pore space. It enables free drainage up to water table. 5) Soil temperature: - Tillage is useful for maintaining optimum soil temperature due to proper air and water in the soil and also by exposing the soil to heat of the sun especially during summer months. 6) Soil colour: Organic matter is mainly responsible for dark gray colour of the soil. Tillage increases oxidation and decomposition resulting in fading of colour. 7) Soil strength: Soil strength or mechanical resistance indicates the resistance offered by the soil to root penetration. It is measured in bars and ranges from - 0.2 bars in puddled submerged rice fields to - 22 bars in dry black soil. Soil strength mainly depends on soil moisture. It is less with high soil moisture content and increases with decrease in soil moisture content. The other factors that influence soil strength are bulk density and soil compaction. II) Effects on chemical properties of the soil: - The chemical properties of soils are important as they are closely related to the capacity of the soil to supply plant food nutrients. 1] It accelerates weathering of the soil. 2] Tillage helps for leaching of toxic salts (Na) from the surface soil in problematic soil such as alkali soils. 3] It improves available of plant nutrients by enhancing decomposition of organic matter, mineralization etc. 4] Tillage operations increase the efficiency of some of herbicides and pesticides which are to be incorporated into the soil e.g. The  16 herbicide fluchloralin (trade name Basalin as 45% EC) when applied as pre-planting (before sowing crop) soil incorporation gives better result as it is volatile. III] Effects on biological properties of the soil: 1] Management of weeds: - Tillage operations like ploughing, discing, harrowing, hoeing and weeding are useful for management of weeds and thereby for increasing crop yield. 2] Management of insects’ pests and diseases: Tillage operations like deep ploughing, harrowing, hoeing etc are useful for management of insect, pests and diseases by exposing them to heat of the sun. Birds also eat some of the insect pests. 3] Proper functioning of plant roots and soil micro- organisms: - Tillage improves aeration of the soil and also the retention of water (optimum moisture), which is useful for proper functioning of plant roots and soil micro-organisms. IV] Effects of tillage of crop growth: The tillage operations carried out at right time and optimum moisture of soil by using suitable implement have beneficial effects on crop growth as given below. 1] It improves aeration in the soil, resulting into the healthy crop growth. 2] It makes soil loose and porous, which helps in increasing infiltration and drainage of water. 3] It controls weeds. As it controls weeds, the competition of weeds with crop plants for space, light, nutrient and soil moisture is less, resulting into healthy crop growth. 4] Tillage helps in destroying insect pests and disease bearing organisms by exposing soil to heat of sun. 5] Regulation the temperate of soil, which is useful for healthy growth of root and increasing activity of soil organisms. 6] Making favorable conditions for germination, emergence and growth of the crop. B] Bad effect or disadvantages of tillage: - The tillage operation carried out at too dry or too wet (excess moisture) soil conditions by using heavy implements or machinery have following adverse effects (bad effects) on the physical properties of the soil, germination, growth and yield of crop. 1] Frequent tillage operations with heavy implement or machinery result into the soil compactions, which affects the pore space and subsequently the bulk density of the soil. Due soil compaction, pore space reduced and the bulk density increased. 2] The repeated tillage operations viz., ploughing, clod crushing, harrowing etc. may result in powdery and fine soil condition cause soil erosion particularly in clay soils and also formation of hard pan in sub –soil. 3] Sometime inter tillage operations may damage the crop plants if proper care is not taken or skilled labours are not employed. 4] The repeated tillage operations with heavy machinery affect soil structure by breaking the stable soil aggregates and formed hard pan below plough sole. This reduces in filtration rate (entry of water into the soil) and increases runoff and soil erosion. 5] The living organisms such as earthworms and useful soil organisms are exposing to heat of sun and this affects the biological properties of the soil. 6] Sometimes seed germination, emergence growth and yield of the crop are affected due to bad effects of improper tillage.  17 Lecture No.3: Tilth its definition, characteristics and ideal tilth, Modern concepts of tillage, minimum, zero and stubble mulch tillage, importance of puddling. Definition of soil tilth: It is the physical condition of the soil resulting from tillage. This is also called seedbed. A soil is said to be in good tilth when it is soft, friable and properly aerated. The purpose of tillage is to alter the tilth or fabricate soil so that water, air, temperature and strength conditions are improved for plant growth. Good tilth should provide adequate aeration, warmth and moisture to crop and ensure good infiltration, besides being favorable for supply of nutrients and growth of microbes and making soil weed free. Tilth indicates two properties of soil viz, 1) Size distribution of soil aggregates and 2) Mellowness or friability of soil. 1) The relative proportion of different sized soil aggregates is known as size distribution of soil aggregates. It is depends on soil type, soil moisture content (at which ploughing done) and subsequent cultivation. Soil with high organic matter cultivated at optimum soil moisture leads to crumb structure with aggregate stability. 2) Mellowness or friability is that property of soil by which the clods when dry become more crumbly. Good tilth cannot be obtained if soils are tilled at their extreme moisture contents (very dry or wet). According at what stage the soil is to be tilled for good tilth depends on contents of clay (particle size texture) moisture and structure. As the clay content increases soil plasticity increases. Plasticity is a physical property of clay that develops due to hydration and brings adhesion, cohesion, consistency and swelling as its companions. Plasticity renders ability of soil to form a ball when wet that does not come back to its original state on drying. Sandy soils are less plastic. They can be made into a ball only when wet, on drying the ball collapse into single grains. This is why a sandy soil can be tilled even after a few hours of rain where as a clay soil needs more time to come to condition for tillage. Similarly, ploughing a clayey soil at high moisture content forms lumps and clods. These clods do not break easily remain sharp and angular and do not produce a good tilth. As drying increases these lumps and clods become very hard and more power is required to break than into finer sizes. It is easier to get desired tilth in sandy and sandy loam soil, but difficult in clay, clay loam and fine soils. It should be noted that by improper use of implement at improper times (soil too wet or dry), the original good tilth that may have been obtained earlier, would be deteriorated and it will be very difficult to bring it again in good tilth. Measuring soil tilth: Soil tilth is easy to describe, but rather difficult to measure. It is measured by following methods. 1) Feel and appearance of the soil: Soil is said to be in good tilth when it is loose, soft, properly aerated, not very powdery but granular and when these granules are felt between fingers, they are soft, friable and crumble (break) easily under pressure. Such soils permit easy infiltration of water and also store more water for satisfactory growth of crops. 2) Pore space content: When the proportion of macro pores (non-capillary pores) and micro pores (capillary pores) is round about equal. 3) Measuring the size of soil aggregates: The best size of granules or aggregate rages from 1 to 6 mm depending upon the type of soil, but in different countries different standards are prescribed. For example in Russia granular size ranges between 2 to 3 mm and in England larger than 15 mm is considered to be the good tilth. Similarly, for irrigated agriculture size of aggregates more than 5 mm while for rainfed agriculture it ranges between 1-2 mm diameters. Ideal soil tilth: It may differ according to soil type and crop. i) Crop-: For small seeded crops like finger millet, pearl millet, sesamum, lucerne etc. require fine seedbed and if it is much cloddy the seeds of these crops may germinate but their emergence above the soil surface will be defective. On the other hand, gram does not suffer in little cloddy seedbed. Jowar and cotton require a moderately firm and compact seedbed. Whereas, crops like turmeric, ginger, potato, groundnut etc. require fine and loose seedbed for better development of underground commercial parts.  18 ii) Soil-: As regard soil type, a very fine and powdery condition of surface soil is not desirable for heavy soil as there is erosion of soil due to runoff by rainwater. However this type of danger is less in case of loamy or lighter soils. CHARACTERISTICS OF GOOD SOIL TILTH: 1) Soil should be loose, porous, and friable. It should have free drainage up to water table. 2) The capillary pores (micro – pores) and non – capillary pores (macro- pores) should be in about equal proportion. Such soil condition is helpful for retaining sufficient amount of moisture in soil and also free movement of water in down layers 3) The size of soil aggregates should be about 1 to 6 mm. depending upon type of soil. 4) It should be favourable for proper germination of seeds, emergence of the crop and proper growth and development of the crop. MODERN CONCEPTS OF TILLAGE: In conventional tillage, the soil is prepared by ploughing clod crushing, harrowing, planking, smoothing of soil surface etc., which require more time, energy is often wasted and also sometimes, soil structure is destroyed due to heavy machinery. Similarly, the cost of tillage operations is also high due to hike in oil prices. To avoid all the ill effects of the conventional tillage the concepts of minimum tillage have been introduced recently. The concept of minimum tillage was started in U.S.A. The main cause for introduction of minimum tillage was high cost of tillage due to step rise in oil prices in 1974. In modern concept of tillage, the minimum tillage, zero tillage and stubble much tillage are practiced in western countries like USA and Europe. But most of these practices are not suitable for Indian conditions due to several reasons. In developed courtiers straw and stubbles are left in the field as mulch. While, In India, it is valuable fodder for cattle and fuel for homes. Use of heavy machinery under Indian conditions is limited and therefore, problem of soil compaction is rare. The minimum tillage can be practiced under Indian conditions by reducing number of ploughings to minimum necessary requirement. The modern concepts of tillage can be followed in fruit crops after proper establishment of fruit crops. The needs of planting zone (row zone) and water management zone (inter row zone) are different. In row crops, it is sufficient to provide fine tilth in the row zone for creating conditions optional for sowing and conducive to rapid and complete germination and seedling establishment. In the inter row zone, secondary tillage is not done and it should be rough and cloddy where soil structure is course and open so that weeds may not germinate and more water infiltrates into the soil. The important object of tillage is weed control, which can be done by herbicides. 1] Minimum tillage: It is aimed at reducing tillage to the minimum necessary for ensuring good seedbed, rapid germination, a satisfactory stand and favourable growing conditions for crop. It can be reduced in two ways: 1] by omitting operations which do not give much benefit when compared to the cost and 2] by combining agricultural operations like seeding and drilling fertilizers by using two bowl seed drill or mechanical seed drill. Using herbicides in this method can control the weeds. Advantages of minimum tillage: - 1] It improves soil conditions due to decomposition of plant residues in situ. 2] Higher infiltration as soil is covered with vegetation &channels are formed by decomposition of dead roots. 3] Less resistance to root growth due to improved soil structure. 4] Less soil compaction by reduced movement of heavy tillage machinery (Vehicles). 5] Less soil erosion compared to conventional tillage. 6] It improves the nutrient & water use efficiency. For obtaining these benefits, the minimum tillage should be practiced for at least 2-3 years. Disadvantages of minimum tillage: 1] Sometimes, the seed germination and emergence of seedlings affects due to minimum tillage. 2] As the rate of decomposition of organic matter is slow, more nitrogen application is required. 3] Nodulation is affected in some of the legume crops like peas and broad beans. 4] Sowing operations are difficult with ordinary implement. 5] The continuous use of herbicides causes environmental pollution problems and dominance of perennial problematic weeds.  19 Methods of minimum tillage: 1] Row zone tillage: After primary tillage with mould board plough, secondary tillage operations like discing and harrowing are reduced. They are carried out in row zone only. 2] Plough plant tillage: After ploughing, a special planter is used and is run over the field, the row zone is pulverized and seeds are sown. 3] Wheel track planting: Ploughing is done as usual. Tractor is used for sowing and the wheels of the tractor pulverize the row zone. 4] Bed planting: It is done with help of bed maker with planter. The machine makes beds and planter is mounted on bed maker to sow the seeds of crop like wheat, 5] Strip ploughing: In this method, a narrow strip of about 22.5 cm is prepared by tilling up to 15 cm depth ahead of the drill opener for sowing of crop like cotton, but soil between the sown rows remain undisturbed. 6] Lister planter: Listing is done with lister planter of 2-4 rows and the crop is sown behind the lister. 2] Zero tillage: It is an extreme form of minimum tillage. The primary tillage (ploughing) is completely avoided and secondary tillage is restricted to seedbed preparation in the row zone only. It is also known as no till or no-tillage or plough less farming. It is adopted in areas where soils are subjected to wind and water erosion, and cost of tillage and labour is too high. In this methods the machinery performs four tasks (functions) in one operation viz, clean a narrow strip over the crop row, open the soil for seed insertion, place the seed and cover it properly. It case of fruits crop only trenches are opened at required distance and other operations are not carried out. In zero tillage, herbicides are used before sowing for destroying vegetation or weeds. Generally, non-selective herbicides with relatively short residual effect (paraquate, glyphosate etc) are used before sowing of the crops. During subsequent stages of crop growth, selective and persistent herbicides are needed; e.g. In rice – wheat cropping system, the field preparation is difficult for wheat sowing. Paraquat 2 litres a.i. / ha is applied to kill rice stubbles and other vegetation. Wheat is drilled in between rice rows (stubbles) and weeds in wheat are controlled by selective post-emergence herbicide application. The seeding establishment in zero tillage is 20 per cent less than conventional methods. Advantages of zero tillage: 1] The zero tilled soil is homogenous in structure with more number of earth worms 2] It increases organic matter content of soil due to less mineralization 3] Surface runoff is reduced and infiltration of water is increased due to mulching 4] It saves cost on preparatory and inter tillage. 5] It moderates soil temperature, due to surface mulch. Disadvantages of Zero tillage: - 1] Some times germination and crop stand is affected as compared to conventional tillage. 2] Sowing operation with ordinary implement is difficult 3] Higher dose of nitrogen is required as mineralization of organic matter is slow. 4] Large population of perennial weeds becomes serious problem. 5] Continuous use of herbicides may cause environmental pollution and pests build up are other problems. 3] Stubble mulch tillage (stubble much farming): The traditional methods of tillage developed in temperate moist climates i.e. clean cultivation, often increase soil erosion. So wind and water erosion is the serious problems in central United States due to clean tillage methods. So clean cultivation increases soil erosion due to heavy rains and winds. Therefore, a new approach was developed for protecting the soil at all times by growing a crop or by crop residues left on soil surface during fallow periods. It is known as stubble mulch tillage or stubble mulch farming. Covering the soil surface with crop residues or stubble during fallow periods for protecting the soil from unfavourable weather conditions (heavy rains and winds) is known as stubble much farming. Generally, disc plough or disc harrow is used to incorporate plant residues into the soil after harvest of crop. This hastens decomposition, but still enough plant residue on the soil in this method, the resides on soil surface interfere with seedbed preparation and sowing operations. Similar to zero tillage heavy power machinery performing various tasks such as cleaning strip, sowing seeds and fertilizer application is  20 used for sowing crop in stubble mulch farming. It is a year round system of managing plant residue with implements that undercut residue, loosen the soil and kill weeds. Importance of Puddling: Rice growth and yield are higher when grown under submerged conditions. The physical, chemical and biological properties of soils are altered due to submergence. Physical Environment: When soils are submerged, most of the favourable changes occur in respect of soil water, soil aeration, soil structure and soil strength for rice growth. Soil water: The amount of water is plenty in submerged soils as compared upland soils. In addition there is standing water above the ground. The energy status of soil water in upland soils ranges from – 0.33 to – 15 bars. In submerged soil it is always zero. So the availability of water to plants in more is submerged soils. Soil air: Immediately after flooding, most of air escapes from soil pores. Air may be present in a few pockets in sub soil. Oxygen entry is very slow through water. A thin layer of 2 mm to 12 mm surface layer of soil is oxidized due to diffused air. Since rice plant has capacity to transport air from leaves to roots, the rhizosphere of rice roots are oxidized, while CO2 released during decomposition of organic matter is dissolved in water to form carbonic acid. Soil structure: Soil structure is purposely destroyed in rice cultivation by puddling to avoid percolation losses of water. Soil strength: Soil strength decreases with the amount of water. In submerged soils, mechanical resistance (Soil strength) is around 0.2 bars to 0.3 bars, while in upland soils; it ranges from 3 to 21 bars. Chemical Environment: Several chemical changes take place in submerged soils and most of them are favourable for rice growth. Changes in Redox Potential: The tendency of a given system to oxidize or reduce the susceptible substance is known as redox potential. In case of flooded soil, sulphate, nitrates etc are susceptible substances. Redox potential expressed in volts. It is positive in aerobic soil and negative in highly reduced soils. The redox potential of water and top layers of submerged soils is + 3 to +5 volts. The lower layers have a stable Eh of 0.2 to -0.3 volts. The oxygen present in the soil constituents like NO3, MnO4, FeO3 etc. is consumed by anaerobic bacteria. Changes in the soil pH: The pH of most acid and alkaline soils converges between 6 and 7 within 2 to 3 weeks after flooding. Thus, in submerged soils the nutrient availability is increased due to favourable pH. Concentration of water-soluble iron from 0.1 ppm shortly after submergence increase to 600 ppm within two weeks. Manganous ions increase steeply within one week after submergence and availability is higher under submerged conditions. Higher supply of Nitrogen is due to fixation of atmospheric nitrogen by rhizospheric bacteria. Availability of phosphate increases in submerged soils due to hydrolysis of Fe and Al phosphates due to increases in pH. Potassium availability marginally increases in submerged soils. Availability of zinc and copper is reduced in submerged soils while sulphur availability increases. Biological environment: The important organisms of submerged soils are Azolla, Blue green algae, denitrifying and rhizosphere bacteria. Actinomycetes and fungi absent in submerged soils. Non- symbiotic bacteria present in anaerobic soils and those in rhizosphere of rice roots fix atmospheric nitrogen. For maintaining standing water in the field throughout growth period of rice is possible with only important tillage operation i.e. puddling. Puddling is ploughing the land with standing water so as to create an impressions layer below the surface to reduce deep percolation losses of water and to provide soft seedbed for planting rice. The condition of the soil due to puddling is called as “puddle” and the soil is called “puddle soil”. During puddling operation individual soil particles viz. sand, slit and clay are separated. Thus, puddling disrupts the continuity pore space, reduces pore space and increases the bulk density resulting into destruction of soil structure. Similarly, the soil layer with high moisture below the plough sole is compacted due to weight of the plough. The soil particles separated during puddling settle later. The sand particles reach the bottom, over which slit particles settle and finally clay particles fill the pores thus making impervious layer over the compacted soil, which causes water stagnation or submerged conditions of the field.  21 Method of puddling: Puddling operation consists of ploughing in standing water until soil becomes soft and muddy. Initially, 5 to 10 cm of water is applied depending on the water status of soil to bring it to saturation and above and 1st ploughing is carried out. After 3 to 4 days, another 5 cm of water is applied and later after 2-3 days 2nd ploughing is carried out, due to which most of the clods are crushed and majority of the weeds are incorporated within 3-4 days, another 5 cm of water is added and 3rd ploughing is done in criss-cross i.e. both the directions. The third ploughing can be done either with wetland plough or wetland puddler. Planking or leveling board is run to level the field. To know whether puddling is thorough or not, a handful of mud is taken into hand and pressed. If it flows freely through fingers and if there are no hard lumps, puddling is considered to be thorough. Puddling implements: Puddling is done with several implements depending on the availability of equipments and nature of the land. Most of the farmers use wetland plough or worn out dry land plough or mould board plough. Wetland puddler, helical blade puddler, Power tiller and tractor with cage wheels are used for puddling operations. Wet land puddler: The wet land puddler consists of a series of blades attached to a beam at an angle or It consists of three angular bladed cast iron buds rigidly fixed to a hallow horizontal pipe and is rotated when dragged by a pair of bullocks. When it is worked, the soil is churned and puddling operations completed quickly compared to the country plough. This implement is also used for trampling the green manure in the puddle field. For satisfactory working of puddler, a preliminary ploughing of land is important. Helical blade puddler: Six to eight blades of 5 cm width are helically bent and fixed in the radial arms by welding. These are mounted on wooden frame having wooden bearings, such that the blades can rotate freely. A handle and shaft are also provided. Helical-shape of blade gives continuous contact between the blades and the soil. While operating an implement the soil is continuously sliced and weeds are cut and buried into the soil. Tractor drawn implements can be used for puddling by attaching cage wheels to prevent sinking of tractor. Similarly, power tiller is also used for puddling by wooden plank for leveling plot.  22 Lecture No.4. Seed, its definition, characteristics of quality seed, seed treatment and its objectives, seed dormancy, causes of seed dormancy and multiplication stages of seed. What seeds are? A seed is a dormant plant, carrier of the desired quality of plant. It is living biological entity. i) They are a way of survival of their species. ii) They are a way by which embryonic life can be almost suspended and the revived to new development; even years after the parents are dead or gone. iii) Seeds protect and sustain life. iv) They are vehicles for spread of new life from place to place. v) It has been referred as a plant package ready for shipment. Seeds are borne by two great and different classes of plants. 1. Less highly developed than the other, produce necked seeds that develop from naked ovules. The plants of this group are called Gymnosperms. e. g. cone bearing trees. 2. Most highly developed and much larger class known as Angiosperms. Seed develop in ovary. The ovary later becomes a fruit with developed ovule seed inside. The grains, which are used for multiplication, are called seeds while those used for human or animal consumption are called grains. Most of the crop plants produce viable seed, which is used for sowing. Those plants, which do not produce seeds, are multiplied by means vegetative parts and required large quantities of vegetative materials. Definition of seed: Any material used for planting and propagation, whether it is in the from of seed of food, fodder, fibre and vegetable crops or seedlings, tubers, bulbs rhizomes, roots, cuttings or grafts and other vegetative propagated material is defined as seed. Sowing / planting good seed/seed material is necessary for a good crop. Importance of seed is realized from beginning of agriculture. Therefore, use of seed of good quality is prime importance to boost agriculture production. Use of improved variety/ hybrid seed can increase the yield to the extent of 20-30% depending upon type of crop. So seed should maintain their quality under proper storage conditions. Seed is symbol of beginning. To a plant breeder seed may be defined as fertilized ovule consisting of intact embryo, stored food and seed coat, which is viable and has got a capacity to germinate. A seed is a dormant plant, carrier of the desired quality of plant. It is a living biological entity. Seed consists of embryo, endosperm (cotyledon food reserve) enclosed in a seed coat capable of germinating in suitable environment. Seeds are the protectors and propagators of their kind. Thus, farmer’s entire crop depends on the quality of the seed he uses for sowing or planting. If the seed has poor germination the farmer will have a poor stand, which would ultimately result in a poor crop yield. Similarly, if the seed is not pure and is mixed with other crop seeds the value of produce will be low while if the seeds contain weed seeds the farmers is introducing troublesome weeds in his field. So quality seed is essential for obtaining higher yield. Good seed must be true to their type (crop / variety), intact in structure, pure, free from mixtures of seeds of other crop / varieties, inert materials and weeds. They must be uniform in size, texture, structure, color, weight and look and free from diseases. Characteristics of good quality seed: 1) It should be genetically pure and should exhibit or bear true morphological and genetically characters of the particular variety/ hybrid of the crop. It must be true to its type. 2) They should be free from any admixtures of seeds of other strains of same crop or other crops, weed seeds, dirt and inert material. 3) They should have assured and high germination capacity which results into vigorous and healthy seedlings. 4) Seed should be mature, well developed and uniforms in size. OR It must be uniform, in its texture, structure and look. 5) They should be free from disease bearing organisms and pests.  23 6) It should be dry and not mouldy in case of cereals, pulses, oilseeds, forage crops etc. However, in case of crops like sugarcane, turmeric, ginger, potato etc, seed material should have sufficient moisture and not dry. 7) Seed should be truthfully labelled and produced under all due cares and strict supervision so that it does not degenerate quality. SEED TREATMENT: It is the process of application of chemicals or protections (with fungicidal, insecticidal, bactericidal or nematicidal properties) to seeds that prevents the carriage of insects or diseases causing pathogen in / on the seeds. It also enables the seed to overcome seedling inductions by soil borne fungi. The seeds of certain crops are subject to some kinds of treatments before sowing for different purposes as mentioned below. 1. Control of disease. 2. Convenience in sowing 3. Quicker germination. 4. Nitrogen fixation. 5. Protection against insects and pests 6. Inducing earliness 7. Inducing variation 8. Breaking seed dormancy 9. Increasing the yield. Seed treatments for different field crops: 1. Cotton: Cottonseeds are subjected to different treatments for easy and convenient sowing, because fuzzy seeds clog the seed tubes and delay the sowing work. i) Cow dung paste treatment: In this method equal amount of cow-dung and soil are taken and paste is prepared by adding required quantity of water. Seeds are rubbed together with the paste on gunny bags, dried under shade and then used for sowing. ii) Sulphuric acid treatment: Seeds are soaked in 5 per cent concentrated H2SO4 solution for 2 minutes, then washed with the water, and dried under shade before sowing. iii) Cotton seeds are also treated with 1 % mercurial compound such as agrosan @ 2 g/kg of seed for control of seed borne diseases like wilt. 2. Coriander: Seeds are splited in to two locules (halves) under slight pressure for even germination as well as to save the seed rate. 3. Garlic: Clover is separated before sowing in order to provide enough space for development and to reduce the seed rate. 4. Sorghum: Seeds are treated with 300 mesh fine sulphur @ 4 g /kg of seed for control of grain smut of sorghum. 5. Pearl millet: Bajara seeds are dipped in 20 % brine solution for removing the fungi causing ergot disease. Brine solution is prepared by dissolving 2 kg. Sodium Chloride (NaCl) in 10 litres of water and seed are dipped in it for about 10 minutes. Floating seeds and selerotia should be collected and burnt. The seeds at the bottom should be washed thrice with clean water and dried in the shade before sowing. In case of small seeded crops like bajara, finger millet, mustard etc. seeds are mixed with fine sand or earth for even distribution on field. 6. Wheat: i) Solar heat treatment: Seeds are soaked in water in morning for 4-5 hours and then spread on iron sheet in thin layer in bright sunlight in the afternoon, for 4-5 hours during the hot and dry summer months i.e. in May. This method is useful as preventive measure against loose smut of wheat. ii) Wheat seeds are also treated with 1 % mercurial compounds such as agrosan or cerasan 2.5 g/kg as preventive measure against loose smut. 7. Paddy: i) Prepare 3% brine solution by mixing 300 gm. of NaCl (Sodium Chloride) in 10 litres of water. Pour the seeds in the solution and stir well. Remove the floating and burnt. Collect the seeds from the bottom wash it thrice with clean water and dry in the shade.  24 ii) Treat the above seeds with 1 % mercurial fungicide @ 2.5 g/kg of seed as preventive measure against bacterial blight, blast etc. 8. Groundnut: Seeds are treated with 1 % mercurial fungicide like agrosan @ 2 g/kg of seed, against seed borne diseases. 9. Sugarcane: i) Soaking the setts in water for 4 hours helps in conversion of sucrose in to glucose for better germination. ii) Hot water treatment against grassy shoots: Dip the setts in hot water at 50oC for 2 hours before planting. iii) Dip the setts in 0.1 % bavistin solution for 5 to 7 minutes against root rot and fungus diseases of sugarcane 0.1 % bavstin solution is prepared by adding 100 g of bavistin in 100 liters of water. iv) Setts are also treated with 1 % fish oil resein soap or malathion to stop the spread of mealy bugs. v) If the buds on the setts are dried then setts are dipped in lime solution for 24 hours before planting for improving the germination. Lime solution is prepared by dissolving 500 g of lime in 180 litres of water. 10) Soybean seeds are treated with Thirum 3 g + 3 g Bavistin (carbendazim) for one kg. seed to prevent externally seed borne diseases. 11) Breaking dormancy: Potato cut pieces are treated with 1 % solution of thio urea for an hour breaking dormancy. 12) Inducing earliness: By giving vernalization treatment to the seed maturity period of a long crop is shortened. This is useful for plant breeders in hybridizing long duration variety with short duration one. In vernalization treatment, seed is soaked in water and incipient germination is induced. Later on seeds are placed in cold storage, so that their germination power remains intact, but process of germination is temporarily halted. So plant spends part of its vegetative period and seed so treated is dormant plant. The period from sowing to flowering is greatly reduced. 13) Seed treatment with bacterial culture and bio-agents: 1) Bacterial culture: Material: Any bacterial culture, water, seed, jaggery, iron basket, empty gunny bag etc. Procedure: i) Use specific culture for specific crop. ii) Store the culture in a cool and dry place. iii) Dissolve 150 g jaggary or sugar in 1.25 litres water and boil it for 30 minutes. iv) Cool it and mix the packet of culture to make slurry. v) Mix the seed sufficient for a hectare is with the culture slurry thoroughly so that all seeds are uniformly coated with culture. vi) Spread the treated seed on a clean cloth and allow drying under shade for 10 minutes. vii) Do not keep the seeds exposed to the Sun. viii) Sow the treated seed immediately and cover the soil over it. ix) Use the culture before expiry date. Sr. No. Culture Crop 1. Azotobacter Paddy, sorghum, pearl millet, maize, sugarcane, cotton, sunflower etc. 2. Rhizobiurm Groundnut, soybean, green gram, black gram, gram (chick pea) etc. 3. Azospirillum All types of cereal crops. They fix more nitrogen, than azotobacter. 4. Beijerinka These are found in acidic soils and useful for cereal crop especially for paddy. 5. Azolla Azolla is a water fern that assimilates atmospheric nitrogen in association with nitrogen fixing blue green algae. It is especially used in paddy field, which is generally water logged. 6. Phospho- It is also bio-agent which supplies available phosphorous to crop compost plants.  25 SEED DORMANCY: Seeds can be said to be dormant if they are viable, but do not germinate even under favourable conditions. or It is an internal condition of viable seed which does not allow its actual germination, although suitable temperature, moisture and aeration etc. are provided. It is as if, a resting period of the seed and unless this resting period is over or is deliberately terminated by some kind of seed treatment, the seed will not germinate. The dormancy period varies greatly according to the crop, species and varieties of the crop. Seed viability: To most seed technologist, viability means that a seed is capable of germinating and producing a normal seedling. or It is the ability or capacity of the seed to germinate. It is probably the highest at the time of physiological maturity. No dormancy e.g. Paddy variety- T.N. 1 Gr. nut variety – Karad 4-11 and J. L.24 But Paddy variety –I. R. 8 have dormancy period of 3-4 weeks while seed potatoes – have dormancy of 2.5 to 3 months. Seed dormancy is helpful because it prevents pre-harvesting sprouting. If the crop is caught in rains at maturity stage, the seed will not germinate. While in case of no dormancy the seed will germinate in field itself, if caught in rains at maturity. Dormancy is a handicap too, as it does not permit the farmer immediate use of his produce as seed. Another it is the survival of many unwanted crop plants or weed species in fields. The dormant seeds should be sown only after completion of its dormancy period or it is broken by giving certain treatments to seed such as pre-chilling, pre-drying, hot water treatment or use of chemicals. e. g. In pre-chilling, especially vegetables seeds are kept at temperature between 5-100 c for 7-10 days. The dormancy period of seed potato can be broken by dipping cut tubers for an hour in 1% aqueous solution of thio- urea. The o.2% solution of potassium nitrate is also used. Types of seed dormancy: 1) Innate dormancy (Primary or physiological dormancy): It may due to the genetical characters of seed or due to hard seed coat, immature embryo etc e.g. impermeable seed coat –Alfalfa. Seed coat dormancy occurs in seeds of grasses. They frequently referred as firm seeds. Rudimentary embryo dormancy e.g. cherry seed. The embryo dormancy is because of the physiological immaturity of embryo e.g. Apple. 2) Enforced dormancy: It is due to the conditions of deficient oxygen, excess Co2 and deep placement of seed in the soil. 3) Induced dormancy (secondary dormancy): Sometimes non-dormant seed encounter the conditions which cause them to become dormant, which is referred as secondary dormancy results due to sudden physiological change in seed by unfavourable climatic conditions. Causes of seed dormancy: The dormancy in seeds may be due to any single cause or a combination of more than one of the following causes. i) Seed coats being impermeable to water e.g. cotton seeds become permeable if they are treated with sulphuric acid or dipped in boiling water for few seconds. ii) Hard seed coat e.g. Mustard, Amaranthus – contain a hard and strong seed coat which prevents any appreciable expansion of embryo. iii) Seed coats being impermeable to oxygen, e.g. Xanthium seeds. iv) Rudimentary embryo of seeds e.g. orchid seeds. v) Dormant embryo e.g. apple, peach, pinus. vi) Synthesis and accumulation of germination inhibitors in seeds. Types of seed or classes of seeds or multiplication and distribution of improved strains: According to the genetic purity and phases of development (multiplication), seeds are classed into the following categories by