AGRIC GRD 10-11 Notes PDF

Agricultural Science note master Grade 10 - 11 Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  Theme 1: General Agriculture 1.1 Agriculture as a career  A career is a person’s occupation Identify care...

Agricultural Science note master Grade 10 - 11 Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  Theme 1: General Agriculture 1.1 Agriculture as a career  A career is a person’s occupation Identify career paths in agriculture  agriculture extension officer  Veterinary officers  farm managers  crop protection advisors  agricultural sales person  Agriculture engineers  Farm mechanics  agronomists  fisheries officers State the roles of the above career paths in improving agricultural production in Namibia Career paths Roles Agricultural extension officer  Help to develop programmes to recover the eroded soils  Help farmers to fight crop and animal diseases  Is a person who gives  Give additional training to farmers about new technologies information and advice on  Advice farmers on how best to utilize natural resources to ensure modern farming technique sustainability  Help to increase the country’s food security Veterinary officers  Controls the movement of animals by giving the movement  Is a medically trained person permits that maintains and promotes  To provide clinical services e.g. vaccination, dosing etc animal health  To control notifiable diseases by putting animals in quarantine.  To do abattoir inspections Farm managers  A person who plans,  marketing farm produce organizes and manages the  budgeting and monitoring farm performance farm activities.  keeping farm records  acquiring and maintaining tools and implements  supervising farm workers  monitoring daily activities Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Crop protection advisors  To monitor and assess progress in disease and pest prevention on  trained to deal with protection farms of crops in fields and storage  To know about different agricultural products including pesticides, fungicides and herbicides  To ensure that all crop products to be imported and exported are disease free and fit for consumption Agricultural sales person  To advise farmers about the improved products  A person who sells products  Selling everyday agricultural inputs and equipment’s permitted for use in farming Agricultural engineer  To plan and design infrastructure and equipment within the  Is a person who is industry manufacturing and  To test equipment to ensure it is safe and reliable maintaining farm machinery  To supervise the construction projects and implements Farm mechanic  To assemble new equipment and machinery  They are trained to maintain  To repair machineries and equipment and repair farm machinery  Advising on new machinery available on the market and implements  Driving farm trucks and large machinery on the farm  Installing irrigation systems and pumps Agronomist  To introduce improved crop cultivars  Studies the science and  To conduct agronomic research technology behind using field  To test and select crop varieties that are suitable for Namibian crops for fuel, food and conditions materials  Advice subsistence farmers on sustainable farming practices  To promote cropping strategies Fisheries officer  To inspect and patrol the rivers, sea  A person responsible for  To issue permits for movement of fish conservation and protection of  They inspect all fishing equipment marine resources  To control and monitor the export of fish to foreign countries  to control the landing methods at harbors and factories  To protect the fish resources and habitats 1.2 Ways of improving Agriculture Define Sustainable Agriculture Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Maximizing profit from natural resources without preventing the future generations to do the same/conserving natural resources for future use  It is the production of food that avoids the total depletion on natural resources , which would deprive future generations of these resources. Define agricultural research  It is an investigation and study with the aim of improving the quality of crops and livestock Discuss examples of agricultural research activities that lead to the improved production of agricultural commodities in Namibia Research on improved crop varieties  Increasing grain quality  Increase drought and temperature tolerance in crops  Focuses on increasing the yield per hectare  Mahangu-varieties such as Okashana1 and Kangara were specially developed to suit the Namibian climate Research on animal feeding  This research is directed towards supplementary feeding programmes for animals.  Improved usage of crop residues as well as protein and mineral supplements to correct nutrient deficiencies. Research on animal health  Diseases and pests can limit livestock productivity therefore this research improves effectiveness of existing preventative treatments and enables the development of new vaccines  Deals with identification of animal diseases; their symptoms and parasites and ways of controlling the spread of diseases and parasites Research on genetic improvement  Genetic modification allows the improvement of crops and animal breeds in terms of their adaptability to harsh conditions, resistance to pests and diseases and production.  Focuses on reproductive technology Agricultural research stations in Namibia: Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  Livestock production research Plant production research Sachinga LDC Bagani RS Alex Muranda LDC Kalimbeza RS Okapya LDC Mannheim RS John Pandeni RS Omahenene RS Sonop RS Okashana RS Omatjenne RS Describe the value of education in agriculture and how this contributes to the improvement of food and cash crop production  Leads to better knowledge about crop varieties and animal breeds  Farmers will gain knowledge of how to increase food production by using fertilizers  Agriculture provides good employment opportunities  Gives farmers skills to practice modern agriculture  Enables farmers to save water and use soil and plants sustainably  Equips farmers with required skills and knowledge to be able to innovate and improve farming practices. Discuss ways of adding value to agricultural products for sustainability  Value addition is a process of changing a raw agricultural product to a more valuable state Preservation and processing methods (Culturing, cooking, processing, freezing, hides, cooling, canning, drying) Culturing - Preserving food by fermentation, when bacteria add beneficial nutrients (protein) to the food e.g. yoghurt Freezing - A method of preserving food by lowering the temperature to inhibit the growth of micro-organisms e.g. meat Cooking - Heat destroys bacteria and enzymes that cause rotting, after cooking the food is cooled or frozen e.g. vegetables Cooling - Food is stored at low temperature in a fridge, storage cold room and ice box etc…e.g milk Canning - Heating the food and store in cans/containers e.g sliced carrots Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Drying - A method that removes moisture from the food for bacteria, molds and yeast not to grow e.g. biltong, fish Discuss how agriculture can bring about the much-needed development and better living conditions for rural people in Namibia Small-scale farmers may apply for loans from agricultural banks in order to expand their production. This can result in establishing commercial farms that leads to job creation in rural areas. Infrastructures will improve as a lot of people move from their homes to their workplaces. Explain how government/ ministry of agriculture can help in the development of rural communities  Introducing conservancies  Training farmers in various farming activities  Providing financial assistance for community projects  Setting up animal handling facilities within the rural communities  Subsiding inputs and services 1.3 Environmental influences on Agricultural practices Explain the effects of the following environmental factors on agriculture: Four environmental factors  Temperature – determined by using a thermometer recorded in degrees Celsius. Rainfall – determined by using a rain gauge recorded in millimeter  Wind - Wind speed using a cup anemometer in kilometers per hour, - Wind direction is measured using a wind vane.  Humidity – determined by using a wet and dry bulb thermometer recorded in percentages. Effects of temperature on plant growth * High temperature (maximum) (40c and above) Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Enzymes are denatured/destroyed  Plants will wilt and die  increase the rate of evaporation  increase the rate of transpiration  closes the stomata to reduce water loss limits/reduces photosynthesis * Low temperature (minimum) 0-15c  Germination is very slow  Enzymes are inactive  Production decrease  decrease the rate of evaporation  decrease the rate of transpiration Optimum temperature (Best for plant growth) 20-30c  Most/ Ideal for plant growth  Enzymes are active  Production increase  Plant processes occur at normal rate Solution to temperature  Apply mulch around the base  Provide shade for plants  Grow in greenhouses  Grow resistant cultivars Effects of wind on plant growth - Negative effects: Strong wind causes soil erosion - Strong wind increase transpiration and evaporation - Strong wind causes physical damage to plants (uprooting, breaking branches, leaves and flower) - Strong wind spread diseases Positive effects: Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Wind promotes pollination  Wind promotes seed dispersals  Wind promotes transpiration stream  Wind dries up excess moisture Solution to wind  Plant windbreakers  Mulch the soil surface Effects of humidity on plant growth  Humidity: The amount of water vapor in the atmosphere  High humidity leads to low transpiration and evaporation  High humidity encourages fungal diseases  High humidity creates the high possibility of rain  Low humidity leads to high transpiration and evaporation  Low humidity decrease fungal diseases  Low humidity causes the wilting of plants Solution to humidity  For high humidity, space plants further away  Low humidity , apply mulch Effects of rainfall on plant growth Factors of rainfall and their effects on the growth of plants Distribution of Rainfall:  It means the amount of rainfall that occurs in different places,  They should be a good distribution of rainfall throughout the growing season. Effectiveness of Rainfall:  How the rain is distributed during the growing season,  Some of the water may be lost due to evaporation, run-off and leaching. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   There must be amount of water available to plants during the growing season, soft rain in form of shower for a considerable period and it must be well spread and allow water infiltration for plant use. Reliability of Rainfall:  Comparing rainfall over a period of time in different areas of Namibia,  This will give an indication to the farmer to judge whether to trust rainfall in a specific area for plant growth or not.  This will enable the farmer to tell what type of the crop to be grown. Intensity of Rainfall:  Refers to the nature and duration of rainfall at a specific time and place,  Nature it may be in the form of heavy thunderstorms or soft rain.  Duration the period of time it has been raining  Soft rainfall in form of shower for considerable period is good for plant growth.  Heavy rain drops cause damage to the plants by breaking their branches. Positive effects of rain  Enables plants to grow and produce Negative effects of rain:  High rainfall causes leaching  High rainfall causes soil erosion  High rainfall causes water logging  High rainfall causes physical damage to plants  Low rainfall causes drought to plants Solution to rainfall  Practice irrigation  Practice mulching as it helps to keep water in the soil longer for plants to use Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Describe the water cycle and the significance of ground water resources The water cycle Explain the water cycle using all the processes involved/explain water cycle by using a labeled diagram:  Water Evaporates from the rivers, soil,  Plants leaves lose water through the process of Transpiration,  Animals lose water through the process of Respiration,  This water moves into the atmosphere as Water Vapor,  And then Condensation takes place to form clouds  And water falls to the ground as precipitation/rain,  The water which falls to the ground Drains/infiltrates into the soil,  Some water Run-off into the rivers, dams, and the process starts again Significance of groundwater resources  The water is less likely to be polluted compared to surface water which makes it fit for consumption  For irrigation purpose  For fish farming  For construction  It is naturally protected against evaporation\ Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Describe the importance of water conservation, including the process of mulching and minimum tillage Soil moisture can be conserved by: Mulching is the practice of covering the soil surface with a layer of decomposing materials. Advantages of mulching are:  It keeps the soil cool and damp at all times  Prevents weed growth  Increases soil fertility  Prevents erosion  Improves soil structure Disadvantage of mulching  It attracts pests  Encourage the spread of fungal diseases Minimum tillage is the process of conserving soil moisture by not digging or ploughing unnecessary Advantages of minimum tillage  Saves labour  Reduces evaporation Disadvantages of minimum tillage  Poor drainage and aeration  Difficult for plant roots to penetrate the unloosened soil 1.4 Principles of land tenure Describe the main features of land tenure systems applicable in Namibia  Rented land Land is for rent It is rented for a short time The agreement is renewed annually Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   State land It is a government land Normally used for game parks nature reserves, national parks Government makes decisions  Leasehold Land is for rent It is rented for a long time, not for a period exceeding 99 years The agreement states the lease fee and period  Freehold Land is privately owned The owner makes decisions Land can be used as collateral  Communal land Land is owned by the community Includes all land used by the traditional authorities Describe methods of land use such as:  Shifting cultivation-an activity of clearing the land for cultivation, when the soil loses fertility it is left to recover by moving on to another land Shifting cultivation: - farmer clear the land by cut down trees and then burn them, - farmer plant crops for several years until the soil becomes infertile, - farmer will shift/move to another place where they will clear the land again. Settled arable land  this type of land is suitable for growing crops Enclosed grazing system  a system whereby animals are kept in fenced areas and provided with food and water Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  Unenclosed grazing system  a system whereby animals move freely looking for food and water, at night they are kept in kraals Method advantages Disadvantages Shifting cultivation -allows the soil time to recover -it is tiresome and time consuming -lowers the risk of pests and -loss of biodiversity diseases -land become scarce when population - new land is very fertile increases -burning adds fertility to the -burning of cut trees leads to climate soil changes Settled arable land -high production due to Its expensive in terms of costs of practicing crop rotation fertilizer used - Enclosed grazing system Grass has time to regrow -the system is expensive -overgrazing and breeding are -demand skills and knowledge to easy to control manage animals Unenclosed grazing system -the system is cheap -animal can graze poisonous plants -overgrazing and breeding are difficult to control 1.5 IMPACT OF HIV/AIDS ON HUMAN RESOURCES AND FOOD PRODUCTION State how different age groups can become victims of HIV/AIDS: Newborns Through mother to child transmission if mother is infected: - during pregnancy, - during childbirth - during breastfeeding Teenagers - Through unprotected sexual intercourse - Having multiple sexual partners - Sexually active - Sharing needles in drug use with an infected person. Elderly Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  - Through unprotected sexual intercourse - Sharing needles in drug use - Accidental exposure e.g. car accident - Taking care of infected children Discuss the effects of HIV/AIDS pandemic on the turnout and productivity of farm workers within the agricultural sector in Namibia  Production of food decreases  High absenteeism of sick workers  Loss of skilled laborers  Loss of active workforce  Less land is farmed because of not enough workers to do farming Explain how the impact of HIV/AIDS reduces the output/productivity from a farm - Food production will decrease - Workers are too sick to work - They cannot perform labour intensive activities Theme 2: Soil Soil formation - Soil is formed through the process of weathering Weathering - The breaking down of rocks into small particles to form soil. Identify the agents of physical weathering (a) Physical weathering - the breaking down of rocks by natural forces without changing the chemical composition of the rock. (i) Water flowing /running water -Pushing rock over one another, the load of particles carried by water causes abrasion, small pieces break off to form soil -Falling water: causes rocks to become very smooth by wearing them away. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  (ii) Strong Wind - Carry stones that are knocked against other stones, making weaker one to break. (iii)Temperature changes - Rock expand when it becomes hot and contract, when it becomes cold this process causes pieces break off to form soil. (iv)Glaciers: moving ice hit against rocks breaking off, pieces to form soil. (b) Chemical weathering: - breaking down of the rocks into soil by changing the chemical composition of the rock Identify the agents of chemical weathering - Rain water combine with carbon dioxide form weak carbonic acid. Falls, enter rock, overtime causes the rock to dissolve. - Oxygen combine with iron in rock form iron-oxide/rust, weakens rock joints. Rock peels off to form soil - Oxygen react with sulfur in rocks weakens rock joint, small pieces if rust peel off, form soil. (c)Biological Weathering: breaking down of rocks by the actions of living organisms Identify the agents of biological weathering (i) Micro-organism such e.g. bacteria fungi; -produce organic acid during decomposition; -that dissolves rocks (ii) Plant roots Grow in cracks of rocks; expand forcing rocks to break off. (iii) Moving animals Hooves break weaker rocks e.g. cattle (iv)Soil living organisms such as termites, ants Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  - Make holes/tunnels into the soil making the rocks to break and form soil Soil profile State what is meant by soil profile This is a vertical cross-section that is exposed when a pit is dug showing different soil layers e.g. top soil, sub-soil parent material, parent rock. Describe various soil horizons (layers) in terms of colour, organic matter and texture. Layerv A: Top soil Dark in colour Contains lots of humus Texture : Mixture of fine and coarse texture Usually consist of good crumb structure Good drainage and aeration Depth ranges from 5cm up to 1m Contain many plant roots and soil living organism Contain water Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Layer B: Sub-Soil Light in colour Contain less humus Poor drainage and aeration Few plant roots Few living organism Contain leached minerals Layer C: Parent material/weathered rocks It lies deeper than the subsoil Could be deeper than 1m Produces subsoil and top soil Very little water No humus Few roots Has coarse and rock particles LAYER D: Parent rock/bedrock Can extend very deep under the ground Contain rocks which are intact/unweathered rock No roots No humus Forms the underlying rock, form water table Soil type Describe the main characteristics of clay soil, sand soil, and loam soil in terms of particle size, pore space, water retention, temperature, cultivation and plant growth. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture SOIL TEXTURE AND STRUCTURE Distinguish between soil texture and soil structure  Soil texture refers to the coarseness and finesse of soil particles when they are felt by fingers.  Soil structure refers to the way in which individual soil particles (aggregates) are arranged in relation to one another. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Describe soil texture in terms of different soil particles; sand, silt and clay Gravel Greater than 2mm in diameter Coarse sand 2mm – 0.2 mm in diameter Fine sand 0.2mm – 0.02mm in diameter Silt 0.02 mm – 0.002mm in diameter Clay Below 0.002mm in diameter Ways to determine soil texture  Nest sieve test  Rubbing test  Sausage test  Settling test Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Settling test Explain what is meant by soil crumb Crumb structure - soil particles are bounded together and yet allow air and water to circulate freely/refers to small crumps of sand and clay with humus. Explain the importance of forming and maintaining a good crumb structure for optimal plant growth - It improves aeration - It improves drainage to prevent waterlogging - It improves water holding capacity - It minimizes the rate of leaching of plant nutrients - It promotes microbial activities - Reduces soil erosion Soil Composition Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Describe the components of different types of soil (sand, clay, and loam) in term of mineral particles, organic matter, air, water and living organisms. Inorganic materials e.g. mineral particle - Soil originates from rock weathering - It is the largest component of the soil which makes up 45% Air - Found it pores between the soil particle - It is an important for respiration for micro-organism and plant roots - It makes 25% of the soil Water - It helps to dissolve plant nutrients before they can be absorbed by plants - Living organisms in the soil also needs water - It makes 25% of the soil Organic materials - This are dead and decomposed plant and animal materials - Add fertility to the soil - Improves the soil structure - Improves aeration - Improves water holding capacity Living organisms - Form part of organic materials - It makes 5% of the soil Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Soil fertility It refers to the ability of the soil to support plant growth and produce a lot and healthy products. Describe the major functions of the following plants nutrients: nitrogen, phosphorus, potassium, calcium, magnesium and sulfur Note: They are needed in large quantity by plants General effects of the major plant nutrients  Nitrogen positive effects - Promote vegetative growth e.g. stem and leaves - Formation of chlorophyll that gives plant leaves green colour. Deficiency of nitrogen on plants (negative effects)  Poor growth rate (stunted growth)  Leaves turn yellow (leaf chlorosis) Organic source of nitrogen  Manure  Compost Inorganic source of nitrogen  Limestone ammonium nitrate (LAN)  Urea  Ammonium nitrate  Phosphorus positive effects (functions)  Promote root and shoot development  Seed germination  Improve disease resistance Deficiency of phosphorus on plant (negative effects)  Reduction in the development of seed  Poor root development Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Stunted growth  Purple leaves Organic source of phosphorus  Manure, compost Inorganic source of phosphorus  Single super phosphate  Double super phosphate  Bone meal  Potassium, positive effects (functions)  Strengthens plant stems and reduce lodging  Promote quality grain seeds, fruits and stem  Helps in the absorption of nutrients Deficiency of potassium on plant (negative effects)  Brown patches on leaf edges  Poor development of flowering and fruits  Stunted growth Organic source of potassium Inorganic source of potassium Manure Potassium permanganate Compost Nitrate of potassium Potash Calcium  Strengthen plant cell wall  Neutralizes toxic in plants  Formation of protein Magnesium  Promote early flowering and fruiting  Formation of chlorophyll, that gives plant its green colour Sulfur  Facilitates physiological process e.g. diffusion, osmosis, photosynthesis, respiration etc., Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   For production of protein and chlorophyll Identify and explain factors affecting soil PH such as rainfall, irrigation, application of fertilizers, removal of crop residues, bacterial/microbial actions and parent material.  Too much application of fertilizer e.g. ammonium nitrate make soil to be acidic  Heavy irrigation/high rainfall: causes leaching of bases/nutrients which are then replaced by hydrogen ions. This makes the soil acidic.  Bacterial action produces organic acids during decomposition which makes the soil acidic.  Removal of crop residues during harvesting, nutrients used by the crop are not replaced. The nutrients tend to be replaced by hydrogen ions and the soil tends to be acidic.  Parent material; the mineral in the rock determines whether the soil will be alkaline or acidic e.g. if the parent rock contains limestone, the soil formed will be alkaline. If the parent rock contains granite , the soil formed will be more acidic Describe the nitrogen cycle in terms of: - Decomposition by type of microorganisms - Nitrogen fixation in the roots - Absorption of nitrogen compounds and their convention to proteins - The role of type of microorganisms in decay and the return of nitrogen to the soil or atmosphere. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Legume crops has root nodules, which contain nitrogen fixing bacteria, these bacteria have ability to fix nitrogen into the soil, in the form of nitrates.  Nitrogen fixation by lighting: lighting releases large amounts of nitrogen gas, which dissolve in the rain water and penetrate the soil  Nitrogen fixation by bacteria during decomposition/ammonification, form ammonia, nitrifying bacteria convert ammonia into nitrate, again nitrifying bacteria convert nitrite into nitrate the process is called nitrification.  Denitrification nitrates are converted into nitrogen that goes back to the atmosphere  Nitrates is absorbed by plants , then converted into amino acids and finally into plant proteins  Animals feed on plants and they break down protein into amino acids; then amino acids are converted into animal protein Explain the negative effects of salt on plant growth Salt becomes toxic to plants Too much salt makes the soil acidic or brackish Plants cannot take up water from the soil Causes stunted growth Describe how to make compost from garden refuse and other available organic substances. Compost is a plant or other organic material that has decomposed - Collect organic materials such as leaves, sticks, weeds, kitchen waste, vegetable peels, eggshells and ash - Lay the sticks on the ground and put a bit of soil - Put a layer of any of the collected materials and put a layer of soil and add water. Then repeat the process until it reaches the required size - Put organic materials into a heap and give it time and space to decay or decompose - Within three to six weeks it should be ready Explain the effects of overuse of fertilizers  Excess fertilizer can pollute water  Contaminate drinking points e.g. borehole causes anaemia in human  Promote algae to grow, cover river, kill aquatic life due to lack of oxygen  Affect soil PH, make soil acidic e.g. ammonium nitrate  Destruction of crumb structure, result soil erosion Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  Explain the significance of legumes in maintaining soil fertility  Legume crops has root nodules; the root nodules contain bacteria(rhizobium); which convert nitrogen gas into nitrates and fix it into the soil Soil Erosion and Soil conservation List the types of soil erosion Soil erosion is the removal of top-soil by wind or water Types of erosions  Sheet erosion  Gulley erosion  Splash erosion  Rill erosion Describe how to control soil erosion on agricultural land, with reference to humus content and loss of biodiversity Keep the soil surface covered through mulching  Applying organic materials on the soil surface to reduce the splash effect of rain drops, when organic material decompose they increase the humus content and also contain microorganisms.  The grass applied on the surface reduces water runoff to encourage infiltration Use contour ploughing  The contour furrows that are formed holds back rain water and encourages infiltration Wind breakers Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Are planted along the crop fields can reduce the speed of the wind and therefore reduces soil erosion Intercropping / strip cropping  A secondary crop is planted among the rows of the main crops, this crop will then cover the soil to reduce erosion Terracing  A flat area is cut of the slope and crops are planted on this flat area. Stones that will hold the soil back are placed in front of the wall Contour ridges  They are ridges made across the slope of the land, crops are then planted behind the ridges Irrigation and soil drainage Define irrigation Irrigation is the artificial application of water to plants. Describe the methods of irrigation applicable in Namibia Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  Explain the need for irrigation and its effects on crop yields and quality Positive  Allow crops to grow any time/extends rainy season/improves growth  Improves crop quality  Allows specific requirements to be met/gives correct amount of water  Keeps plant cell turgid  Increases availability of minerals/nutrients  Provides water to prevent wilting  Improves yield Negative  Causes leaching  Soil erosion Explain what is meant by leaching Leaching Is the loss of soluble plant nutrients dissolved in water downward into the soil, and away from the reach of plant roots. Discuss the effects of leaching on plant growth  Nutrients move down into the soil  Replaced by hydrogen ions  Makes the soil acidic  Micro-organisms (enzymes) become inactive  Plant show deficiency e.g. yellow leaves, stunted growth Drainage Define drainage - Is the removal of excess water from the soil to improve soil aeration Discuss the necessity of draining waterlogged agricultural land  Prevent water bone diseases  Improve soil aeration /improve plant roots respiration  Prevents root rotting Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Prevents waterlogging  Promotes microbial activities  Reduces leaching of nutrients Describe how soil is drained by means of ditches  Channel are dug on the surface  Ditches should be 1 to 2m deep and 80 to 100 m apart depending on soil type  Ditches should have a down slope towards the end to allow water to drain Describe how to drain water by pipe drains  Digging furrows in the ground  Place the drainage pipe in the furrow /underground  Pipe with holes  Open ended pipes with wire mesh to prevent blockage then pave with stones Method Advantages Disadvantages Ditches Cheaper to make Weeds grow in ditches Implements cannot be used over the land Not suitable for sand soil as they keep filling up Pipe drains Fewer weeds Pipes are expensive Implements can be used over the land Water resource management State what is meant by water resource management Water resource management entails the planning, development, distribution and management of freshwater resources so that they are used optimally. Discuss sustainable methods of managing water resources Sustainable ways of managing water resources:  Drip irrigation – ensures that crops get the right amounts of water without wasting water on areas that do not need to be irrigated.  Earth dams – collect enough water for crop irrigation for seasons when there is no rainfall or during dry spells. Earth dams are also called embankment dams because they are made simply by creating barrier in existing river. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Catchment area – an area in the natural environment where rainwater collects and from where it runs into rivers or streams. The farmers must make sure that the catchment area gets enough rainwater to fill the dam.  Pollution control – farmers cannot irrigate their crops with polluted water. Land preparation and soil tillage Discuss methods of preparing and tilling the land/soil Conventional tillage  The use of mechanical farm implements for land preparation  It involves primary tillage, which is ploughing; the implements used for primary tillage are mouldboard plough, disc plough, subsoil plough and chisel plough  secondary tillage which is harrowing or leveling to make the soil fine Conservation/minimum tillage  Tilling and disturbing the soil is done as little as possible  It involves slashing of weeds and vegetation that grow on the farm, and leveling the soil with a rake. Which makes greater use of plant residues, as a means of conserving both soil fertility and water. No-till/zero till method  Is a system where no pre planting soil preparation is done.  Sowing is done directly into undisturbed soil using seed drilling equipment.  Weed control is done using herbicides Strip tilling  It involves minimal tillage because only the area of the soil where the seeds will get planted is tilled. Ridge tilling  The soil is left undisturbed from harvesting to planting, except for fertilizing the soil. Seeds are planted and crops grow on the ridges. Mulch tilling  Is any conservation tillage system that cannot be classified as no till, strip or ridge tilling  Farmers use sub-soilers or chisel ploughs for deep ploughing. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   The sub-soiler ploughs deep into the subsoil to ensure that crop roots will later develop deep enough, and in the best possible conditions. State the advantages and disadvantages associated with methods of land preparation and soil tillage Describe reasons for choosing specific tillage methods  Soil factors – include relief, slope, erodibility, root depth, texture and structure, organic matter content and mineral composition.  Climatic factors – deals with the amount and distribution of rainfall, the length of the dry period, growing season, soil temperature etc.  Crop factors – include the growing duration, the rooting characteristics, the crop’s water requirements and seed characteristics. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Socioeconomic factors – determine which tillage method to choose are farm size, availability of a power source, family structure and composition, labour situation, access to cash and credit facilities. THEME 3: PLANT PRODUCTION TOPIC: Principles of plant growth. State the conditions necessary for plant growth and their importance.  Suitable temperature -Plants require optimum temperature to grow, if the temperature is too high, plants will wilt and die, and if the temperature is too low, the enzymes will not be activated. - Plants grow best within an optimum temperature range between 20-30c  Water - Plants need adequate water for all physiological activities to go on, i.e. photosynthesis, transpiration, and translocation etc. - Water is needed for proper transportation of nutrients within the plant. - Little water causes the plant to wilt and die. - Water helps plants to regulate its temperature. Light- Light is essential for photosynthesis.  Air (oxygen) - Plants need carbon dioxide for photosynthesis and oxygen for root respiration. - Plants need fresh, clean air for optimum growth. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture - Air is essential for seed germination.  Nutrients - Nutrients are needed for plant growth.  Carbon dioxide - plants need carbon dioxide for photosynthesis to take place  Space - Adequate space is needed by plants to absorb sufficient light,water,carbondioxide and oxygen. Explain the absorption of plant requirements from the soil, including the principles of diffusion, osmosis, the passage of water and dissolved mineral salts through vascular tissues. PRINCIPLES OF DIFFUSION This is the movement of ions and gas molecules from the region of higher concentration to the region of lower concentration down a concentration gradient. Nutrients such as glucose move via diffusion through the plant, from the cells with high concentration to cells with low concentration. PRINCIPLES OF OSMOSIS This is the movement of water molecules from the region of higher water potential to a region of lower water potential through a partially permeable membrane. OR Osmosis is the movement of water molecules from the region of higher water potential to the region of lower water potential through a semi –permeable membrane. A semi-permeable membrane is a membrane that allows small molecules eg water to pass through it while large molecules like dissolved salts cannot pass through. IMPORTANCE OF OSMOSIS  Provide water to all plants parts  Keep cell firm  Prevent the wilting of plants  Provide water for photosynthesis  Absorb water from the soil  Absorption of nutrients from the soil Describe the passage of water and dissolved minerals salts through vascular tissues.  Vascular tissues in plants transport water and nutrients or minerals throughout the plants.  The vascular system consists of xylem tissues and phloem tissues. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Xylem tissues transport water and dissolved minerals from the root cells to the stems and leaves.  Phloem tissues transport manufactured food (glucose) from the leaves to the stem and roots.  Minerals and water are in a solution form in concentration.  The root hairs are in close contact with the water and dissolved minerals in soil, there is more water in the soil than in the plant, the soil has a high water potential while the plants has a lower water potential, water enters the root hairs by osmosis through the cell membrane into the xylem vessels down a water potential gradient. HOW WATER IS ABSORBED BY A PLANT 1 Water enters root hairs 2 Water passes across 3 Water is drawn up into by osmosis the root, from cell to the xylem vessels of the cell, by osmosis. root, water moves in the xylem of the stem to the leaves by transpiration stream/pull. 4. Water then evaporates into the air space in spongy mesophyll of the leaves/ water vapour escapes through the stomata. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Explain the concepts of turgor and plasmolysis Turgor is when water enters the plant cell, the vacuole swells pushing the cytoplasm against the cell wall and the membrane stretches. Importance of Turgor in plant.  Helps plants to grow,  stomata opening,  maintain the shape of plants  enables plant to stand straight. PLASMOLYSIS: is when water leaves the plant cell, the cell membrane pulls away from the cell wall and the cytoplasm shrinks and the cell become flaccid. Plasmolysis occurs when the plant cell loses more water than it absorbed, the cytoplasm shrinks and the cell membrane pulls away from the cell wall, this will lead to wilting and death of plant. Describe the structure and function of the root hairs Root hairs are tiny, hair –like structures that grow out of the roots that absorb water and nutrients from the soil. They have thin membrane to allow water and nutrients to move through it. It has selective permeability to allow only certain minerals to enter the root. The vacuole is filled with a salt solution that is more concentrated than the soil and thus enables water to enter the plant by osmosis. Root hairs help to anchor the plant in the soil. Root hairs consist of a cell wall, membrane, cytoplasm, a vacuole and a nucleus.Figure: A Structure of a root hair Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Describe how water molecules moves from the soil into root hairs The process of osmosis is responsible for water absorption in plant, usually the cell sap in plant cell is of higher concentration than the surrounding areas hence it draws water from the surrounding soil particles into the root hairs MOVEMENT OF WATER THROUGH THE VASCULAR TISSUES OF PLANTS. _ Water enters root hairs by osmosis _Water passes across the roots from cell to cell by osmosis _Water is drawn up into the xylem vessels of the roots, water moves in the xylem of the stem to the leaves by transpiration stream/pull. _Water then evaporates into the air space in spongy mesophyll of the leaves / water vapour escapes through the stomata. XYLEM VESSEL: It transport water and mineral from the roots to the leaves/ rest of the plant. PHLOEM TUBES: It transport manufactured food in the leaves to other parts of the plant where it is stored. HOW DISSOLVED MINERALS ARE TAKEN UP BY PLANTS IN TERMS OF DIFFUSION AND ACTIVE TRANSPORT. Minerals are in a solution form in concentration, minerals are absorbed by the root hairs against their concentration gradient by active transport. Plant roots takes up minerals through diffusion, Property of Zambezi Regional Council, Directorate of Education, Arts & Culture These minerals are then transported through the xylem vessels, along with water through the stems and to the leaves, If the mineral concentration inside the plant cell is higher than the concentration outside, then Energy is needed to move the mineral particles from a lower concentration to a higher concentration. This movement of particles through a membrane against a concentration gradient is called active transport. ACTIVE TRANSPORT: The movement of minerals from the region of low concentration to a region of higher concentration, against concentration gradient, using energy. Explain how the structure of a leaf is related to function Leaves are flat with wide surface to enable them to use maximum light for photosynthesis. Its thin for easy absorption of carbon dioxide. It has many stomata for carbon dioxide to enter It has chloroplasts containing chlorophyll that absorbs the sunlight. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture FUNCTIONS OF LEAF Site for photosynthesis Exchange of gases It absorbs sunlight for photosynthesis Outline gas exchange by diffusion through stomata Carbon dioxide enters the leaves and oxygen moves out of the leaves. The gases move in and out the leaves through the stomata in the leaves by means of diffusion. Each stoma has guard cells around it that allow the stomata to open or close. Describe the significance of carbon dioxide in the process of photosynthesis. Carbon dioxide is essential to make the reactions with sunlight in the photosynthesis process. It combines with water to allow the plant extract the nutrients it needs. Carbon dioxide combines with hydrogen atoms to form glucose during photosynthesis. PHOTOSYNTHESIS: The process by which green plants form carbohydrates (food) from carbon dioxide and water in the presence of light The chemical equation for photosynthesis The process of photosynthesis  Carbon dioxide diffuses from the air through the stomata into the air spaces between cells of spongy layers.  Water is absorbed from the soil, water moves by osmosis from the roots through the xylem vessels to the leaves.  In the palisade cells, Carbon dioxide and water combine in the presence of sunlight absorbed by chlorophyll, to produce carbohydrates (glucose) and oxygen.  Carbohydrates and Oxygen produced are used for respiration to produce energy. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Describe the importance of photosynthesis for plant growth. Photosynthesis helps the plant to convert light energy into chemical energy to sustain its life processes. Glucose produced during photosynthesis is used for the formation of cellulose that makes up the plant cell wall. The energy produced during photosynthesis is used for respiration. Extra glucose produced during photosynthesis is the one stored in a form of fruits and vegetables. RESPIRATION: Respiration is process in which oxygen from the air is used to breakdown carbohydrates to release energy. Respiration takes place in all living plant cells at all times. The mitochondria is the site of respiration within the cell. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Discuss the significance of respiration in plant growth Respiration produces energy needed by plants to form new plant materials (such as leaves) and maintaining existing once.The balance between respiration and photosynthesis makes the plants to grow well. Define translocation. Translocation is the movement of dissolved food materials made in leaves to other parts of the plant. The manufactured food (glucose) is moved through the phloem vessel by active transport. The diagram above shows how water, minerals and food move in a plant. Discuss the significance of translocation in plant growth. It helps all parts of the plant to receive glucose needed for plant growth. Explain the principles of modification of different parts of plants to form food storage organs and their relation to the type of food stored  Some plants have modified parts that are used as storage structures. That means when a plant manufactures more food than it require, the excess food substances are stored for future use. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Storage structures in most plants are: seeds, roots, stems, leaves and fruits.  Reserve food is stored in a form of starch.  In maize and beans food stored in the endosperm and cotyledons (seeds)  Potatoes store food (carbohydrates) in tubers.  Fruits like mango, paw-paw and watermelons store food in thick fleshy parts of the fruit.  Carrots store food (carbohydrates and water) in the taproot.  Sweet potatoes store food (carbohydrates) in tubers.  Onion store food (carbohydrates and water) in bulbs. Define transpiration Transpiration - Is the loss of water vapour from the leaves through the stomata into the atmosphere. Discuss the significance of transpiration in plant growth. It helps with photosynthesis as water that reaches the leaf is used for photosynthesis. It cools the plant down. It helps the plant to absorb minerals from the soil. It supplies carbon dioxide to the plant that enters the leaf through the open stomata, where the water evaporates. TRANSPIRATION PROCESS Define sexual reproduction Sexual reproduction is the process in which new plants grow from seeds produced from two gametes. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  In this process a male and female cells fuse together and grow to become a new plant. Describe the structure and function of the flower of a maize plant and a bean plant. Maize plant Sexual parts of a maize plant STRUCTURES OF A MAIZE FLOWER AND THEIR FUNCTIONS Tassel is the male part of a maize plant and is composed of a large number of anthers. The anthers produce pollen grains falls and carried by wind. Cob is the female part of maize plant It has many ovules inside A style grows from each ovule at the tip of each cob. These styles trap pollen grain from the wind. Collectively all styles are called silk. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture STRUCTURES OF BEAN FLOWER AND ITS FUNCTIONS. BEAN PARTS INVOLVED IN REPRODUCTION The anthers contain the pollen grains, the male sex cells. Filaments hold the anther. The ovary is the female reproductive organ that contains ovules. Ovary develops into a bean pond. Ovule is the reproductive cell that becomes the seed/beans after fertilization. Stigma receives the pollen grains. Styles transport the pollen from stigma to the ovary. Petal attracts the insect for pollination. Sepal [Calyx] holds the parts of the flower together. [Anther and filament forms up stamen male part of the flower] [Stigma, style , ovary and ovules forms up the pistil female part of the flower] Describe the mechanism of pollination in maize plants (wind pollination) and bean plant (insect pollination) Define pollination It is the transfer of pollen grains from the anther to the stigma. This can be done by insects and wind. There are two types of pollination 1. Self-pollination this occurs when a pollen grain lands on the stigma of the same flower or flower of the same plant. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture 2. Cross pollination occurs when a pollen grain lands on the stigma of a flower of a different plant of the same species Describe the differences between insect and wind pollinated flowers Insect pollinated Wind pollinated Large flower Small flower Bright petals Dull colour petals Scented petals No scent Nectar present No nectar Firm/small anthers/anther inside Loose/large anthers/anthers outside Thick stigma inside the flower Feathery stigma/outside the flower Mechanism of Pollination In Maize Plant (Wind Pollination) A maize plant has no petals Therefore it cannot attract insects to itself for pollination The structure of a maize flower (tassel) and cob is adapted for wind pollination e.g. pollen grain is light and powdery and can therefore be carried by the wind, Style can easily trap pollen because they are long and sticky. State the reason why self-pollination in maize is very unlikely to occur Male and female part mature at different times Mechanism of pollination in beans plant (insect pollination) When insect lands on the flower to collect nectar, pollen sticky to the hair of an insect. When it visits another bean flower the pollen is dropped (left) on the stigma of that flower. Describe the process of fertilization in a named plant Define fertilization - Fertilization is the fusion of the male and female sex cells to form a zygote. How fertilization occur in a bean plant.  When pollen grain lands on the stigma,  it develops a pollen tube inside the style to the ovary  It enters the ovule[micropyle]  The male gamete fuses with the female gamete to form a zygote.  The ovary develops into a bean pod.  The ovules develop into seeds/beans. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Describe asexual reproduction from stem tubers: Irish potato Define asexual reproduction Asexual reproduction is the process in which a new plant grows from a part of a single parent.e.g. a stem cutting or stem tubers, Such as Irish potatoes and Sweet potatoes. (Solanum tuberosum) and from stem cuttings: sweet potatoes. Asexual reproduction in sweet potato (Ipomoea batatas) [stem cuttings] Sweet potatoes develop from stem cuttings. Pieces of stem cuttings are planted. Cuttings are kept moist before planted. Buds or new stems with root develop from the stem. Tubers act as storage organs. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture 1 2 3 Asexual reproduction in Irish potatoes (Solunum tuberosum) [Stem tubers]  New plants are grown from a stem tuber from a parent plant.  Buds develop  Shoots develop from buds  New plant grows above ground  Produce starch during photosynthesis  Stored in new tubers 1 2 3 Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  ADVANTAGES OF ASEXUAL REPRODUCTION  It grows or mature faster  Cheaper , no seed cost  Offspring’s are identical with their parents. CEREAL CROPS CEREAL CROPS PRODUCTION IN NAMIBIA. Explain what is meant by a cereal crop  Cereal crops are crops that produces grains e.g. maize, rice, millet/mahangu, wheat, oats, sorghum and barley Explain what is meant by seed viability SEED VIABILITY  Is the ability of the seed to germinate and develop into seedlings/plants when planted under suitable conditions or  Seeds that are alive and able to germinate  Viable seed is a seed that is alive and able to germinate and grow. Outline the importance of viable seeds  It can germinate and grow  Its free from pests and diseases Determining the germination percentage of the seeds Collects a sample of seeds Place the seeds on a petri-dish with a damp paper towel/cotton wool Leave the petri-dish under a warm condition /suitable condition for 5-6 days Count the number of seeds germinated after 5-6 days. Calculations on seeds germination percentage (%) Calculate the percentage of seeds germinated by dividing the number of seeds placed in the dish multiplied by hundred. % viable seeds= number of seeds germinated/number of seeds placed in the dish x 100 Discuss factors that determine plants spacing and planting depth of cereal crops Water availability: in areas with enough soil water or where rainfall is high, seeds can be planted closely together as there will be no competition of water or In areas with less soil water or less rainfall, seeds should be planted far apart to avoid competition of water Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  Soil type: in clay soil, seeds can be sown closely together; the soil can hold water for a longer period or In sandy soil, seeds can be sown further apart because water drains faster leading to competition of water and nutrients Soil fertility: The higher the fertility of the soil, the closer the spacing can be, soil with low fertility needs wider spacing. Describe the methods employed in the cultivation of one of the following crops MAIZE Describe the soil and climatic requirement of maize crop Soil requirement of maize  A deep, well-drained soil/ well aerated  A fertile loam soil  Soil pH of 5.5 – 7.0 Climatic requirement of maize  High temperature/ optimum temperature  A lot of sunshine  Rainfall of about 450 mm – 900 mm per annum. Describe the seedbed preparation  Clearing/removing stones  Digging/ploughing/cultivating the soil  Harrowing/leveling the soil to a fine tilth.  Application of fertilizers/manure. Sowing/planting time After the first rain in summer, (October-December). Planting space  Inter row: 1-2 m  In row: 30-60 cm Planting depth  2-6 cm deep Define seed rate: the total number of seeds to be planted per hole in kilograms (25kg/ha). Planting methods for maize  Using a planter /machine (planting in rows).  Using hands (by broadcasting). APPLICATION OF FERTILIZERS (ORGANIC AND INORGANIC FERTILIZERS) Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Describe the fertilizer requirement of maize  Basal dressing: application of fertilizers before sowing/planting. During winter before planting, incorporate 300-400 kg of superphosphate/ha. Apply 400 kg/ha of NPK (2:3:2)  Top dressing: application of fertilizer after planting/ germination. Apply more or less 120 kg/ha of LAN with six weeks after planting or any fertilizer containing nitrogen. Describe the recognition of crop maturity, harvesting and storage Crop maturity Harvesting method Storage conditions  When kernels are  Using hands.  Store in dry place. hard/dry.  Using a combine  Free from pests.  When silk turns brown. harvester/ machine.  Store in a cool, well  When cobs hang ventilated place. downwards.  Clean place.  When grains are hard.  When leaves turns brown. Explain reasons for the suitability of cereal crops to local conditions Millet/sorghum  Drought resistance/adapted to extreme heat and drought experienced in the area;  Has a short growing period as Namibia/the area receive seasonal rainfall;  It does not require more water/regular rainfall during the growing season Maize  It require high temperature experienced in the area  It requires a lot of sunshine/cloudless sky making it suitable as Namibia receives so much sunshine;  Require high rainfall thus grow well in North-eastern Namibia where rainfall is higher;  Prefers alluvial soil (clay) found in North-east of Namibia where it is mostly planted. Rice/wheat  Prefers alluvial soil (clay) found in North-east of Namibia where it is mostly planted  Requires a lot of water making it suitable to grow in the area as it receives high rainfall  Requires cooler temperatures experienced in the area  Requires a lot of sunshine/cloudless sky making it suitable as Namibia receives so much sunshine. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture SUITABLE CULTIVARS Explain what is meant by a cultivar Cultivar is the variety of crop that has been developed for its desired characteristics. Cultivar is a variety of a plant produced by selective breeding for its needed characteristics. Identify specific cultivars of a chosen crop Cultivars of maize grown in Namibia  Kalahari Early Pearl (90-105 days to mature).  Potchefstroom Pearl (125-105 days to mature). State reasons for choosing a particular cultivars  Short growing period/mature early.  High yield.  Good quality products.  Resistant to pests and diseases.  Adapted to local conditions/adaptability.  Resistant to drought. Crop Protection  Pest control Weeds, insects and other pests, plant diseases and mineral deficiency frequently limit the development of crop plants; this causes a reduction in the yield and quality of the produce. The losses due to pests, diseases and weeds are very substantial mostly in tropical and sub-tropical countries, where high temperature and humidity in these areas facilitate the rapid and constant multiplication of the pests and diseases more than in temperate countries. To reduce these pests, weeds and diseases to a lower population, crop protection has now become one of the key aspects of crop cultivation. Describe the following types of pest and the nature of the damage they cause: a. Biting and chewing: These are insect pests whose mouth part is adapted for biting and chewing by possessing strong mandible and maxillae (mouth-parts) which enable Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  them to bite and chew plant parts. Examples include: termites, grasshoppers, leaf worms, army worms, locusts, beetles, etc. Army worms in action Picture by: Simaimbula R Mouth part of a Biting and Chewing insect pest. Damage caused: The damage caused by the biting and chewing insects includes: making holes in the leaves or stems; semicircular holes along the edges of the leaves; discolouration on the surface or the Property of Zambezi Regional Council, Directorate of Education, Arts & Culture edges of the foliage/ leaf and flower petal; severed stems and leaves; and plant wilting hence reducing the process of photosynthesis. 1. Piecing and Sucking: The mouthparts of sucking insects are developed for piercing and sucking. These pests damage plants by inserting their mouthparts into plant tissue and removing juices. Heavily infested plants become yellow, wilted, deformed or stunted, and may eventually die. Their mouth parts are pointed like a needle very sharp and adapted to pierce and then suck out cell sap or juice in plants. e.g aphids, mealy bugs. aphids 2. Boring pests: Boring insects are serious pests that can severely endanger plant health and kill it. Many of the boring insects that attack crops are in the insect order Coleoptera or beetle family of insects. These pests have a mouth mainly adapted to create a hole or tunnel inside the stalk or fruit and even seeds of a plant. The damage caused by these pests is such that they tunnel and feed under the bark inside the stem, destroying water- and sap-conducting tissues. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  3. Soil pests. Soil pests are harmful pests which include snails, sciara fly, nematodes and eel worms. During their life cycle, all these organisms have one or more stages in which they parasitise on the plant roots. In addition to this 'underground' damage they also cause damage to above-ground parts. These pests reside in the soil. They cause so much damage especially the roots of crops, mainly tomatoes, these pests cut off the connective tissues like xylem and phloem vessels. Describe the methods of controlling pests, weeds and diseases including: Biological, chemical and cultural. (a). Biological: this is a method in which pests, weeds and diseases are controlled using other living organisms. Mainly natural enemies or control agents are introduced. Birds are a natural enemy of the cutworms so a farm with a healthy bird life may not suffer from the damaging effects of the cutworms. However, birds may tend to be pests on the other hand. ADVANTAGES DISADVANTAGES Easy to control specific organisms At times the enemy may eat crops instead Effective Does not remove the pests entirely Cost effective in the long term Expensive to start (b). Chemical method. This is a method of controlling pests using chemicals called pesticides. Pesticides are any chemicals that kill, repel or prevent pests, weed and diseases from the any damage. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture herbicides: these are chemicals used to kill weeds insecticides: these are chemicals used to kill pests Examples:  Non- selective herbicides/pesticides- these affects a wide range of weeds.  Selective herbicides/pesticides- kills some plants but not others. The ways in which different types of herbicides affects weeds  Systemic herbicides/ pesticides: the chemicals are absorbed into the plant sap and move throughout the plant, through the vascular system. This disrupts normal growth and function which then kills the weeds or pests.  Contact herbicides/pesticides: these are toxic to plant tissue with which they come into contact. The chemical enters the stomata by diffusion causing the plant to gradually die. Soil Sterilents: these are applied to the soil and prevent the emergence of weeds for some time. They are absorbed by the roots of the plants and enter plant tissue and kill the weed. ADVANTAGES DISADVANTAGES Quick or rapid effect Guaranteed efficient and effectiveness It is expensive to buy chemicals Large areas are covered within a short time Labour intensive in applying chemicals on large fields Easy to use May result in pollution of water and soil, making them unsuitable for use Prevents the return of pests Can result into chemical resistant for pests Kills specific pests It kills beneficial insects Boosts the growth of plants as they are free Excessive use of chemicals may lead to poor from damage crop yield Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Cultural method: this is method of controlling pests, weeds and diseases using traditional and locally available environment friendly means. This may include methods such as, crop rotation, deep ploughing, careful selection of varieties to grow, etc. This helps in reducing pests through preventing a buildup of a number of pests over a period of time and sometimes breaking their lifestyles ADVANTAGES DISADVANTAGES It is environmental friendly as it cannot cause Pests cannot be eradicated completely at once any pollution to the environment No much costs encountered Effective only for a single type of pest. Safe for most crops Detailed knowledge of pest and crops is needed. Describe integrated pest management as an ecosystem based strategy which focuses on long term prevention of pests or their damage through a combination of techniques Integrated pest management. IPM is a combination of all well-known pest, weed and disease control methods. This method is based on a strategy to prevent the loss of both crops from pest, weed and disease attack. IPM uses information about the pest, weed and disease and the environment to plan that includes all the known methods. The aim of IPM is to minimize at the lowest cost and with the least amount of damage to the environment, properties and people. ADVANTAGES DISADVANTAGES Promotes sound structures and healthy crops Are extremely complex and require a high level of understanding to utilize Promotes sustainable bio-based pest Involves a lot of time management alternatives Reduces environmental risk associated Are sometimes more costly than traditional with pest management by encouraging the methods of spraying pesticides adoption of more ecologically benign control tactics. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  DISEASE CONTROL Describe the mode of infection, harmful effects, prevention and control of one plant disease A disease refers to any sickness that affects the normal functioning of an organism. Diseases can be grouped according to the organism that causes them namely: bacteria, fungi, and virus. BACTERIAL DISEASES Bacteria are said to be very small single celled organisms. Bacteria differs in so many ways some are beneficial for example the nitrogen fixing bacteria which are more beneficial for plant growth. Some other bacteria are used to make yoghurt and beer. However, there are some bacteria that can cause diseases to crops and humans. The table below shows some common examples of bacterial diseases. DISEASES MODE OF INFECTION HARMFUL EFFECTS PREVENTION Bacterial The bacteria lives in moist soils. The bacteria block the xylem No chemical control method wilt They move through roots to the and phloem in the stem exists. The infected plant stem of the plant. preventing the movement of must be removed both water and manufacture immediately. food and the plant eventually Cultural control method is the dies. best e.g. crop rotation. Bacterial The bacteria are found in crop The leaves of the plants Plant resistant varieties. Blight residues and can be transmitted develop yellow spots that Rotate the crops. through seeds. turn brown reducing Use clean seeds only. photosynthesis. Black rot The bacteria survive in seeds, The leaves of the plant go Use only clean seeds, once a plant is infected, the brown and then black and Use clean transplanted bacteria move between plants in the plant may die. seedlings. splashes of water. Use crop rotation and cultural The bacteria also move through methods. transplanted seedlings. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  FUNGAL DISEASES; A Fungus is a small, spore-producing organism that decomposes organic materials. DISEASES MODE OF INFECTION HARMFUL EFFECTS PREVENTION Damping off. Soil- borne. The fungus Seeds and seedlings rot Do not plant old seeds can be carried in tools and beneath the soil. Plants Do not overcrowd seedlings. any soil that is moved. germinate but after a while Plant seeds at a they become soaked and fall recommended depth and over then die. distance apart. Downy Soil borne. The fungus Plant leaves develops a Grow resistant varieties mildew spends winter in the soil yellow to white stripes Do not plant sorghum near and then infects seedlings covered in a white downy sugar cane. planted in the soil. layer. Maize and A fungal disease of cereals The tassels and ears of Plant resistant varieties sorghum in which parts of the ear cereals are deformed and Fertilize soil well smut change to black powder kernels do not form on cobs. Treat seeds with a fungicide Plants have stunted growth (a chemical that destroys and some yield fungus). VIRAL DISEASES; A virus is a very small agent or parasite that is able to multiply (reproduce itself) within the cells of living organisms or hosts. The following are a list of viral diseases. DISEASE MODE OF INFECTION HARMFUL PREVENTION EFFECTS Mosaic Virus Mosaic Virus is transported by Plant leaves change Plant resistant variety aphids and affects mostly sugar colour, become Control aphid biologically by cane, maize, and sorghum. stunted unable to encouraging ladybird beetles. produce and can even die. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Maize streak virus Transmitted between crops by Stunted growth in Plant early insects, e.g. leaf hoppers; they plants Apply NPK lay infected eggs on maize Remove all infected plants. leaves and when they hatch they feed on the crop and infect it. Rosette virus Aphids spread this disease by Leaves turn yellow Plant resistant variety feeding on an infected plant then resulting into stunted Crop rotations help. move to another healthy plant growth. Destroy all the debris or crop hence infecting it. remains after harvest. WEED CONTROL Identify a named weed species affecting crops in Namibia A weed is a plant that grows where it is not wanted and mostly tend to be in a competition with cultivated crops. Investigate and describe its harmful effects and the mode of spread EXAMPLE HARMFUL EFFECTS MODE OF EXPLANATION SPREAD Dandelion Compete for: Nutrients, water, Wind Weeds that are spread by the wind sunlight, resulting to poor yield. are light and easily blown or carried away. Mangroves Compete for: Nutrients, water, Water Such weeds float on water and are sunlight, resulting to poor yield. carried somewhere else. Downy thorn Compete for: Nutrients, water, Animal digestion Such seeds have a hard cover so as to apple sunlight, resulting to poor yield. pass through the animal’s digestive tract and be excreted Black jack Compete for: Nutrients, water, Catching on clothes Such weeds are spread by catching on sunlight, resulting to poor yield. and skin of people the fur and clothing of animals and and animals. humans respectively. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Spotted Compete for: Nutrients, water, Mechanical means Such weed seeds explode and scatter knapweed sunlight, resulting to poor yield. to far directions. Effective Does not remove the pests entirely Cost effective in the long term Expensive to start (b).Chemical method. This is a method of controlling pests using chemicals called pesticides. Pesticides are any chemicals that kill, repel or prevent pests, weed and diseases from the any damage. Herbicides: these are chemicals used to kill weeds Insecticides: these are chemicals used to kill pests Examples:  Non- selective herbicides/pesticides- these affects a wide range of weeds.  Selective herbicides/pesticides- kills some plants but not others. The ways in which different types of herbicides affects weeds  Systemic herbicides/ pesticides: the chemicals are absorbed into the plant sap and move throughout the plant, through the vascular system. This disrupts normal growth and function which then kills the weeds or pests.  Contact herbicides/pesticides: these are toxic to plant tissue with which they come into contact. The chemical enters the stomata by diffusion causing the plant to gradually die. Soil Sterilents: these are applied to the soil and prevent the emergence of weeds for some time. They are absorbed by the roots of the plants and enter plant tissue and kill the weed. ADVANTAGES DISADVANTAGES Quick or rapid effect Guaranteed efficient and effectiveness It is expensive to buy chemicals Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Large areas are covered within a short time Labour intensive in applying chemicals on large fields Easy to use May result in pollution of water and soil, making them unsuitable for use Prevents the return of pests Can result into chemical resistant for pests Kills specific pests It kills beneficial insects Boosts the growth of plants as they are free from Excessive use of chemicals may lead to poor crop yield damage Cultural method: this is method of controlling pests, weeds and diseases using traditional and locally available environment friendly means. This may include methods such as, crop rotation, deep ploughing, careful selection of varieties to grow, etc. This helps in reducing pests through preventing a buildup of a number of pests over a period of time and sometimes breaking their lifestyles. ADVANTAGES DISADVANTAGES It is environmental friendly as it cannot cause Pests cannot be eradicated completely at once any pollution to the environment No much costs encountered Effective only for a single type of pest. Safe for most crops Detailed knowledge of pest and crops is needed. Integrated pest management. IPM is a combination of all well-known pest, weed and disease control methods. This method is based on a strategy to prevent the loss of both crops from pest, weed and disease attack. IPM uses information about the pest, weed and disease and the environment to plan that includes all the known methods. The aim of IPM is to minimize at the lowest cost and with the least amount of damage to the environment, properties and people. ADVANTAGES DISADVANTAGES  Promotes sound structures and healthy crops 1. More involvement in the technicalities of the  Promotes sustainable bio-based pest method management alternatives  IPM needs to be planned Property of Zambezi Regional Council, Directorate of Education, Arts & Culture   Reduces environmental risk associated  IPM demands more attention and dedication  Requires expertise of various field with pest management by encouraging the  All those involved in the IPM needs to be educated adoption of more ecologically benign and trained which often requires much time. control tactics. 2. Time and energy consuming  Application of IPM takes time.  Much time is needed in planning itself.  As IPM strategies differs from region to region, a separate plan is required for each region.  The expected results of intervention may take long time to be achieved. Challenges in IPM:  Financial constraints in initiation of the IPM  Lack of involvement of the expertise  Inadequate research on pests  Lack of supportive government and policies  In developing countries where traditional farming is still practiced, farmers are unknown to the concept of IPM as well as IPM seems difficult to practice DISEASE CONTROL A disease refers to any sickness that affects the normal functioning of an organism. Diseases can be grouped according to the organism that causes them namely: bacteria, fungi, and virus. BACTERIAL DISEASES Bacteria are said to be very small single celled organisms. Bacteria differs in so many ways some are beneficial for example the nitrogen fixing bacteria which are more beneficial for plant growth. Some other bacteria are used to make yoghurt and beer. However, there are some bacteria that can cause diseases to crops and humans. The table below shows some common examples of bacterial diseases. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture DISEASES MODE OF INFECTION HARMFUL EFFECTS PREVENTION Bacterial wilt The bacteria live in moist The bacteria block the xylem No chemical control method soils. They move through and phloem in the stem exists. The infected plant roots to the stem of the preventing the movement of must be removed plant. both water and manufacture immediately. food and the plant eventually Cultural control method is dies. the best e.g. crop rotation. Bacterial Blight The bacteria are found in The leaves of the plants Plant resistant varieties. crop residues and can be develop yellow spots that Rotate the crops. transmitted through seeds. turn brown reducing Use clean seeds only. photosynthesis. Black rot The bacteria survive in The leaves of the plant go Use only clean seeds, seeds, once a plant is brown and then black and Use clean transplanted infected, the bacteria move the plant may die. seedlings. between plants in splashes Use crop rotation and of water. cultural methods. The bacteria also move through transplanted seedlings. FUNGAL DISEASES; A Fungus is a small, spore-producing organism that decomposes organic materials. DISEASES MODE OF INFECTION HARMFUL EFFECTS PREVENTION Damping off. Soil- borne. The fungus Seeds and seedlings rot Do not plant old seeds can be carried in tools and beneath the soil. Plants Do not overcrowd seedlings. any soil that is moved. germinate but after a while Plant seeds at a recommended they become soaked and depth and distance apart. fall over then die. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture Downy mildew Soil borne. The fungus Plant leaves develops a Grow resistant varieties spends winter in the soil yellow to white stripes Do not plant sorghum near and then infects seedlings covered in a white downy sugar cane. planted in the soil. layer. Maize and A fungal disease of The tassels and ears of Plant resistant varieties sorghum smut cereals in which parts of cereals are deformed and Fertilize soil well the ear change to black kernels do not form on Treat seeds with a fungicide (a powder cobs. Plants have stunted chemical that destroys growth and some yield fungus). VIRAL DISEASES; A virus is a very small agent or parasite that is able to multiply (reproduce itself) within the cells of living organisms or hosts. The following are a list of viral diseases. DISEASE MODE OF HARMFUL PREVENTION INFECTION EFFECTS Mosaic Virus Mosaic Virus is Plant leaves change Plant resistant variety transported by aphids colour, become Control aphid and affects mostly stunted unable to biologically by sugar cane, maize, produce and can even encouraging ladybird and sorghum. die. beetles. Maize streak virus Transmitted between Stunted growth in Plant early crops by insects, e.g. plants Apply NPK leaf hoppers; they lay Remove all infected infected eggs on plants. maize leaves and when they hatch they feed on the crop and infect it. Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  Rosette virus Aphids spread this Leaves turn yellow Plant resistant variety disease by feeding on resulting into stunted Crop rotations help. an infected plant then growth. Destroy all the debris move to another or crop remains after healthy plant hence harvest. infecting it. WEEDS A weed is a plant that grows where it is not wanted and mostly tends to be in a competition with cultivated crops. EXAMPLE HARMFUL DISPERSAL EXPLANATION EFFECTS Dandelion Compete for: Wind Weeds that are spread Nutrients, water, by the wind are light sunlight, resulting to and easily blown or poor yield. carried away. Mangroves Compete for: Water Such weeds float on Nutrients, water, water and are carried sunlight, resulting to somewhere else. poor yield. Downy thorn apple Compete for: Animal digestion Such seeds have a Nutrients, water, hard cover so as to sunlight, resulting to pass through the poor yield. animal’s digestive tract and be excreted Black jack Compete for: Catching on clothes Such weeds are and skin of people spread by catching on and animals. the fur and clothing Property of Zambezi Regional Council, Directorate of Education, Arts & Culture  Nutrients, water, of animals and sunlight, resulting to humans respectively. poor yield. Spotted knapweed Compete for: Mechanical means Such weed seeds Nutrients, water, explode and scatter to sunlight, resulting to far directions. poor yield. Describe biological, cultural and chemical weed control Various methods of weed control CULTURAL CONTROL Use of clean seeds- Crop seeds should be free from weed seed