Agronomy Fundamentals and Relationships

Agronomy Fundamentals

• Agronomy is a branch of agricultural science focused on field management for crop production
• Scope includes crop production, soil management, proper tillage methods, and suitable sowing times.
• Agronomy is important for higher yields, organic farming, sustainable agriculture, forestry, poultry, sheep and goat rearing, and mixed cropping.

Agronomy Relationship with Other Sciences

• Agronomy has close connections with soil science, agricultural chemistry, genetics, plant breeding, horticulture, crop physiology, animal husbandry (and dairy science), agro-meteorology, agriculture extension, agriculture engineering, agriculture economics, agro-forestry and statistics.
• Agronomy specialists should be knowledgeable in theory and practical applications.
• Specialists should be able to coordinate with subject matter specialists (SMS) and act as consultants for farmers.
• Expertise in agricultural production, conducting experiments (on sowing, seed rates, spacing, fertilizer requirement, weed management, and cropping systems), is needed.

Tillage Operations

• Tillage involves manipulating soil with tools and implements to loosen the surface and improve seed germination and crop growth.
• Objectives of tillage include making the soil loose and porous, removing weeds, mixing manures and fertilizers, destroying insects and eggs, aerating the soil, increasing soil temperature, removing stubbles, breaking hard pans, incorporating organic manures, and increasing exchange of air and gases.

Soil Tilth

• Soil tilth refers to the physical condition of soil resulting from tillage, considered good when soft, friable, and properly aerated.
• Characteristics of good soil tilth include a high percentage of larger aggregates, porosity, and free drainage. These characteristics must be measured properly.

Types of Tillage Operations

• Preparatory tillage operations are performed before sowing/planting to prepare the land for the next crop.
• Examples of methods include plowing, clod crushing, land leveling, and manure mixing.
• Seedbed preparation is a step after preparatory tillage.
• Intercultural operations, or inter-tillage, is performed on established crops.
• Examples of methods include thinning, gap filling, weeding, and top dressing of fertilizers.

Modern Concept of Tillage

• The modern goal of tillage is minimizing cultivation costs by reducing tillage operations.
• This is accomplished by decreasing the number of tillage steps and using minimum or no-till methods.

Seed and Seed Treatment

• Seed is the material used for sowing or planting.
• Qualities of good seed include genetic purity, high germination rate, freedom from pests and diseases, as well as other factors.
• Objectives of seed treatment are disease and pest control (including seedborne, soilborne, and airborne diseases and insects) and improving germination, and seed viability.

Seed Dormancy

• Seed dormancy is a condition wherein seeds do not germinate even when conditions are favorable.
• Causes include insufficient oxygen, unsuitable moisture levels, temperature variations, pests attacks, unsuitable sowing depth, rough or poor seedbed preparation, or diseased seeds.
• Methods of breaking dormancy include scarification, light exposure, and soaking in hot water.

Sowing Methods

• Broadcasting, drilling/line sowing, dibbling, transplanting, and planting in furrows are the different methods of sowing.

Plant Population

• Plant population is defined as the number of plants per unit area.
• Plant population influences crop growth and yield.

Crop Geometry

• Crop geometry is the distribution pattern of plants over the area including.
• Methods like solid planting, paired planting and skip row planting are used.

Manures and Fertilizers

• Manures are decomposed stable and barn yard refuse (including animal excreta).
• Fertilizers are manufactured chemicals used to improve plant nutrients.
• Both help increase crop yield.

Green Manuring

• Green manuring is the practice of incorporating undecomposed green plant tissues to improve soil fertility.
• This can be done in situ or as green leafy manures.
• Advantages are increased soil fertility, nitrogen fixation, weed suppression, improved soil structure, and stimulation of soil microorganisms.

Weeds

• Weeds are unwanted plants growing where they're not needed.
• Weed characteristics include high reproductive capacity, adaptability to different conditions, similarity to crop plants, and defense mechanisms against humans and livestock.
• Weeds are classified based on life cycle, habitat, dependence on other hosts, and soil types.

Weed Control

• Weed control encompasses both preventive methods like using clean seeds, and curative options including mechanical (hand weeding, tillage), cultural (crop rotation), biological (using specific insects or organisms), and chemical control.

Herbicides

• Herbicides are chemicals used to control weeds.
• They are classified based on their chemical composition, selectivity (i.e., target species), application type, and residual effects.

Allelopathy

• Allelopathy is a biological phenomenon where one organism produces chemicals, influencing other organisms. These chemicals often affect target plant growth negatively.
• Weeds can produce chemicals that reduce the yield or growth of crops.

Crop Rotation

• Crop rotation is the sequential planting of different crops on same land.
• Principles include adapting it to current soil-climate conditions, including all types of crops, managing organic matter, and controlling pests and diseases.
• Advantages include increased yield, enhanced soil fertility, and reduced pest/disease pressure.

Growth and Development

• Growth is an irreversible increase in size, volume, or mass, usually measured by dry weight increase.
• Development is a broader term encompassing various changes during a plant's life cycle.
• Factors affecting growth and development: genetic factors (genes, chromosomes, genomes), and environmental factors (temperature, moisture, sunlight, soil nutrients, soil aeration and soil reaction).
• growth curves include the lag phase, logarithmic phase, the diminishing phase and the stationary phase.

Plant Ideotypes

• Plant ideotype is a biological ideal or model representing the plant's traits.
• Ideotypes may be classified based on isolation, competition, or market needs.

Nutrient Use Efficiency

• Nutrient use efficiency (NUE) is the crop yield per unit of nutrients input.
• Factors affecting NUE include: type of soil, climate, type of fertilizers, time and methods of application, amount of fertilizer, nutrient's interaction.
• Crop distribution refers to the movement of crop varieties or technologies from one geographic area to another.

Harvesting and Threshing

• Harvesting is the process of separating and removing the crop plants from the field.
• Signs of maturity in crops often include changes in color, dryness, and seed release.
• Threshing is the process of separating grains from stalks or heads, and methods include beating, using animals or machinery.
• Post-harvest processes include cleaning, drying and storage of crops to improve the quality.