UNIT – 1 Fundamentals of Agronomy 4(3+1)
Agronomy and its scope
Agronomy is derived from a Greek word ‘agros’ meaning ‘field’ and ‘nomos’ meaning
‘management’. Principles of agronomy deal with scientific facts in relations to environment in
which crop are produced.
Definition of Agronomy
- It is defined as an agricultural science deals with principles and practices of crop
production and field management. - Agronomy is branch of agricultural science, which deals with principles, & practices of
soil, water & crop management. - It is branch of agricultural science that deals with methods which provide favorable
environment to the crop for higher productively.
Scope of Agronomy
Seasonal Cultivation:
- Identifying the proper season for cultivating a wide range of crops.
Cultivation Methods:
- Developing methods to reduce cultivation costs and maximize yield and economic returns.
Chemical Fertilizers:
- Generating knowledge to mitigate ill-effects of excess fertilizer application and prevent yield losses from unscientific application.
Weed Control:
- Developing knowledge on the selectivity, timing, and method of herbicide application.
Water Management:
- Addressing water demand issues by determining optimal water application amounts and timing.
Intensive Cropping:
- Increasing production and reducing environmental hazards through proper time and space intensification.
Dry Land Agriculture:
- Developing technology to combat moisture stress in dry land conditions, crucial for future agriculture.
New Varieties:
- Creating packages of practices to fully exploit the potential of new crop varieties.
Farm Implements:
- Maintaining and efficiently utilizing farm implements to address labor shortages.
Seeds and Sowing
Seed – Seed is an embryonic part covered in a seed coat often containing some food. It is
formed from the ripened ovule of a plant after fertilization.
Grain – A grain is a small edible fruit usually hard on the outside, harvested from crops.
Grains basically grow in a cluster on top of the mature plant.
Differences between seed and grain
| Seed | Grain |
| A seed is an ovule containing an embryo. | Grain is a fusion of the seed coat and the fruit. |
| Use for planting and growing new plants. | Primarily use for consumption, either by humans or livestock. |
| It is selected for its genetic qualities and viability. | It is selected for its nutritional value and yield. |
| Usually more expensive due to the selection process, treatment, and quality assurance measures. | Generally less expensive per unit compared to seed. |
Classification of seed –
1 . Breeder Seed
- Breeder seed is the progeny of nucleus seed.
- Produced by the originating breeder or by a sponsored breeder.
2. Foundation Seed
- Foundation seed is the progeny of breeder seed.
METHODS OF SOWING
- Broadcasting
- Dibbling
- Sowing behind the country plough (manual and mechanical drilling)
- Seed drilling
- Nursery transplanting
1. Broadcasting
- Broadcasting is otherwise called as random sowing. Literally means ‘scattering the seeds’.
- Broadcasting is done for many crops.
- Mostly followed for small sized to medium sized crops.
- This is the largest method of sowing followed in India, since; it is the easiest and cheapest and requires minimum labours.
- All the seeds broadcasted do not have contact with the soil. 100% germination is not possible.
- Enhanced seed rate is required.
- Seeds cannot be placed in desired depth. Desired depth ensures perfect anchorage.
- Lodging (falling down) is common in broadcasting.
2. Dibbling
- Dibbling is refers to inserting a seed through a hole at a desired depth and covering the hole.
- Actually dibbling is a line sowing method.
- Dibbling is practiced on plain surface and ridges and furrows or beds and channels.
- This type of sowing is practiced only under suitable soil condition.
- This is done for wider spaced crops and medium to large sized seeds.
- Sorghum, maize, sunflower, cotton are dibbled on ridges and furrows.
- Advantages of line sowing are, (i) uniform population, (ii) better germination, (iii) reduced seed rate.
3. Sowing behind the plough
- Sowing behind the plough is done by manual or mechanical means.
- Seeds are dropped in the furrows opened by the plough and the same is closed or covered when the next furrow is opened.
- The seeds are sown at uniform distance.
- Manual method is a laborious and time consuming process.
- Seeds like redgram, cowpea and groundnut are sown behind the country plough.
- Major sown crop is ground out.
- Seeds are sown by mechanical means by Gorus – seed drill.
- Advantages: i) The seeds are placed at desired depth covered by iron planks, ii) except very small, very large seeds most of the seeds can be sown, e.g. maize, sorghum, millets, sunflower, etc.
4. Drill sowing (or) Drilling
- Drilling is the practice of dropping seeds in a definite depth covered with soil and compacted.
- In this method, sowing implements are used for placing the seeds into the soil.
- Both animal drawn Gorus and power operated (seed drills) implements are available.
- In this method, depth of sowing can be maintained and fertilizer can also be applied simultaneously.
- It is possible to take up sowing of inter crops also.
- It requires more time, energy and cost, but maintains uniform population per unit area.
- Seeds are placed at uniform depth, covered and compacted.
5. Transplanting
- This method of planting has two components, a. nursery and b. transplanting.
- In nursery, young seedlings are protected more effectively in a short period and in a smaller area.
- Management is easy and economical.
- Advantages –
- Can ensure optimum plant population
- Sowing of main field duration, i.e., management in the main field is reduced
- Crop intensification is possible under transplanting.
- Disadvantages
- Nursery raising is expensive.
- Transplanting is another laborious and expensive method.
Tillage and Tilth
Definition –
Tillage refers to the mechanical manipulation of the soil with tools and implements so
as to create favourable soil conditions for better seed germination and subsequent growth of
crops.
Tilth-
Tilth is a physical condition of the soil resulting from tillage.
Tilth is a loose friable (mellow), airy, powdery, granular and crumbly condition of the soil with optimum moisture content suitable for working and germination or sprouting of seeds and propagules i.e., tilth is the ideal seed bed.
Objectives of tillage
- To prepare ideal seed bed favourable for seed germination, growth and establishment;
- To loosen the soil for easy root penetration and proliferation;
- To remove other sprouting materials in the soil;
- To control weeds;
- To certain extent to control pest and diseases which harbour in the soil;
- To improve soil physical conditions;
- To ensure adequate aeration in the root zone which in turn favour for microbial and
biochemical activities; - To modify soil temperature;
- To break hard soil pans and to improve drainage facility;
- To incorporate crop residues and organic matter left over;
- To conserve soil by minimizing the soil erosion;
- To conserve the soil moisture;
- To harvest efficiently the effective rain water;
- To assure the through mixing of manures, fertilizers and pesticides in the soil;
- To facilitate water infiltration and thus increasing the water holding capacity of the soil, and
- To level the field for efficient water management.
Types of tilth
- Fine Tilth refers to the powdery condition of the soil.
- Coarse Tilth refers to the rough cloddy condition of the soil.
Fine seedbed is required for small seeded crops like ragi, onion, berseem, tobacco.
Coarse seedbed is needed for bold seeded crops like sorghum, cotton, chickpea, lablab etc.
Types of tillage
- On Season Tillage: It is done during the cropping season (June–July or Sept.–Oct.).
- Off Season Tillage: It is done during fallow or non-cropped season (summer).
- Special Types of Tillage: It is done at any time with some special objective/purpose.
On Season Tillage
Tillage operations done for raising the crops in the same season or at the onset of the crop
season are called as on season tillage.
A. Preparatory Tillage
It refers to tillage operations that are done to prepare the field for raising crops. It is divided
into three types viz., (i) primary tillage, (ii) secondary tillage, and (iii) seed bed preparation.
(i) Primary tillage – The first cutting and inverting of the soil that is done after the harvest of
the crop or untilled fallow, is known as primary tillage. It is normally the deepest operation
performed during the period between two crops. Depth may range from 10–30 cm.
(ii) Secondary tillage – It refers to shallow tillage operation that is done after primary tillage
to bring a good soil tilth. It includes cultivating, harrowing, pulverizing, raking, leveling and ridging operations.
(iii) Seed bed preparation – It refers to a very shallow operation intended to prepare a seed
bed or make the soil to suit for planting. Weed control and structural development of the soil
are the objectives.
Off Season Tillage
Tillage operation is done for conditioning the soil during uncropped season with the main
objective of water conservation, leveling to the desirable grade, leaching to remove salts for
soil reclamation, reducing the population of pest and diseases in the soils. etc. They are:
(a) Summer tillage – done during summer season in tropics to destroy
weeds and soil borne pest and diseases, checking the soil erosion and retaining the rain water.
(b) Winter tillage – It is practiced in temperate regions where the winter is severe that makes
the field unfit for raising crops.
(c) Fallow tillage – It refers to the leaving of arable land uncropped for a season or seasons
for various reasons.
Special Types of tillage
(i) Subsoil tillage (sub soiling) is done to cut open/break the subsoil hard pan.
(ii) Levelling by tillage – Arable fields require a uniform distribution of water and plant
nutrition for uniform crop growth.
(iii) Strip tillage – Ploughing is done as a narrow strip by mixing and tilling the soil leaving
the remaining soil surface undisturbed.
(v) Strip tillage – Ploughing is done as a narrow strip by mixing and tilling the soil leaving
the remaining soil surface undisturbed.
Blind tillage – It refers to tillage done after seeding or planting the crop (in a sterile soils)
either at the pre-emergence stage of the crop plants or while they are in the early stages of
growth so that crop plants (cereals, tuber crops etc.) do not get damaged, but extra plants and
broad leaved weeds are uprooted.
Crop density and geometry
Crop geometry is the pattern of distribution of plant over the ground or the shape of the area
available to the individual plant, in a crop field.
Crop geometry is altered by changing inter and intra-row spacing (Planting pattern).
(i) Square planting – Square arrangements of plants will be more efficient in the utilization of
light, water and nutrients available to the individual plants than in a rectangular arrangement.
(ii) Rectangular planting – Sowing the crop with seed drill, wider inter-row and closer intrarow and closer intra-row spacing leads to rectangularity.
(iii) Triangular planting – It is a method to accommodate plant density under perennial/tree
crops.
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