Unit I
DEFINITION OF AGRICULTURE, MEANING AND SCOPE OF AGRONOMY
Part-1
Agriculture word is derived from two Latin words “ager” or “agri” meaning “soil” &
‘cultra’ meaning ‘cultivation’
Agriculture is a very general term surrounding all aspects of crop production, livestock farming, fisheries, forestry etc.
Agriculture may be described as the art, the science and the business of producing crops and livestock for man’s use and employment.
Agriculture is the cultivation of lands for the production of crops for a steady supply of food and other needs for the
progress of the nation.
Agriculture is affected by a large number of factors, some of which can be controlled by man (soil and irrigation) which others are beyond the control (climate).
Agronomy word is derived from the two Greek words “Agros” meaning “field” & “nomos” meaning “to manage”
Agronomy is a part of agricultural science that deals with the principles & practices of soil, water and crop management.
It gives methods which provide a favourable environment to the crop for higher productivity.
Value of basic sciences for the development of Agricultural science
• Basic science - the study of basic principles & fundamentals of the respective subject.
• Applied science - the study in which the basic principles & fundamentals of respective the subject is applied in a practical field.
• Agricultural sciences are primarily applied sciences and are based on fundamental sciences of physics, chemistry, mathematics, physiology, biochemistry, zoology, botany, ecology, economics etc.
For example
1. Information of Botany is helpful in plant breeding and plant genetics. Evolution of different varieties in crops suitable to particular agro-climatic condition is possible because of botany.
2. The knowledge of zoology (basic science of entomology) helps the farmer to identify the insect pests which are accountable for damage to agricultural produce.
3. Soil chemistry helps in knowing the plant nutrient status in the soil and the deficiency
symptoms in plants.
4. physics helps in knowing the weather phenomena and soil conditions
5. Mathematics is essential in agricultural research and experimentation through statistics and Agricultural economics.
6. Study of economics is important in estimating the costs and returns and existing conditions of farmers in villages for making the improvements.
Out basic science, there can be no development in applied science. Basic and applied sciences are interrelated to each other in the field of Agriculture.
Scope of Agronomy
Agronomy is a dynamic discipline. with the progression of knowledge and a better understanding of plant and environment, agricultural practices are modified and new practices developed for high productivity,
for example, availability of chemical fertilizer has compelled the generation to know the method, quantity and time of application of fertilizers. Similarly, the availability of herbicides for the control of weeds has directed to the development of knowledge about selectivity, time and method of application of herbicides. To subdue the problems different management practices are developed.
Population pressure is increasing but the area under cultivation is the same, therefore more number of crops have to be grown on the same piece of land to grow the yield. This resulted in the practice of intensive cropping.
New technology has to be developed to subdue the effect of moisture stress under dryland conditions. As new varieties of crops with high yield potential become available new practices have to be formed to exploit their full potential.
Recovery of soil fertility, use of proper seed rates, preparation of good seedbed, proper conservation and management of soil moisture, correct dates of sowing for each improved variety and proper control of weeds are agronomic practices to make our limited land & water resources more productive.
Relation of Agronomy to other sciences
Agronomy is a combination of several disciplines like soil science, Agricultural chemistry, biochemistry, crop physiology, plant ecology and economics. Soil physical, chemical and biological characteristics have to be understood thoroughly to effect modification of soil environment. Similarly, it is necessary to know the physiology of crops to meet their requirements. Advancements in economic analysis helped in the production of crops economically.
Agronomist aims to achieve maximum production at minimum cost. He utilises the knowledge developed by basic and applied science for higher crop production. Agronomist has to test their suitability in the field whatever may be the research findings of other scientists and accept them finally and also judge the reactions of the farming community. He is an important person with working knowledge of all agricultural disciplines and coordinator of different subject matter specialists.
Role of Agronomist
Agronomist is the scientist who mainly deals with the research of problems of crop production, adopting and recommending practices of better field crop production and soil management to get high yield and income.
• Agronomist tries to obtain maximum production at minimum cost by exploiting the information of the basic and applied sciences for higher crop production.
• In a wider sense, agronomist is involved with the production of food and fibre to meet the needs of the growing population.
• He generates efficient and economic field preparation method for sowing crops in a different season. (Flatbed, Ridges and furrows)
• He is also regarded with the selection of suitable crop and varieties to suit or to match varied seasons and soils. Eg. Red soil - groundnut, Black soil - cotton, Saline soil – Finger millet (Ragi), Sandy soil – tuberous crops. In Kharif, if the water is sufficient to go for rice and water is not sufficient to go for sorghum, maize.
• Develops the efficient method of cultivation (nursery, whether broadcasting and transplantation or dibbling, etc.) which gives a better crop establishment and sustain the required population
• He has to know various types of nutrients required by crops including time and method of application.
• Agronomist must take a better weed management practice. Either through physical work or chemical (herbicides or weedicides) or cultural (by having wide space it may increase weed growth by practising interspace crops). Weeds are managed by an integrated weed management method also.
• Agronomist selects the proper method of Irrigation, Irrigation scheduling i.e. irrigation timing and quantity
based on the crops to be irrigated, whether to irrigate continuously or stop in between and how much water to be provided is computed by agronomy science to achieve maximum water use efficiency.
• Crop planning (i.e.) suitable crop sequence is produced by agronomist (i.e.) what type of
crop, cropping pattern, cropping sequence, etc. (Rice - Rice - Pulse)
• He also develops the method of harvesting, time for harvesting, etc. (Appropriate
time of harvest essential to prevent yield loss)
• Agronomist is accountable for every decision made in the farm management. (What type of crop to be produced? How much area should be allotted for each crop? How and when to market? How and When to take other management activities?) All the decisions should be exercised at an appropriate time to efficiently use resources available).
Seed and sowing
Requirements for sowing:
1. Good tilth
2. Optimum soil moisture at sowing depth
3. Manures and fertilizers
Seed material:
1. Seeds (grains used for sowing)
2. Veg propagules (stem cutting's rooted slips, tubers, rhizomes, etc)
Stem cuttings – sugarcane, rose
Rooted slips – forage crops. (Fodder crops)
Tubers – potato
Rhizomes – turmeric
Characteristics of seed or seed material:
1. Purity:
Free from rogues (off-types)
Free from other crop seeds
Free from weed seed.
Free from inert material
2. Fully matured & well developed.
3. Free from storage pests & seed born diseases
Ex. Red rot in sugarcane
Tikka leaf spot in groundnut
4. Free from dormancy (dor. prob are seen in groundnut, rice, sunflower)
5. Viable (soybean loses viability quickly)
6. High rate of germination (98-99%)
(germ Percentage in many panes of grass is 20-25%)
METHODS OF SOWING
1. Broadcasting
2. Dibbling
3. Sowing behind the country plough (manual & mechanical drilling)
4. Seed drilling
5. Nursery transplanting
1. Broadcasting
Broadcasting is differently called as random sowing. It means ‘scattering the seeds’.
Broadcasting is done for many crops. Broadcasting is often followed for small-sized to medium-sized crops. This is one of the most used methods of sowing in India as it is cheap, simple and requires minimum labours. To have optimum plant population in the unit area certain rules should be followed.
• A skilled person broadcasts the seeds for uniform scattering.
• The ploughed field should be in perfect condition to trigger germination.
The seeds are broadcasted in a narrow strip & the sowing is completed strip by strip. To
ensure a good & uniform population, it is better to broadcast in either direction. This is called criss-cross sowing. If the seed is too small, it is mixed with sand to make a big one and for easy handling. Ex. Sesame seeds are mixed with sand and sown.
In a few cases, the person sowing the seeds will be beating it against the basket for uniform scattering. e.g. Sorghum, pearl millet etc.
After broadcasting, the seeds are covered smoothly by using a country plough by a shallow ploughing or some wooden planks are used to cover the surface. In some cases, shrub branches or tree twigs are used. If the seeds are large, levellers collect the seeds & leave on the other side. Comb harrow is the best-used one.
Disadvantages
• All the seeds that are 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
This is actually line sowing. Inserting a seed in a hole at the desired depth and covering the hole. Dibbling is practised on plain surface and ridges and beds or furrows and channels. This type of sowing is practised only in suitable soil condition. On a plain surface, Rice fallow cotton is dibbled. The seeds are dibbled at 2/3rd from the top or at 1/3rd from the bottom of the ridge. Before sowing, furrows are opened & fertilizers are applied above which seeds are sown. The seeds do not come in contact with the fertilizers. Dibbling is done for wider spaced crops and medium to large-sized seeds. e.g- maize, cotton, sunflower, sorghum etc. are dibbled on ridges and furrows. Both 'Beds & channels' and 'Ridges & furrows' come under line sowing. While earthing up, the plant obtains the middle of the ridge. Earthing up is crucial for the proper anchorage of the root system.
Benefits of line sowing-
(i) uniform population,
(ii) better germination,
(iii) reduced rate of seed.
3. Sowing behind the plough
Sowing behind the plough is performed by manual or mechanical means. Seeds are drooped in the furrows and closed when next furrows opened by the plough.
The seeds are sown at an equal distance. Manual method is a laborious and time-consuming process. Seeds like groundnut, red gram, and cowpea are sown behind the country plough. The main sown crop is ground out. Seeds are sown by mechanical means with Gorus - seed drill. A seed drill has a ploughshare & hopper. Seeds are placed on a hopper. Many types of seed drills are available, for example- simple Goru - Guntakas.
Advantages:
i) The seeds are placed at the desired depth covered by iron planks.
ii) Most of the seeds can be sown by this method except very small and very large seeds., e.g. millets, maize, sunflower, sorghum, etc.
4. Drill sowing (or) Drilling
Drilling is the method of dropping seeds in a definite depth covered with soil and compacted. In this method, sowing tools are used for placing the seeds into the soil. Both animal-drawn Gorus and power operated (seed drills) implements are possible. Seeds are drilled continuously or at equal intervals in rows. In this method, the depth of sowing can be maintained & fertilizer can also be applied at the same time. It is possible to take up sowing of intercrops too. It requires more time, energy and cost, but maintains a uniform population per unit area. Seeds are placed at a uniform depth, covered & compacted.
5. Transplanting
This method of planting has two components, a. nursery and b. transplanting. In the nursery, young seedlings are protected more efficiently in a short period and in a smaller area. Management is easy and economical.
Advantages
• Can ensure excellent plant population
• Duration of sowing of the main field is reduced, i.e., management in the main field is reduced
• Crop intensification is possible under transplanting
Disadvantages
• Nursery raising is high
• Transplanting is another laborious plus expensive method
Time of sowing:
1. Sowing very early in the season may not be beneficial.
Example- sowing rainfed groundnut early may result in the failure of crop if there is a prolonged dry spell from the 2nd week of June to 2nd week of July.
2. Late sowing invariably reduces yields
a. Eg: rainfed sorghum yields are decreased due to delay in sowing beyond June
reason – sorghum if sown late is subjected to a severe attack of shoot borer.
b. Example- sowing rainfed groundnut beyond July reduces the yields of all varieties at Tirupathi.
3. Advancing sowing of Rabi sorghum from November-September to October Increases the yields considerably as more moisture would be available for the early sown crop.
4. Sowing the crop at the optimum time increases yields due to a proper environment at all the growth stages of the crop.
1. June or July is the Optimum time of sowing for Kharif crop.
2. Optimum time for Rabi crop - last week of October to the first week of November
3. Summer crop - First fortnight of January.
Depth of Sowing:
Uneven depth of sowing ends in uneven crop stand.
• Plants will be of various sizes and ages and eventually, harvesting is a problem as there is uniformity in maturity.
• The thumb rule is to plant seeds to a depth about 3-4 times their diameter.
• The optimum depth of sowing for most of the field crops ranges between 3-5 cm
• Shallow depth of sowing of 3-5 cm is sufficient for small seeds like finger millet, pearl millet and sesamum.
• Very small seeds e.g tobacco are placed at a depth of ICM. Bold seeded crops like maize, cotton, groundnut, castor etc. are placed at a depth of 6-7 cm.
Seed rate:
1. Tobacco - 30g per hector
2. Mustard - 2-3 Kg/ha
3. Pulses - 10-12Kg/ha
4. Soybean - 80-100 Kg/ha
5. Groundnut - 100-120 Kg/ha
6. Forage grasses (rooted slips) - 2-3 tons/ha
7. Potato tubers - 5-7 tons/ha
8. Sugarcane (selts) - 7 tons/ha
Tags:
BSc Ag. 1st Semester