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Village Agriculture, Horticulture and Sericulture Assistant · Chapter 1

Crop Production Principles and Practices (Agronomy)

What to remember

  • Agronomy is the science of crop production and soil management; its parts are tillage, sowing, nutrient, water and weed management, and cropping systems.
  • Kharif crops are sown with the south-west monsoon (June-July) and harvested in autumn; rabi crops are sown in winter (Oct-Nov) and harvested in spring; zaid crops grow in the short summer season.
  • Quick numbers: urea is 46% N; DAP is 18% N and 46% P₂O₅; 1 ha-cm of water = 100 cubic metres = 1,00,000 litres.

Seasons and classification of crops

India has three cropping seasons.

SeasonSowingHarvestExamples
KharifJune-July (monsoon onset)Sept-Octrice, maize, jowar, bajra, cotton, groundnut, red gram, green gram
RabiOct-NovFeb-Aprilwheat, Bengal gram, sunflower (also grown in kharif), safflower, rabi rice and maize in AP
Zaid (summer)Feb-MarchMay-Junewatermelon, cucumber, summer groundnut, vegetables

In Andhra Pradesh, rice, groundnut, cotton, chilli, redgram, maize, sugarcane, blackgram and green gram are important crops, and farmers raise them in both kharif and rabi under irrigation or rain.

Classification by use: cereals (rice, wheat, maize); millets (jowar, bajra, ragi); pulses (red gram, black gram, green gram, Bengal gram); oilseeds (groundnut, sesame, sunflower, castor); fibre crops (cotton, jute); sugar crops (sugarcane); commercial/cash crops (cotton, chilli, tobacco); fodder crops (sorghum, berseem); green manure crops (sunhemp, dhaincha, pillipesara); cover crops and catch crops.

Tillage and seedbed

Tillage is the mechanical manipulation of soil to give good seedbed conditions. Primary tillage (ploughing) opens hard soil; secondary tillage (harrowing, planking, cultivating) refines it. Tilth is the physical condition of the soil after tillage. Benefits: weed control, aeration, moisture storage and insect control by exposing pests. Minimum tillage and zero tillage reduce cost and save moisture. A fallow is land kept without crop for a season.

Sowing and plant population

Seed rate depends on seed size, germination, spacing and sowing method. Plant population per hectare = 10,000 sq m / (row spacing × plant spacing in m).

Sowing methods:

  • Broadcasting: scattering seed by hand; uneven spacing.
  • Drilling (seed drill): seed in rows at uniform depth.
  • Dibbling: placing seeds in holes at fixed spacing (e.g. cotton, maize, groundnut).
  • Transplanting: raising seedlings in a nursery and planting them (rice, chilli, tomato).
  • Sowing behind the plough and seed-cum-fertilizer drill.

Depth of sowing is about 2-3 times the seed diameter; small seeds need shallow sowing. Gap filling and thinning maintain the right stand. In rice, System of Rice Intensification (SRI) uses young seedlings (8-12 days), single seedling per hill, wide spacing and alternate wetting and drying.

Nutrient management

Plants need 17 essential elements. Macro: N, P, K (primary); Ca, Mg, S (secondary). Micro: Zn, Fe, Mn, Cu, B, Mo, Cl, Ni. Fertilizers carry the following percentages.

FertilizerNutrient content
Urea46% N
Ammonium sulphate20.6% N, 24% S
Single super phosphate (SSP)16% P₂O₅ (with S and Ca)
Diammonium phosphate (DAP)18% N, 46% P₂O₅
Muriate of potash (MOP)60% K₂O
NPK complexe.g. 17:17:17

Fertilizer needed = nutrient dose / % nutrient × 100. Example: 92 kg N per ha through urea = 92/46 × 100 = 200 kg urea.

Principles: apply basal dose at sowing (all P and K, part of N) and split the rest of N at critical stages (tillering, panicle initiation). Integrated nutrient management (INM) combines organic manures, biofertilizers and chemical fertilizers. Biofertilizers: Rhizobium (legumes), Azotobacter and Azospirillum (non-legumes), phosphate-solubilising bacteria (PSB), blue-green algae and Azolla (rice). Green manuring with sunhemp or dhaincha adds N and organic matter.

Water management

Irrigation supplies water when rain is not enough. Methods: surface (flooding, furrow, border strips, basin), sprinkler, and drip (water-saving, suited to orchards and widely spaced crops). Critical stages for water are the stages where stress reduces yield most, e.g. crown root initiation in wheat, tillering to flowering in rice, flowering and pegging in groundnut, flowering and boll formation in cotton. Water requirement is the total water needed per crop season; consumptive use is evapotranspiration plus water used for tissues.

Units: 1 ha-cm = 100 m³ = 1,00,000 L. To give 5 cm depth over 1 ha, volume = 500 m³.

Dryland (rainfed) farming practices: soil and moisture conservation, contour sowing, mulching, use of drought-tolerant varieties, and contingency crop plans for delayed monsoon.

Weed management

A weed is a plant growing where it is not wanted. Weeds compete for light, water and nutrients. The critical period of weed competition is usually the first 20-40 days (crop-specific). Methods: cultural (summer ploughing, stale seedbed, crop rotation), mechanical (hand weeding, hoeing), chemical and biological. Herbicides: pre-plant, pre-emergence (sprayed within 0-3 days of sowing before weeds and crop emerge, e.g. pendimethalin, butachlor in rice) and post-emergence (after emergence). Selective herbicides kill particular plants; non-selective (e.g. glyphosate) kill all green plants. Always follow label dose and use protective equipment.

Cropping systems

SystemMeaningExample
Mixed croppingtwo or more crops grown together without row patternjowar + red gram mixed
Intercroppingtwo or more crops in definite row ratiogroundnut + red gram (e.g. 6:1 or 7:1)
Relay croppingsecond crop sown before harvest of the firstrice then pulses in standing rice
Sequence croppingcrops one after another in a yearrice-rice, rice-pulse
Crop rotationrepeating a sequence over yearscereal-legume rotation
Sole croppingone crop on the fieldrice alone

Benefits of rotation: better soil fertility (legumes fix N), pest and disease break, and spread of labour. Multiple cropping index tells how many crops are grown per year on the same land. Harvest index = economic yield / biological yield × 100.

Important crop notes

  • Rice: raised in nursery, transplanted at 3-4 weeks (traditional); needs standing water in early stages; major pests are stem borer and brown planthopper; blast and sheath blight are diseases.
  • Groundnut: legume with pod formation underground; gypsum is applied at flowering for pod filling; kharif and rabi crops.
  • Cotton: sown by dibbling; Bt cotton hybrids are common in Andhra Pradesh; pink bollworm is a pest.
  • Red gram: long-duration legume often intercropped; nodules fix atmospheric N.
  • Maize: heavy feeder on N; sowing on ridges or flat beds.
  • Sugarcane: planted by setts (three-budded); ratoon crop grows from stubble.

Harvesting and post-harvest basics

A crop is harvested at physiological maturity or when grain moisture is right for the crop. Rice is harvested when about 80% of the panicles turn straw-coloured; pulses are harvested when most pods turn brown. After harvest, grain is threshed, winnowed and dried to a safe moisture level before storage. Drying to about 12-14% moisture in cereals and lower in oilseeds protects against moulds and insects. Clean, dry, well-aired godowns and proper bags prevent storage losses.

Pest and disease management (agronomic view)

Integrated pest management (IPM) combines cultural methods (deep summer ploughing, crop rotation, resistant varieties), mechanical methods (hand picking, light traps, pheromone traps), biological control (natural enemies such as parasitoids and *Trichoderma*) and need-based chemicals. A pest is treated only when it crosses the economic threshold level (ETL). Pesticides must be used at the label dose and by the right method, and waiting periods before harvest should be observed.

Growth stages of cereals (simple guide)

StageWhat happensManagement point
Germination and seedlingroot and shoot emergeseed treatment, gap filling
Tilleringside shoots formtop dressing of N, weeding
Panicle initiation / bootingear head formssecond split of N, water
Floweringpollinationavoid water stress
Grain fillingdry matter goes into grainadequate water and K
Maturitygrain hardensdrain field, harvest on time

Exam traps

  • Kharif is sown at monsoon onset; rabi in winter, not the other way round.
  • Rhizobium is for legumes; Azospirillum is for cereals and other non-legumes.
  • Pre-emergence herbicides are applied before weeds emerge, not after.
  • Mixed cropping has no row ratio; intercropping has a definite row ratio.
  • Urea is 46% N; DAP is 18% N, not 46% N.
  • Tillage means soil manipulation; tilth means soil condition after tillage.
  • Relay cropping: second crop sown before harvest of the first.
  • 1 ha-cm is 100 m³, not 1000 m³.

One-liners

  • 1. Agronomy: science and art of crop production.
  • 2. Zaid: summer season between rabi and kharif.
  • 3. Dibbling: seeds placed in holes.
  • 4. Harvest index: economic yield ÷ biological yield × 100.
  • 5. MOP contains 60% K₂O.
  • 6. SSP contains 16% P₂O₅.
  • 7. Sunhemp and dhaincha are green manure crops.
  • 8. SRI uses single young seedlings at wide spacing.
  • 9. Drip irrigation saves the most water.
  • 10. Glyphosate is a non-selective herbicide.
  • 11. Ratoon crop is raised from stubble of the harvested crop.
  • 12. Rhizobium forms nodules on legume roots.

Practice questions

  1. How much urea is needed to supply 92 kg N per hectare?

    1. 100 kg
    2. 46 kg
    3. 200 kg
    4. 92 kg
    Answer

    C. 200 kg

    92/46 x 100 = 200 kg urea.

  2. How many plants per hectare at a spacing of 20 cm x 10 cm?

    1. 50,000
    2. 1,00,000
    3. 2,00,000
    4. 5,00,000
    Answer

    D. 5,00,000

    10,000 / (0.2 x 0.1) = 5,00,000.

  3. The volume of water in 1 ha-cm is

    1. 10 m³
    2. 100 m³
    3. 10,000 m³
    4. 1000 m³
    Answer

    B. 100 m³

    1 ha = 10,000 sq m x 0.01 m = 100 m³.

  4. A 5 cm irrigation to 1 ha needs

    1. 500 m³
    2. 5000 m³
    3. 50 m³
    4. 5 m³
    Answer

    A. 500 m³

    5 x 100 m³ = 500 m³.

  5. A crop needs 120 kg P₂O₅ per ha through DAP (46% P₂O₅), ignoring N from DAP. The DAP needed is closest to

    1. 552 kg
    2. 261 kg
    3. 46 kg
    4. 120 kg
    Answer

    B. 261 kg

    120/46 x 100 = 260.9 kg.

  6. Seed rate is 25 kg per ha. For 2 ha the seed needed is

    1. 50 kg
    2. 12.5 kg
    3. 100 kg
    4. 25 kg
    Answer

    A. 50 kg

    25 x 2 = 50 kg.

  7. Economic yield is 3000 kg and biological yield is 8000 kg. The harvest index is

    1. 30%
    2. 26.7%
    3. 62.5%
    4. 37.5%
    Answer

    D. 37.5%

    3000/8000 x 100 = 37.5%.

  8. A 20 kg bag of muriate of potash (60% K₂O) contains K₂O of

    1. 10 kg
    2. 6 kg
    3. 12 kg
    4. 20 kg
    Answer

    C. 12 kg

    20 x 0.60 = 12 kg.

  9. The Kharif season crop sowing normally begins with

    1. winter
    2. post-monsoon
    3. the monsoon onset
    4. summer heat
    Answer

    C. the monsoon onset

    Kharif sowing is at monsoon onset (June-July).

  10. Which of the following is a zaid (summer) crop?

    1. Mustard
    2. Watermelon
    3. Bengal gram
    4. Wheat
    Answer

    B. Watermelon

    Watermelon and cucumber are grown in the summer season.

  11. The science and art of crop production and soil management is

    1. Pomology
    2. Olericulture
    3. Agrostology
    4. Agronomy
    Answer

    D. Agronomy

    Agronomy deals with crop production.

  12. Which of the following is a green manure crop?

    1. Sunhemp
    2. Cotton
    3. Chilli
    4. Sugarcane
    Answer

    A. Sunhemp

    Sunhemp and dhaincha are green manure crops.

  13. Biofertilizer for legume crops is

    1. Azospirillum
    2. Azolla
    3. Rhizobium
    4. Blue-green algae
    Answer

    C. Rhizobium

    Rhizobium nodulates legume roots.

  14. Azolla is used as a biofertilizer mainly in

    1. rice
    2. maize
    3. cotton
    4. groundnut
    Answer

    A. rice

    Azolla is an aquatic fern for flooded rice.

  15. Seeds placed in holes at fixed spacing is called

    1. transplanting
    2. broadcasting
    3. drilling
    4. dibbling
    Answer

    D. dibbling

    Dibbling is hole-by-hole sowing.

  16. Raising seedlings in a nursery and planting them is called

    1. broadcasting
    2. transplanting
    3. dibbling
    4. drilling
    Answer

    B. transplanting

    Transplanting uses nursery seedlings.

  17. In System of Rice Intensification, the seedlings are planted

    1. in clumps of five old seedlings
    2. by broadcasting
    3. with continuous deep flooding
    4. single, young and widely spaced
    Answer

    D. single, young and widely spaced

    SRI uses young single seedlings at wide spacing.

  18. Primary tillage means

    1. weeding by hoe
    2. levelling with a plank
    3. opening up the soil by ploughing
    4. interculture
    Answer

    C. opening up the soil by ploughing

    Ploughing is primary tillage; harrowing and planking are secondary.

  19. The physical condition of soil after tillage is called

    1. tilth
    2. texture
    3. tillering
    4. fallow
    Answer

    A. tilth

    Tilth is the condition of the seedbed.

  20. A herbicide sprayed within 3 days of sowing before weeds emerge is

    1. post-emergence
    2. pre-emergence
    3. pre-plant incorporated only
    4. a defoliant
    Answer

    B. pre-emergence

    Pre-emergence is applied before emergence of weeds.

  21. Glyphosate is an example of a

    1. selective herbicide for rice only
    2. non-selective herbicide
    3. fungicide
    4. insecticide
    Answer

    B. non-selective herbicide

    Glyphosate kills almost all green plants.

  22. The critical period of crop-weed competition is generally

    1. after flowering
    2. the last 10 days before harvest
    3. before sowing
    4. the first 20-40 days of the crop
    Answer

    D. the first 20-40 days of the crop

    Early growth is when weeds cause most loss.

  23. Mixed cropping differs from intercropping because in mixed cropping

    1. a definite row ratio is followed
    2. only one crop is grown
    3. crops are grown in sequence
    4. no definite row pattern is followed
    Answer

    D. no definite row pattern is followed

    Mixed cropping has no row pattern.

  24. Sowing a second crop in the standing first crop before its harvest is

    1. sole cropping
    2. crop rotation
    3. relay cropping
    4. catch cropping
    Answer

    C. relay cropping

    This is relay cropping.

  25. Rice-rice sequence in a year is an example of

    1. sequence cropping
    2. mixed cropping
    3. relay cropping
    4. intercropping
    Answer

    A. sequence cropping

    One crop after another in a year is sequence cropping.

  26. Which nutrient is a secondary macronutrient?

    1. Sulphur
    2. Zinc
    3. Potassium
    4. Nitrogen
    Answer

    A. Sulphur

    Ca, Mg and S are the secondary nutrients.

  27. Which is a micronutrient?

    1. Sulphur
    2. Zinc
    3. Calcium
    4. Phosphorus
    Answer

    B. Zinc

    Zn, Fe, Mn, Cu, B and Mo are micronutrients.

  28. The nutrient content of DAP is

    1. 46% N and 18% P₂O₅
    2. 16% P₂O₅ only
    3. 60% K₂O
    4. 18% N and 46% P₂O₅
    Answer

    D. 18% N and 46% P₂O₅

    DAP is 18-46-0.

  29. The nutrient content of single super phosphate is about

    1. 46% N
    2. 60% K₂O
    3. 16% P₂O₅
    4. 20.6% N
    Answer

    C. 16% P₂O₅

    SSP carries 16% P₂O₅.

  30. The water-saving irrigation method best suited to orchards is

    1. flood irrigation
    2. wild flooding
    3. drip irrigation
    4. basin flooding only
    Answer

    C. drip irrigation

    Drip supplies water at the root zone.

  31. In groundnut, gypsum is applied mainly to supply

    1. calcium for pod filling
    2. nitrogen
    3. boron
    4. potassium
    Answer

    A. calcium for pod filling

    Calcium aids pod development.

  32. Sugarcane is propagated by

    1. bulbs
    2. setts
    3. true seeds
    4. tubers
    Answer

    B. setts

    Three-budded setts are planted.

  33. A ratoon crop is raised from

    1. cuttings of leaves
    2. fresh seed
    3. the stubble of the harvested crop
    4. tubers
    Answer

    C. the stubble of the harvested crop

    Ratoon regrows from the stubble.

  34. Consider the statements. 1. Rhizobium is used for legumes. 2. Azospirillum is used for non-legume cereals. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Neither 1 nor 2
    4. Both 1 and 2
    Answer

    D. Both 1 and 2

    Both are standard uses.

  35. Consider the statements. 1. Tilth is the physical condition of the soil after tillage. 2. Zero tillage involves heavy ploughing. Which is/are correct?

    1. 2 only
    2. Both 1 and 2
    3. 1 only
    4. Neither 1 nor 2
    Answer

    C. 1 only

    Zero tillage means sowing with little or no ploughing.

  36. Consider the statements. 1. Urea is 46% N. 2. MOP is a source of phosphorus. Which is/are correct?

    1. 2 only
    2. 1 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 1 only

    MOP supplies potassium (60% K₂O).

  37. Consider the statements. 1. Pre-emergence herbicides are applied after weeds emerge. 2. Hoeing is a mechanical weed control method. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Pre-emergence is before emergence.

  38. Consider the statements. 1. Drip irrigation saves water. 2. Flooding irrigation gives the highest water use efficiency. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Drip has higher efficiency than flooding.

  39. Match the pair correctly.

    1. Berseem - fibre crop
    2. Chilli - fodder crop
    3. Jute - sugar crop
    4. Dhaincha - green manure
    Answer

    D. Dhaincha - green manure

    Dhaincha is a green manure crop.

  40. Cropping index tells

    1. the number of crops grown per year on the same land
    2. the water requirement
    3. the seed rate
    4. the harvest index
    Answer

    A. the number of crops grown per year on the same land

    Cropping intensity measures crops per year per unit land.

  41. Nitrogen fixation in red gram roots is by

    1. Azolla
    2. Rhizobium in nodules
    3. Mycorrhiza only
    4. Trichoderma
    Answer

    B. Rhizobium in nodules

    Legume nodules house Rhizobium.

  42. A catch crop is

    1. the main crop of the season
    2. a perennial crop
    3. a fodder tree
    4. a short-duration crop grown between two main crops
    Answer

    D. a short-duration crop grown between two main crops

    Catch crops fill the gaps in the season.

  43. Which method of sowing gives uniform depth and row spacing using a machine?

    1. Broadcasting
    2. Transplanting
    3. Seed drilling
    4. Dibbling by hand
    Answer

    C. Seed drilling

    A seed drill sows in rows at uniform depth.

  44. A rainfed farmer should, for moisture conservation, practice

    1. heavy flooding
    2. deep irrigation
    3. summer fallow only
    4. mulching
    Answer

    D. mulching

    Mulch reduces evaporation.

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