Course Content
Crop Production (Unit 6)
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ASRB NET / SRF / Ph.D. Agronomy
Conservation Cropping in Drylands

Introduction

  • Drylands, defined by low and erratic rainfall (generally <750 mm annually), high potential evapotranspiration (1500–2000 mm), and frequent droughts, present unique challenges for agriculture. Under such conditions, conservation cropping emerges as a critical strategy.
  • Definition: Conservation cropping refers to a set of agricultural practices designed to conserve soil moisture, reduce erosion, improve soil fertility, and enhance system resilience in rainfed/dryland areas.

The underlying philosophy is to:

  • Conserve every drop of rainwater,
  • Preserve every particle of soil,
  • Sustain every unit of organic matter.

 

Objectives of Conservation Cropping

  • Moisture Conservation: Maximize effective use of limited rainfall.
  • Risk Minimization: Reduce crop failure under variable rainfall.
  • Soil Health Improvement: Maintain organic matter and fertility.
  • Resource Efficiency: Reduce dependence on external inputs.
  • Sustainability: Ensure long-term productivity of fragile dryland ecosystems.

 

Core Principles of Conservation Cropping

  • Reduce Soil Disturbance: Minimum or zero tillage helps retain moisture and structure.
  • Maintain Ground Cover: Residues, mulches, or cover crops protect against erosion and evaporation.
  • Diversify Cropping Systems: Intercropping, rotations, and agroforestry reduce risk and improve nutrient cycling.
  • In-situ Moisture Management: Water harvesting and soil structures improve infiltration and reduce runoff.
  • Soil Fertility Maintenance: Recycling of organic residues, incorporation of legumes, and integrated nutrient management.

 

Conservation Cropping Practices in Drylands

(i) Conservation Tillage

  • Minimum Tillage / Reduced Tillage: Limits soil disturbance, reduces water loss, and conserves soil structure.
  • Zero Tillage: Direct sowing without ploughing; maintains surface residues.
  • Mulch Tillage: Crop residues spread on the soil surface act as mulch.
    • Impact: 10–20% higher soil moisture retention, reduced weed emergence, improved yields in dry years.

 

(ii) Mulching

  • Organic Mulches: Straw, stover, leaves, farmyard manure. Reduce evaporation, moderate soil temperature, add organic matter.
  • Plastic Mulching: Polyethylene sheets used for high-value crops (groundnut, vegetables). Retain soil moisture and suppress weeds.
  • Dust Mulch: Created by shallow cultivation to break capillaries → reduces evaporation losses.

 

(iii) Crop Rotations and Intercropping

  • Crop Rotations: Cereals–pulses rotations (e.g., Sorghum–Chickpea, Pearl millet–Pigeon pea) maintain fertility and reduce pest cycles. Improves nitrogen economy of soils through legumes.
  • Intercropping Systems: Millets + Pulses (Pearl millet + Cowpea, Sorghum + Pigeon pea). Provides stability of yield — one crop often survives under stress.
  • Strip Cropping: Alternate strips of erosion-resistant and erosion-prone crops.

 

(iv) Residue Management and Cover Crops

  • Retaining crop residues on soil surface reduces runoff and erosion.
  • Cover crops like cowpea, green gram, or horse gram grown in off-season:
    • Protect the soil.
    • Fix nitrogen.
    • Improve infiltration.

 

(v) Agroforestry and Alley Cropping

  • Integration of trees/shrubs with field crops:
    • Windbreaks & Shelterbelts: Reduce evaporation and wind erosion.
    • Alley Cropping: Crops grown between hedgerows of leguminous trees (e.g., Leucaena, Gliricidia).
    • Provides fuel, fodder, and organic matter.

 

(vi) In-situ Moisture Conservation & Water Harvesting

  • Contour Bunding, Graded Bunds, Compartment Bunding: Reduce runoff, enhance infiltration.
  • Ridges and Furrows: Conserve rainwater for row crops.
  • Farm Ponds and Percolation Tanks: Collect runoff for supplemental irrigation.
  • Micro-catchments: Especially for tree plantations in arid zones.

 

Conservation Cropping Systems in Indian Drylands

Zone

Rainfall & Challenges

Conservation Practices

Crops/Systems

Western Rajasthan (Arid)

<300 mm, frequent drought, sandy soils

Intercropping, fallowing, water harvesting, agroforestry

Pearl millet + Cluster bean; Pearl millet + Moth bean

Deccan Plateau (Semi-arid)

500–750 mm, shallow soils, high ET

Contour bunding, intercropping, mulching, residue retention

Sorghum + Pigeon pea; Sunflower + Chickpea

Central Plateau (Semi-arid)

700–1000 mm, black soils prone to cracking

Watershed management, strip cropping, crop rotations

Soybean–Wheat, Soybean–Pigeon pea

Rain Shadow (TN/AP)

600–850 mm, erratic rainfall

Mulching, groundnut-based intercropping, micro-catchments

Groundnut + Pigeon pea; Millets + Pulses

 

Benefits of Conservation Cropping

  • Moisture Conservation: Enhances soil water storage and crop survival during dry spells.
  • Risk Reduction: Crop diversification reduces probability of total crop failure.
  • Soil Fertility Improvement: Organic matter maintained, biological activity enhanced.
  • Reduced Erosion: Surface cover reduces wind/water erosion.
  • Higher Input Use Efficiency: Nutrients and water are used more effectively.
  • Sustainability: Builds resilience of farming systems against climate variability.

 

Limitations and Challenges

  • Initial adoption costs (e.g., mulching, zero-till machinery).
  • Competing uses for residues (fodder vs. mulching).
  • Need for farmer training and extension support.
  • Socio-economic constraints in smallholder systems.

 

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