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.