Model Answer
0 min readIntroduction
Dryland areas, characterized by low, erratic, and unevenly distributed rainfall (typically 375 mm to 1125 mm annually), constitute a significant portion of India's agricultural landscape, with nearly 80 million hectares under dryland farming, contributing approximately 44% of the total food grains. In-situ moisture conservation refers to practices that aim to capture, store, and utilize rainwater within the farm field itself, minimizing runoff and evaporation losses. These techniques are crucial for stabilizing and enhancing crop yields in rainfed regions, especially given the intensifying impacts of climate change which cause increased temperature, water stress, and unpredictable rainfall patterns.
In-situ moisture conservation practices are vital for enhancing the resilience and productivity of dryland agriculture. These practices primarily focus on reducing runoff, increasing infiltration, and minimizing evaporation to ensure maximum utilization of the limited rainfall received. They can be broadly categorized into agronomic and mechanical methods.
Agronomic Moisture Conservation Practices
These practices involve manipulating crop management and surface cover to improve soil moisture retention.
- Mulching: Covering the soil surface with organic or inorganic materials.
- Crop Residue Mulch: Using straw, crop stubbles, or other plant residues (e.g., groundnut shells, coir pith) helps reduce direct evaporation, intercepts raindrops, and improves soil organic matter over time. Studies indicate mulching can conserve 40-60% of moisture.
- Plastic Mulch: Synthetic sheets (e.g., polyethylene) can effectively suppress weed growth, reduce evaporation, and maintain higher soil temperatures beneficial for early crop growth.
- Conservation Tillage: Practices that minimize soil disturbance, leaving crop residues on the surface.
- Minimum Tillage/No-Tillage: Reduces soil erosion, improves water infiltration, and enhances soil organic carbon content. This practice leaves a significant portion of crop residue on the soil surface, forming a protective layer.
- Deep Tillage/Summer Ploughing: Ploughing during summer helps create a rough soil surface, increasing the infiltration capacity of rainwater and storing it in deeper soil layers for longer periods.
- Cover Cropping: Planting non-cash crops (e.g., blackgram, greengram, specific fodder grasses) between main crops or during fallow periods to cover the soil.
- Protects the soil from direct impact of rainfall and wind, reduces evaporation, and adds organic matter. Effective on slopes less than 2%.
- Contour Farming: Ploughing, planting, and cultivating across the slope, following the natural contours of the land.
- Creates small ridges and furrows that act as miniature dams, slowing down runoff and allowing more time for water to infiltrate the soil. This can be effective on slopes up to 6%.
- Improved Cropping Systems:
- Intercropping/Mixed Cropping: Growing two or more crops simultaneously in the same field. This optimizes resource utilization, provides better ground cover, and reduces moisture loss. Examples include intercropping of pulses with cereals.
- Crop Rotation: Alternating different crops in sequence over time. It helps in improving soil structure, nutrient cycling, and water use efficiency.
Mechanical Moisture Conservation Practices
These involve physical alterations to the land surface to enhance water retention and reduce runoff.
- Bunds and Terraces: Earth embankments constructed across the slope to intercept runoff.
- Contour Bunding: Constructed along contours in areas with slopes up to 6%. These bunds hold water in the field, reducing runoff and promoting infiltration. They are typically 15 cm wide and 15 cm high.
- Graded Bunding: Used in areas with higher rainfall or steeper slopes, these bunds have a gentle gradient to allow excess water to drain slowly, preventing erosion.
- Compartmental Bunding: Dividing fields into small compartments (e.g., 40 sq. m size with 15cm high bunds) to reduce runoff and enhance uniform infiltration, particularly suitable for red and black soils with 0.5-1% slope.
- Broad Bed Furrow (BBF) System: A system where crops are grown on raised beds, and furrows between them collect and store water.
- The broad beds facilitate good aeration and drainage for crops, while furrows efficiently harvest rainwater and direct it to the root zone. This system has shown to increase soil moisture conservation by 5.5% to 49.3% at various crop stages compared to conventional practices, leading to significant yield increases (e.g., 24-26% in pigeonpea).
- Ridge and Furrow System: Creating alternating ridges and furrows.
- Crops are planted on ridges, and furrows collect rainwater, concentrating it near the plant roots. This is particularly useful for row crops and helps in both moisture conservation and drainage during heavy rainfall.
- Tied Ridges: Ridges formed across the slope with small earthen ties or cross-bunds at regular intervals.
- These ties prevent water from flowing down the furrows, creating mini-basins that temporarily store rainwater, increasing infiltration. Tied ridging can increase crop yields by 100-300% when combined with soil fertility improvements.
- Basin Listing: Creating small, staggered basins on the soil surface.
- These basins trap rainwater, preventing runoff and allowing maximum time for infiltration. It's effective in undulating terrains.
- Sub-soiling and Ripping: Breaking up compacted layers of soil below the surface without inverting the soil.
- Improves water penetration and root growth, increasing the soil's capacity to store moisture. When combined with soil fertility improvements, it can increase crop yields by 50-100%.
Implementing a combination of these practices, tailored to specific agro-climatic conditions, soil types, and crop requirements, can significantly improve water use efficiency, enhance soil health, and ensure sustainable agricultural production in dryland areas.
Conclusion
In-situ moisture conservation practices are indispensable for transforming dryland agriculture into a sustainable and resilient farming system. By effectively capturing and retaining rainwater within the crop root zone, these agronomic and mechanical techniques mitigate the impacts of erratic rainfall and prolonged dry spells, which are exacerbated by climate change. Their widespread adoption can lead to improved soil health, increased crop yields, and enhanced livelihood security for millions of farmers dependent on rainfed areas. Strategic implementation, coupled with government support and farmer education, is crucial for realizing the full potential of these practices in ensuring national food security.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.