Soil and Soil Management
What this domain covers
Soil and Soil Management tests soil properties, soil-test interpretation and practical correction of fertility and sodicity problems. Haryana's soils are mostly alluvial, but south-western districts have appreciable sodic and saline patches, so the exam often contrasts the two.
Core rules and concepts
- Soil texture (sand, silt, clay) controls water holding and aeration; structure controls infiltration. Sandy loam is easier to till but holds less water than clay loam.
- Take a composite sample from 0–15 cm for cultivated fields, from 10–15 random spots, mix and quarter to about 500 g. Avoid sampling just after fertilizer application or near bunds.
- Key soil-test values: pH, electrical conductivity (EC), organic carbon, available N, P, K and micronutrients. Sodic soil typically has pH above 8.5, high exchangeable sodium percentage and low EC; saline soil has high EC.
- Organic matter is maintained with farmyard manure, green manure, crop residues and rotations. Continuous rice-wheat with residue removal depletes organic carbon.
- Sodic soils are reclaimed with gypsum, which supplies calcium to replace sodium; leaching with good-quality water and drainage are essential. Saline soils need drainage and salt-tolerant crops.
- Conservation tillage and raised beds reduce erosion and waterlogging.
Worked example
A soil test reports pH 9.2, EC 0.3 dS/m and ESP 22. The field has patchy, poor wheat stands. Reasoning: high pH with low EC and high ESP indicates sodicity, not salinity. Gypsum is the correct amendment; apply it on soil-test basis, incorporate, and leach with canal water where drainage exists. Rice or barley can be grown while reclamation proceeds. Adding more urea will not correct the sodium problem.
Traps that cost marks
Do not prescribe gypsum for a saline soil without checking drainage. Do not confuse pH with EC. Do not sample immediately after fertilizer application, and do not treat a single spot as representative.