Soil Science and Agronomy
This section asks about soil properties, fertility ratings and the arithmetic of crop sequences and fertilizer doses.
Soil properties
Sand, silt and clay combine into textural classes, with loam the balanced class. Bulk density, field capacity, permanent wilting point and available water decide irrigation depth. Madhya Pradesh has deep black vertisols on the Malwa and Nimar plains with high clay and moisture retention, red and yellow soils in eastern districts, and alluvial strips along the Narmada and Chambal.
Fertility ratings and fertilizers
Organic carbon below 0.5% is low and 0.5-0.75% medium. Urea carries 46% N, DAP 18% N with 46% P2O5, SSP 16% P2O5 and MOP 60% K2O. Soil health card and STCR recommendations replace blanket doses.
Seasons and cropping indices
Kharif (June-October): soybean, rice, maize, cotton. Rabi (October-March): wheat, gram, mustard, potato. Zaid: moong, vegetables, fodder. Cropping intensity = (gross cropped area / net sown area) x 100.
Worked example
A crop needs 120 kg N per hectare, supplied only through urea: 120 / 0.46 = 261 kg urea. If 100 kg DAP is also applied it brings 18 kg N, so urea falls to (120 - 18) / 0.46 = 222 kg. Subtracting the nitrogen carried in DAP before quoting urea is the step most candidates skip.
Traps
- Using net sown area on both sides while computing cropping intensity, which always gives 100.
- Forgetting that DAP supplies nitrogen as well as phosphorus.
- Treating elemental phosphorus and P2O5 as the same, ignoring the 2.29 conversion factor.