Soils of India

What soil is

Soil is the thin top layer of the Earth’s crust in which plants grow. It gives crops nutrients, water and a firm place for their roots, which makes it a farmer’s most important resource. Healthy soil is full of life: bacteria, fungi, earthworms and insects break down dead matter and keep the soil fertile. Soil also holds minerals, organic matter, water and air.

How soil forms

Soil forms as rocks break down and plants and animals decay. Rain, heat and cold crack the bedrock (the original rock), a process called weathering. Small plants grow in the cracks and their remains add organic matter, which helps break the rock further into parent material. Slowly layers form, with a dark topsoil that holds humus, decayed plant and animal matter that is rich in nutrients and holds moisture. The whole process takes from about a century to many thousands of years, which is why soil lost to erosion is so hard to replace.

Six major soils of India

Soil	Main features
Alluvial	silt, sand and mud brought by rivers from mountains and plateaus; rich in nutrients; northern plains and coasts
Black (cotton soil)	from weathered volcanic rock; holds a lot of moisture; very fertile; Deccan Plateau
Red	from weathered lava or old rocks; red because of iron; not very fertile
Laterite (brick earth)	rock weathered by heavy rain washes most minerals away; hard in hot weather; not fertile
Desert (sandy)	mostly small grains of sand, with a little water, air and organic matter
Mountain (alpine)	rock broken by freezing and melting ice; thin, rough and rocky

Soils also tell stories about a place: the history of its rocks, its rivers and how people have used the land.

Soils and crops

Crops depend on soil as well as climate. Alluvial plains grow rice, wheat, maize, barley, chana, mustard, sugarcane and jute. Black soil grows cotton, jowar, wheat, urad, sunflower, linseed and sugarcane. Red soil grows rice, ragi, arhar, groundnut and tobacco. Laterite areas grow tea, coffee, rubber, coconut, areca nut, cashew and tapioca. Desert soil grows bajra and groundnut, and mountain soils grow tea, fruits and vegetables. Some crops can be grown on soils that do not suit them well, but only with careful irrigation.

Looking after the soil

Farmers protect soil, which is called soil conservation. Traditional methods include crop rotation (different crops in different seasons, so the soil does not keep losing the same nutrients), multiple cropping (several crops in one field, which lowers the risk from pests and gives harvests at different times), contour ploughing (furrows along the curves of a slope) and organic manure such as cow dung. Panchagavya, a fermented mix of five cow products, has been found to work as a biofertiliser. Today, terraces on hills, planting trees, mulching, ploughing crop leftovers back into the soil and careful use of fertilisers also keep soil healthy. Bananas planted on the bunds of rice fields break the wind, hold the soil and give farmers another crop.

Why it matters

Healthy soil means good harvests year after year, and damaged soil can take centuries to rebuild. See which crops grow in which season in what grows where and when, and how farming methods have changed in traditional and modern farming. Answers to the textbook questions are in the NCERT solutions for Part 2 Chapter 1; see all of Part 2 Chapter 1 notes.