Water Management in Horticultural Crops

Soils of India

Soils of India have been formed over different geological periods from parent rocks of varied origin. They are derived from a wide variety of minerals.
Alluvial Soils

• They are the transported soils carried away and deposited by the tributaries of Ganges and Brahmaputra system of rivers.
• These soils vary in character according to the nature of soils that occur in the region of their transportation.
• Generally they are deep soils.
• The Indo-Gangetic alluvium is the most productive soil and the largest of all soil groups in India and occupies thickly populated areas of the country.
Black Soils

• These are clay soils varying from clay to loam with clay content 40 to 50 per cent.
• Their thickness vary from 1 to 4 m or more.
• These soils vary in colour from dark grey, black or blue black.
• Black soils are fine grained containing high water holding capacity but suffer from poor drainage and consequent on drying.
• Thus swelling and shrinkage with increase or decrease in moisture content is characteristic of black soils.
• Black soils are distinguished into shallow (30 cm or less) medium (30-100 cm) and deep (over 100 cm).
Red Soils

• These are red in colour due to the presence of iron oxide. The colour varies from red to black with intermediate shade of dark brown. Red soils are mostly sandy loam or sandy clay in texture. They are deficient in nitrogen, phosphorous, lime and organic matter. They are responsive to farming practices manures, fertilizers and irrigation.
Laterite Soils

• These are formed as a result of decay of many types of rocks.
• They are red in colour.
• They are deficient in nitrogen, phosphorus, potassium and lime.
• These soils are developed on the summits of hills of Karnataka, Kerala, Madhya Pradesh, Orissa and Assam.
• The principal crops are barley, great millets, coffee, tea, potato, fruits, etc. They are poor in production.
Forest and Hill Soils
• The soils, typical of forests and mountains, occur along the slopes or in depressions and valleys in forested areas.
• They are very shallow, steep and stony.
• They show high content of organic matter and nitrogen and are developed in Himachal Pradesh, Punjab and Tamil Nadu.
• These soils are deposited as a result of their movement through water erosion of the Himalayan ranges.
• They lie at the foot of the Himalayan range.
• They are deep and moderately fertile soils but become highly productive with the provision of drainage.
Desert Soils

• These are sandy soils occurring in low rainfall areas of Gujarat, Rajasthan and parts of Punjab.
• They are abundant in soluble salts but low in organic matter.
• They are productive when irrigated.
Saline and Alkaline Soils

• Saline soils contain toxic concentration of salts in root zone.
• Electrical conductivity is taken as a measure of salts. If the solution extracted from the saturated paste of a soil has an electrical conductivity of more than 4 mmhos/cm (dSm^-1) the soil is termed as saline.
• High salt content in soil result in reduction in yield. In alkali soils exchangeable sodium constitutes more than 15 per cent of total exchangeable cations. pH value of these soils is usually more than 8.5.