Characteristics of Rainfed Soils:
Poor Quality: Rainfed soils are generally of poor quality, characterized by low fertility, high erodibility, fragility, and shallowness. They are susceptible to physical degradation.
• Weak Buffering and Resilience: These soils have limited capacity to buffer and recover from disturbances. They are vulnerable to changes in environmental conditions.
• Salts and Acids: Arid and semi-arid areas have excess salts, leading to saline-alkali soils, while subhumid and humid areas suffer from acid soils. These conditions affect soil health and nutrient availability.
• Micronutrient and Ameliorant Deficiencies: Rainfed soils often lack essential micronutrients and may require periodic supplementation. Examples: Lime is commonly needed to address soil acidity.
• Coarse Textured and Highly Degraded: Rainfed soils are mostly coarse-textured, which reduces their water-holding capacity. They are highly degraded, with multiple nutrient deficiencies, making them unsuitable for intensive cropping.
Factors Affecting Soil Formation:
Parent Material: The nature of the underlying material influences soil characteristics. In arid regions, physical weathering is the primary process of soil formation.
• Climate: Climate plays a vital role in soil formation. Rainfall patterns, temperature, and evaporation rates affect soil properties.
• Vegetation: Vegetation influences soil development through organic matter inputs, root activity, and nutrient cycling.
• Soil Organisms: Soil organisms, such as microorganisms and earthworms, contribute to the formation of soil structure and nutrient availability.
• Topography: The shape and slope of the land affect water movement, erosion, and deposition processes, which influence soil formation.
Soil Types in Dryland Regions :
Red soils (Alfisols):
• Moderately weathered soils derived from metamorphic rocks.
• Light texture, slightly acidic to slightly alkaline.
• Low in organic matter, nitrogen, and phosphorus.
• Suitable crops: Groundnut, sorghum, pearl millet, and red gram.
Black soils (Inceptisols and Vertisols):
• High clay content, neutral to slightly alkaline pH.
• Impeded drainage, low permeability.
• Low in organic matter, but rich in calcium, magnesium, and potassium.
• Suitable crops: Groundnut, sorghum, cotton, pulses.
Laterite soils (Ultisols):
• Well-drained soils formed through laterization. • Acidic, low in nitrogen and phosphorus in top layer, richer in lower layers. • Suitable crops: Rice, minor millets, tea, coffee, rubber.
Desert soils (Aridisols):
Sandy texture, low clay content.
• Poor in organic matter, nitrogen, and phosphorus.
• Saline or sodic characteristics.
• Suitable crops: Barley, oats, mustard, salt-tolerant grasses.
Sub-montane soils:
Occur in undulating lands of sub-Himalayan regions.
High rainfall, acidic nature.
Low in available nitrogen and phosphorus.
Suitable for double cropping.
Saline and sodic soils:
Occur in arid and semi-arid regions with high temperatures.
Saline soils have excessive soluble salts, sodic soils have high sodium content.
Poor in organic carbon, nitrogen, and zinc.
Suitable crops: Salt-tolerant legumes, millets, rice, wheat, cotton, certain trees.
Important Nutrient Information for Dryland Agriculture:
• Red soils are low in organic matter and nutrients like nitrogen and phosphorus.
• Black soils are low in organic matter but rich in calcium, magnesium, and potassium.
• Laterite soils are acidic, low in nitrogen and phosphorus in the top layer, richer in lower layers.
• Desert soils are poor in organic matter, nitrogen, and phosphorus. • Sub-montane soils Low in available nitrogen and phosphorus
• Saline and sodic soils are generally poor in organic carbon, nitrogen, and zinc.
