Soil Fertility and Nutrient management (1+1)

I. Natural Factors

• I. Natural Factors: are those which influence the formation of the soil.
  These include

  a. Parent material
  b. Climate and vegetation
  c. Topography and age of soil

  a. Parent material:

• Rocks and minerals are the parent materials, act as very important raw materials for the formation of any soils. If the parent material is rich in plant nutrients, the soils formed from it are usually quite fertile. The property of soil depends on the property of parent rock.

  Ex: a. Sandy loam soils (Red), formed from granite and granite gneiss are low to medium in fertility.
  b. Lime stone and Basalt rock which are easily weathered results fine textured, very fertile and dark colored (black) soil.
  c. Soils derived from calcareous rock contain more P than the soil derived from granite.
  d. Sand stone-leads to coarse textured, sandy soil of low fertility.
  e. Shale- forms clayey soil, but not very fertile.

  b. Climate and vegetation:

   
• They are interrelated factors as the amount and type of vegetation in an area depends on climate especially rainfall and temperature. These two factors in turn influence the type of soil fertility. Under heavy rainfall of humid region, the natural vegetation is forest, which develops more fertile soils due to accumulation of forest litter and organic matter.
• On the other hand temperate soils are not very fertile compared to tropical soils because of the lesser decomposition of organic matter in soil due to very low temperature. The tropical soils are more fertile soils due to constant high temperature which helps in faster rate of disintegration and decomposition of organic matter in the tropics than in temperate regions.
• In semi arid conditions the natural vegetation is grass which leads to more accumulation of organic matter in soil surface layer due to fibrous root system, and good soil aggregation. These soils are hence more fertile than the area under forest vegetation.

  c. Topography and Age of soil:
  

• The soils of hilly tracts are usually poor because of excessive leaching and erosion of the top soil. In sloppy land, the soils of low lying areas are usually richer because of the transportation and accumulation of soil and plant nutrients. Similarly, old soils are less fertile due to excessive weathering, leaching and continuous cultivation.
  Top