soil fertility

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The term soil fertility is difficult to define precisely & is the combined product of various natural processes & management options.A fertile soil is one which is capable of producing a desired crop with favourable yeild & quality characteristics.The natural requirements for individual palnt species vary & therefore the fertility of a soil varies for individual plant species.For this,nutrient inputs & outputs must be balanced over a reasonable timescale.Removal of nutrient elements with harvested crop is a major potential cause of decline in soil fertility losses therefore should be replenished.
                                                                  Natural levels of soil fertility are seldom adequate to sustain a resonable long term degree of agricultural productivity.Numerous factors influence soil's potential fertility.Of particular importance is the mineralogy of parent materials.Many of the fundamental chemical & texture related properties of mineral soil including cation exchange capacity,base saturation,PH etc. may be directly related to parent material & it's secondary weathering products.several variables other than parent materials ails have important local influences.Eg.-Reith et al demonstrated the importance of soil rooting  volume for the supply of adequate nutrients for crop productivity.Both the total amount & concentration of available nutrients in  a soil profile are important regarding soil's fertility status.The heterogeneous nature of soil imposes limitations on our understanding & prediction of soil fertility.
Greatly,improved control of soil fertility has played an important role in maximising agricultural production over recent decades.These includes-
a)crop rotation;
b)intercropping;
c)artificial availability of naturally unavailable nutrient pools in specific regions;&
d)plant breeding & selection.

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