<P> Other important soil organisms include nematodes, mycorrizha and bacteria . </P> <P> Degraded soil requires synthetic fertilizer to produce high yields . Lacking structure increases erosion and carries nitrogen and other pollutants into rivers and streams . </P> <P> Each one percent increase in soil organic matter helps soil hold 20,000 gallons more water per acre . </P> <P> To allow plants full realization of their phytonutrient potential, active mineralization of the soil is sometimes undertaken . This can involve adding crushed rock or chemical soil supplements . In either case the purpose is to combat mineral depletion . A broad range of minerals can be used, including common substances such as phosphorus and more exotic substances such as zinc and selenium . Extensive research examines the phase transitions of minerals in soil with aqueous contact . </P>

What are the steps to be taken for soil conservation