AgricultureAgronomySoil SciencesSoil FertilitySoil Organic MatterSoil ScienceNitrogen NutritionNutrient AvailabilitySoil CompositionSoil Nitrogen ChemistrySoil Nutrient AvailabilitySoil-plant Nutrient RelationsDryland EcosystemsOrganic Matter AvailabilityPlant-available NitrogenSoil Nitrogen MineralizationSoil Organic Matter CharacterizationSoil Organic Matter ContentSoil Organic Matter ContributionsSoil Organic Matter Effects On Nutrient Availability
Plant growth and crop production depend to a large extent on soil N supplying capacity(SNSC):The higher the SNSC,the higher the dependence of crops on soil and the lower the N fertilizer recovery.Of the SNSC,soil organic N(ON)played a key role in supplying N nutrient to crop production and still does in many subsistence and low-input farming systems.In this paper,soil ON contents,types,chemical components and its contribution to plant production are reviewed up to date in details,the characteristics of ON in dryland soils discussed together with its chemical components,and the mineralization and availability to plants of some important chemical components are emphasized at the last part for practical considerations.