The nitrogen and carbon balance in soil

Factors influencing the decrease in nitrogen and carbon stocks in soils upo n mineral fertilizer application are examined. One of these factors is the additional mineralization of N sources from soil organic matter. It is demo nstrated that, due to prevailing of mineralization over immobilization, a d eficit of microbiologically consumable C is formed. As a result, the immobi lization of fertilizer N to organic forms does not compensate for mineraliz ation of organic N. The main criterion for the estimation of ecologically o ptimal N regime providing high yields with minimal losses of nitrogen and o rganic C is a balance between microbiologically consumable organic C and st ocks:of mineral N. An ecologically optimal N regime in soil may be provided in conditions when the C-org: N-min ratio lies within the range from 30 to 50.