| Abstract: | During the last three decades, large amounts of soil organic matter (SOM) and associated nutrients have been accumulated in arable soils of Western Germany (former FRG) due to deepening of the plough layers (from < 25 to > 35 cm) and to fertilizer application rates which have exceeded the amounts of nutrients removed in harvested crops. Organic carbon and total nitrogen balances (1970—1998) on 120 plots from 16 farms in southern Lower Saxony yielded a cumulative increase of up to 16 t C ha?1 and 1 t N ha?1 in loess soils used for cash crop production and up to 26 t C ha?1 and 2.4 t N ha?1 in sandy soils under livestock production. The buffering capacity for reactive compounds, particularly of C, N, S and P and of other (organic or inorganic) pollutants will reach its limits in the near future, after organic matter ”?equilibria” have been re‐established. An immediate adaptation of the current fertilizer application rates to the nutrient export by field crops is therefore urgently needed. |
