STRATEGIES FOR UTILIZATION OF BEET SOIL I N AGRICULTURE UNDER SPECIALCONSIDERATION OF NITRATE-NITROGEN

In 2-year pot trials and several-year field trials strategies for the utilization of beet soil (soil and partly root residues from washing p rocess of beets) on agricultural areas were developed. Beet soils are rich of nitrogen and therefore the effect on nitrate leaching was prim arily investigated (analysis of mineral nitrogen content in 5 m deep s oil profiles, N-leaching calculated by the soil water nitrate content, gained by ceramic candels, and the volumes of water percolated in lys imeters, nitrogen balances). Under consideration of N-conserving tilla ge systems a 15 cm beet soil application resulted in small nitrate lea ching on deep sandy and silty loams. Although the application of 30 cm beet soil did not considerably increase nitrate leaching at the locat ion of Weihenstephan, we suggest an application of 15 cm only, because the expected N-mineralization is then better in agreement with the N- uptake of plants. A prerequisite for a high utilization of the beet so il nitrogen was a quick growth of plants (Lolium perenne or similiar p lants with a high N-uptake) on the treated areas as well as shallow ti llage without incorporation of the beet soil into the existing surface soil. Application in late summer after the harvest of corn should be favoured.