Aspects of sugar beet nutrition with green fellow-derived nitrogen

Annual set-aside may cause a different return respectively input of organic nitrogen from aboveground plant material to the soil, depending on the cro pped plant species (here: perennial ryegrass, phacelia, phacelia/clover, oi l radish, oil radish/clover). As a consequence, this may lead to increased N-uptake by the following sugar beet crop when compared to a common w.-whea t/w.-wheat/sugar beet rotation (control). A two-year field experiment was l aid out to investigate whether the increased N-uptake by sugar beet after s et-side was due to stimulated microbial N transformation. The amounts of so il N-min proved to be increased in most green fallow plots, whereas some so il biological parameters (microbial biomass N and C, dehydrogenase activity , basal respiration) showed no significant difference from the control and hence could not explain the increased N-uptake of the sugar beet.