| Abstract: | Influence of long-time Nitrogen-fertilizing on yield response of agricultural crops and mineralized Nitrogen in soil
In the years 1979–1986 a fertilizer trial with increasing Nitrogen amount was performed in order to prove the Nmin-method according to S charpf and W ehrmann . The Nmin-method regards the mineralized N in soil (Nmin) for optimizing the N-fertilizer amount at the begin of vegetation, could be confirmed. The optimal N-rate (including Nmin) was for winter wheat and winter barley 120 kg/ha, winter rye 100 kg/ha and sugar beet 200 kg/ha. For cereals additional N-rates were given at the end of tillering 20 kg/ha N and at ear emergency 60 kg/ha N. For the optimal N-fertilizing system we found a positive N-balance (input-output) in a range of 10–25 kg/ha. The influence of N-fertilizing on the mineralized N-amount in soil was very small comparing to influence of weather, soil type or crops. Only at one location a little increase of Nmin (10–15 kg/ha) could be observed after a positive N-balance (50 kg/ha). |
