Der Einfluss von Bewirtschaftungsmaßnahmen auf die Stickstoffverluste in NÖ-Alpenvorland

Gumpenstein

2004

S. 9-14

12 Lit. Ang.

Artikel aus einer Zeitschrift

200111527

In a lysimeter study in the humid region of Lower Austria the contribution of cover crops to reduce nitrate leaching was evaluated in a rotation consisting of 50 % maize over a 4 years period. The presence of frost susceptible cover crops or winter hardy cover crops reduced N-losses and nitrate concentration in the seepage water by 35 or more than 70 % compared with fallow at a medium fertilised level, where 28 kg NO3-N per hectare and year were lost and the nitrate concentration at 42 mg/l was just below the limit level. N leaching was not intensified by cattle slurry doses of 30 m3 to the cover crops. Slurry application before sowing of frost susceptible cover crops resulted mostrly in significant yield effects for the subsequent maize. However positive yield effects of slurry applied in the late autumn to well established winter hardy species could only by found, when the incorporation of the plant residues took place at least three to four months before the intensive N uptake period of the succeeding crop. Also the mixture of legume with non-legume cover crops resulte mostly in significant yield effects for the subsequent maize. However positive yield effects of slurry applied in the late autumn to well established winter hardy species could only be found, when the incorporation of the plant residues took place at least three to four months before the intensive N uptake period of the succeeding crop. Also the mixture of legume with non-legume cover crops had positive yield and environmental effects (N losses reduction of 40 % compared to fallow at medium fertilised level) and is favourable for organic farming systems, when N-inputs from manure are generally low or not available. With continuous cover cropping, especially in combination with slurry application, a positive N input to the soil is indicated, which may be held as immobilised organic N. Therefore the farmers should reduce the nitrogen inputs to the subsequent crops at the same degree to maintain the effective contributions of cover crops for the improvement of ground water quality in the long run.