Silage maize in crop rotations with different grass mixtures - N balances and N leaching.

The cultivation of maize in Germany is expanding due to its use as fodder or corn and increases in biogas production based on renewables. The biogas boom helped to make maize the most cultivated crop in the federal state of Lower Saxony in 2007. A further increase in maize production is, however, viewed with criticism, because it affects the landscape and its biodiversity and might pose a risk to groundwater protection. For future developments maize needs to be integrated in economically and ecologically sound crop rotations. We tested the effect of different grass mixtures, with and without clover, reduced or moderate N supply, on yield and N leaching of corn as a follower crop in a 3-year field experiment on sandy soils. The yield of silage maize is an important factor in evaluating the suitability of such crops within a rotation, as is the amount of N leaching for the environmental impact of the whole system. We found that integrating maize in crop rotations with a reduced N input has the potential to achieve satisfying DM yields of 160 dt ha-1 combined with lower risks of N leaching losses (60 kg ha-1 versus 123 kg ha-1 with high N input).