There is a trend in organic dairy farming towards higher milk yields associated with more concentrates and less grazing. Grazing is usually compulsory but grass intake from grazing varies greatly. This has consequences for nitrogen (N) transfer from stable to field and for the risk of N leaching. Our aim was to compare different management options for grazing in moderate to intensive organic farming. In a two-year study five differently managed fields on three farms in northwest Germany were compared. We analysed parameters of milk production and grassland management, calculated N balances and quantified residual soil mineral N (SMN) as an indicator for N leaching. Residual SMN (0–90 cm) varied on average from 33–84 kg N ha⁻¹ in grazed areas and from 71–180 kg N ha⁻¹ in functional areas like watering places. Soil mineral N increased with higher stocking rate, more grazing days and higher N surpluses. Consequently, SMN was higher in pastures used for exercise grazing or night grazing and around watering places. We conclude that intensifying organic dairy farming when associated with a massive N transfer from stable to field, little fodder uptake on pasture, and higher stocking rates increases N leaching risk.

有机奶牛养殖业有一个趋势，那就是更高的牛奶产量，更多的精矿和更少的放牧。放牧通常是强制性的，但放牧引起的草摄入差异很大。这对氮（N）从稳定态向田间转移以及氮淋溶的风险具有影响。我们的目的是比较中度至集约化有机农业放牧的不同管理方案。在一项为期两年的研究中，比较了德国西北部三个农场的五个不同管理的田地。我们分析了牛奶生产和草地管理的参数，计算了氮平衡并定量了残留土壤矿质氮（SMN），作为氮淋失的指标。残余SMN（0–90 cm）在放牧区平均为33–84 kg N ha ^-1，在71–180 kg N ha ^{-1之间变化}在诸如饮水场所之类的功能区域中。土壤矿质氮随着放牧率增加，放牧天数增加和氮剩余增加而增加。因此，SMN在用于运动放牧或夜间放牧的牧场和浇水场所附近较高。我们得出的结论是，与大量的氮从稳定地转移到田间，草场对草料的吸收少以及较高的放养率相关联，强化有机奶牛养殖会增加氮浸出的风险。