Productivity and N-leaching in organic dairy grass-arable crop rotations

摘要

The increasing size of Danish organic dairy farms means that uniform grazing of all cropped land becomes inexpedient due to long distance to the milking facilities. We investigated nutrient dynamics and feed production in two dairy crop rotations withinternal differences in proportions of grazing and cutting land. One six-year crop rotation represents land close to the farm buildings (barley (Hordeum vulgare L.) undersown with grass-clover (Lolium perenne L.-Trifolium repens L.), 4 years of grass-clover, spring barley/catch crop) and another represents land further away (barley undersown with grass-clover, 2 years of grass-clover, barley/catch crop, maize (Zea mays L.)/catch crop, lupin (Lupinus angustifolius)/catch crop). In each of the crop rotations there were five management treatments for grazing/cutting strategy and manure application. Results from the first experimental year show that herbage production was high in year 1-4 of grass-clover. Nitrate leaching in the crop rotations were highest in grazed and manured 2-4-year-old grasslands, but also following maize and lupin considerable losses occurred despite the presence of catch crops. Following grassland cultivation, a barley silage crop undersown with Italian ryegrass (Lolium multiftorum L.) reduced leaching to a minimum.