NITROGEN POLLUTION FROM SWEDISH BEEF PRODUCTION BASED ON SUCKLE-COWS

摘要

Measures to improve N-use efficiency and thus reduce N-pollution are scrutinized in beef production based on suckle-cows. Measures in feed production, animal feed conversion and the use of animal manure are included and their economic opportunities are analysed. The results suggest that production based on non-N-fertilized grass gives very low losses of NO_3, NH_3 and N_2O per ha. Production based on pastures and leys given 100 kg N ha~(-1) results in considerably higher losses, especially per ha but also per kg of produced beef. Beef production without input of mineral fertilizers might be profitable in regions abundant in land with low opportunity cost, especially if environmental support is provided. Clover-based beef production gives relatively high N losses both per ha and per kg of beef. The reason is unnecessarily high N-content in the clover, resulting in high N-level in excreta and increased losses from manure and pastures. A change from a deep straw bed manure system to slurry spread only in spring and immediately incorporated can reduce N-losses considerably but is unprotitable in suckle-cow-production. Beef production has lower N-losses than pork production per ha but higher per kg of produced meat.