Can manipulation of microorganisms within perennial ryegrass dairy pastures result in reduced nitrogen fertiliser requirements and losses of nitrogen from the system whilst maintaining production?

摘要

Utilisation of N_2 fixing (rhizobia) white clover as the nitrogen (N) input into a perennial ryegrass pasture is likely to give pasture and milk production similar to that with addition of 200 kg inorganic N ha~(-1) annum~(-1) and avoid greenhouse gasemissions resulting from N fertiliser production. Use of the nitrification inhibitor dicyandiamide that de-activates the ammonia monooxygenase enzyme in ammonia-oxidising bacteria can substantially reduce N0_3~- leaching and N_2O emissions from perennial ryegrass pastures while increasing productivity. In addition, there is considerable potential to manipulate rumen microorganisms such that the proportion of N uptake that is excreted in urine is decreased while production is maintained or increased.