Performance of a fertiliser management algorithm to balance yield and nitrogen losses in dairy systems

摘要: Abstract To demonstrate the use of a previously developed fertilisation algorithm and to determine its potential effects on nitrogen (N) losses from grazed pastoral systems, simulation study was performed using Agricultural Production Systems Simulator (APSIM). The considered dairy system with irrigated ryegrass pasture silt loam soil in Canterbury region New Zealand. Firstly, parameterised for each month based yield N contents run over 20 years wide range rates. then used management hypothetical farm under different scenarios where performance increasing more efficient tested. were targets proposed (50, 75, 90 or 100% average maximum yield) included scheduled mimic typical management. For realistic evaluation, simulations took into account changes stocking rates flows resulting fertiliser also uneven return urinary by grazing animals, which are crucial these systems. Both general agreement available measured data similar systems comparable inputs. Thus providing support as valid way changing 10 years showed that direct lower when controlled compared at However, animals paddock thus including urine patches, not significantly different. As there an increase consequent numbers, area receiving increased, counter balancing increased efficiency algorithm. Nonetheless, larger lead greater productivity, this resulted about 13% reduction per unit milk production.