Simulating the influence of management decisions on the nutrient balance of dairy farms

In order to evaluate the influence of management decisions on the nutrient balance of dairy farms a simulation model was developed. Three farm systems have been simulated: zero grazing, winter milk and summer milk. From the simulated farm systems the zero grazing farm has in all scenarios the lowest N-surplus. The winter milk farm system has a higher N-surplus than zero grazing but lower than the summer milk farm system. The results further indicate the positive effects of maize feeding in addition to grazing. More maize in the ration is especially good to lower the N-surplus during the grazing period in the summer. The benefits of more maize in the ration decrease when the fertilizer application rates decrease.