Effectivity of measures on dairy farms to improve nitrogen balance and nitrogen use efficiency

The aim of this study is to evaluate the effects of measures taken on dairy farms to reduce nitrogen (N) losses in the framework of a national initiative improving agricultural N use efficiency (NUE). Farm gate N balances were assessed to determine the N surplus and the NUE of 11 dairy farms (6 specialized with >65% grassland of total agricultural land and 5 mixed with >40% arable land of total agricultural land). The farmgate N balances were assessed in 2019 and 2020 and compared to the baseline (2015 to 2017) in order to evaluate the effects of the measures taken on the farms. Individual measures were taken on each farm to reduce the N surplus and to increase the NUE. On all farms N input via concentrates was reduced and manure composition was analysed to improve fertilisation. Additional measures consisted of the optimisation of animal management, manure application and crop rotation. The mean N surplus was reduced from 146 to 106 kg N/ha and NUE increased from 44 to 53% on average in the years where measures were taken. These results show an improvement regarding N surplus when measures were taken and indicate a general potential for improvement in N use on dairy farms.