Dissertation

Soil and crop management options to improve nitrogen cycling on dairy farms on peat soil

The main research question of this thesis was: Can nitrogen cycling on dairy farms on peat soil in the Dutch Green Heart area be improved by adapting management to the nitrogen supply from soil and by using other grassland species and crops without affecting milk production?

Author: J. Pijlman
Date: 31 January 2024
Links: Thesis in Leiden Repository

There is increasing pressure to reduce nitrogen losses from dairy farming on peat soil. Ambitious policy targets regarding N loss have been put in place by the Dutch government. This thesis comprised four studies, which focused on 1) estimating the nitrogen supply from soil, 2) the possibility of lowering nitrogen levels of perennial ryegrass through population selection, 3) on the effect of plantain on the soil nitrogen cycle and 4) on growing cattail as alternative roughage on rewetted peat soil. The results of the research were used to estimate the effects of nitrogen fertilisation adapted to the nitrogen supply from soil and of the cultivation of low-nitrogen perennial ryegrass, plantain and cattail on nitrogen losses of an average dairy farm. The estimated nitrogen loss reductions were, even when combined, not sufficient to achieve policy targets on farm level. The options may however be combined with other options which were not investigated in this thesis.