Urine patches in grazed pastures have been identified as important sources of nitrous oxide (N2O) emissions. An increase in N2O emissions is possible where urine patches coincide with dung patches and farm dairy effluent (FDE) applications. The aim of the present study was to quantify the effects of dung additions and fresh FDE applications on N2O emissions from urine patches. A field experiment was conducted on a pasture site at the AgResearch’s Ruakura dairy farm in Hamilton, New Zealand. A closed soil chamber technique was used to measure the N2O emissions from a free-draining volcanic soil that received urine (492 kg N/ha, simulated urine patches), with or without dung (1146 kg N/ha) and fresh FDE (100 kg N/ha) and to compare these with controls receiving no urine. The addition of dung delayed the peak N2O fluxes from the urine patches by ~30 days. This could be due to temporary nitrogen (N) immobilisation during decomposition of carbon from the dung. However, over the whole measurement period (271 days), dung addition increased the N2O emission factor (EF, % of applied N emitted as N2O) for the urine from 1.02% to 2.09%. The application of fresh FDE increased the EF to 1.40%. The effluent- or dung-induced increases in N2O emissions from the urine patches were possibly caused both by the direct input of N from effluent or dung and through the indirect priming effect of addition of dung or effluent on the availability of N from urine patches for N2O production. We conclude that when EFs are used in calculations of N2O emissions from urine, consideration should be given to the likelihood of coincidence with dung or FDE applications.
Correction to: Can the application of farm dairy effluent enhance cadmium leachingfrom soil?
