Study examines the effects of livestock grazing and tillage on forage cropping systems

The impacts of winter forage crop grazing usually include soil compaction from livestock treading, and increased urea on soil. Potential risks of these include impacts on subsequent crop production and nitrogen loss from soil via leaching into waterways or N2O (nitrous oxide) greenhouse gas emissions.

Using crop establishment techniques that reduce soil compaction and its adverse effect on nitrogen loss, while supporting overall crop production, is an important consideration for growers.

A new study, part of the Forages for Reduced Nitrate Leaching (FRNL) programme and the Plant & Food Research-led Strategic Science Investment Fund programme, Sustainable Agro-Ecosystems, looked at the effects of soil compaction and urine from livestock on subsequent crop production and nitrogen loss.

A specific focus was on whether no-tillage (direct drill) crop establishment could help to reduce the risk of nitrogen losses and the performance of subsequent crops. Continue reading

Study of nitrous oxide emissions from cattle urine deposited on soil supporting kale crop

The New Zealand Journal of Agricultural Research plays an important role in disseminating topical information to researchers in universities, research institutes, and other centres concerned with animal or pastoral science.

The journal publishes original research papers, review papers, short communications, book reviews, letters, and forum articles. Subject matter includes soil science, fertilisers, insect pests, plant pathology, weeds, forage crops, management systems, agricultural economics, agronomy, and animal science.

Recent articles include a study of nitrous oxide emissions from cattle urine deposited on to soil supporting a winter forage kale crop.

The authors are . J. van der Weerden, T. M. Styles, A. J. Rutherford, C. A. M. de Klein & R. Dynes.

The abstract says:

Wintering cows on forage crops leads to urine being excreted onto wet, compacted soils, which can result in significant emissions of nitrous oxide (N2O).

A field trial was conducted to determine the N2O emission factor (EF3; proportion of urine-N lost as N2O-N) for dairy cows wintered on a kale forage crop on a poorly drained soil. Urine was collected from non-lactating dairy cows on a forage kale diet and applied at 550 kg N ha−1 to artificially compacted soil to simulate trampling and non-compacted soil in a kale field.

Cumulative N2O losses over four months were 7.38 and 2.64 kg N2O-N ha−1 from urine applied to, respectively, compacted and non-compacted soil. The corresponding EF3 values 0.75% and 0.30%, respectively, differed (P = .003) due to compaction.

Combining these results with previous studies, where brassica-fed livestock urine was applied to soils supporting a forage brassica crop, suggests a significant relationship between soil water-filled pore space (WFPS) and brassica-derived urine EF3 (P = .005).