Pasture dry matter responses to the use of a nitrification inhibitor: A national series of New Zealand farm trials

Abstract

The use of nitrification inhibitors has become increasingly common on dairy farms in NZ since 2004, ostensibly to reduce nitrogen (N) loss from nitrate leaching and nitrous oxide emissions. A potential benefit of this reduction in Nloss, however, is an increase in dry matter (DM) production. Pasture response data were collated from a national series of farm trials conducted in 132 paddocks on 37 farms in the North Island (NI) and South Island (SI) of New Zealand where paddocks were randomly split into two halves with one half treated with the nitrification inhibitor eco-n™. Measurements conforming to a strict protocol were made using pasture plate meters. There was a highly significant overall DM response to inhibitor use of 19% across all trials (14% NI, 21% SI) although full-year responses were more variable between NI regions (4-27%) than SI regions (12-31%). Generally, DM responses were greater than those demonstrated by previous small-scale experimental trials and this may indicate the influence of a farm-system effect. Several reasons are speculated for this effect but further research is required to identify the factors involved. © 2012 The Royal Society of New Zealand.