An investigation of the incorporation of a standoff facility with the grazing of fodder beet in a Canterbury dairy wintering system

Abstract

Dairy farmers are under scrutiny for the negative effect their farming operations have on the environment, particularly in regard to nitrate leaching. The National Policy Statement for Freshwater has directed regional councils to set limits for nutrient losses by 2030. Of particular interest are the traditional fodder crop wintering systems which have a higher density of urine patches at times of greater drainage. Since plant demand is low, high levels of nitrate leaching result. Current proposed alternative strategies, such as shed housing can have a large initial cost, with impacts on the financial viability of the business. This project investigated the environmental and economic effects of a fodder beet/standoff pad wintering system as an alternative to the current Lincoln University Dairy Farm (LUDF) forage crop wintering system, where all crop/supplement are fed in paddock. These systems were modelled using partial budgets for the winter period and analysis in Overseer® version 6.1.3 to quantify the economic and environmental effects. In the models, 400 cows were either grazed 24 hours per day on the crop with silage, or an alternative system which restricted grazed fodder beet for six hours per day for the 61 day period, with silage fed on a pad that collects all effluent. In both case the cows were allocated 8 kg DM per cow of fodder beet. For the paddock option, they were allocated 6 kg DM of silage and on the pad 4.8 kg DM of silage (due to better utilisation). This analysis concluded that the proposed system cost $41.07 per cow per week, which was 82.3% more expensive than the historical system at $22.53 per cow per week. The proposed system’s levels of nitrogen lost to water were 56.9% lower than the historical system, with losses of 28 kg N/ha for the proposed system and 65 kg N/ha for the current system. These results conclude that a fodder beet/standoff pad system provides a viable means of reducing nitrate leaching in a wintering system in Canterbury; however, the cost of this is significantly higher than a traditional paddock based system. A calculation estimated that the use of a structure to reduce leached nitrogen was $171 per kg of leached nitrogen mitigated.