Farming under nitrate leaching limits.

Executive Summary

This report investigates the impact that altering the farm system of Singletree Dairies in mid Canterbury to achieve a predicted nitrogen leaching loss in Overseer of 24kgN/ha/year will have on both the operation management of the farm and the financial effects of this.

Singletree Dairies currently has a predicted leaching loss of 32kgN/ha/year and through the implementation of more pivot irrigation, increasing the area that effluent is applied along with altering nitrogen fertiliser management in April and May the level of leaching loss can be reduced to 24kgN/ha/year. The management and financial implications of these alterations are minor and are viewed as quite achievable.

When modelled on a ‘light’ soil with and available water holding capacity of 60mm, the leaching estimate for Singletree Dairies increased to 62kgN/ha/year. Significant management alterations are required to reduce leaching to the desired 24kgN/ha/year – notably a decrease in stocking rate from 3.76cows/ha to 2.90 cows/ ha. The financial implications at a farm level of these alterations were not as great as initially thought with a reduction in return on asset from 6.91% to 6.75%.

Singletree Dairies is able to continue to operate profitably under the level of nitrogen leaching suggested in this document, however there is likely to be a decrease in production levels in dairy farming areas of light soils which may affect the local communities the greatest.

Farming Under Nitrate Leaching Limits – William Grayling

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