Precision agriculture (PA) tools and techniques have been used in New Zealand (NZ) since the early 1990's. There has been wide-scale uptake of some PA tools such as autosteer; planter and sprayer section control; and variable-rate irrigation. However, there has been a limited uptake of Site-Specific Crop Management (SSCM) using variable-rate seeding, nutrient and lime applications to different Management Zones (MZ).

This paper outlines examples of the use of SSCM on maize crops, and the effect on whole-paddock profitability of the resulting crop, as well as the sustainability of crop production measured using metrics such as nitrogen leaching.

Hybrid maize seed in NZ is approximately double the price than in North America, and as such the potential benefits to growers using variable-rate seeding (VRS) are significant. However, VRS has not been undertaken in commercial maize crops in New Zealand. Two trials carried out in the 2015/16 growing season showed that the use of SSCM and VRS can provide a relatively simple, practical way of improving maize crop gross margin; in this case by an average of NZ$96 per hectare. Targeting different maize yields to different MZ is a valuable tool to minimise losses due to nutrient over-supply to poor performing zones in maize crops. Nitrogen leaching losses could be reduced from up to 150kg N/ha in parts of the paddock to less than 10 kg N/ha using SSCM.

Spatial clustering analysis of the results established a good basis for site-specific management by identifying MZ. In conjunction with the growers’ knowledge, a practical analysis of crop agronomic decisions can be made based on geospatial crop and soil data to inform crop management decisions in the future.

SSCM is a practical tool to help manage variability in New Zealand cropping paddocks to improve profitability and reduce environmental impacts.