New sensors for measuring soil nutrients

This project will provide farmers and their advisers with tools to help them make the best possible decisions in nutrient and water management. It will develop sensor technology that enables detailed measurement of soil nutrient status and supply, through the soil profile and across the field.

This will provide unprecedented insight into the nutrient status of their soil and the mobility of these nutrients under irrigation and rainfall scenarios. With this technology the distribution of nutrients through the soil profile can be better controlled to maximise both farm profitability and environmental sustainability.

The efficiency of nitrogen applied in-season (e.g. at planting) is low throughout the northern cereal cropping regions. This is attributed to low nitrogen mobility through the soil profile. Yields in these situations are then constrained by low subsoil nitrogen. In these regions, nitrogen management and cropping decisions extend over multiple seasons to build and maintain subsoil nitrogen reserves. In high rainfall regions such as New Zealand and Great Barrier Reef coastal catchments, the mobility of nitrogen is high throughout the profile and so nutrient management decisions require greater focus on leaching potential. Here, nitrogen application must be closely monitored and continually matched to crop demand throughout the root zone.

The ability to cost effectively measure soil nutrient status will be significant. However this addresses only part of the problem. Correct decisions also require understanding soil nutrient supply and dynamics under irrigation and climate scenarios. The development of nutrient sensing technology must be closely linked to sensors that can extend these measurements across the field and through time (i.e. dynamics, soil supply and crop demand) of which soil water status and retention characteristics are highly significant factors. The sensor technology and algorithms that we will develop in this project will be the mechanism by which information on nutrient status and dynamics can finally be provided to farmers and their advisers – enabling a step-change in soil management practices for both profitability and environmental sustainability.