Lowering nitrogen use in temperate pasture based dairy systems through the adoption of nitrogen smart green seeker

This document is the final report to DairyTas for the project: Lowering nitrogen use in temperate pasture based dairy systems through the adoption of N smart Green seeker technology. The project has been successfully completed to the schedule detailed in the project proposal. The objectives of this project were to:
1. Evaluate the technology, i.e. can products be applied between or onto nitrogen rich patches within a paddock?
2. How is the ability to detect nitrogen rich zones influenced by management and environment?
3. How soon after grazing will the technology detect nitrogen rich patches?

These objectives were successfully met through a field experiment undertaken on the University farm at Cambridge in Southern Tasmania. This experiment investigated the level of detection of artificial urine patches for a range of nitrogen concentrations (0 kgN/ha, 150 kgN/ha, 300 kgN/ha, 450 kgN/ha and 600 kgN/ha) over a period of 44 days in a temperate pasture sward. The technology was assessed across a range of sensitivity settings; 2,6,8,9 and 10, where the 2 represents a lower normalised difference vegetation index (NDVI) threshold and 10 a higher NDVI threshold.
The data from this experiment was used to assess the accuracy and potential benefits/saving if the technology is used to avoid the application of nitrogen to urine patches or used for the application of nitrification inhibitors to urine patches. A summary of this analysis is provided Table 1. This study concluded that the Smart-N™ is capable of detecting differences in the NDVI between high N and low N areas. However, limitations with the calibration methodology of the equipment cause the system to work at a sub-optimal level. Improvements in calibration methodologies will improve the performance of this technology and should be the focus of further research.

During the life of this project, key learning’s have been communicated to industry through a variety of channels. This project has been reported on in the TIA Dairy Centre newsletter Tassie Dairy News, and the results were presented at the DairyTas annual general meeting and the TIA dairy centre open day. The findings from this project has led to the development of a larger joint project being undertaken in collaboration with Western Dairy that will investigate the potential reduction in nitrogen fertiliser use and nitrox oxide emissions and the consequences to pasture production and nitrous oxide emissions from utilising this technology within commercial dairy systems.