Integrating spatial technologies in a mixed farming system to increase production efficiency of crop grazing

Summary

​This project evaluated contemporary spatial technologies to assist in crop grazing management on a mixed farming enterprise in Western Australia.  There is a need for tools to better predict crop biomass to assist producers to determine when to begin crop grazing and when to remove sheep to minimise the impact on final yield. Lactating Merino ewes (n=403) and their lambs (n=425) were grazed on a barley crop for 2 weeks in June 2017. Measurement of crop biomass using quadrant cuts and Greenseeker measurement of NDVI were taken at the start and end of the trial. Low-level remote sensing (UAV) and Pastures from Space satellite imagery were also evaluated for their ability to provide near real-time biomass data. Spatial utilisation of grazed crops was determined using GNSS tracking collars and correlated with geophysical soil measurements, biomass and yield. The GNSS collars derived livestock grazing maps and harvester yield maps were also used to produce an overalldual-purpose crop profit map for the paddock.

A key finding from this study is that the Greenseeker can accurately predict the available biomass (kg DM/ha) when stubble is removed from the area being measured.  Producers can potentially use the Greenseeker NDVI tool in conjunction with other tools to predict biomass during crop grazing and the economic potential of the paddock.  The spatial grazing patterns of sheep on crop varied across the grazing period, showing higher levels of activity as available biomass declined.  However, the seasonal conditions experienced early in the growing season may have supressed any relationships between grazing patterns and yield measurements.  Producers should take into account the additional grazing benefits of liveweight gain and reduced supplementary feed costs from crop grazing when evaluating the gross margins of a grazed paddock.  In this project, with these costs included, crop grazing resulted in a higher paddock gross margin despite a decline in crop yield.  This project has identified a number of potential benefits and new areas for further research on crop grazing using spatial technologies.