Active Optical Sensors for grazing systems research

Abstract

Efficiently measuring and mapping green herbage mass using remote sensing devices offers substantial potential benefits for improved management of grazed pastures over space and time. In particular, the integration of data from the spatial monitoring of livestock with spatio-temporal measures of biomass will offer considerable insights into pasture utilisation, one of the key drivers of profitability in grazing systems. Several techniques and instruments have been developed for estimating herbage mass, however, they face similar limitations in terms of their ability to distinguish green and senescent material and their use over large areas. The Precision Agriculture Research Group has been exploring the application of an Active Optical Sensor (AOS) to quantify and map pasture biomass mass using a range of derived spectral indices (Trotter et al. 2010). In order to map pasture biomass, the AOS has been integrated with a Global Positioning System on a 4-wheel motor bike (Figure 1). The systems offers obvious benefits in terms of quantifying pasture biomass in situations where tree cover precludes the application of remote sensing (airborne or satellite) or where spatial variability in ground cover exceeds the spatial resolution of remote sensing instruments. There is also the opportunity to develop rapid assessment systems based on 'representative transects', thereby reducing the requirement to cover all ground in surveys.