Phosphorus (P) use efficiency has been identified as a key issue for Australian grazing systems. This project examined the spatial variability in soil P concentration from two separate surveys of grazed pasture fields. A field on the central tablelands of NSW had a range in Bray P of 1.2 to 140 mg/kg and a COV of 107%. The other field on the northern tablelands of NSW reported a range in Colwell P from 13.0 to 121.1 mg/kg and a COV of 59%. Maps of the spatial variability of soil P demonstrated that there is a relationship with field elevation. Application of critical P values to both fields enabled an estimation of the value of site specific fertiliser management. For one field, fertiliser inputs could potentially be isolated to 37% and the other 56% if nutrient additions were targeted at responsive areas. The opportunity for increased fertiliser use efficiency through site specific management (SSM) warrants further investigation. Research is required into both the value of SSM and the techniques that might enable the development of this strategy.

Precision Agriculture (PA) is changing how producers manage their land. PA involves the use of sensors and management strategies that target the spatial and temporal variability that occurs across a landscape. The introduction of PA has increased profitability and resource use efficiency across many agricultural systems and is now widely applied in cropping and horticultural enterprises. However, development of PA strategies for grazing systems has largely been ignored, possibly due to the complex relationships that exist when considering soil, plant and animal interactions across variable pastoral landscapes. There is a growing interest in the potential of PA management strategies, for example Site Specific Nutrient Management (SSNM) to assist in increasing the fertiliser use efficiency in grazing systems (Simpson et al., 2011). Technologies such as soil EM38 mapping and plant vigour sensors (Crop Circle - Active Optical Sensor) have been extensively used in PA cropping operations and these tools offer some ability to monitor the soil and plant systems in a pasture. The more recent development of GPS livestock tracking has now unlocked the ability to monitor the spatial and temporal variability of the animal component of a grazing system. The integration of these technologies holds significant potential in providing an understanding of how grazing systems vary and how this variability can be managed, particularly through SSNM. This study aims to investigate how common PA tools such as soil EM38 and plant vigour sensors along with GPS tracking information from livestock can be used to understand the spatial distribution of soil nutrients in grazing systems. It is anticipated that this information will lead to an understanding of how producers can zone pasture paddocks to apply SSNM strategies in a similar way to what is currently applied in cropping systems.

Precision agriculture (PA) technologies and applications have largely been targeted at the cropping and horticultural industries. Little research has been undertaken exploring the potential for PA in grazing systems. This paper reports on the results of five studies examining PA technologies and techniques in grazing systems including: spatial variability in soil nutrients and fertiliser response across the grazing landscape; spatial landscape utilisation in relationship to individual animal productivity and health; spatial variability in pasture pests; and the development of a sensor network for monitoring spatial soil moisture, soil temperature and ambient temperature across a grazing landscape. The large variability exhibited in our trials suggests there is an enormous opportunity for precision agriculture in grazing systems. Sensing and responding to this variability will require careful application of modern PA technology and a substantial investment in research to better understand spatial variability in our grazing landscapes.