THE USE OF GEO-REFERENCED SOIL TEST DATA IN THE HERBERT DISTRICT

SURFACE soil samples have been collected for many years to develop on-farm nutrient management guidelines but their precise locations were largely unknown because geo-referencing technology was previously unavailable. Consequently, spatial analysis of the data was not possible. Over the past four years, the Herbert Cane Productivity Services Limited (HCPSL) has provided a service to growers to co-ordinate soil sample collection, sample analysis, and reporting of soil test information; a geo-referenced position is recorded for every sample. This information is collated in a spatial database and forms a layer in the geographic information systems (GIS) managed jointly by HPCSL and the Herbert Resource Information Centre (HRIC). Interpretation of the data has provided spatial patterns of soil properties across the district. This paper presents examples of the spatial distribution of different nutrients and soil chemical characteristics such as soil pH, extractable phosphorus, cation exchange capacity, exchangeable calcium and extractable aluminium. It shows how georeferenced soil test data can be used to develop nutrient management strategies within the region and to address specific issues associated with nutrient deficiencies and excesses.