The dataset for total soil phosphorous was downloaded from NLWRA website. This dataset presents a surface of predicted total phosphorus of top soil (A Horizon) surface for the intensive agricultural areas of Australia. Data was modelled from the spot observations taken by soil agencies both State and CSIRO. The point information were extrapolated to produce the map. For details of modelling methodology, see Henderson et al (2001). This map can be used to identify areas where the natural fertility of soils is low and fertiliser inputs would be required to enhance crop production. It can be combined with the pH map to predict where and how much phosphorous is likely to be available to plants under natural conditions. Combined with the pH map, it can also be used to identify the areas where fertiliser needs to be added and to estimate the amount of lime required to bring the pH to a level where the phosphorous will be available for plant uptake. Total phosphorous is presented as weight % phosphorous (eg. g P per 100g soil).

The NLWRA Landuse map was used to identify areas that were cropped for Grains (More information- Landuse Map metadata). Thereafter using the identified cropped area, the area of land under each nutrient category was extracted for each GRDC zone (More information- GRDC Zone metadata).

Data quality: This raster data set has a grid resolution of 0.001 degrees (approximately equivalent to 1.1 km). The data set is a product of the National Land and Water Resources Audit (NLWRA) as a base dataset.

Very few measurements of total phosphorus were available for soils in NSW and Vic. Most measurements were from Qld and WA. The modelled estimates are most reliable for Qld, and least reliable for NSW, eastern Vic, SA and NT. The models were created using the regression tree software Cubist and a suite of 40 environmental predictors. Uncertainty surfaces corresponding to ASRIS point model prediction surfaces is also available with NLWRA for this soil property.

Reference- Original metadata

ANRDL (2001) Soil total phosphorous for Australian areas of intensive agriculture (derived from site measurements) Available from: http://asdd.ga.gov.au/asdd/tech/zap/basic-full.zap?&target=brs-4&syntax=html&cclfield1=all&cclfield2=phrase&cclfield3=any&cclterm1=total%20phosphorous&cclterm2=&cclterm3=&start=1&number=1.

Henderson, B; Bui, E; Moran, C.; Simon, D.; Carlilie, P. (2001) ASRIS: Continental-scale soil property predictions from point data. Technical Report 28/01, CSIRO Land and Water, Canberra. 107p.