Developing a Tool for Growers to Predict Sulfur Availability in Their Soils.

Sulfur is increasingly becoming a limiting nutrient in parts of the U.S. farmlands. Farmers lack a reliable way by which they can make informed decisions about sulfur fertilization for their crops. The existing diagnostic soil or plant testing methods vary in their effectiveness of predicting any potential sulfur deficiency that the crops might be facing during the growing season. Besides, these laboratory methods are generally cost prohibitive, time consuming and spatially variable. For rapid assessment of sulfur availability, across the varying agricultural landscapes in the US, we have developed a model-based sulfur availability assessment in a Geographic Information System framework. The sulfur availability model developed by our team for Ohio (Kost et al. 2008) was adapted for the purpose of extending the model to the entire conterminous US. Geoprocessing of the gSSURGO data, and other freely available geodatabases at the national level was performed to retrieve factors that determine the sulfur availability in agricultural landscapes. The sulfur availability index was computed for low and high sulfur requirement crops. A GIS based web tool that the farmers could use to identify the probability of observing a response to sulfur fertilization on their farm fields and to investigate the visual relationships between low yielding areas on their farm fields and sulfur availability was developed.