The sulfur (or S) deficiency model was developed
for two rates of crop requirements. The low rate was for a crop requiring 15 kg
S/ha/year, such as corn, and the high rate was for a crop requiring 30 kg
S/ha/year, such as alfalfa. The model can be used to estimate the S status of
other crops that have S requirements similar to either corn or alfalfa.
You search the database by entering criteria in one or more data fields and then clicking the "Submit" button. The data fields (County, Soil Series, S Status (corn), etc.) have pop-up menus to choose from. When you do a search based on one or more criteria, the program lists those soils that match the defined criteria without regard for other characteristics that are not defined. For example, if you select “moderately deficient” for S status (corn), the program will list all soils that are estimated to be “moderately deficient” in S for corn without regard for county, soil series, soil texture, SO4 deposition, soil organic C, or the S status (alfalfa). If you want to find only those soils that are “moderately deficient” in S for corn and have sandy loam texture, you must select both “moderately deficient” under S status (corn) and sandy loam under soil texture before submitting the request.
If doing a search based on SO4 deposition or soil organic C, the basic model has pop-up menus from which you choose suggested minimum and maximum values. The values in these pop-up menus are based on the ranges for SO4 deposition and soil organic C in the database. Atmospheric SO4 deposition varied from 17.5 to 32.0 kg S/ha/yr. Soil organic C varied from 0.17% to 83.98%. If you click the “Advanced” button, you can enter any values you choose for SO4 deposition or for soil organic C.
As an example of a simple search that shows the results for all soils in Morrow County in the database, select Morrow from the pop-up list under County. Then click the '"Submit" button. The results will show the sulfur status for 7 soil series in Morrow County.
There are five categories of S status that are based on the expected response of a crop to supplemental S fertilization when grown on the particular soil series: