Evaluation of some soil and plant analysis procedures as predictors of the need for sulfur for corn production

The objective of this study was to evaluate the usefulness of measures of mineralized sulfur (S), soil sulfate‐sulfur (SO4‐S), concentration of S in plant tissue, and the N: S ratio in plant tissue as predictors of the need for S in a fertilizer program for corn (Zea mays L.). Data to evaluate the use of plant analysis for S as a predictor were obtained from ten sites where various rates of N and S were applied to corn. Regression analysis was used to relate the S concentration in the ear leaf tissue as well as the N: S ratio in the same tissue to relative yield when the rate of applied N was held constant at a rate of 168 kg/ha. These measures of S in plant tissue were not significantly related to relative yield at sites where there was no response to fertilizer S as well as sites where added S increased yield. Data from the same sites were used to assess the ability of soil tests to predict the need for fertilizer S. A measurement of extractable SO4‐S in the surface soil (0–15 cm) was not reliable for predicting the need for S for corn grown on soils with a silt loam texture. Static incubation techniques were used to evaluate the amount of S mineralized from soil collected from seven sites. The amount of SO4‐S measured after four and twelve weeks of incubation was curvilinearly related (p <.05) to yield increase from a S fertilizer. Net mineralized S was less than 2.1 and 3.7 ppm SO4‐S after four and twelve weeks of incubation, respectively, for soils taken from sites where response to fertilizer S was obtained. Data collected in this study indicate that a measure of mineralized S could improve the ability to predict S needs for corn production on soils with a silt loam texture and a low organic matter content.