Maize Response to Sulfur Fertilizer in Three Iowa Soils
2021
Kovar, John L.
Maize (Zea mays L.) yield increases from sulfur (S) fertilizer have recently been documented in Iowa, but responses have not been consistent. The objective for this study was to evaluate the response of juvenile maize to S applied as ammonium sulfate (AMS), ammonium thiosulfate (ATS), and S-enhanced mono-ammonium phosphate (MAPS). Clarion loam (Typic Haplaquolls), Fayette silt loam (Typic Hapludalfs), and Muscatine silt loam (Aquic Hapludolls) were collected from eroded hillslopes in Iowa, and amended with 0, 22, 34, and 45 kg S ha⁻¹. Maize (Pioneer 36N71) seedlings were planted in pots, placed in a controlled-climate chamber, and harvested after 21 days. Fertilizer S increased maize shoot dry matter (DM) when AMS was applied to Clarion loam, and when S from any source was applied to Muscatine silt loam. Sulfur fertilizer had no effect on DM accumulation in Fayette silt loam. Whole-plant S concentrations were generally higher than the control for all S sources. The agronomic efficiency of S (DM yield per unit applied) was greatest for the Muscatine soil, and was not related to S source or application rate. Early season growth of maize in Iowa may benefit from S fertilizer application, but the response may be site-specific.
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