Comparing various sulfur sources for soybean grown on an acid Oxisol in Brazil

A greenhouse experiment and a 2-yr field trial were conducted to compare various S sources for soybean [Glycine max (L.) Merr.] grown on an acid Oxisol in Brazil. In the greenhouse, included ammonium sulfate (AMS), monoammonium phosphate with ratio = 50:50 of AMS/elemental (ES) – (AMS + ES), ES bentonite containing 90% ES. All surface-applied at 0, 5, 10, 20, 40 mg kg–1. Separately, all incorporated into soil 20 Yield uptake by grain followed order AMS MAP ES) > bentonite. No significant differences yield observed between surface application incorporation, except those greater than incorporation ES). trial, single superphosphate (SSP) phosphogypsum (PG) also included. 30 kg ha–1 yr–1. Additionally, was split-applied equal amounts planting R1 stage. both years, PG SSP control. The highest split-application first but not second year. benefit split over one-time year probably caused reduced SO4–S leaching.