Effect of sources and doses of sulfate on soybean crop

Crop demands for the macronutrient sulfur (S) are similar or greater than those for phosphorous. However, S is often overlooked in the management of crop fertilization. This study aimed to evaluate the effect of sources and doses of S on soybean cultivation under field conditions. A randomized block design, with 4 replications, was used. The treatments were arranged in a factorial scheme with one additional treatment (3 x 5 + 1), totaling 64 experimental units. Sources (elemental sulfur, single superphosphate and agricultural gypsum) and doses (20 kg ha-1, 40 kg ha-1, 60 kg ha-1, 80 kg ha-1 and 100 kg ha-1) of S were used, in addition to one control (without fertilizer). The following parameters were assessed: plant height at flowering, 1,000-seed weight, yield and agronomic efficiency, which were affected by the doses and sources of S; number of pods per plant, only affected by the sources of S; and number of pods with 3 seeds, with no statistical difference for any of the treatments. The highest yield recorded was 1,927 kg ha-1, at the dose of 80 kg ha-1 of S for gypsum, and the greatest agronomic efficiency was observed for the single superphosphate, at the dose of 20 kg ha-1 of S.