Sulfur fertilization sources for multisite sugarcane ( <i>Saccharum</i> spp.) fields in Brazil

Abstract Sulfur (S) deficiency in soils has become a common problem in Brazilian sugarcane ( Saccharum spp.) fields due to high nutrient extraction by the crop without adequate replacement. Five field trials were conducted in Brazil over two consecutive ratoon cycles to evaluate S fertilizer sources and application rates and their residual effects on soil S availability and sugarcane yield. The treatments included (1) two S application rates (50 and 100 kg S ha −1 ), (2) four S sources (gypsum, elemental sulfur [ES], ammonium sulfate [AS], and polysulfate [PS]), and (3) a control (no S application). The PS and AS were applied in band over sugarcane rows, whereas gypsum and ES were broadcast during the first ratoon, subsequently, no S was reapplied and residual effects were assessed in the second ratoon. The broadcast application of gypsum at 100 kg S ha −1 increased the available soil S concentration after 6 and 12 months. However, S levels remained below 10 mg dm −3 after two ratoon harvests, regardless of the S source. Leaf S concentration increased after band application of PS at 100 kg S ha −1 in both ratoon cycles and after broadcast application of ES and gypsum (residual effect) in the second ratoon. Stalk yield increased by an average of 5–7 Mg ha −1 across sites in the first ratoon with S sources application. In the second ratoon, significant residual effects of S sources led to an increase in stalk yield, averaging 7–9 Mg ha −1 compared to the control. Our findings indicate that S fertilization should be applied annually, with sulfate‐based fertilizers preferred in the short term. ES shows potential for long‐term S supply.