Efecto de la aplicación de caliza y azufre en cultivo de soja

Soybean cultivation [Glycine max. (L.)] is currently one of the main summer crops in Uruguay. Despite this notorious increase in the sowing area, the general average yield has remained around 2000 kg/ha of grain, with temporal and spatial variations associated with management and/or environmental factors, among others. Within these, nutrient management and soil acidity stand out. The objectives of this work were: a) to study the response of the soybean crop to liming and the addition of S; and b) determine the effect of adding agricultural limestone on soil pH. The study was carried out on a Subeutric Brunosol, from the Libertad Formation, in a commercial farm. The treatments were three levels of limestone (0, 2000 and 4000 kg/ha) and three levels of S (0.12 and 24 kg/ha of S), with and without N. Calcium carbonate ( CaCO3), applied one month prior to planting, manually, broadcast on the surface, and incorporated with tillage. The doses of S and N were adjusted with ammonium sulfate and urea. Final grain yield, soil pH evolution during the crop cycle, N and S content in the plant in three phenological stages of the crop and grain S content were evaluated. There was a response in grain yield to the addition of limestone, although only up to the lowest dose of limestone (2000 kg/ha). The increase in yield due to the addition of limestone was 310 kg/ha on average (between 18 and 30% compared to the control). No response was found to the addition of S, neither in the concentration of this nutrient in the plant nor in the final yield. Possibly due to the level of sulfate in the soil, the high value of organic matter and the good mineralization conditions during crop growth. There was no limestone interaction with S. The estimated increase in soil pH was 0.17 units for each ton of limestone added and the maximum increase occurred after 62 days of limestone addition.