Abstract

Soil sulfur (5) deficiencies have been detected lately, affecting crop production and nitrogen (N) uptake. The objective of this study was to assess the effect of S application on crop N recovery efficiency. N and S mineralization, potentially available N, and urease activity were measured in Andisol and Mollisol soils. No differences were found (P <= 0.05) between the soils in terms of microbiological parameters, but soil mineralization kinetics showed a small increase in the Andisol soil. The Mollisol soil was used to carry out a pot assay with rye grass (Lolium multiflorum), including four treatments: S, N, the combined application of S and N at a rates of 30 kg S ha(-1) and 100 kg N ha(-1), and a control treatment. Crop biomass dry matter, N concentration, and N recovery efficiency were determined sixteen weeks after sowing. N recovery efficiency increased by 26% with S application, but it was not significantly different from the control treatment (P >= 0.05). The S content in the crop biomass was low, and a large residual soil S was observed at the end of crop growth. However, the combined application of N and S resulted in an increase (P <= 0.05) in the root growth of plants.