Partitioning of 35S in ryegrass grown in sulfur-deficient soils

Abstract

A pot study was conducted in a growth chamber using 35S labelled gypsum to study the fate of applied 35S fertilizer in a soil-plant system. The distribution among plant parts and soil fraction of applied 35S was investigated with ryegrass grown in sulfur-deficient soils. Of the applied 35S, 19–35% was recovered in the shoot and 4–16% in root tissues. Within the soil, extractable 35S accounted for 41–55% of applied S, microbial biomass 35S accounted for 2–6%, and the remaining 4–14% was unrecoverable. In addition to the available soil S fraction, it was concluded that S in the unharvested plant residue could be an important supplementary S source for succeeding crops. Keywords: Radioactive sulfur, soil sulfur, plant sulfur, ryegrass