Fertilizer sulphur uptake and transformations in soil as affected by plant species and soil type

Abstract The fate of fertilizer sulphur (S) in soil is important to S availability to plants and consequently, the crop growth and quality of the harvested products. In a pot experiment, we studied the partitioning of 35 S-labelled Na 2 SO 4 in soil compartments ( 35 S in CaCl 2 extract, labile and non-labile 35 S determined by hot water extraction) and in plant biomass. Rape ( Brassica napus ) and barley ( Hordeum vulgare ) were chosen for their contrasting S requirements. They were cultivated 28, 42 and 63 days in two contrasting soils: a calcareous soil (Rendzic Leptosol, pH 8.2, 2.3% organic C) and an acid brown soil (Fluvic Cambisol, pH 5.3, 1.0% organic C). Microbial activity was stimulated by the addition of glucose alone or glucose with N and P. Rape took up 2–3 times more S than barley. For both species, S accumulation in shoots was an exponential function of shoot biomass: S in shoots =  α (shoot biomass) 1− β , which suggests that the content of S in the shoot might be used as an index of plant S nutrition. In the calcareous soil, CaCl 2 - 35 S dominated whereas in the acid brown soil, labile 35 S extracted by hot water (HW- 35 S) and CaCl 2 - 35 S were equally important. In both soils, CaCl 2 - 35 S was decreased by plant cultivation and when C was added whilst 35 S in non-labile forms increased in parallel. In case of rape, the effect of the plant on 35 S transformations in soil was of the same order of magnitude as the effect of the soil type.