A comparison of sulfur extractants for weathered acid soils
1995
Santoso, D. | Lefroy, R.D. | Blair, G.J. (New England Univ., Armidale (Australia). Dept. of Agronomy and Soil Science)
An incubation experiment was conducted using 3 acid soils varying in S sorption capacity. The soils were a gleyed podzolic (Aquic Haplustalf), a red earth (Haplohumult) and krasnozem (Haplohumult). A factorial combination of S, P, and lime was applied to the soils which were incubated at 70 percent of field capacity at 25 deg. C for 3 weeks. The concentration of S extracted varied between soils, treatments and extractants. In the krasnozems, the order was MCP less than water less than CaCl2. In the gleyed podzolic the amounts extracted by the 3 methods were similar and in the red earth the order was water less than CaCl2 less than MCP. The addition of P and lime affected the extractants in different ways. The use of 35S-labelled sulfate allowed a calculation of the recovery of added S and this differed between soils and extractants. The results indicate that on low S-sorbing soils the extractants used were not sensitive enough to account for differences brought about by P and liming and that care is needed in interpreting results from such experiments.
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