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Sulfur Balances and Sulfur‐34 Abundance in a Long‐Term Fertilizer Experiment
Author(s) -
Kirchmann H.,
Pichlmayer F.,
Gerzabek M. H.
Publication year - 1996
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1996.03615995006000010028x
Subject(s) - leaching (pedology) , peat , loam , chemistry , soil water , sulfur , fertilizer , agronomy , mineralization (soil science) , environmental chemistry , organic fertilizer , lessivage , environmental science , zoology , soil science , ecology , biology , organic chemistry
Reduced SO 2 emissions, increased use of non‐S‐containing fertilizers, and higher crop yields may lead to S deficiency in agricultural soils in the future. In a long‐term field experiment on a clay loam soil (Typic Eutrochrept) at Uppsala, Sweden, S balances were evaluated for plots under continuous fallow, plots receiving inorganic fertilizers [(NH 4 ) 2 (SO 4 or Ca(NO 3 ) 2 ; 80 kg N ha ‐1 yr ‐1 ], and plots receiving organic amendments (2000 kg C ha ‐1 yr ‐1 ) with the aim of estimating plant uptake, leaching losses, immobilization, and variations of δ 34 S in soil. Total N was correlated with total S concentrations in soil ( R 2 = 0.980), but organic C was less well correlated ( R 2 = 0.741). Total soil S decreased in all treatments where no organic material was added, the largest decrease occurring in the continuous fallow plots with a S mineralization rate of 6 kg ha ‐1 yr ‐1 . Sulfur added through (NH 4 ) 2 SO 4 and sewage sludge was mainly leached, whereas SO 4 leaching was reduced in the Ca(NO 3 ) 2 ‐treated plots as a result of increased crop uptake. Of the organic amendments, 26 to 54% of the S remained in the soil with a half‐life of 24 to 38 yr. Recoveries of S from organic amendments in soil were correlated with their initial C/S ratios ( R 2 = 0.999) excluding peat. A significant enrichment of 34 S was found only in plots receiving peat. Peat was more highly enriched in 34 S than the other organic materials studied and was more resistant to decomposition. The results indicate that shifts in soil δ 34 S cannot be used as a tool for quantitative determinations of S turnover. Nitrogen transformations were the main cause of acidification in the (NH 4 ) 2 SO 4 ‐treated plots, as opposed to S leaching in the sewage‐sludgetreated plots.