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Sulfur Nutrition of Rapeseed: I. Influence of Fertilizer Nitrogen and Sulfur Rates
Author(s) -
Janzen H. H.,
Bettany J. R.
Publication year - 1984
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/sssaj1984.03615995004800010019x
Subject(s) - rapeseed , sulfur , nutrient , nitrogen , fertilizer , soil water , brassica , agronomy , chemistry , nitrogen balance , crop , dilution , yield (engineering) , zoology , environmental science , biology , soil science , organic chemistry , physics , materials science , metallurgy , thermodynamics
Both sulfur and nitrogen deficiencies have been observed in large acreages of western Canadian soils. These deficiencies prompted an investigation of the interactive effects of N and S on rapeseed ( Brassica napus L.), a S‐sensitive crop that is extensively grown on these soils. Four rates of N (0, 50, 100, 300 mg N kg −1 soil) and four rates of S (0, 5, 15, 40 mg S kg −1 soil) were applied in all combinations to rapeseed grown in a pot culture experiment. Maximum seed yield responses to N and S were observed only when the availability of N and S was in approximate balance. Excessive N applications relative to S availability severely suppressed seed production. This effect was attributed to the accumulation of toxic levels of N metabolites. Excessive S applications relative to N availability produced excessive accumulation of S in the plant tissue. The leaves, and, to some extent, the stems, were the predominant sites of excess nutrient accumulation. Seed nutrient concentrations remained relatively stable over all fertilizer treatments. In most plant parts, the applications of one element reduced the concentrations of the other element by a “dilution” effect. The optimum ratio of available N to available S in the soil was estimated to be 7 to 1. Ratios below 7 resulted in inefficient utilization of the assimilated S, while ratios exceeding 7 resulted in reduced seed yields.