Effect of Application Method on Availability of Elemental Sulfur in Cropping Sequences
- S. H. Chien ,
- D. K. Friesen and
- B. W. Hamilton
There have been indications that many rice-growing areas in developing countries are becoming deficient in S. This greenhouse study was conducted to compare the effectiveness of elemental S (ES) mixed with soil (incorporated) or deep-placed in a band to that of incorporated gypsum on crop growth in sequences of rice-rice (Oryza sativa L.) or rice-maize-maize (Zea mays L.). The soil used was an S-deficient Josephine sandy loam (Typic Hapoxerults). Rates of S applied were 0, 14, 28, 42, 56 or 112 mg S kg−1. Incorporated elemental S and gypsum were equally effective in increasing grain and straw yields of the first rice crop, whereas deep-placed ES was less effective. Deep-placed ES became more effective than incorporated ES and gypsum for the subsequent crop of rice in terms of increasing plant dry-matter yield. Two statistically distinct relationships were obtained between S uptake by the second rice crop and P-extractable SO4-S in the soil prior to that crop: one for incorporated ES and gypsum treatments, and the other for deep-placed ES treatments. A weak S response was observed for the first maize crop after rice, regardless of sources and methods of S application. However, a strong S response was obtained with the second maize crop (the third crop in the sequence). At lower initial rates of applied S, the residual effect of deep-placed ES was greater than that of incorporated ES and gypsum. A single relationship for all the S treatments was obtained between total S uptake by the second maize crop and P-extractable SO4-S in the soil after the first maize crop.
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