Nitrogen and Sulfur Nutrition of Sweet Corn in Relation to Fertilization and Water Composition
1971
Daigger, L. A. | Fox, R. L.
The external and internal S and N requirements of field-grown sweet corn (Zea mays) were investigated. The experimental soil was a Bridgeport fine sandy loam of western Nebraska. It contained 4 ppm extractable sulfate-S. Irrigation water contained 3 ppm S. Nitrification rate was 14 ppm during 10 days at 25 C. Five N levels (45, 90, 135, 180, and 225 kg/ha as NH₄NO₃) and 3 S levels (0, 22, and 666 kg/ha as gypsum) were arranged factorial combination, randomized block with five replications. Increases in yield from S fertilization were observed at low rates of applied N. Critical levels of S and N in the ear leaf were about 0.24% and 2.9% respectively. Yields were closely associated with N percentage of the ear leaf and N percentage of the ear leaf was increased by both N and S fertilization. When no S was added, 225 kg N/ha was required for maximum yield (13.5 tons), but when 66 kg S/ha was applied, yield was maximum (13.4 tons) at 135 kg N/ha. A case for the usefulness N:S ratios could not be made from the data examined. Sampling at silking stage is probably too late for effective foliar diagnosis of S deficiency in corn. The probability that S was borderline deficient under these conditions suggests that the external requirement for SOM₄-S in the soil solution is about 3 ppm.
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