Growth and Tissue Composition of Sweet Corn as Affected by Nitrogen Source, Nitrapyrin, and Season1

Sweet corn ( Zea mays L.) was grown to evaluate the effect of N source, N rate, time of N application, and the nitrification inhibitor, 2-chloro-6-(trichloromethyl) pyridine (nitrapyrin), on crop efficiency and movement of applied N on a Kanapaha fine sand. Sweet corn yield was not affected by nitrapyrin rates of 0, 0.56, and 1.12 kg/ha, during 2 seasons. During a wet 1976 summer season, total yield was 65% higher with N applied as (NH 4 ) 2 SO 4 than as Ca(NO 3 ) 2 . Total yield increased linearly from 6. 1 to 9.8 MT/ha with an increase in N rate from 56 to 224 kg/ha as (NH 4 )SO 4 . With Ca(NO 3 ) 2 , total yield averaged 4.9 MT/ha and was not influenced by N rate. During the drier 1977 spring season, marketable yield was not influenced by N source. Total yield increased linearly from 9.1 to 14.6 MT/ha with an increase in N rate. In the wetter season, the application of N in split rather than single applications as Ca(NO 3 ) 2 increased yield. During the dry season, timing of N application had no effect on yield with either N source. The suppressing action of NH 4 -N absorption on the absorption of other cations was evident but was not consistent throughout the study. The application of (NH 4 ) 2 SO 4 as compared to Ca(NO 3 ) 2 resulted in higher plant dry weights at an early sampling stage in the wet season but not during the dry season. Higher soil N (NH 4 -N + NO 3 -N) levels were maintained above a 20-cm soil depth with (NH 4 ) 2 SO 4 than with Ca(NO 3 ) 2 during the wet season.