Effect of nitrogen rate,nitrogen timing,and nitrification inhibitors on grain sorghum production in Arkansas |
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| Abstract: | Abstract Nitrogen efficiency may be improved in grain sorghum Sorghum bicolor (L.) Moench.] production by using the optimum N rate, splitting the N applications, and by the use of nitrification inhibitors. Nitrogen rates of 0, 56, 112, 168, and 224 kg N/ha with and without nitrification inhibitors, dicyandiamide (DCD) and nitrapyrin, were evaluated in 1985 and 1986 at two locations in Arkansas. Selected N rates were evaluated when applied all preplant and when the applications were split. In 1986, at one location, two N rates (0 and 168 kg N/ha), DCD and nitrapyrin, and different times of N application were evaluated. These treatments were evaluated at two soil water deficits, 2 and 4 cm. The soils were a poorly drained Sharkey sc (Vertic Haplaquept) in northern Arkansas and moderately well drained Hebert sl (Aeric Ochraqualf) in southern Arkansas. Maximum grain sorghum yield occurred at a lower N rate on the silt loam soil than on the clayey soil in both years of the study. Based on soil inorganic N, the DCD nitrification inhibitor tended to inhibit nitrification during the early growing season on the Sharkey sc. However, the inhibitors did not affect the soil inorganic N on the Hebert sl. Grain yield and plant N were not increased by the inhibitors in any of the studies. Grain yield was not increased by the split N application treatment compared to the preplant N application. However, split N applications increased plant N above the preplant application under high soil moisture conditions. |
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