Effects of Different Dicyandiamide Rates on Sesame Yield and Nitrate Nitrogen under the Equivalent Nitrogen Condition in Red Soil, Jiangxi Province

Dicyandiamide and nitrogen combination can improve nitrogen use efficiency, but the optimal rate of dicyandiamide varies in different soils.The objective of this study was to explore the effect of optimal rate of dicyandiamide on sesame yield and nitrate nitrogen under the equivalent nitrogen condition in red soil.Seven dicyandiamide rates were implemented with 0%, 3%, 5%, 7%, 10%, 15% and 20% in field, respectively.The result showed that dicyandiamide with nitrogen fertilizer could improve sesame yield, harvest index and economic benefits.The 5% dicyandiamide rate treatment was the best in all treatments.Compared with control treatment, 5% dicyandiamide rate increased sesame yield, harvest index and economic benefits by 126%, 29.0% and 183%, respectively; sesame yield, harvest index and economic benefits decreased with the increase in dicyandiamide rate.However, soil nitrate nitrogen content decreased with the increase in dicyandiamide rate, and the nitrate nitrogen content in all dicyandiamide application treatments decreased by 11.6%~22.3% compared to control treatment.Therefore, 5% dicyandiamide was the optimal rate for sesame under 90 kg N·hm^-2 application, which not only significantly increased the sesame yield and economic benefits, but also decreased soil nitrate nitrogen accumulation in red soil.