Effect of preplant nitrogen and phosphorus application method and source on sorghum (Sorghum bicolor L.) grain yields

Abstract

Nitrogen (N) losses can occur with different fertilizer sources and methods of application. Both N and phosphorus (P) are essential macronutrients for cereal production; however, there is little research done to demonstrate the effect of using different P sources and how these can be applied with N using different methods. The objective of this study was to determine NH4-N effects on sorghum growth when applied pre-plant with different phosphate fertilizers on sorghum grain yield using different methods of application in field conditions. To accomplish this study, we used a randomized complete block design with eleven treatments replicated three times. Urea ammonium nitrate (UAN) was used at the N source; diammonium phosphate (DAP) and liquid ammonium polyphosphate (APP) were used as P sources. The N-P application method was the dual placement of APP and UAN, Broadcast of DAP and UAN, and dribble surface band of APP and UAN. Grain yields were consistently higher when N was applied, 112.1 kg N ha-1 compared with the non-fertilized check. Dual placement of N and P increased grain yields by 35%. Also, the application of 20 kg P ha-1 gave better yield across sites. Application of N and P did not increase grain N except in two site years. The results were inconsistently affected by the method of application and fertilizer source that was shown by lack of effect in some years. N uptake was higher when N and P were dual placed and broadcast compared to the surface band.