Influence of Preplant Nitrogen and Sulfur Fertilization On Bell Pepper

Field studies were conducted to determine the effect of different preplant nitrogen (N) and sulfur (S) fertilizer sources and rates on the growth and yield of ‘Aristotle’ bell pepper (Capsicum annuum). Fertilizers were applied 2 weeks before transplanting in two bands on bed tops at 15 cm from either side of the planting row and incorporated 2.5 cm deep. Fertilizer sources were ammonium sulfate (AS; 21% N, 24% S), ammonium nitrate (AN; 34% N), and fusion ammonium sulfate nitrate (FASN; 26% N, 14% S). Fertilizer rates were 112, 224 and 336 kg/ha of N. AS and FASN supplied 128, 255 and 383 kg/ha and 60, 121 and 181 kg/ha of S at their corresponding N rates, respectively. Data showed that there were no significant differences in plant vigor and height at 6 WAT, and petiole sap NO₃-N concentration at 8 WAT. However, there was significant effect of N sources and rates on bell pepper fruit weight. When N rates increased from 112 to 224 kg/ha, bell pepper yields increased 14%, regardless of N sources, with no further yield change with higher N rates. However, AS and FASN improved bell pepper yields by 9% and 10% in comparison with AN at a N rate of 224 kg/ha. There were no significant differences on bell pepper yield when AS or FASN were used at rates of 224 or 336 kg/ha.