Response of Sorghum (Sorghum bicolor (L.) Moench) Yield for Plant Density and Blended Fertilizer Rates under Irrigated Condition in Lowland Areas of South Omo Zone, Ethiopia

Sorghum is among the very important cereal crops in Ethiopia. However, the yield of this crop is very low due to lack of appropriate crop management and soil fertility decline. To solve these problems a field experiment was conducted to investigate the effects of different intra-row spacings and blended fertilizer rates on yield and yield components of sorghum in Dasenech and Nyangatom districts of South Omo Zone, Southern Ethiopia. The experiment comprised of 12 treatment combinations; i.e., three intra-row spacing (15, 25, and 35 cm) and four rates (i.e., 0, 50, 100, and 125 kg ha-1) of blended Nitrogen, Phosphorus, Sulfur and Boron (NPSB) fertilizer. Arranged as 3X4 factorial based on randomized complete block design in three replicates. The analysis of variance indicated that the interaction between intra-row spacing and blended fertilizer rate had a highly significant effect (P < 0.01) on grain yield. According to the result the highest grain yield (5.28t ha-1) and net benefit  (90,890 Eth-birr ha-1) with 2475 % Marginal Rate of Return (MRR) was obtained from 25cm (intra-row spacing) treated with 100 kg ha-1 of NPSB fertilizer rates at Nyangatom location. Whereas, at Dasenech location, the highest grain yield (3.96 t ha-1) and net benefit (67872 Eth-birr ha-1) with MRR of 11600 % were obtained from similar spacing but treated with 50 kg ha-1 of NPSB fertilizer rates. Based on the yield response and economic analysis, 100 kg ha-1 of NPSB blended fertilizer with 25 cm of intra-row spacing for Dasenech, and 50 kg ha-1 of NPSB blended fertilizer rates with 25 cm of intra-row spacing for Nyangatom locations can be adopted under irrigated conditions.