Optimizing Inter-row Spacing and Blended NPS Fertilizer to Boost Production of Sorghum (Sorghum bicolor (L) Moench) and Ensure its Economic Feasibility

Due to varietal variation in architecture, the conventional inter-row spacing of 75cm is not always applicable to all varieties in sorghum production. Similarly, the blanketfertilizer recommendation assumes equal fertility levels across all soil types, making itunsuitable. Thus, a field experiment was conducted to find the optimum rate of blendedNPS and inter-row spacing for sorghum in Southeast Ethiopia. The experiment consistedof a factorial combination of five NPS levels (0, 50, 100, 150 and 200 kg NPS ha-1) andthree inter-row spacing (55, 65 and 75cm). The treatments replicated thrice withrandomized complete block design. The results showed that NPS fertilizer and inter-rowspacing had significant (P<0.05) effect on various parameters, but their interaction effecthad no significant effect (P>0.05) on all parameters. Increased inter-row spacing and NPSrate prolonged days to flowering and maturity. The increase in the rate of NPS and interrow spacing significantly increased leaf area, leaf area index, panicle weight, and 1000- kernel weight. Similarly, plant height increased with increasing rate of NPS but decreasedwith increasing inter-row spacing. The maximum grain yield (3336.81 kg ha-1) andbiomass weight (7900.01 kg ha-1) were recorded with a rate of 150 kg NPS ha-1, while thelowest grain yield (1730.21 kg ha-1) and biomass (5660.44 kg ha-1) were obtained undernil-treated plots. The highest grain yield (2734.27 kg ha-1) and biomass (7490.12 kg ha-1)were recorded with spacing of 65 cm. The partial budget analysis showed that the highestnet benefit of 85,913 birr ha-1 with maximum marginal rate of return (2534.22%) wasobtained in the treatment that received 150 kg NPS ha-1 with 65 row-spacing. Therefore,150 kg ha-1 blended NPS with 65 cm inter-row spacing is recommended in the study areaand in dry and semi-arid regions with similar agro-ecological conditions