Modification of Synthetic Nitrogen Fertilization Using Goat Manure in Sorghum (Sorghum bicolor L.) Cultivation

Abstract

Sorghum (Sorghum bicolor L.) is a resilient cereal crop widely cultivated in marginal environments; however, its production often relies heavily on costly synthetic nitrogen fertilizers which also pose environmental concerns. Integrating organic nutrient sources such as goat manure may provide a more sustainable fertilization strategy without adversely affecting crop performance. This study evaluated the effects of partial substitution of synthetic nitrogen fertilizer with goat manure on the growth and yield of sorghum under upland conditions. A field experiment was conducted using a randomized complete block design with six fertilization treatments: no fertilizer (control), 100% synthetic fertilizer (urea, TSP, and KCl), 100% goat manure (15 ton ha⁻¹), and combinations of synthetic fertilizer and goat manure at ratios of 75:25, 50:50, and 25:75. Vegetative growth parameters, biomass accumulation, and yield components were analyzed using ANOVA followed by DMRT at the 5% significance level. The results showed that fertilization treatments significantly affected vegetative growth. The combination of 25% synthetic fertilizer and 75% goat manure produced the tallest plants, greatest stem diameter, and highest leaf number, outperforming the full synthetic fertilizer treatment. In contrast, fresh and dry biomass and all yield components, including panicle weight, panicle length, and 100-seed weight, did not differ significantly among treatments. These findings indicate that sorghum can maintain yield stability across diverse nutrient source combinations as long as basic nutrient requirements are satisfied. Overall, goat manure can substitute up to 75% of synthetic nitrogen fertilizer while supporting sustainable nutrient management.