Economic Optimization of Poultry Manure in Organic African Spinach (<i>Amaranthus</i><i> </i><i>hybridus</i>) Production

Organic crop production is a potential sustainable solution to food insecurity in Sub-Saharan Africa, including Nigeria; however, the rising cost of poultry manure, commonly used in organic crop production to boost soil fertility in depleted soil, poses a challenge to its economic viability and sustainability. Thus, a field experiment was conducted in 2024 at the Teaching and Research Farm of the Department of Horticultural Technology, Enugu State Polytechnic, Iwollo, Southeast Nigeria, to evaluate the economic viability of using different application rates of poultry manure for <i>Amaranthus</i><i> </i><i>hybridus</i><i> </i>production under organic conditions towards optimizing its use and profitability. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. The treatments comprised five poultry manure rates: 0, 5, 10, 15, and 20 tons per hectare. Data on shoot weight per plant and derived yield per hectare were collected, and analyses of variance at the 5% significance level were conducted. The treatment means with significant differences were separated using Fisher’'s least significant difference at the 5% probability level. Economic analysis, such as gross margin as well as return on investment (RoI), was performed to assess the profitability of different poultry manure application rates. The results showed that poultry manure significantly (p<0.05) improved Amaranthus hybridus shoot yield, with optimum yield obtained at 20 tons per hectare. The highest gross margin was obtained at 20 tons, but the highest return on investment was at 10 tons per hectare. A graph of RoI against poultry manure rates showed a steady increase in RoI from 0 tons to 10 tons beyond which it began to diminish. Poultry manure application at a rate of 10 tons per hectare was the most profitable rate and, therefore, the most economically viable rate; it could be recommended for organic <i>Amaranthus</i><i> </i><i>hybridus</i> production in the study area and similar agro-environments for enhanced food security.