Agro-Economic Implications of Combined Application of Organic and Mineral Fertilizers on Maize

Continuous cultivation without adequate fertilizer application is responsible for plant nutrient depletion and yield decline of major food crops in sub-Saharan Africa. Field experiments were conducted on umbric Cambisol in Babungo and ustic Oxisol in Bansoa in the Western Highlands of Cameroon over two years to evaluate the effects of combined application of leaf biomass of agroforestry species and mineral fertilizers with their economic returns on maize yield performance. Ten treatments encompassing sole mineral fertilizer, sole leaf biomass of Calliandra, Leucaena, Acacia and Cassia, leaf biomasses combined with mineral fertilizer and absolute control were laid in a randomized complete block design and replicated three times. Data collected on maize grain yield was subjected to analysis of variance using XLSTAT version 2014 statistical software. In addition, an economic analysis was performed to evaluate the profitability of the different treatment combinations. The results showed significant differences (P ≤ 0.05) amongst the different treatments on maize yield on both soil types. The highest maize yields which stood at 5.93 t/ha and 6.01 t/ha were recorded in plots treated with Acacia and Cassia plus half recommended mineral fertilizer on umbric Cambisol and ustic Oxisol respectively. Economic analyses showed that Acacia and Cassia plus half recommended mineral fertilizer gave the highest net benefit and return to labor of 286500 FCFA and 5.1 on umbric Cambisol and 296051 FCFA and 5.3 on ustic Oxisol respectively. On both soils, all the treatments except Calliandra with half recommended mineral fertilizers were economically profitable with benefit to cost ratios that ranged from 2.02 to 2.92. Combined application of agroforestry tree species leaf biomass and mineral fertilizers is an appropriate technology to enhance maize grain yield and is economically profitable except Calliandra with half recommended mineral fertilizers and is therefore recommended for degraded Calliandra and Oxisols in the Western Highlands of Cameroon.