Ex-ante economic analysis of alternative biomass management systems for perennial plantain in southeastern Nigeria

Due to a rapid yield decline, plantain fields in Southeastern Nigeria are reverted to fallow after two years. However, population pressure leads to shorter fallow periods and high rates of deforestation. This study investigates the potential of mulch-based systems for perennial plantain production. Two alley cropping technologies with Dactyladenia barteri and natural bush, and a cut-and-carry technique using Pennisetum purpureum are evaluated against traditional systems. The analytical framework consists of a bio-economic model incorporating soil nutrient dynamics, plantain response function and returns maximization over a 30-year horizon. The study indicates that the lack of capital limits the adoption of perennial production systems. Only the traditional systems allow plantain growers some production under average resource levels. To allow an economic assessment of alternative organic matter management systems, the model assumes that capital now used on three 0.25-ha plots can be concentrated on one plot. This would provide sufficient capital for additional resources required by mulch and fertilizer use. Under baseline conditions, the alley cropping system with natural bush outperforms the other two improved technologies with a 154% and 72% increase in net returns over continuous and shifting traditional systems respectively. The cut-and-carry technique yields a 151% and 70% increase in net returns. Improved fallow with D. barteri ranks third with a 140% and 62% increase in net returns followed by continuous traditional cropping with fertilizer use, which shows a rise in returns by 121% and 50% over traditional systems without fertilizer. The traditional system had the worst performance when no fertilizer was used. Model results simulate yields decline usually observed after two years of production under field conditions. When moderate amounts of mulch are used in improved systems, fertilizer application is still necessary to maintain soil fertility. Net returns in mulch-based systems decrease with the introduction of fallows though an improvement in the capacity of soil fertility restoration is observed. A sensitivity analysis shows that the marginal benefit of fertilizer in the alley cropping and traditional systems is considerable. The negative effect of an increase in fertilizer price on net returns is less pronounced than the lack of access to fertilizer