Integrated soil fertility management for sustainable teff (Eragrostistef) production in Halaba, Southern Ethiopia

Low applications of inorganic fertilizer and decline in soil organic matter often contribute to loss of production in Sub-Saharan Africa. A trial was conducted on integrated soil fertility management of teff (Eragrostis tef) in Southern Ethiopia during the main cropping season of 2015. Treatments were based on recommended rates of inorganic fertilizer, applying organic fertilizer to provide the equivalent amount of N. Randomised treatments were replicated across six farms, including 100% as inorganic fertilizer, and inorganic and organic fertilizers in ratios 50:50, 67:33 and 33:67. All crop characteristics measured, except number of tillers and straw yield, showed statistically significant differences (p < 0.05). An inorganic-to-organic fertilizer ratio of 67:33 provided highest grain yield, while lowest total variable costs were obtained with the 33:67 ratio. Highest net benefit (520(±50) US$/ha) was obtained with the ratio 67:33, but the marginal rate of return over the 33:67 treatment was only 54(±8)%, and so did not provide sufficient return on the extra investment for inorganic fertilizer. Therefore, 33% inorganic fertilizer to 67% organic fertilizer is more economically viable. These trials demonstrate that, in addition to reducing long-term soil degradation, integrated soil fertility management can be an economically viable way of managing crops.