Soil Fertility Management and Cropping System Function in Ameliorating Maize Productivity in Ethiopia: a Review

Abstract

Maize is the most important cereal crop in terms of area coverage, production, and economic importance in Ethiopia. However, decline in soil fertility was the major factor for lower productivity of maize in the country. To ward off this soil infertility problems, chemical fertilizers have been relied to boost the productivity of maize in continuous production system. However, rising costs of inorganic fertilizers may not encourage the smallholder farmers to use the full dose of fertilizers recommended for their crops. It is thus, in sourcing for an alternative that reduces the cost of production while increasing the productivity of soils, integrated soil fertility management and improved cropping system has been proven to harmonize the current need of smallholder farmers and to produce maize using low input fertilizers from organic and inorganic sources such as farmyard manure, green manures, compost, crop residues and biogas sludge. Therefore, several research attempts have been made to optimize the integrated uses of inorganic and organic fertilizers at different locations. Uses of legumes such as mucuna and Dolichos lablab at Bako and crotalaria, sesbania and mucuna at Jimma as short fallows and green manures enhanced soil fertility and confirmed to replace either partially or fully the N-fertilizer requirement of maize from external sources. Application of 70 g (corresponding to 3.71 tons per ha) of manure, combined with a small quantity (0.5 g per pocket) of fertilizer, improved maize grain yield by 77% compared to non-use of inputs in Borena. Yearly application of 4 ton FYM ha-1 with 46/10 kg NP ha-1gave maize yield comparable to 110/20 kg NP ha-1 and use of compost also had similar trends at Bako. Another work done at Ebantu showed that combination of vermicompost at 2.5 t ha−1 and mineral P fertilizer (20 kg ha−1 ) with lime (4 t ha−1 ) was optimum. Research reports on integration of crop residues with NP fertilizers at Haramaya and coffee by products integrated with N-fertilizer at Areka could enhance soil fertility and made maize production trends sustainable in Ethiopia. It was observed that maize production system can be sustained through integrated uses of 90 kg N ha-1 with six ton ha-1 coffee by product in Hawasa. The integration of biogas slurry and NP fertilizer produced significantly higher grain yield of maize and improved soil physico-chemical properties at Bako. In terms of integrating cropping sequence with NP and FYM, studies show that intercropping of maize with climbing bean with integrated application of 69/10 kg NP ha-1 with 4–8 t FYM ha-1 gave better grain yields and is recommended for sustainable production of component crops. At Bako maize rotated with nug and at Jimma maize following soybean reduced the recommended fertilizer rates by 50%. The combined use of organic and inorganic fertilizers has a positive synergy that can reduce the chemical fertilizer cost as well as mitigate the environmental hazardous effect along with intercropping and rotating potential grain legumes and forage and fodder legumes with maize to enhance soil fertility and to boost grain production at low cost for maize based farming system in Ethiopia. Thus, this paper attempts to present a narrative review of published research manuscripts on integrated soil fertility management and cropping system options for maize production in Ethiopia.

Keywords: Fertilizer management, Soil Fertility, Cropping system, Maize, grain Yield

DOI: 10.7176/JNSR/11-13-01

Publication date:July 31^st 2020