Profitable and sustainable nutrient management systems for East and Southern African smallholder farming systems challenges and opportunities: a synthesis of the Eastern and Southern Africa situation in terms of past experiences, present and future opportunities in promoting nutrients use in Africa

Abstract

Sustainable agricultural intensification is still one of the major issues to meet the growing demand for food in the coming decades, and to make sub-Saharan Africa (SSA) a food-secure sub-continent. The majority of soils in SSA are unsuitable for intensified crop production without thorough recognition of their inherent soil fertility constraints. In addition, continued mining of soils during the past decades has rendered even originally fertile soils low-productive. The combined average depletion rate of N, P and K of all SSA countries is 54 kg/ha/yr. Thus, not surprisingly, nutrient limitation is the major bottleneck for increasing yields in Africa. However, nutrient depletion rates vary significantly spatially, depending on the overall crop productivity level and farmer’s access to fertilizer. Site/region-specific knowledge of the soil fertility levels is thus a precondition for the establishment of profitable and sustainable nutrient management systems. It has been argued that in the short term, chemical fertilizers are the best way to feed Africa. Clearly, this is because fertilizer consumption of SSA is stagnating at a mere 8-12 kg/ha/yr since at least last ten years. In 2010, none of the SSA countries reached the 50 kg/ha/yr target set by the Abuja Fertilizer Summit in 2006 to be reached on average for SSA in 2015. Lack of enabling policies for the private industry, poor infrastructure (access to fertilizer), and low demand by fertilizer consumers, especially in rural areas of SSA, are three major causes of low consumption. The benefit-cost ratio often is too low to encourage farmers to apply fertilizer, because of the relatively high fertilizer price at farm gate, the low market price of food crops like maize and the high year-to-year variability of the agronomic efficiency of fertilizer applied. An overestimation of the risk of failure to break even when applying fertilizer by farmers adds to the dilemma. Furthermore, fertilizer recommendations developed in the past often ignore differences between soils and are highly incompatible with smallholders' resources. To develop and disseminate appropriate nutrient management recommendations, up-to-date and spatially explicit information about the condition and trend of soil health is necessary. Results of the CIAT-led Africa Soil Information Service (AfSIS) project showed that, clearly, N and P were not the only yield constraining factors in SSA. K-deficiency was common and multi-nutrient deficiency observed in 15 % of the sites. Mid-Infrared Spectroscopy (MIRS) in combination with multivariate statistical analysis allowed for describing soils in terms of their inherent yield potential, and as such offering the potential to bypass labour, money and time-consuming lab-based wet-chemistry analysis. MIRS, however, is still in its infancies and further research is required to consolidate this promising technology for broader scale, mainstream application. The optimal technical approach of SSA countries to increase the use of mineral fertilizer is likely to be a function of a number of location-specific, agro-climatic, demographic and economic variables. In most SSA countries the private sector was not able to stop the decrease in total fertilizer consumption after market liberalisation and abolishment of subsidies. After the re-introduction of targeted fertiliser subsidies in the 2000s, some East and Southern African countries (Malawi, Zambia and Tanzania) have realised increased fertiliser consumption growth. Key policy measures for the establishment of well-functioning fertilizer markets are: the establishment of a consistent and predictable price (subsidized, if warranted) and trade policy, introduction of risk-sharing financial mechanisms, investment in human capital development (farmers and private sector), development and enforcement of fertilizer legislation and regulatory framework. Farm-scale bio-economic models, like APSFARM, offer the possibility to quantify benefits from the adoption of alternative technologies, aiming at identifying “best-fit” pathways out of poverty. Results of such modelling analysis revealed that for the poorest farmers in East and Southern Africa, investment in N-fertilizer would be difficult to finance and therefore, to increase nutrient inputs, these farmers might need to initially rely on cheaper options, such as rotation with N-fixing legumes. Two sustainable, intensified nutrient management concepts, that have been proven successful in famer’s field, are Integrated Soil Fertility Management (ISFM) and Conservation Agriculture (CA). ISFM includes the combined use of mineral fertilizer and organic resources management with the aim to improve agronomic efficiency and crop yields. These components and others (e.g. improved varieties) can be adopted stepwise. CA, on the other hand, is advocated as a package that the farmer should preferably adopt as a whole. Also, CA is stricter than ISFM in regard to the must-have key components, above all minimum tillage and surface residue retention. Even though proven profitable in the long-run, the attractiveness of ISFM and CA is often impaired by smallholders’ limited resources (money, labour) as well as the delayed responsiveness in terms of improved yields. In mixed crop-livestock systems it is primarily the competition for crop residues that vitiate the farmer’s willingness to adopt. Farmers keeping livestock see little value in leaving residues on top of the soil (CA) or incorporating it into the soil (ISFM). Feeding residues to the animals is considered a much better investment. Research is needed to identify the true value of residues, so as to be able to balance the competing uses. Both, ISFM and CA, intend to move farmers out of subsistence and therefore depend on access to input (credit, fertilizer, herbicides, and modern varieties) and output markets (selling surplus production). They also are knowledge intensive as far as management of residues, fertilizer, herbicides and (zero-tillage) direct seeding of crops is concerned. We believe that the combination of ISFM and CA, which we named ISFM+ — i.e. working towards full adoption of CA but using the step-wise approach of ISFM — allows for easier, smoother and faster adoption, as farmers can implement improved management components at the pace they feel comfortable with. Innovation Platforms offer a promising way to put farmers into the position to link with the fertilizer and agro-input sector, as well as to establish collaboration with the (micro-) finance sector, NGOs or (contract farming) companies that provide such services. Combining IPs and the stepwise adoption of ISFM+ seems to be a powerful alliance to move farmers into intensified, sustainable production. During the last 1-7 years a new generation of entrepreneurs has appeared in the agricultural development arena, with in part sizeable financial means, a clear goal-driven agenda and an impressive short-term track record. We believe that these players in combination with the renewed strong interest of the classic major stakeholders (such as The Word Bank) in agricultural development provide reason for optimism that after some decades of stagnation there is now the time to achieve notable impact in sub-Saharan Africa for intensifying farming systems in a sustainable manner. Yet, most of these new players will require, and indeed explicitly ask for, scientific backup to make sure that their chosen intensification pathways are not only profitable in the short run, but also sustainable in the long run.