Sustainable Intensification with Cereal-Legume Intercropping in Eastern and Southern Africa.

Much research has been conducted on cereal-legume intercropping as a sustainable intensification (SI) practice in Eastern and Southern Africa (ESA). However, the role of inorganic fertilizers in sustainably intensifying intercropping systems has not been systematically analyzed. Therefore, the objective of the present analysis was to assess the role of inorganic fertilizer use in cereal-pigeonpea (Cajanus cajan) intercropping in terms of SI indicators, namely, yield, production risks, input use efficiency, and economic returns. The data used for this analysis were gathered from over 900 on-farm trials across Kenya, Tanzania, and Mozambique. All SI indicators assessed showed that intercropping combined with application of small amounts of inorganic fertilizers is superior to unfertilized intercrops. Fertilizer application in the intercropping system improved cereal yields by 71-282% and pigeon pea yields by 32-449%, increased benefit-cost ratios by 10-40%, and reduced variability in cereal yields by 40-56% and pigeonpea yields by 5-52% compared with unfertilized intercrops. Improved yields and reduced variability imply lowering farmers' risk exposure and improved credit rating, which could enhance access to farm inputs. We conclude that the strategic application of small amounts of inorganic fertilizers is essential for the productivity and economic sustainability of cereal-pigeonpea intercropping under smallholder farming in ESA.

Agriculture in Africa: strategies to improve and sustain smallholder production systems.

Agricultural development lies at the heart of poverty reduction and increased food security of most developing nations. Sub-Saharan Africa (hereafter referred to as Africa) is, however, the only region in the world where per capita agricultural productivity has remained stagnant over the past 40 years. In Asia and Latin America, the use of tailored techniques and technologies has transformed agricultural practice and its productivity, leading to what has been called the "green revolution." The dissemination of uniquely African green revolution technologies has not occurred on the continent. This chapter will argue that the same results in increased productivity and food security can be achieved in Africa if the appropriate investments are made in key interventions: soil fertility improvement, improved seeds, water management, market access, extension services, access to credit, and improvements in weather forecasting. Where these have happened, even partially, the outcome has been remarkable. However, bringing them to scale in ways that sustainably increase agricultural productivity and alleviate poverty requires increased investments and innovative institutional arrangements. Fortunately, several research and development projects on the continent, including the Millennium Villages Project, are providing valuable insights. Finally, this chapter outlines the key remaining challenges.

The African Millennium Villages.

We describe the concept, strategy, and initial results of the Millennium Villages Project and implications regarding sustainability and scalability. Our underlying hypothesis is that the interacting crises of agriculture, health, and infrastructure in rural Africa can be overcome through targeted public-sector investments to raise rural productivity and, thereby, to increased private-sector saving and investments. This is carried out by empowering impoverished communities with science-based interventions. Seventy-eight Millennium Villages have been initiated in 12 sites in 10 African countries, each representing a major agro-ecological zone. In early results, the research villages in Kenya, Ethiopia, and Malawi have reduced malaria prevalence, met caloric requirements, generated crop surpluses, enabled school feeding programs, and provided cash earnings for farm families.

Potential of East African phosphate rock deposits in integrated nutrient management strategies.

Phosphorus deficiency affects around 80% of the acid soils of western Kenya, but fertilizer use is limited due to high prices. This paper explores the potential of local phosphate rocks (PR) as a remedy within the context on an integrated soil fertility management approach. A promising phosphate rock is Minjingu PR (MPR, Tanzania), a sedimentary/biogenic deposit which contains about 13% total P and 3% neutral ammonium citrate (NAC) soluble P. On-farm trials in P-deficient soils in western Kenya demonstrate MPR to be as effective as triple superphosphate (TSP, 20% P) at equal P rates. The benefits are most pronounced with the integration of agroforestry technologies that improve soil fertility. Besides Minjingu PR, Busumbu PR from Uganda (BPR) is potentially another source of P. It is typical of the abundant but unreactive igneous PRs in eastern, central and southern Africa. Agronomic performance of BPR is poorer, though its lower cost and location near to P-deficient areas in western Kenya make it attractive in some situations. The policy implications of these findings are discussed further in the paper.

Potential of East African phosphate rock deposits in integrated nutrient management strategies

Phosphorus deficiency affects around 80 percent of the acid soils of western Kenya, but fertilizer use is limited due to high prices. This paper explores the potential of local phosphate rocks (PR) as a remedy within the context on an integrated soil fertility management approach. A promising phosphate rock is Minjingu PR (MPR, Tanzania), a sedimentary/biogenic deposit which contains about 13 percent total P and 3 percent neutral ammonium citrate (NAC) soluble P. On-farm trials in P-deficient soils in western Kenya demonstrate MPR to be as effective as triple superphosphate (TSP, 20 percent P) at equal P rates. The benefits are most pronounced with the integration of agroforestry technologies that improve soil fertility. Besides Minjingu PR, Busumbu PR from Uganda (BPR) is potentially another source of P. It is typical of the abundant but unreactive igneous PRs in eastern, central and southern Africa. Agronomic performance of BPR is poorer, though its lower cost and location near to P-deficient areas in western Kenya make it attractive in some situations. The policy implications of these findings are discussed further in the paper.

A deficiência de fósforo afeta em torno de 80 por cento dos solos ácidos do Quênia ocidental, mas o uso de fertilizantes é limitado devido aos preços altos. Este artigo explora o potencial das rochas fosfáticas locais (PR) como regenerador da fertilidade dos solos dentro do contexto de uma abordagem de gestão integrada. Uma rocha fosfática promissora é a Minjingu PR (MPR, Tanzânia), um depósito sedimentar/biogênico que contém por volta de13 por cento total P e 3 por cento citrato neutro de amônia (NAC) P solúvel. Testes em fazendas agrícolas com solos deficientes em P no Quênia ocidental demonstram que a MPR é tão efetiva quanto o superfosfato triplo (TSP, 20 por cento P) na mesma proporção de P. Os benefícios são mais pronunciados com a integração das tecnologias agroflorestais que melhoram a fertilidade do solo. Da mesma forma que o Minjingu PR, Busumbu PR de Uganda (BPR) é outra fonte potencial de P. É típica do abundante, porém não-reativo complexo ígneo PRs do leste, centro e sul da Africa. A performance agronômica de BPR é inferior ainda que tenha custo mais baixo e localização próxima às áreas deficientes de P no Quênia ocidental, tornando-se mais atrativo em algumas situações. As implicações políticas dessas descobertas são discutidas mais adiante neste artigo.