Over the past half-century, agricultural production gains have provided a platform for rural and urban economic growth worldwide. In African countries, however, agriculture has been widely assumed to have performed badly. Foresight commissioned analyses of 40 projects and programmes in 20 countries where sustainable intensification has been developed during the 1990s–2000s. The cases included crop improvements, agroforestry and soil conservation, conservation agriculture, integrated pest management, horticulture, livestock and fodder crops, aquaculture and novel policies and partnerships. By early 2010, these projects had documented benefits for 10.39 million farmers and their families and improvements on approximately 12.75 million ha. Food outputs by sustainable intensification have been multiplicative—by which yields per hectare have increased by combining the use of new and improved varieties and new agronomic—agroecological management (crop yields rose on average by 2.13-fold), and additive—by which ...

/pdf/sustainable-intensification-in-african-agriculture-w9efgsvgm3.pdf

Sustainable intensification in African agriculture

Sustainable intensification in agricultural systems

Agriculture and fishing are the primary source of almost all our food, as well as of many other products, so remain vital activities even though their share in the economy is small and in continuous decline. Partly for this reason public policy in these areas is almost entirely integrated at European level in the Common Agricultural Policy (CAP) and Common Fisheries Policy (CFP). Forestry policies are also heavily affected by EU-level decision-making. As agriculture dominates in terms of direct contribution to GDP and numbers of people engaged in it, as well as accounting for the largest amount of public support expenditure, it is agriculture that will receive the greatest attention here.

Agriculture, Forestry and Fisheries

Tithonia diversifolia, a shrub in the family Asteraceae, is widely distributed along farm boundaries in the humid and subhumid tropics of Africa. Green biomass of tithonia has been recognized as an effective source of nutrients for lowland rice (Oryza sativa) in Asia and more recently for maize (Zea mays) and vegetables in eastern and southern Africa. This paper reviews the potential of tithonia green biomass for soil fertility improvement based on recent research in western Kenya. Green leaf biomass of tithonia is high in nutrients, averaging about 3.5% N, 0.37% P and 4.1% K on a dry matter basis. Boundary hedges of sole tithonia can produce about 1 kg biomass (tender stems + leaves) m−1 yr−1 on a dry weight basis. Tithonia biomass decomposes rapidly after application to soil, and incorporated biomass can be an effective source of N, P and K for crops. In some cases, maize yields were even higher with incorporation of tithonia biomass than with commercial mineral fertilizer at equivalent rates of N, P and K. In addition to providing nutrients, tithonia incorporated at 5 t dry matter ha−1 can reduce P sorption and increase soil microbial biomass. Because of high labor requirements for cutting and carrying the biomass to fields, the use of tithonia biomass as a nutrient source is more profitable with high-value crops such as vegetables than with relatively low-valued maize. The transfer of tithonia biomass to fields constitutes the redistribution of nutrients within the landscape rather than a net input of nutrients. External inputs of nutrients would eventually be required to sustain production of tithonia when biomass is continually cut and transferred to agricultural land.

/pdf/tithonia-diversifolia-as-a-green-manure-for-soil-fertility-3osn0nqhu0.pdf

Tithonia diversifolia as a green manure for soil fertility improvement in western Kenya: A review

Integrated Pest Management (IPM) is a leading complement and alternative to synthetic pesticides and a form of sustainable intensification with particular importance for tropical smallholders. Global pesticide use has grown over the past 20 years to 3.5 billion kg/year, amounting to a global market worth $45 billion. The external costs of pesticides are $4–$19 (€3–15) per kg of active ingredient applied, suggesting that IPM approaches that result in lower pesticide use will benefit, not only farmers, but also wider environments and human health. Evidence for IPM’s impacts on pesticide use and yields remains patchy. We contribute an evaluation using data from 85 IPM projects from 24 countries of Asia and Africa implemented over the past twenty years. Analysing outcomes on productivity and reliance on pesticides, we find a mean yield increase across projects and crops of 40.9% (SD 72.3), combined with a decline in pesticide use to 30.7% (SD 34.9) compared with baseline. A total of 35 of 115 (30%) crop combinations resulted in a transition to zero pesticide use. We assess successes in four types of IPM projects, and find that at least 50% of pesticide use is not needed in most agroecosystems. Nonetheless, policy support for IPM is relatively rare, counter-interventions from pesticide industry common, and the IPM challenge never done as pests, diseases and weeds evolve and move.

/pdf/integrated-pest-management-for-sustainable-intensification-52rixyto4s.pdf

Integrated Pest Management for Sustainable Intensification of Agriculture in Asia and Africa

Although the biological advantages in terms of animal production and improved soil fertility of the use of herbaceous legumes have been well demonstrated in Kenya and elsewhere, adoption by small-scale farmers has often been disappointing. This has led to increased research into the use of both indigenous and exotic fodder trees. In common with conventional pasture legumes, tree fodders contain high levels of crude protein and minerals and many show high levels of digestibility. They are readily accepted by livestock and presumably because of their deep-root systems, they continue to produce well into the dry season. Antinutritive factors can be a problem, however, and polyphenolics, toxic amino acids, cyanogenic glycosides and alkaloids are found in many tree species. There are abundant niches on small farms where fodder trees can be grown without affecting crop production. Although detailed management recommendations are lacking, guidelines exist with regard to appropriate cutting heights and harvesting frequencies. In the Embu region, it has been estimated that three kg of fresh fodder of Calliandra calothyrsus has the same effect on milk production as one kg of commercial dairy meal. Up to about 500 trees (250 m of hedgerow) will produce enough fodder to supplement one dairy cow for a complete lactation. The tree fodder can either replace the concentrate without loss of yield, or it can complement it to produce more milk. It is being enthusiastically adopted by small-scale farmers, many of whom are starting to produce their own seed. Other tree species are now being studied in order to avoid over-reliance on a single fodder species.

A review of tree fodder production and utilization within smallholder agroforestry systems in Kenya

African indigenous vegetables (AIVs) have been part of the food systems in sub-Saharan Africa for generations. The region is a natural habitat for more than 45,000 species of plants, of which about 1,000 can be eaten as green leafy or fruit vegetables that happen to be the mainstay of traditional diets. During the colonial era, adventurers and slavers sailing in Africa introduced exotic plants such as maize, cassava and beans and, later, commercial crops such as sugarcane, cocoa, coffee and cotton, which began contributing more to life. Farmers integrated these crops into their age-old livelihood strategies at the expense of traditional subsistence crops. AIVs were almost entirely neglected and considered ‘poor people's' plants. To reverse the trend, FARM-Africa and its partners reintroduced AIVs which are now forming part of families’ diets as well as becoming a source of income for smallholder farmers in Arumeru, Tanzania and Kiambu, Kenya. AIVs are robust and productive, and thus well suited to feeding...

https://www.tandfonline.com/doi/pdf/10.3763/ijas.2010.0561

African indigenous vegetable enterprises and market access for small-scale farmers in East Africa

Indigenous fodder trees and shrubs are now receiving increased research attention. Systematic information from farmers about the species they use is, however, scanty. The objective of this study was to find out farmers' ranking of local fodder tree species of their choice; their criteria for assessing fodder trees; how the most preferred species rated on each criterion; species' uses, management, and ways of establishment; and implications of these results for the design of similar studies in the tropics. The study consisted of informal and formal surveys in three agroecological zones with mean annual rainfall of 775, 950 and 1300 mm, respectively. Farmers used an indigenous board game, bao, to rank species. Improved, stall-fed dairy animals were the dominant livestock type in the subhumid zone whereas communally-grazed, local-breed cattle and goats were common in the dry zone. A total of 160 different local fodder trees and shrubs were used by farmers in the three zones. The three most preferred species in the subhumid zone were Triumfetta tomentosa, Commiphora zimmermanii, and Bridelia micrantha; in the medium zone, Aspilia mossambicensis, Lantana camara, and Grewia tembensis, and in the low zone, Melia volkensii,Crotalaria goodiiformis, and A. mossambicensis. In the subhumid zone, the most frequently mentioned criteria were the ability of the fodder to satisfy hunger and contributions to animal health. Palatability and drought resistance of the tree were the most important criteria in the medium zone and, effect on the condition of the animal and palatability were most important in the dry zone. Farmers' ratings on palatability for cattle and goats, and milk production for goats differed significantly among tree and shrub species (P < 0.05). The study has helped identify species for further research and development activities, with the aim of improving their productivity and disseminating them among farmers.

Farmers' preferences and use of local fodder trees and shrubs in Kenya

Recent work on the production and utilization of tree fodder in East Africa

The objective of this study is twofold, to demonstrate (1) the effects of fodder shrubs on milk production and their value at the household and regional level and (2) the contribution of research by the World Agroforestry Centre toward strengthening the impact of fodder shrubs. The study is a synthesis of previous studies related to dissemination, adoption and impact combined with two new analyses, one quantitatively measuring the impact of the shrubs through econometric analysis and the other a qualitative analysis to better understand constraints on adoption and gender issues related to participation and control of benefits from fodder shrubs. Among the study findings are that fodder shrubs have been widely adopted in East Africa, by an estimated 205,000 smallholder dairy farmers by 2005. Women were active in planting shrubs, as monitoring found almost half of planters to be women. Several studies have confirmed that shrubs do have an impact on milk production. While feeding trials have found that 1 kilogram of calliandra increases milk production by 0.6–0.8 kilograms, a new survey of farmers’ perceptions in Kenya found the effect to be about half as large after controlling for the effects of breeds, season and other feeds. Whether the effect is the lower or higher estimate, the overall impact of the shrubs in terms of additional net income from milk is high, at US$19.7 million to $29.6 million in Kenya alone over the past 15 years.

R.L. Roothaert

Papers

A review of tree fodder production and utilization within smallholder agroforestry systems in Kenya

African indigenous vegetable enterprises and market access for small-scale farmers in East Africa

Farmers' preferences and use of local fodder trees and shrubs in Kenya

Recent work on the production and utilization of tree fodder in East Africa

The impact of fodder trees on milk production and income among smallholder dairy farmers in East Africa and the role of research