Microfertilizing, consisting of applying small amounts of mineral fertilizer to the planting hole or pocket, was tested in Mali. Yields of sorghum increased by 34% and 52% compared with the control after applying 0.3 g of fertilizer per pocket for the years 2000 and 2001 respectively. For pearl millet, the corresponding yield increase was 48% and 67% for 2001 and 2003 respectively. Higher yield increases were observed when 6 g of fertilizer was applied per pocket than when 0.3 g of fertilizer was applied. The value–cost ratio varied from 3.4 to 11.9 in the 0.3 g treatment, and from 0.43 to 1.17 in the 6 g treatment. Application of 0.3 g of fertilizer appeals to farmers because of the good return on investment, low financial risk, low cash outlay and low workload required.

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Despite their contribution to food security, animal products and vegetables from urban and peri-urban agriculture (UPA) often raise public health and environmental concerns, given high use of agrochemicals, organic fertilizers and wastewater. This study exemplarily investigated contamination of selected horticultural and livestock products (milk and irrigated lettuce with a potentially high microbiological contamination; and tomato and cabbage on which various pesticides were used) from Bobo Dioulasso (Burkina Faso) and Sikasso (Mali). Samples of irrigation water, organic fertilizer and lettuce were collected from six gardens; cabbage and tomato samples were collected from 15 gardens, and samples of raw and curdled milk were collected from six dairy herds in February, May, and November 2009. Thermo-tolerant coliforms and Escherichia coli in irrigation water significantly exceeded WHO recommendations for unrestricted irrigation of vegetables consumed raw. Microbial contamination of lettuce at garden level and market place in Bobo Dioulasso, and at garden level in Sikasso was higher than at Sikasso market (P<0.05). Pesticide residues were detected in only one cabbage and one tomato sample and were below the maximum residue limit for consumption. Counts of thermo-tolerant coliforms and E. coli were higher in curdled than in raw milk (P<0.05). Given the differences in microbial load between produce of different origin and subsequent stages along value chains, there is scope for low-cost improvement of the safety of UPA smallholders' products. However, studies of higher spatial and temporal resolution along all stages of the value chains for these products are needed in order to derive respective recommendations.

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