Dioscorea hirtiflora Benth. is an indigenous wild edible tuberous climbing plant native to Zambia. Known as lusala, the tubers are sold in markets across southern Zambia. Lusala collection, consumption, and trade were investigated through interviews with rural households (four districts) and market traders (three towns), and supplementary focus group discussions. Of 278 households interviewed, high proportions collected (83%), consumed (96%), and sold (59%) lusala, not varying amongst district or wealth category. Lusala populations were perceived to be declining in the wild by 79% of households. Tuber collection, largely by females and mainly from March to September, peaked in April when households engaged in each activity and collected 27.9 kg, consumed 12.0 kg, and sold 35.7 kg (from 129, 108, and 69 reporting households, respectively) that month, regardless of district, wealth category, or gender. Those sales provided an average household income of USD 16 in April 2017. In August 2017, each market trader purchased an average of 899 kg for USD 383. Local knowledge of D. hirtiflora was considerable. Lusala collected from forests is an important edible wild tuber in the local economy of the Southern Province of Zambia; it provides a seasonally important food supply and income to rural households and supplies demand for urban populations.

Forest products, wood and non-wood, remain vital among smallholder households in Zambia with charcoal being the most sought after product. This has led to increased exploitation of forest trees to meet the needs for fuel wood, among others. However, Jatropha curcas plant has been identified as a potential fuel source. In the early 2000s, profit-making organizations encouraged smallholder households to grow Jatropha for use as an alternative fuel source. This paper reports on a study conducted in Solwezi between 2011 and 2014 to evaluate the impact of Jatropha cultivation for biofuel production. A sample of 100 small-scale farmers involved in Jatropha cultivation and key informants were interviewed to evaluate the impact of growing Jatropha at the small-scale level. Results show that farmers lost out on time; income from sale of edible non-wood forest products; and experienced reduction in maize (Zea mays) and bean (Phaseolus vulgaris) production, worsening household economic conditions. Farmers attributed this loss to unclear policy alignment on biofuel production by government. We therefore recommend that project implementation should involve interactions of all legislative bodies and any other concerned stakeholders. There is also a need to promote the value chain, from production to marketing, which focuses on minimizing detrimental effects on the livelihood of small-scale farmers. OPEN ACCESSSustainability 2015, 7 9908

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Agricultural activities that encourage slashing, burning and ploughing greatly affect the soil structure and soil organic matter on which soil water retention depends. In this study, we hypothesized that inclusion of rotational leguminous tree species improves soil water retention in a semi-arid conservation agriculture system. In a study done in Kibwezi, semi-arid eastern Kenya, results showed that the amount of water retained in the different soil strata from plots with different tree species and tillage practices was highly significant (P = 0.032). Plots with planting basins and Gliricidia sepium and Faidherbia albida tree species retained more water in both the upper and lower strata. Plots with G. sepium tree species under planting basins and zero tillage under F. albida had significantly higher soil organic carbon levels than plots that were managed under ridges and ploughing (P = 0.002). On the other hand, bulk density in plots with planting basins and zero tillage and ridges ranged between 1.35 g/cm 3 and 1.53 g/cm 3 . Conventional tillage plots had bulk density values of 1.65 g/cm 3 and 1.72 g/cm 3 in the upper and lower strata respectively. The timedependent nature of rotational leguminous tree species on soil organic matter and soil water retention in the semi-arid conservation agriculture system highlights the importance of considering these species for improving organic carbon and water retention for improved crop production.

SummaryLusala (Dioscorea hirtiflora Benth. subsp. pedicellata Milne-Redh) is an important wild edible tuber foraged widely from natural forests in Southern Zambia, but at risk from overharvesting and deforestation. Its propagation was investigated in glasshouse studies to explore potential domestication and future in situ and ex situ genetic resources conservation. Almost all tubers planted with visible shoot buds produced vines, with no effect of tuber size on vine emergence or tuber yield. Few tubers without visible shoot buds at planting produced vines, but those that did not re-tuberized. The progeny provided good vine emergence and similar tuber yield, with vines from tubers produced by re-tuberization being more vigorous. Re-tuberization in the absence of vine emergence also occurred in other experiments. Minisetts cut from the proximal end of tubers provided better vine emergence (with more from 20-mm than 10-mm-long sections) and greater tuber yield than mid- or distal minisetts. Nodal stem cuttings rooted well, vined, and provided small tubers. This study shows that lusala can be propagated successfully from tubers, minisetts, nodal vine cuttings, or mini-tubers from nodal vine cuttings, for genetic resources conservation and/or domestication. Domestication is likely to be hampered by the long period required for vines to emerge and establish. More sustainable foraging, including re-planting in natural forests, is recommended to balance consumption of lusala in the region and promote its long-term conservation.