Innovations in soil and irrigation technologies to improve Senegalese vegetable production

Cultivating high-value vegetables for both national consumption and export have been shown to generate substantive positive socio-economic impacts whilst also contributing to achieving the UN Sustainable Development Goals. The transformation of agriculture towards export-orientated production can also enhance the livelihoods of smallholder farming communities. However, sustainable agricultural development in Senegal and sub-Saharan Africa (SSA) faces a number of fundamental agronomic, environmental and economic challenges including the need for more integrated approaches to soil and water management to build resilience to climate, water-related risks.

Micro or drip irrigation (DI) is being widely promoted globally and across SSA as a means by which smallholders and commercial farmers can increase yields and reduce vulnerability to climate variability. The low application rates and low energy requirements also provide major scope for improvements in irrigation efficiency, but this is contingent on good in-field management. Managing DI crops on drought prone soils is a major challenge -- farmers often over-irrigate leading to high drainage losses and nutrient leaching. To address these risks, SNF has developed an innovative low-cost polymer that can be applied via the drip irrigation systems. Initial trials in Chile and the USA have shown reduced leaching risks, improved irrigation to the root zone and increased yields. This innovation has the potential to drive a 'step-change' in water and nutrient use efficiency for smallholders and commercial farms growing vegetables in SSA. This exploratory project focuses on a 'dual innovation' -- the evaluation of the low cost soil conditioner coupled with assessing soil health can be improved through the use of a cover cropping can increase yields and economic returns. The tropical legume Sunn Hemp is a valuable inter-season cover crop that helps trap nitrogen, is antagonistic to southern root-knot nematode (a major yield threat in SSA) whilst also increasing soil organic carbon. However, the beneficial effects of Sunn Hemp on soil attributes relevant to water and nutrient management remain unknown. Working with our partners in the UK (Barfoots) and Senegal (SCL Diama), this project will evaluate the combined interactions of the soil conditioner and Sunn Hemp on soil and crop management practices. The project will use field trials on crops grown for local and export markets including sweetcorn, green beans, chillies, onions and 'Niebe' beans. Smallholder dissemination will be led a local NGO (Universal Purpose). The project will also engage with ongoing initiatives to ensure substantial numbers of smallholder farmers are beneficially impacted.