A quick overview of recent VIA research publications
Authors: M. Mdemu, L. Kissoly, H. Bjornlund, E. Kimaro, E. W. Christen, A. van Rooyen, R. Stirzaker & P. Ramshaw
Published: 30 June 2020
Smallholder irrigation is an important pathway towards better livelihoods and food security in sub-Saharan Africa. This article assesses the contribution of farmer-friendly soil and water monitoring tools, and agricultural innovation platforms, towards household income and food security in two small-scale irrigation schemes in Tanzania. Quantitative and qualitative data from farmer’s field books, household surveys and focus groups were used to assess the impacts of the two interventions. The two interventions together contributed to enhancing smallholders’ food security and household income in the two schemes, as did the agricultural innovation platform on its own.
Authors: M. Chilundo, W. de Sousa, E. W. Christen, J. Faduco, H. Bjornlund, E. Cheveia, P. Munguambe, F. Jorge, R. Stirzaker & A. F. van Rooyen
Published: 18 June 2020
Over four years, a research-for-development project was implemented at the 25 de Setembro irrigation scheme in Mozambique. The project introduced agricultural innovation platforms to overcome barriers to production such as input and output supply chains and poorly maintained irrigation canals. Soil moisture and nutrient monitoring tools were provided so that farmers could improve their irrigation and fertilizer management. The farmers increased their crop production through the use of the tools and better irrigation infrastructure, and increased their income and overall well-being through better links to markets and new information sources facilitated by the agricultural innovation platforms.
Authors: Martin Moyo, André Van Rooyen, Henning Bjornlund, Karen Parry, RichardStirzaker, Thabani Dube & Mthulisi Maya
Published: 21 May 2020
Successful irrigated agriculture is underpinned by answering two critical questions: when and how much to irrigate. This article quantifies the role of the Chameleon and the Wetting Front Detector, monitoring tools facilitating decision-making and learning about soilwater- nutrient dynamics. Farmers retained nutrients in the root zone by reducing irrigation frequency, number of siphons, and event duration. Water productivity increased by more than 100% for farmers both with and without monitoring tools. Transitioning smallholder irrigation systems into profitable and sustainable schemes requires investment in technology, farmers and institutions. Importantly, technologies need embedding in a learning environment that fosters critical feedback mechanisms, such as market constraints.
Authors: Richard Stirzaker, Ikenna Mbakwe & Nuru Ressa Mziray
Published: 19 May 2017
Better yields of high-value crops are necessary for a profitable irrigation industry in sub-Saharan Africa. We introduced two simple tools, the Chameleon soil moisture sensor and the Full Stop wetting front detector, which represent soil water, nitrate and salt levels in the soil by displaying different colours. These tools form the basis of an experiential learning system for small-scale irrigators. We found that farmers quickly learned from the tools and changed their management within a short time. The cost of implementing a learning system would be a small fraction of that of building or revitalizing irrigation schemes.
Authors: Richard Stirzaker
Wetting Front Detectors (WFD) are simple instruments that provide a yes/no response when a front of certain strength passes a set depth. This paper describes two different designs of wetting front detector and determines their sensitivity under experimental conditions. The FullStop WFD comprises a specially shaped funnel that distorts the downward flow of water through the soil, producing saturation at its base. The sensitivity was determined by applying water via intermittent misting at rates of 0.1 to 0.8 mm/h. For the soil type under study, the minimum flux at which water was collected by the WFD was 0.2 mm/h. The experiment was repeated for drip irrigation, and the FullStop WFD collected water at application rates less than 0.05 L/h, corresponding to a soil suction of about 2 kPa. Whereas these application rates are lower than what can physically be applied in the field, wetting fronts do weaken with depth and time after the irrigation is turned off. Fronts can then move at rates below 0.2 mm/h or suctions drier than 2 kPa, which could go undetected.