a International crop research Institute for the semi-arid tropics, Bulawayo, Zimbabwe; b school of commerce, university of south australia, adelaide, australia ABSTRACT Productivity barriers and opportunities influencing smallholder irrigation sustainability in Zimbabwe were identified using case studies of the Silalatshani and Mkoba irrigation schemes. The major barriers were poor infrastructure and soil fertility, and poor access to farm inputs, farm implements, functioning markets and agricultural knowledge, which resulted in low yields, food insecurity and negative farm income. Most irrigated land remains unused, and marketing of produce is uncoordinated. Mobile technologies provide opportunities for market information dissemination. Institutions are needed to continuously encourage dialogue among agricultural value chain stakeholders to allow irrigators to align their operations to market demands and improve the viability of irrigation systems.
Next to drought, poor soil fertility is the single biggest cause of hunger in Africa. ICRISATZimbabwe has been working for the past 10 years to encourage small-scale farmers to increase inorganic fertiliser use as the first step towards Africa's own Green Revolution. The program of work is founded on promoting small quantities of inorganic nitrogen (N) fertiliser (micro-dosing) in drought-prone cropping regions. Results from initial on-farm trials showed that smallholder farmers could increase their yields by 30-100% through application of micro doses, as little as 10 kg Nitrogen ha -1 . The question remained whether these results could be replicated across much larger numbers of farmers. Wide scale testing of the micro-dosing (17 kg Nitrogen ha -1 ) concept was initiated in 2003/2004, across multiple locations in southern Zimbabwe through relief and recovery programs. Each year more than 160,000 low resourced households received at least 25 kg of nitrogen fertiliser and a simple flyer in the vernacular explaining how to apply the fertiliser to a cereal crop. This distribution was accompanied by a series of simple paired plot demonstration with or without fertiliser, hosted by farmers selected by the community, where trainings were carried out and detailed labour and crop records were kept. Over a 3 year period more than 2,000 paired-plot trials were established and quality data collected from more than 1,200. In addition, experimentation to derive N response curves of maize (Zea mays L.), sorghum (Sorghum bicolor (L.) Moench) and pearl millet (Pennisetum glaucum (L.) R.Br.) in these environments under farmer management was conducted. The results consistently showed that micro-dosing (17 kg Nitrogen ha -1 ) with nitrogen fertiliser can increase grain yields by 30-50% across a broad spectrum of soil, farmer management and seasonal climate conditions. In order for a household to make a profit, farmers needed to obtain between 4 and 7 kg of grain for every kg of N applied depending on season. In fact farmers commonly obtained 15-45 kg of grain per kg of N input. The result provides strong evidence that lack of N, rather than lack of rainfall, is the primary constraint to cereal crop yields and that
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.
This article explores the value of Ostrom's socio-ecological systems framework and Meadows's leverage point hierarchy, as structured diagnostics, to define systemic problems and avoid approaches based on linear thinking. These frameworks were applied as an ex post analysis of an irrigation scheme in Zimbabwe, drawing on the scheme's baseline condition and the intervention outcomes. Strong leverage points, particularly those driving feedback mechanisms and institutional design, interacted with other intervention points, initiating systemic change. This analysis suggests that dysfunctional schemes can be transitioned towards complex adaptive systems by using agricultural innovation platforms to identify systemic challenges and intervention points.
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