Farmers' perceptions on mechanical weeders for rice production in sub-Saharan Africa

Competition from weeds is one of the major biophysical constraints to rice (Oryza spp.) production in sub-Saharan Africa. Smallholder rice farmers require efficient, affordable and labour-saving weed management technologies. Mechanical weeders have shown to fit this profile. Several mechanical weeder types exist but little is known about locally specific differences in performance and farmer preference between these types. Three to six different weeder types were evaluated at 10 different sites across seven countries – i.e., Benin, Burkina Faso, Côte d'Ivoire, Ghana, Nigeria, Rwanda and Togo. A total of 310 farmers (173 male, 137 female) tested the weeders, scored them for their preference, and compared them with their own weed management practices. In a follow-up study, 186 farmers from Benin and Nigeria received the ring hoe, which was the most preferred in these two countries, to use it during the entire crop growing season. Farmers were surveyed on their experiences. The probability of the ring hoe having the highest score among the tested weeders was 71%. The probability of farmers’ preference of the ring hoe over their usual practices – i.e., herbicide, traditional hoe and hand weeding – was 52, 95 and 91%, respectively. The preference of this weeder was not related to gender, years of experience with rice cultivation, rice field size, weed infestation level, water status or soil texture. In the follow-up study, 80% of farmers who used the ring hoe indicated that weeding time was reduced by at least 31%. Of the farmers testing the ring hoe in the follow-up study, 35% used it also for other crops such as vegetables, maize, sorghum, cassava and millet. These results suggest that the ring hoe offers a gender-neutral solution for reducing labour for weeding in rice as well as other crops and that it is compatible with a wide range of environments. The implications of our findings and challenges for out-scaling of mechanical weeders are discussed

Status quo of chemical weed control in rice in sub-Saharan Africa

If future rice production is to contribute to food security for the increasing population of sub-Saharan Africa (SSA), effective strategies are needed to control weeds, the crop’s fiercest competitors for resources. To gain better insights into farmers’ access to, and use of, herbicides as part of weed control strategies, surveys were conducted in key rice production locations across SSA. Farm surveys were held among 1965 farmers across 20 countries to collect data on rice yields, farmer’s weed management practices, herbicide use, frequencies of interventions and information sources regarding herbicides. Markets were surveyed across 17 countries to collect data on herbicide availability, brand names and local prices (converted to US$ha−1). Herbicides are used by 34$17 ha−1). They are also the most popular herbicides among farmers. For advice on herbicide application methods, farmers primarily rely on their peers, and only a few receive advice from extension services (<23%) or inform themselves by reading the product label (<16%). Herbicide application timings are therefore often (38%) sub-optimal. Herbicide technologies can contribute to reduced production losses in rice in SSA. However, through negative effects on crop, environment and human health, incorrect herbicide use may unintentionally counteract efforts to increase food security. Moving away from this status quo will require strict implementation and monitoring of national pesticide regulations and investment in research and development to innovate and diversify the currently followed weed management strategies, agricultural service provision and communications with farmers

Variability and determinants of yields in rice production systems of West Africa

Rice (Oryza spp.) is the major staple food for most countries in West Africa, but local production does not meet demand. Rice is grown mainly by smallholder farmers, and yields are generally low with high temporal and spatial variability. Low yields have been attributed to unfavorable climate conditions, poor soil quality, and sub-optimum agricultural practices. The objectives of this study were to assess variation in yields of three major rice production systems (irrigated lowland, rainfed lowland, and upland) across three climatic zones (semi-arid, sub-humid, and humid), and identify factors affecting that variation. We analyzed data on yield, climate, soil, and agricultural practices for 1305 farmers’ fields at 22 sites in 11 West African countries between 2012 and 2014. A boundary function approach was used to determine attainable yields. Random forest algorithm was used to identify factors responsible for yield variation. Average rice yield was 4.1, 2.0, and 1.5 t ha−1 in irrigated lowland, rainfed lowland, and rainfed upland systems, respectively, with maximum attainable yields of 8.3, 6.5, and 4.0 t ha−1. Yield difference between attainable and average yield tended to be higher in irrigated and rainfed lowland systems. In those two systems, yields were highest in the semi-arid zone, while no difference in yields among climatic zones was apparent for upland rice. High rice yields were associated with high solar radiation, high maximum temperature, intermediate air humidity, multiple split nitrogen (N) fertilizer applications, high frequency of weeding operations, the use of certified seeds, and well-leveled fields in the irrigated lowland system. Minimum temperature, solar radiation, rainfall, construction of field bunds, varietal choice, and the frequency of weeding operations were determinants of rice yield variation in the rainfed lowland system. Varietal choice, bird control, and frequency of weeding operations affected rice yields in the upland system. Improving access to inputs, improving input use efficiencies, and site-specific management strategies are recommended as priority interventions to boost rice yields at regional scale independent of production system and climatic zone