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Banana Xanthomonas Wilt (BXW) is the major threat to banana in Rwanda, causing up to 100% yield loss. There are no biological or chemical control measures, and little is known about potential direction and magnitude of its spread, so cultural control efforts are reactive rather than proactive. In this study, we assessed BXW risk under current and projected climate, to guide early warning and control by applying maximum entropy (Maxent) model on 1,022 georeferenced BXW datapoints and 20 environmental variables. We evaluated the variables’ significance and mapped potential risk under current and future climates to assess spatial dynamics of the disease distribution. BXW occurrence was reliably predicted (mean validation AUC ranging from 0.79 – 0.85). Precipitation of the coldest quarter, average maximum monthly temperature, annual precipitation, and elevation were strongest predictors, explaining 21.1%, 13%, 12.6%, and 9.4% of the observed incidence variability, respectively, while mean temperature of the coldest quarter has the highest gain in isolation. Further, the most susceptible regions (in western, northern, and southern Rwanda) are characterized by elevation (1,350m – 2,000m), annual precipitation (900mm - 1700mm), and average temperature (14oC - 20oC), among other variables, suggesting that a consistent, rainy, and warm climate is more favorable for BXW spread. Under future climate, the risk is predicted to increase and spread to other regions. We conclude that climate change will likely exacerbate BXW-related losses of banana land area and yield, under temperature and precipitation influence. Findings support evidence-based targeting of extension delivery to farmers and national early warning for timely action.

To determine whether a farmer’s accessibility predicts the delivery of extension services, this study used banana Xanthomonas wilt (BXW) disease-management advisory as a typical case with which to collect extension-delivery information from 690 farmers, distinguished by their respective accessibility. Cost–distance analysis was applied to define each farmer’s accessibility. The results revealed that a farmer’s accessibility does not predict extension delivery to that farmer in all forms of the examined extension parameters. Significant factors contributing to the delivery of extension services included BXW incidence and membership in Twigire Muhinzi groups. Given the results of this paper, I argue that the nature of the advisory and the type of farmers’ networks are more predictive factors than physical proximity. The findings of this study support the argument that the group-based extension approach is more effective; therefore, the Twigire Muhinzi initiative is recommended as a suitable model for delivering agricultural advisory services. The absence of a significant association between extension delivery and distance (accessibility) suggests that extension agents do not follow the first-reached, first-served rule but instead follow the problem-solving-based approach.

Conservation agriculture (CA) is becoming popular in sub-Saharan Africa as potential solution to soil degradation. However, most findings are based on large scale, mechanized agricultural production systems which are not easy to apply within the smallholder farmer’s context. This study assessed the implications of tillage practices, management of soil surface and fertilizer application on sustainable dryland agriculture of Eastern Rwanda. The experimental design was Split Plot with 4 replications. The main plots were conventional tillage (CT) and no tillage (NT) and sub-plots were: Control, sole residues application (RR); residues application with inorganic fertilizers (RR+IF) and inorganic fertilizers (IF) applied alone. Inorganic fertilizers application increased bean grain and biomass yield by 103%. In no tillage inorganic fertilizers had higher maize grain and biomass yields whereas residues application had 68% higher maize grain and biomass yield in conventional tillage. The significant increase in organic carbon was observed in residues applied with inorganic fertilizers. There was a significant N decrease in all treatments however control and residues had the highest N pool compared to other treatments. Sole residues application and residues applied with inorganic fertilizers treatment increased significantly Available P. The use of inorganic fertilizers in conservation agriculture systems should be promoted as the engine toward successful of CA practices for Bugesera district conditions. These results provide a basis for conducting trade-off analyses to support the development of CA crop management and international development strategies based on available scientific evidence. Key words: Conservation agriculture, no tillage, residues management, Bugesera District.

Nutrient-balance assessments are valuable tools for both planning and monitoring the implementation of sustainable integrated soil fertility management strategies. The aim of this study was to assess nutrient flows as affected by cropping systems and production niche in soils of Cyabayaga watershed. yabayaga watershed is located in Nyagatare district, Eastern province of Rwanda. Production niches considered are homestead fields, remote hillside fields and wetland fields. Partial nutrient (N, P and K) flows were collected through a survey using MonQi structured questionnaire, administrated to a random sample of 35 farmers. There was nitrogen (N) and Potassium (K) negative balances (– 67.5 kg N ha-1 season-1 and – 7.7 kg K ha-1 season-1 respectively) whereas phosphorous (P) balance was positive (17.4 kg P ha-1 season-1). N, P and K balances were negative in bean, maize-bean, cassava, groundnut, maize, onion, sorghum and tomato and positive in rice, banana and banana-bean. Highest amount of nutrients were significantly allocated in wetland fields while allocation of nutrients in homestead fields and remote hillside fields was almost the same. Groundnut and maize plots were experiencing highest negative nutrients balance (e.g. N balance in groundnut plot was – 40.6 N ha-1 season-1). N and K balance were positive in rice and banana plots; whilst P balance was positive in banana, bean, maize, rice and tomato plots. Partial nutrients flow and balance from this study show that nutrient depletion is a problem in the study area. A special attention should be put to fertility management and alternative solution for less fertile soil (uplands in particular), especially for farm that have reduced land size. From this respect, conservation agriculture is the main farm management which could be recommended.