Poor agricultural practices among small-scale sub-Saharan African farmers can lead to soil erosion and reduce agricultural productivity. However, information on such practices is normally not well documented, making it challenging to design future mitigation strategies. We conducted a fine-scale agricultural survey on 200 farm households within the transboundary Sio Malaba Malakisi River Basin (SMMRB) between Kenya and Uganda to quantify the frequency and type of soil conservation practices (SWCPs) implemented. Information on farm sizes, ownership, crops grown, soil fertility, soil erosion, soil water conservation practices, and the decision-making processes was collected. Descriptive and chi-squared statistics were used to present trends in land use, decision-making processes and the extent of adoption of SWCPs, as well as to analyse the relationship between the SWCPs and the farmers’ perceptions on soil erosion. The region showed highly fragmented farms (mean area: 0.6 ha), primarily practising rain-fed subsistence farming. The principal decision-makers of each farm were mainly (63%) male. Various farmers (28%) lacked soil and water conservation practices (SWCPs). However, most farmers (35%) implemented one type of soil and water conservation practice, while 37% practised a combination of two to five soil and water conservation practices. Extensive soil and water conservation practices such as intercropping were widely practised as they were more affordable than intensive measures. Results on the farmers’ perceptions on soil erosion showed that most farmers in the SMMRB reported soil erosion (60%) and even more (92%) reported to have experienced a loss of soil fertility over the last 5 years. There was a significant positive correlation (X2 (2, n = 198) = 92.8, p = < 0.001) between the perception of soil erosion and the perception of the change in soil fertility, suggesting that reducing soil erosion could result in a reduction in the loss of soil fertility. Thus, there is still a need for strategies and measures to address the soil erosion risks currently faced by Sio Malaba Malakisi River Basin farmers. This study is a baseline study that shows the importance of farmers’ perceptions on the practice of soil and water conservation measures in the Sio Malaba Malakisi River Basin and therefore becomes an important avenue for improving the currently practised soil and water conservation measures as well as developing adoption programs as well as future studies that combine scientific and farmers’ perception/knowledge for sustainable agriculture. Further research into the efficiency of currently adopted SWCPs as well as the extent of the farmers’ knowledge and the accuracy of their perceptions is recommended.

Surface water pollution driven by land use practices and soil erosion remains a persistent challenge in tropical river basins of East Africa. Despite its socio-economic importance, the transboundary Sio Malaba Malakisi River Basin (SMMRB), shared by Kenya and Uganda, lacks comprehensive data on spatial and seasonal water quality dynamics. This study provides the first year-long baseline assessment of surface water quality in the SMMRB, using water samples collected from 12 monitoring sites across three distinct hydrological seasons: dry, short rainy, and long rainy. Twelve physicochemical parameters were analyzed following standardized protocols from the American Public Health Association (APHA), resulting in 854 data points. Multivariate statistical techniques: agglomerative hierarchical clustering, Wilk’s lambda analysis, and exploratory factor analysis (EFA), were used to identify patterns and key drivers of water quality variation. Three distinct spatial clusters, corresponding to the Sio, Malaba, and Malakisi sub-catchments, were identified, each exhibiting unique water quality profiles. Elevated concentrations of total phosphorus (TP), soluble reactive phosphorus (SRP), and total suspended solids (TSS) were observed, exceeding typical background levels for unpolluted rivers. Seasonal differences highlighted the role of sediment transport and dilution processes, particularly during the rainy seasons. These findings provide novel insights into nutrient transport and hydrogeomorphological influences in a tropical, data-scarce, transboundary basin. The results offer a scientific basis for setting up targeted monitoring stations and adaptive water management strategies. Future studies should assess long-term interactions between sediment and nutrients. Evaluating the effectiveness of soil and water conservation practices will also be important for improving water quality.

Hope Mwanake1, Gabriel Stecher1, Bano Mehdi-Schulz1, Karsten Schulz1, Nzula Kitaka2, Luke Olang3, Mathew Herrnegger11Institute of Hydrology and Water Management (HyWa), University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria2Department of Biological Sciences, Egerton University, P.O. Box 536 – 20115 Egerton-Njoro, Kenya3Department of Biosystems and Environmental Engineering, Technical University of Kenya, Nairobi, KenyaAbstractThe complexity of shared governance, the variety of land use practices that affect water quantity and quality, and the fluctuating socioeconomic conditions that lead to different regional priorities are some of the reasons that pose particular challenges for sustainable resource management for transboundary river basins. This study carried out in the Sio Malaba Malakisi River Basin (SMMRB), shared by Kenya and Uganda, examines how combining a scientific evaluation of local soil erosion risk together with farmer-reported views of soil erosion and field conservation measures enhances soil conservation efforts.Through participatory surveys involving 200 farming households to gather data on their estimations of soil loss, and on their farm management practices, together with the regional application of geospatial analysis to estimate soil erosion with the Universal Soil Loss Equation (USLE), we identified significant discrepancies between farmer perceptions and estimated USLE soil erosion outcomes. While 60% of farmers reported visible soil erosion and 92% noted declining soil fertility, the spatial modeling of the USLE estimates revealed that over 76% of the region lacks effective soil and water conservation practices (SWCPs), leaving vast areas vulnerable to erosion. These findings highlight a substantial gap between farmer perceptions and modeled estimates, emphasizing the need for targeted interventions. Furthermore, transboundary water quality assessments revealed nutrient "hotspots" linked to erosion, stressing the need for joint management strategies to address shared challenges.To address these challenges, a Best Management Practices (BMPs) scenario was developed based on the knowledge of the 200 farmers interviewed within the basin and the practices of "best-practice farmers" from the survey results. This scenario assumes that farmers are more likely to adopt measures already practiced in their vicinity, such as terracing for steep slopes or crop rotation for maize and beans, reflecting local topography and cropping systems. The BMP scenario predicts a 25% reduction in severely eroded areas, demonstrating the transformative potential of scaling up the SWCPs to reduce soil loss. These outcomes reinforce the importance of leveraging local knowledge to design regionally relevant conservation strategies.In this study, farmers expressed a strong willingness to share their insights on soil erosion and conservation, highlighting the need for community-driven conservation efforts that integrate farmer knowledge into scientific frameworks. These efforts can lead to more effective erosion control and sustainable land management by fostering a sense of ownership and encouraging locally informed decision-making.This research highlights the need for data-driven, context-specific conservation strategies in data-scarce regions like the SMMRB, emphasizing the importance of local data, and farmer engagement for the adoption of BMPs. The results provide a scalable model for comparable data scarce areas around the world and highlight the significance of coordinated transboundary collaborations, and inclusive capacity-building balancing between ecosystem restoration and sustainable livelihoods.