Ludovic, Reuben Adolph2026-03-042026-03-042004https://www.suaire.sua.ac.tz/handle/20.500.14820/7346DissertationA study was conducted to assess the spatial and temporal variability of soil fertility under rainwater harvesting (RWH) systems in three villages along the toposequence on the Makanya river catchment, Same district, Tanzania. The study aimed at assessing the soil fertility status and patterns along the toposequence, mapping spatial patterns of soil fertility under RWH, identifying and determining the nature and magnitude of the factors causing soil fertility changes under RWH systems along the toposequence within the cropping seasons, and assessing spatial and temporal variability of soil fertility within selected fields under RWH systems in Makanya village. Random soil samples were collected from Makanya, Mwembe and Tae villages and were used for the characterization of physical and chemical soil properties on the catchment. Runoff water samples were collected and analysed for plant nutrients in the runoff. GPS and GIS were used for positioning both soil and water sampling points and to establish geospatial information database and generate maps of the study area. Geostatistical analysis was done to carry out soil fertility surface interpolation. Soil fertility management practice data were collected through a questionnaire survey and analysed using SPSS software. The study revealed that, more than 92% of 144 interviewees were practicing RWH systems in the study area. The soil fertility attributes showed that, total nitrogen was very low to medium level (0 - 0.5 %). Soil pH ranged from strongly acid to moderately alkaline. Exchangeable K on the upper zone was very low (0-0.13 cmol(+)/kg) for the majority of samples (62 %), whereas available P was adequate (39.49 - 81.16 mg P /kg soil) only on the lower zone. Fertility attribute maps on the mid and upper zone tended to be systematically distributed following the slope facet, while on the lower zone, maps showed the patterns distribution to follow availability of harvested rainwater. Generally, most of the soils under rainwater harvesting in the area had low fertility status attributable to low organic carbon, total nitrogen and potassium, thus required improvement for high and sustainable crop yields.enRain water harvestingSoil fertilityRainwater harvesting systemsThesis