Spatial-temporal relationships between crops production and soil erosion: Case of Western Province of Rwanda

Abstract

The Western Province of Rwanda is vulnerable to soil erosion due to its steep topography, high rainfall and deforestation. Consequently, the agriculture on steep slopes exceeding more than 5 % without adequate soil erosion control measures, has intensified the soil erosion and the decline in agriculture productivity. The objectives of this thesis are to study the spatial-temporal relationship between the soil erosion and crop production in Western Province of Rwanda and to recommend strategic interventions for decision and policy-makers on how to allocate agricultural investments and watershed management efforts. The ratio of Normalized Difference Vegetation Index (NDVI) between the year 2000 and the year 2015 was overlaid to the ratio of soil erosion rates between the same period. The results revealed that between 2000 and 2015, 18% of the area under cultivation was enduring increasing crop production and increasing soil erosion or tradeoff between the two ecosystem services while 19% of the area under cultivation was suffering a decrease in crop production and an increase in soil erosion which is also called a trap or a loss between the two ecosystem services. Amongst others, we recommend that in tradeoffs areas, farmers should invest a part of their returns in soil conservation in order to make their harvest sustainable while Government efforts in areas of traps or loss are urgent to help farmers who are blocked under critical thresholds in production–asset investment relationships.