The Impact of Land Degradation on Agricultural Productivity in Nyabihu District-Rwanda, A Case Study of Rugera Sector
Abstract
This study looked at the impact of land degradation on agricultural productivity in Nyabihu district. Specific objectives were to assess the factors influencing land degradation in Nyabihu district, Rugera sector, the vulnerability level of land degradation and propose suitable land management conservation strategies.
Geographical Information system (GIS) and Remote sensing data were used for the assessment of factors influencing land degradation, where Land cover (classified) maps were produced based on data extracted from google earth and cultivated slope was computed based on the Digital elevation model (DEM) of 2018 downloaded from earthexplorer.usgs.gov. GIS vulnerability assessment and classification method was used to assess level of vulnerability to soil degradation and land slide. To propose suitable land management conservation strategies practical Tools on Soil and Water Conservation measures alongside with W4GR matrix of soil and water conservation measures documents were consulted. The data collected were analyzed using ArcGIS 10.4software, and Excel; the results were presented using maps, bar graphs and tables. Based on two main factors (slope and soil depth) a conservation map and matrix were developed with proposed options of restoration and conservation of land degraded.
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Introduction
Land degradation in the world stands at about 85% and this is associated with soil erosion, most of which occurred since the end of World War II, causing a 17% reduction in crop productivity. The extent of soil erosion shows that it’s a worldwide environmental problem with some areas such as the horn of Africa and majority of sub – Saharan region being extremely prone to erosion due to prolonged dry periods and heavy erosive rainfall, falling on steep slopes with fragile soils, causing inconsiderable amounts of erosion. (Abdallah, 2016)
According to Sileshi (2016), land degradation is one of the most serious environmental challenges and an issue in both developed and developing countries. However, the severity and magnitude of its impact are much more pronounced in low income countries at which the livelihood of the majority is dependent on agriculture.
It was found that land degradation was associated with soil degradation through exploitative cropping (Boardman, Poesen and Evans,2003). Soil quality decline is one of the main causes of land degradation and is considered to be responsible for 84% of the ever diminishing acreage.
According to Twagiramungu (2006), Land degradation specifically soil degradation is a major environmental problem in Rwanda, The degradation is particularly linked to hydrous erosion that affects a big portion of cultivated lands. It was assumed that the hydrous erosion reduces the capacity to feed 40 000 persons per year and causes annual losses of about 15 000 000 tons of soil.
According to Sileshi (2016), the vulnerability to land degradation needs to be assessed continually to take appropriate resource conservation measures. Therefore, the aim of this study was to assess the impact of land degradation on agriculture productivity in Nyabihu district through the integration of GIS and RS. More specifically, the study is targeted to map the spatial and temporal changes in agriculture land use and land cover, to assess soil erosion and landslide as factors of land degradation, as well as other factors that affect agricultural productivity.
It is against this background that the study assessed factors influencing land degradation, the level of land degradation, the impact of land degradation on crop production in Nyabihu district and the specific proposed land conservation measures. This study will provide an understanding of influencing factors and level of land degradation in Nyabihu district and the relationship between land degradation and agriculture productivity. The study will significantly benefit farmers’ policymakers and policy implementers in trying to enforce mitigation measures to cope with land degradation process. The research is also proposed so that people can end up benefiting from the environment they are living in and later they contribute to the country economic advancement and the world as well. It will also be a great contributor to land management policies that will be implemented after this research by suggesting ways by which land can be protected so that agricultural productivity can be improved to sustain food security in Nyabihu district.
Findings from this research are expected to describe the evolution of the problem within a period of 5 years; hence, the impact of soil degradation on agricultural productivity in Nyabihu district; from year 2014 to
Conclusion
4.1 Conclusion From the results obtained in this study, it can be concluded that in Nyabihu district, Rugera sector land degradation is influenced by biophysical and anthropogenic factors. Those factors are land cover and land use change, high amount of precipitation and high density population cultivating sloping land. Land degradation that occurred from (2014-2018) alongside with other factors such pests and diseases, lack organic manure, mineral fertilizers, Quality of seed, timely planting and Inter-annual temperature variability had impact on agriculture productivity. From 2014, 2015, 2016, 2017 and 2018 a decline in annual crop production was observed in Nyabihu district. Land degradation through soil erosion and landslide were found to be more frequent and affecting agriculture productivity in the study area. Using GIS assessment about 2190 ha were found to be exposed to moderate, high and very high landslide and needed special attention for conservation and restoration measures, while 1855ha were exposed to moderate, high and extremely high soil loss. For effective conservation measures on land degradation the study recommends the use of both combined agronomic measures and land conservation measures adapted from proposed conservation matrix under Rwanda water and Forestry Authority (RWFA). 4.2 Recommendations Based on the findings from the study, recommendations have been formulated to cope up with the effects of Land degradation on agriculture productivity in Nyabihu district: We recommend Nyabihu district all sectors deep assessment of the most vulnerable areas exposed to land degradation through erosion and landslide as most frequent hazards that contribute to the agriculture land degradation. While selecting conservation measures for land degradation, Nyabihu district officials must consider proposed conservation matrix under Rwanda water and Forestry Authority (RWFA). District agronomist in collaboration with Sectors agronomists must increase awareness and followup on the use of land conservation agronomic measures including mulching, crop management and agroforestry as it was found to be the less expansive. Farmers should be involved actively in the process of land management and conservation measures in order to achieve land conservation sustainability.
