MORE THAN 745,000 hectares of agricultural land in Rwanda potentially loses its topsoil every year, a new report shows, adding that the country loses more than Rwf800 billion annually due to soil erosion. 

Using a reference year of 2021 agricultural season A, the report-by Rwanda Water Resources Board (RWB) in partnership with International Union for Conservation of Nature (IUCN) under support from Kingdom of the Netherlands-says that above three million tonnes of crop produce are estimated to be lost seasonally, an equivalent of six million tonnes annually.

It shows that 22,000 tonnes of maize and 15,000 tonnes of beans are estimated to be lost every season due to severe erosion.

"The total economic loss in agricultural productivity due to severe erosion in Rwanda is around Rwf37.9 billion every season,” reads part of the report.

The country is losing 25 tonnes of topsoil per hectare every year, and the total area at risk is over one million per hectare, or 45 percent of the country total.

Of one million hectares of land at risk in all provinces, only 282,352 hectares are fully protected against erosion.

The discharge is estimated to an average of 27 million ton of top soil lost annually.

"The annual loss due to soil erosion is estimated to be Rwf810 billion on average,” the report shows.

Another effect of soil erosion is soil fertility depletion and incurred cost of fertilisers as soil erosion removes the upper fertile part of soils that contains nutrients.

Josaphat Kanyeshuri, a researcher and lecturer in environmental studies, told The New Times that soil erosion and mining activities are top of activities polluting rivers such as Nyabarongo.

"There have been many projects to control soil erosion and conserve the river, but there is lack of proper monitoring to ensure implementation of the existing projects is successful, and ownership among citizens,” he said.

Erosion control actions and recommendations

Minister for Agriculture and Animal Resources, Geraldine Mukeshimana, has requested local government leaders to intensify campaigns against soil erosion.

The campaign has been launched in all provinces across the country.

"There should be increased efforts in terraces, agro-forestry and protecting rivers and lakes among others,” she said.

The study estimates that the total cost of erosion control actions is estimated at Rwf514 billion, of which Rwf323 billion is required for protection of agricultural land against soil erosion (about 60 percent of the total risk areas) using bench terraces, contour bank terraces known as progressive terraces, agroforestry and  plantations on contour banks.

"This would require about eight years from 2022 to 2030 to complete the activity by investing about Rwf42 billion every year to protect agricultural land against excessive erosion using community approach,” experts have mentioned.

There should be a switch of emphasis to focus on the promotion of a high quality integrated soil management system rather than stand-alone erosion control measures in agricultural land, the study recommends.

It also shows that rainwater harvesting in settlements and storm-water infrastructure in urban areas has potential to address accelerated erosion and other problems resulting from rainfall run-off across the country.

The contour bank terraces are recommended in high-risk agricultural lands, ditches are recommended in forested areas while bench terraces are recommended in areas at extremely high risk where bench terracing was started but wasn’t done in the entire area.

Grassed waterways have been recommended for existing terraces which were made without waterways or with waterways but no grasses.

No-till agriculture (zero tillage) has been recommended for perennial crops in extremely high-risk areas while storm-water management facilities or water harvesting facilities have been recommended in built-up areas.

Bamboos are recommended to close gullies or to protect rivers while forests (afforestation or reforestation) are recommended in extremely high-risk areas.

Contour bank terraces are required on 510,096 hectares, which is about 47 percent of the total country land at risk, while afforestation and reforestation are required on 39,901 hectares (4 percent of the country land at risk).

Agroforestry is required on 101,232 hectares (9 percent of the total country land at risk).