In the last three farming seasons (over a year’s time), farmers grouped under IABM – a cooperative mainly growing maize in Muhanga District, Southern Province, saw 28 hectares of their farms gradually washed away by torrential rain induced erosion, causing them at least Rwf112 million annual income loss.

Jean d’Amour Ntamabyariro, president of this cooperative with over 1,500 members , told The New Times that it was carrying out farming on 215 hectares for maize seed multiplication purposes, but currently does it on 187 hectares, because of the water induced erosion that destroyed part of their farms.

He estimated maize production at four tonnes per hectare, indicating that the completely eroded 28 hectares of farmland could produce 112 tonnes. With a kilogramme of maize seed costing Rwf1,000 that totals to over Rwf112 million.

"Rainwater flows from hillsides and roadsides and takes away our soil, and that has an economic implication. Sometimes, we lose part of our land, while in some cases, fertile soil is washed away by erosion, forcing us to apply three times the amount of fertilisers we would normally use as we try to restore soil fertility,” he said.

He indicated that their land is carried away by streams such as Makera and Kagorogonzo into the River Nyabarongo and heads downstream to Egypt.

This is one of the examples of how erosion is deteriorating agricultural productivity, increasing production costs for farmers (as they try to recover productivity) and the country at large.

Indeed, according to the State of Soil Erosion Control in Rwanda May 2022, more than 745,000 hectares of agricultural land in Rwanda are potentially eroded every year.

It was produced by the Rwanda Water Resources Board (RWB) and the International Union for Conservation of Nature (IUCN).  

Using a reference year of 2021, season A, the report revealed that over 3 million tonnes crop produces are estimated to be lost seasonally (6 million tonnes annually) due to severe erosion, of which 22,000 tonnes of maize and 15,000 tonnes.

According to the report, the crop productivity lost to severe erosion in Rwanda translates into a loss of about Rwf37.9 billion (5.5 percent) of the Rwf690 billion agricultural sector contribution to Rwanda’s GDP in the first quarter of 2021.

The above produce loss due to erosion is far more than the 10,000 tonnes of maize and 5,000 tonnes of beans that MINAGRI wants to purchase and store – at a cost of Rwf7.4 billion – in the National Strategic Grain Reserve in this fiscal year, with aim to provide food relief to needy people in case of food shortages.

And this is happening while 467,000 Rwandan households or 18.7 percent of the country’s all households were food insecure, according to the 2018 Comprehensive Food Security & Vulnerability Analysis.

Soil fertility depletion and the incurred fertiliser cost

The report indicated that soil erosion removes the upper fertile part of soils that contains nutrients. Given that 641,280 hectares are affected by soil erosion, the report estimated that 16 tonnes of soil is displaced, carrying soil nutrients including about 1,282,560 tonnes of soil Carbone (C) and 128,256 tonnes of nitrogen (N) loss per year.

In order to compensate for soil nutrient loss and improve land productivity, the report showed that fertilisers such as urea and di‐ammonium phosphate (DAP) are applied.

In the substitution of nitrogen loss with urea, with an average price of Rwf564,000 per tonne – reference  to MINAGRI subsidised price of urea in 2021); it would cost Rwf72 billion per year to Rwandan farmers, a cost that excludes Government subsidies.

Cost and benefits of erosion control actions

In Rwanda, of 1,080,168 hectares of land at erosion risk in all provinces, only 282,352 hectares – or 26 percent – are protected against erosion.

The total cost of erosion control actions in the country is estimated at Rwf514 billion, of which 323 billion are for the 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 and agroforestry and hay plantation on contour banks.

This would require about eight years from 2022 to 2030 to complete the activity by investing about Rwf40 billion every year to protect agricultural land against excessive erosion using a community approach.

High quality soil management could be achieved through an integrated conservation agriculture approach that provides profitable agricultural yields, while minimising environmental damage, the report recommended.

Speaking to The New Times, Charles Bucagu, Deputy Director General in charge of Agriculture Development, said that the Government was working with other partners to increase forest and grass cover, as well as constructing terraces among other efforts to control erosion.

He said that erosion is a major issue in the country, pointing out that it takes away a lot of its soil.

"And that’s a fact because if you look at [River] Nyabarongo, it is carrying away much soil. So, there is a need to protect the land from erosion, but also tackle the loss caused by the fact that the fertiliser applied by the farm is washed away by erosion, and the expected harvest that is lost because crops are also washed away,” he said.

Meanwhile, he said that about 20 million tree seedlings, including agroforestry and fruit trees, will be planted in October this year, countrywide in order to support anti-erosion efforts.