By Milliam Murigi
To prevent nutrient loss and reduce emission of greenhouse gases, farmers should cover heaps of solid manure that are often left bare.
Dr. Sonja Leitner, senior scientist at the International Livestock Research Institute (ILRI), said during the International Greenhouse Gas and Animal Agriculture Conference.
“Manure is one of the most valuable resources on a farm, but when it is exposed to sun and rain, it quickly loses nutrients that crops need. To reduce this, the first step is basically to cover the manure, because then you have less of these gas emissions and also less leaching. So more of the nitrogen is contained in the manure, which means also more of the nitrogen then reaches the crop field and improves the yields for the farmers,” said Dr Leitner who is in charge of CIRcularity of Nutrients in Agroecosystems and co-benefits for animal and human health (CIRNA) project.
The CIRNA project aims to develop and promote farmer-approved manure management practices that address environmental, health, and economic concerns, and contribute to sustainable development goals.
According to her, covering manure heaps not only conserves nutrients but also minimizes unpleasant odors and prevents environmental pollution. The key nutrient lost from uncovered manure is nitrogen, which is highly volatile and can either be emitted as a gas or leached out as nitrate, leading to significant nutrient loss.
Besides, it also helps reduce methane emissions, a potent greenhouse gas contributing to climate change. Dr. Leitner noted that while the exact figures depend on the type of manure and management system used, proper covering can cut Nitrous Oxide (N2O) emissions by up to 30 percent a significant step toward making livestock production more climate-friendly.
Nitrous oxide is a potent greenhouse gas, the third most significant human-caused one after carbon dioxide and methane, with a global warming potential nearly 300 times carbon dioxide greater than over 100 years.
Human activities, primarily the use of synthetic fertilizers and manure in agriculture, are the main source of its growing atmospheric concentration, which is increasing faster than expected and poses a threat to climate and the ozone layer.
“If manure is left uncovered, farmers lose most of its nitrogen content sometimes up to 75 percent of what was originally there,” she explained. “By covering it, more nitrogen is retained and eventually released into the soil as a slow-release fertilizer, boosting crop growth and improving yields.”
The practice is already common in many countries in the Global North according to her, where it is even a legal requirement. However, in countries such as Kenya and Uganda, where the approach has been introduced, farmers have also embraced it and appreciate its benefits.
The good thing about this practice is that it is simple and feasible, making it easy for smallholder farmers to adopt. It can be implemented using locally available materials such as plastic bags, banana leaves, or any other cover that can keep rainfall off the manure to protect it and prevent nitrogen loss.
What are the environmental benefits that countries are going to get from shifting from uncovered to covered heaps of manure? She reveals that covering manure will basically reduce greenhouse gas emissions. It will also reduce ammonia emissions, which contributes to air pollution, so countries will have cleaner air. Covering will also reduce nitrate leaching, and nitrate is a groundwater pollutant, so it also improves the water quality in the long term.
Her call to action is for the governments to start developing and implementing improved manure management policies. She noted that a major challenge has been the lack of clear responsibility among institutions, as the issue often overlaps between the ministries of health, environment, and agriculture.
Establishing clear policies, she said, would be a crucial first step toward better coordination. ILRI is working to generate evidence to support policymakers in making informed decisions and adjusting existing policies accordingly.
