The Importance of Covering Manure Heaps for Sustainable Farming
To prevent nutrient loss and reduce the emission of greenhouse gases, farmers should cover heaps of solid manure that are often left exposed. This practice is gaining attention as a simple yet effective solution to address environmental and agricultural challenges.
Dr. Sonja Leitner, a senior scientist at the International Livestock Research Institute (ILRI), highlighted this during the International Greenhouse Gas and Animal Agriculture Conference. She emphasized that manure is one of the most valuable resources on a farm, but when it is exposed to the sun and rain, it quickly loses nutrients that crops need. By covering the manure, farmers can significantly reduce gas emissions and nutrient leaching, ensuring more nitrogen remains in the manure to benefit crops.
- “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 the 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, contributing to sustainable development goals. According to Dr. Leitner, covering manure heaps not only conserves nutrients but also minimizes unpleasant odors and prevents environmental pollution.
Key Nutrient Loss and Environmental Impact
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. In addition, covering manure helps reduce methane emissions, a potent greenhouse gas contributing to climate change.
- “Proper covering can cut Nitrous Oxide (N2O) emissions by up to 30 percent, a significant step toward making livestock production more climate-friendly,” said Dr. Leitner.
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 greater than carbon dioxide 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.
Benefits of Covering Manure
“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.”
This practice is already common in many countries in the Global North, 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.
Simple and Feasible Solution for Smallholder Farmers
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.
Environmental Benefits of Covered Manure Heaps
What are the environmental benefits that countries are going to get from shifting from uncovered to covered heaps of manure? Dr. Leitner revealed that covering manure will 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.
Call to Action for Governments
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 would be a crucial first step toward better coordination,” she said. “ILRI is working to generate evidence to support policymakers in making informed decisions and adjusting existing policies accordingly.”
