The exceptional potential for climate change in cattle is mainly associated with methane, which it releases into the atmosphere during daily digestion. Cattle urine is a less well-known climate breaker. Produces nitrous oxide (N2O), which has a higher calorific value than carbon dioxide (CO2), the main driver of global warming. A study by the International Center for Tropical Agriculture (CIAT) and its partners shows that2O emissions can be significantly limited by healthy pastures.
For the study, scientists collected cattle urine at research sites in five countries in Latin America and the Caribbean. They shed these 500 ml samples on the paired fields of cattle, classified as degraded or healthy, as determined by vegetation. In six of the seven test sites, degraded pastures emitted significantly more nitrogen.2O – sometimes up to three times more. The results were published on January 29 in Scientific reportsPublishers Open Access Magazine Nature,
“Degraded pastures are bad in many ways,” says Ngonidzashe Kirinda, a CIAT researcher and lead author of the study. “This study adds to the land restoration case. Degraded pastures not only affect the food security and livelihood of farmers today, but also the livelihoods of future farmers, because they emit more gases that cause global warming. ”
The results increase the relevance of global land restoration agreements, including the 20 × 20 Initiative, which aims to restore 20 million hectares of land in Latin America by 2020 as the first important step towards even more ambitious restoration goals.
Estimates vary, but Chirinda estimates, conservatively, that there are 150 million hectares of degraded land in Latin America. In Brazil alone, there are about 80 million hectares of degraded pastures.
Degraded livestock is usually characterized by overgrazing, soil compaction, loss of organic matter and low levels of nutrients and carbon in the soil. Large-scale land restoration with improved fodder grasses, rotational grazing and the addition of shrubs and trees (forest grazing) can significantly mitigate the negative climatic consequences caused by degradation. In addition to reducing N2O emissions, restored landscapes, as a rule, contain more carbon, have more healthy soils and stronger and more productive livestock.
“This study underlines the importance of preventing land degradation in the first place,” said Todd Rosenstock, co-author of World Agroforestry (ICRAF). "Preserving healthy pastures helps strengthen the goals of both the United Nations Framework Convention on Climate Change and the UN Convention to Combat Desertification at the same time."
The curious results at the only test site, which did not coincide with the results of the study – in Talum, Colombia – can be explained by a number of factors that deserve further study. N2O emissions were lowest at any test site and were the same on both degraded and healthy pastures. In the urine of cattle used in the experiment, the nitrogen content was the lowest compared with other areas of the study, which probably contributed to the results. Used grass feed Brachiaria humidicolaalso has a particularly high ability to inhibit nitrification, which means that it prevents the conversion of nitrogen to N2ABOUT.
Power of data from remote locations
The study is a victory for a well-designed, modest budget science. The project began with a week-long training at CIAT headquarters in Cali, Colombia, where there is a team of doctors of science. Students from other participating countries — Argentina, Brazil, Nicaragua and Trinidad and Tobago — helped develop a research plan and standardized research methodology.
The students returned to their countries and conducted an experiment to coincide with the rainy season in their area in order to provide similar climatic conditions in different places of study. (The exception was Talum, which was selected during a period characterized by low precipitation, which is also another possible reason why2O emissions were lower).
“The strength is in the number of data points from different countries,” said Chirinda.
Best Cattle Greenhouse Gas Assessment
The researchers said that the study is a useful step towards creating a more detailed picture of the extent of greenhouse gas emissions from livestock in LAC.
“Since work on emissions from livestock in the region is not common, this study provides at least one piece of information that is missing from theoretical estimates of greenhouse gases in the LAC region,” said Miguel Andres Arango, co-author and scientist in Colombia. AGROSAVIA, the country's largest agricultural research organization.
“The ability to assess the real impact of livestock production will allow us to offer potential methods to reduce emissions,” said Arango. “It’s time to find out the emission factors for our agricultural systems.”