The exceptional climate change capabilities of livestock are mainly due to methane, which explode in the atmosphere during their daily digestive routine. Cattle urine is a lesser known climber delinquent. It produces nitrous oxide (N2O), which has a warming power much higher than that of carbon dioxide (CO2), the main motor of global warming. A study by the International Center for Tropical Agriculture (CIAT) and partners shows that these N2The emissions of O can be significantly reduced by healthy livestock pasture.
For the study, researchers collected urine from livestock in research sites in five countries in Latin America and the Caribbean. They defeated these samples of 500 ml in fields of paired sheep classified as degraded or healthy, which were determined by the coverage of the vegetation. In six of the seven test sites, degraded pastures emitted significantly more N2O – sometimes up to three times more. The results were published on January 29 a Scientific reports, a journal of open access by editors of Nature.
"The degraded meadows are bad in many ways," said Ngonidzashe Chirinda, a researcher at CIAT and principal author of the study. "This study adds to the case of land restoration. Degraded pastures not only affect the food security and livelihoods of farmers today, but affect the livelihoods of future farmers because They emit more gases that cause global warming. "
The results add urgent importance to global land restoration agreements, including the 20 × 20 Initiative, which aims to recover 20 million hectares of land in restaurants in Latin America by 2020 as an important first step towards restoration goals even more ambitious.
Estimates vary, but Chirinda estimates, conservatively, that there are 150 million hectares of degraded land in Latin America. Brazil only houses about 80 million acres of degraded grassland.
The degraded cattle is generally characterized by overgrazing, soil compaction, loss of organic material and low levels of nutrients and soil carbon. Large-scale restoration of land, with improved forage grasses, rotational pasture and the addition of shrubs and trees (silvopastoral agriculture) could significantly mitigate the negative effects of climate caused by degradation. In addition to reducing the N2The emissions of O, the restored landscapes generally contain more carbon, have a healthier soil and a more robust and productive cattle.
"This study highlights the importance of avoiding soil degradation in the first place," said Todd Rosenstock, co-author with the World Agroforestry (ICRAF). "Maintaining healthy pastures seems to reinforce the objectives of the United Nations Framework Convention on Climate Change and the United Nations Convention to Combat Desertification simultaneously."
The curious results of the single test site that are not aligned with the results of the study – in Taluma, Colombia – can be attributed to several factors that are worth more research. N2The emissions of O were, to a large extent, the lowest in any test site and were the same in degraded and healthy meadows. The cattle urine used in the experiment had the lowest nitrogen content compared to other research sites, which probably contributed to the results. The forage lawn used there, Brachiaria humidicola, it also has a particularly high nitrification inhibition capacity, which means that it avoids nitrogen from becoming N2O.
Power of data from distant places
The study is a victory for a well-designed and modest budget science. The project began with a weekly training session at the CIAT headquarters in Cali, Colombia, where a PhD student team from additional participating countries (Argentina, Brazil, Nicaragua and Trinidad and Tobago) helped design the plan for research and standardized the methodology of the study.
Students returned to their home countries and conducted the experiment to match the rain stations in their area, to ensure similar weather conditions in study sites. (The exception was Taluma, which was shown during a period characterized by scarce precipitation, which is also another possible reason for which the N2The emissions of O were lower there).
"The power is in the number of data points in all the different countries," Chirinda said.
Best estimates of livestock gases of livestock
The researchers said that the study is a useful step to create a more detailed view of the GHG emissions of livestock in Latin America.
"Given that the work on livestock emissions in the region is not common, this study generates at least one information missing from the theoretical estimates of greenhouse gases in the ALC region," said Miguel Andrés Arango, co-author and scientist from Colombia AGROSAVIA, the largest agricultural research organization in the country.
"Being able to estimate the real impact of livestock production will allow us to propose potential practices to reduce emissions," Arango said. "It is time to know the emission factors of our agricultural systems."