by CIAT Comunicaciones | Jan 28, 2019

Figure: Verónica Ruiz, coautora del estudio basado en Nicaragua, lleva a cabo investigación en pasturas. 
Crédito: UNAN

When cow urine falls on degraded land, it releases far more nitrous oxide – a potent greenhouse gas – than when absorbed by healthy pasture. The findings show additional benefits of landscape restoration and conservation.

The exceptional climate-altering capabilities of cattle are mainly due to methane, which they blast into the atmosphere during their daily digestive routine. Cattle urine is a lesser-known climate offender. It produces nitrous oxide (N₂O), which has warming power far greater than that of carbon dioxide (CO₂), the main driver of global warming. A study conducted by the International Center for Tropical Agriculture (CIAT) and partners shows that these N₂O emissions can be significantly curbed by healthy cattle pastures.

For the study, researchers collected urine from cattle at research sites in five countries across Latin America and the Caribbean. They spilled these 500 mL samples on paired cattle fields classified as degraded or healthy, which was determined by vegetation coverage. In six of the seven test sites, degraded pastures emitted significantly more N₂O – sometimes up to three times as much. The results were published January 29 in Scientific Reports, an open-access journal by the publishers of Nature.

The results add urgency to global land restoration agreements, including Initiative 20x20, which aims to bring into restoration 20 million hectares of land into restoration in Latin America by 2020 as a first major step toward even more ambitious restoration targets.

Estimates vary, but Chirinda calculates, conservatively, that there are 150 million hectares of degraded lands in Latin America. Brazil alone is home to some 80 million hectares of degraded pastureland.

Degraded livestock land is generally characterized by overgrazing, soil compaction, loss of organic material and low levels of nutrients and soil carbon. Large-scale land restoration with improved forage grasses, rotational grazing and the addition of shrubs and trees (silvopastoral farming) could significantly mitigate the negative climate effects wrought by degradation. In addition to reducing N₂O emissions, restored landscapes generally contain more carbon, have healthier soils and more robust and productive livestock.

The curious results from the single test site that did not align with the study results – in Taluma, Colombia – may be attributed to a number of factors that merit further research. N₂O emissions there were by far the lowest at any test site and were the same on both degraded and healthy pastures. The cattle urine used in the experiment had the lowest nitrogen content compared to the other research sites, which likely contributed to the results. The forage grass used there, Brachiaria humidicola, also has an especially high nitrification inhibition capacity, meaning that it prevents nitrogen from becoming N₂O.

See more: https://blog.ciat.cgiar.org/cattle-urines-planet-warming-power-can-be-curtailed-with-land-restoration/