Methane and nitrous oxide emissions from grazing steers' dung with or without supplement in Argentina

LOMBARDI, B.; ALVARADO, P.I.; RICCI, P.; JULIARENA, P; GONDA, H.

Foz do Iguassu

Conferencia; 7th International Greenhouse Gas and Animal Agriculture Conference; 2019

EMBRAPA

Increasing the proportion of starch rich supplements in the diet of ruminants can decrease the emission of enteric methane (CH4) and can increase its emission from manure. However, the effect of diet composition on nitrous oxide (N2O) emission from manure is less known. The objective of this study was to quantify CH4 and N2O emissions, and estimate their emission factors (EF) from fresh dung collected from 20 steers grazing pasture without (P) or with daily maize grain supplementation (S; equivalent to 1% steer?s body weight). Emissions were measured, over 125 days, in static chambers (5 chambers/treatment plus 2 chambers as control) placed on a plot without grazing. Fresh dung was collected once from two groups of steers and homogenized to form a composite sample for each diet. One kilo of composite sample was placed on the ground inside the chambers. As dung dry matter in P was lower, S had a major carbon and nitrogen concentration. Even so, with greater amount of carbon, S cumulative CH4 emissions (1738 mg CH4-C m-2) were lower than P (4033 mg CH4-C m-2; P