Mitigating Effects of Forage Legumes on Greenhouse Gases Emission and Some Pollutants

The demand for high quality foods is increasing due to increase of urbanization, population and disposable income. Thus increased global food production is required and this increase must be achieved through environmentally sustainable production systems. It is a fact that CO 2 concentration of atmosphere about 100 ppm, average global temperature about 0.9 C, and sea level about 20 cm increased in the last century. Some agricultural activities such as, enteric fermentation, agricultural chemicals, paddy farm, agricultural machines and burning of stubble causes highly greenhouse gases (GHG) emission. Regard the results of studies, forage legumes used in crop rotation and livestock feeding decreases GHG emissions and pollute of natural sources. Currant agricultural production is highly N limited, while the provision of industrial N is largely based on fossil energy with its associated emission of GHG. Thus, substitution of industrial N fertilizer with N derived from legumes’ symbiotic N 2 fixation is an important contribution to more environmental friendly and resource efficient agricultural systems. Livestock production is a significant source of GHG emissions, generating CO 2 , CH 4 and N 2 O from enteric fermentation, manure management and other production activities. Inclusion of forage legumes in ruminant diets can potentially improve productivity while at the same time reducing the C footprint of meat and milk production through reduced CH 4 and N 2 O emissions as well as enhanced C sequestration. Several forage legumes possess plant secondary metabolites that include tannins and polyphenoloxidase. In the rumen, these secondary metabolites protect proteins from degradation and ruminants excrete less urinary N but more fecal N. This is important because the urinary N is quickly converted to ammonia and N 2 O which induces environmental problems. There is evidence that forage legumes, as components of mixed grass-legume swards, can provide multiple benefits to agriculture by acting at different stages in the soil-plant-animal-atmosphere system.