Oats hay supplementation to yak grazing alpine meadow improves carbon return to the soil of grassland ecosystem on the Qinghai-Tibet Plateau, China

Abstract

Supplementation of livestock feed is a common strategy for improving animal production in pasture-based systems worldwide. On the Qinghai-Tibet Plateau of China, however, the grassland ecosystem is fragile and therefore sensitive to disruption by external forces. We therefore investigated the effects of supplementing yaks feed with oats hay on animal production, forage biomass, and carbon return in litter and dung as well as the effects on soil organic carbon stock. Two grazing systems—native grazing, or grazing with hay supplementation—were established in 2010. For the native grazing system, yaks were rotationally grazed in two paddocks (3.3 yaks/ha) with each 15 days during the warm season (July through October) and 20 days during the cold season (November through June). The hay supplementation system was the same as the native system except that each yak also received oats hay (1.5 kg/day, dry matter basis) during the cold season. For each system, yak growth, forage biomass of the pasture, carbon return from litter and dung to soil, and soil organic carbon stock were measured from 2010 to 2014. The yaks supplemented with oats hay had greater growth performance compared with non-supplemented animals, thereby providing economic benefits for herdsmen. With respect to carbon cycling, supplementation increased carbon return in litter and dung and consequently reduced the soil carbon stock loss. The results indicate that supplementation with oats hay positively impacted forage production and carbon cycling in alpine meadows and thus may help remediate degraded soils and improve grassland utilization on the Qinghai-Tibet Plateau.