Compost amendment to enhance carbon sequestration in rangelands

Rangelands, which hold 20% of the world’s soil carbon, have experienced significant soil carbon losses due to past management practices, jeopardizing their long-term productivity and sustainability. Compost amendments have been proposed as a strategy to enhance soil carbon sequestration while providing multiple benefits to rangeland ecosystems and land managers. A review of the literature reveals that compost applications, derived from sources such as green waste, food waste, manure, and biosolids, have been studied in rangelands across eight countries and five continents. These studies have documented both short-term (less than one year) and long-term (over 12 years) effects of compost on soil and plant characteristics. On average, compost amendments were found to increase aboveground production by over 40% and belowground carbon content by 50%. Additional benefits of compost amendments included improved aggregate stability by approximately 42%, enhanced water retention by 18%, and increased nutrient availability, with nitrogen and phosphorus availability rising by 37% and 126%, respectively. Compost additions also generally reduced erosion, though the variability was high. However, the impact on plant diversity was minimal, and few studies explored the effects on soil microbial communities and functions. Both field and modeling studies indicated that compost amendments could lead to long-term carbon storage in soils. Overall, the findings suggest that compost amendments can improve rangeland resilience to climate change and offer a viable climate mitigation strategy through enhanced soil carbon sequestration.

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