Effects of Land Use and Land Use Change in Agricultural Systems on Soil Carbon Sequestration in North-West Europe
There is a pressing need to halt the accelerated climate change, due to its adverse effects on the productivity and stability of global ecosystems. Agricultural intensification and land use change (LUC) are leading contributors to the agricultural-related greenhouse gas (GHG) emissions, due to their negative impact on soil organic carbon (SOC) stocks. Limiting SOC losses in carbon-rich grasslands and promoting soil carbon sequestration (SCS) in carbon-depleted arable lands are considered pertinent for mitigating climate change. Several approaches aiming to reduce the SOC losses during grassland conversion to arable land and those aiming to promote the SCS rates of arable lands were assessed in northern Germany. No-till (NT) as a method to mitigate SOC losses was investigated both after conversion to continuous silage maize and after renovation of a 10-year old grassland, and compared to the use of conventional tillage (CT) in continuous silage maize over 7 years (2014-2021). Using NT reduced SOC losses by 28 % compared to using CT after grassland conversion and contributed to conserve SOC levels after grassland renovation. Promoting SCS in arable land was tested by integrating crop-livestock system practices including the use of either annual leys or pulses and cover crops combined with cattle slurry fertilization in forage, mixed and grain-based crop rotations, over 10 years (2010-2019). Adjacent to the arable land, establishing a ley-containing forage rotation after grassland conversion was investigated as a method to mitigate SOC losses compared to establishing a continuous silage maize, over 12 years (2010-2022). Using leys produced no increase in SOC stocks, whereas using cover crops yielded SOC losses in the arable land. Establishing ley-containing rotations produced 30% lower SOC losses compared to establishing continuous silage maize after grassland conversion. The role of grasslands for mitigating climate change in the region was highlighted in the study.