Optimizing soil multifunctionality of coastal peat grasslands

Abstract

Soils have the capacity to provide a wide range of soil functions that can help address socio-environmental challenges, such as climate change and biodiversity loss. Here, we apply the Functional Land Management framework aimed at optimally balancing supply and demand of soil functions at a landscape-scale to drained coastal peat (Histosols) in Friesland, The Netherlands. We focus on the supply side by assessing the capacity of grassland peat soils with different topsoil types to provide five soil functions: climate regulation, habitat provision, nutrient cycling, water storage, and primary productivity. A field campaign was conducted in March 2022 to collect data on soil, water, vegetation, and management from 30 grasslands mapped as peat on the national soil map (Basisregistratie Ondergrond). Results revealed significant differences in above and belowground field conditions between peat with different topsoil types. Peat soils with a mineral cover are predominantly used as grasslands for dairy farming, with a clear differentiation in functioning between fields managed by organic and conventional farmers. Peat soils without a mineral cover are generally owned by nature organizations and managed as semi-natural grasslands aimed at optimizing aboveground habitat provision. Our results show that conventional agricultural management, including deep drainage and high fertilizer inputs, results in moderate to high nutrient cycling and primary productivity, along with low climate regulation, water storage and habitat provision. Extensification results in a decrease in primary productivity and nutrient cycling along with a strong increase in climate regulation, water storage, and habitat provision. To optimize landscape-scale provision of soil functions, we recommend promoting soil multifunctionality while maintaining moderately high yields on peat with a mineral cover. To benefit from the unique and yet unmet potential of peat soil for climate regulation and water storage, we recommend tailoring management of peat soils without a mineral cover to fully restore natural peatlands.