Drivers of soil carbon stabilization in oil palm plantations

Abstract

Increasing soil organic carbon (SOC) in agroecosystems is necessary to mitigate climate change and soil degradation. Management practices designed to reach this goal call for a deeper understanding of the processes and drivers of soil carbon input stabilization. We identified main drivers of SOC stabilization in oil palm plantations using the well‐defined spatial patterns of nutrients and litter application resulting from the usual management scheme. The stabilization of oil palm‐derived SOC (OP‐SOC) was quantified by δ13C from a shift of C4 (savanna) to C3 (oil palm) vegetations. Soil organic carbon stocks under frond piles were 20% and 22% higher compared with harvest paths and interzones, respectively. Fertilization and frond stacking did not influence the decomposition of savanna‐derived SOC. Depending on management zones, net OP‐SOC stabilization equalled 16–27% of the fine root biomass accumulated for 9 years. This fraction was similar between frond piles and litter‐free interzones, where mineral NPK fertilization is identical, indicating that carbon inputs from dead fronds did not stabilize in SOC. A path analysis confirmed that the OP‐SOC distribution was largely explained by the distribution of oil palm fine roots, which itself depended on management practices. SOC mineralization was proportional to SOC content and was independent on phosphorus availability. We conclude that SOC stabilization was driven by C inputs from fine roots and was independent of alteration of SOC mineralization due to management. Practices favouring root growth of oil palms would increase carbon sequestration in soils without necessarily relying on the limited supply of organic residues.

Soil organic carbon sequestration and its stability after vegetation restoration in the Loess Hilly Region, China

“…Our study also revealed that SOC stability at the surface gradually decreased as the recovery years increased. In general, SOC stability is susceptible to vegetation coverage, litter, root exudates, fine root, and soil environmental conditions (Fontaine et al, 2007;Johanna et al, 2019). During the early restoration stages, vegetation composition and diversity were comparatively simple, the community structure was unstable, and soil organic matter input from , 2013).…”

“…This may lead to poor permeability and weak sunlight, which are not conducive to the growth and reproduction of soil aerobic microorganisms. In addition, according to Johanna et al (2019), SOC stabilization was mainly driven by carbon inputs from fine roots. It is possible that the HR has a large quantity fine roots which may promote the decomposition and transformation of SOC.…”

Soil Microbial Community and Litter Quality Controls on Decomposition Across a Tropical Forest Disturbance Gradient

“…These are typically pruned manually twice a year and green fronds may also be pruned during harvesting to access fruit bunches (Corley and Tinker, 2015). These are stacked in piles or rows, therefore significant aboveground C inputs occur only within the vicinity of these frond piles in mature plantations (Ruegg et al, 2019). Leguminous cover crops may also be planted in in young plantations to stabilize soils and improve fertility (Luke et al, 2019).…”

Long-Term Effects of Organic Amendments on Soil Organic Matter Quantity and Quality in Conventional Cropping Systems in Switzerland

“…In addition to the higher degradability of GM and Str, the stoichiometry of the input may be responsible for the very low C retention of these two amendments (Table 1). Soil amendments with high C-to-nutrient ratios are expected to reduce the microbial C use efficiency and to promote nutrient mining in SOM [61][62][63]. The stronger increase in phosphatase and chitinase activities compared to glucosidase activities in GM and Str suggests a lack of nutrient availability for microbial communities [64].…”