Formation efficiency of soil organic matter from plant litter is governed by clay mineral type more than plant litter quality

Authors: YUZHI, XU - Chinese Academy Of Sciences; LIU, KAI - Chinese Academy Of Sciences; YAO, SHUIHONG - Chinese Academy Of Agricultural Sciences; ZHANG, YUELING - Chinese Academy Of Agricultural Sciences; ZHANG, XUDONG - Chinese Academy Of Sciences; HE, HONGBO - Chinese Academy Of Sciences; FENG, WENTING - Chinese Academy Of Agricultural Sciences; NDZANA, GEORGES - Chinese Academy Of Agricultural Sciences; CHENU, CLAIRE - Agro Paris Tech; Olk, Daniel - Dan; MAO, JINGDONG - Old Dominion University; BIN, ZHANG - Chinese Academy Of Agricultural Sciences

Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2022
Publication Date: 4/15/2022
Citation: Yuzhi, X., Liu, K., Yao, S., Zhang, Y., Zhang, X., He, H., Feng, W., Ndzana, G.M., Chenu, C., Olk, D.C., Mao, J., Bin, Z. 2022. Formation efficiency of soil organic matter from plant litter is governed by clay mineral type more than plant litter quality. Geoderma. 412. Article e115727. https://doi.org/10.1016/j.geoderma.2022.115727.
DOI: https://doi.org/10.1016/j.geoderma.2022.115727

Interpretive Summary: The organic part of soil, the soil organic matter, plays several important roles in soil performance and aquatic ecology. However, we do not fully understand the factors of its formation and preservation. In agricultural soils, soil organic matter forms largely from crop materials that are incorporated into soil after harvest. Portions of soil organic matter cycle over weeks to months, while other portions can be stable for centuries. We do not fully understand how soil properties, including clay minerals, affect the distribution of newly forming soil organic matter into quickly cycling portions or instead into stable portions. Here we demonstrate that common clay minerals affected the amount and composition of newly forming soil organic matter. This information can help explain why the soil organic matter content of different soils responds variably to management practices. It may also prove useful for predicting organic matter responses of different soils to altered management practices, including their cycling rates. This information is useful to scientists who study the preservation of soil organic matter and to land managers who wish to increase soil retention of organic matter.

Technical Abstract: Soil organic matter (SOM) contributes to fundamental processes in the soil ecosystem. Much SOM forms when decomposition products of plant litter inputs become closely associated with soil minerals. Yet, a mechanistic understanding of mineral-organic association (MOA) is still lacking, and no SOM models adequately predict SOM formation and cycling by soil type or clay mineralogy. Here, we demonstrate controls of clay mineral types over the formation efficiency and chemical nature of mineral-associated soil organic matter (MASOM) following 120-day decomposition of two plant litter types. We developed a new decomposition model to estimate MOA strength and demonstrate that the MOA strength of a mineral soil was predictable from its clay mineral composition for either plant litter type. Labile litter components and fungal residues were associated with montmorillonite through surface coating, while recalcitrant litter components and bacterial residues were associated with kaolinite and illite. We conclude that MASOM forms at both its formation and stabilization stages. The availabilities of labile and recalcitrant litter components and also clay minerals determine the occurrence of MASOM at the early formation stage, while the relative dominance between two mechanisms of MOA and the MOA strength for individual clay mineral types direct the preferential associations of litter-derived and microbial residues at the stabilization stage.