Soil Enzyme Activity and Stoichiometry: Linking Soil Microorganism Resource Requirement and Legume Carbon Rhizodeposition

Abstract

Legumes provide multiple ecosystem services in agricultural systems. The objectives of this study were to evaluate the influence of different legumes through C rhizodeposition on the dynamics of C, N and P in soil and on microbial communities’ resource requirements. Legumes pea (Pisum sativum L.), faba bean (Vicia faba L.), white clover (Trifolium repens L.), crimson clover (Trifolium incarnatum L.) and non-legume wheat (Triticum aestivum L.) were grown in pots. Carbon rhizodeposition was quantified by using 13CO2 labeling, and six soil enzyme activities were measured: β-glucosidase (BG), arylamidase (ARYLN), N-acetyl-glucosaminidase (NAG), phosphatases (PHO) and alkaline and acid phosphatases (AKP and ACP). Enzyme stoichiometry approaches were applied. The results showed that BG, NAG and ACP activities were positively influenced by faba bean and clovers. Enzyme stoichiometry analysis revealed a limitation of microorganisms in C and P resources at the plant reproductive stage. These results were explained by plant functional traits. Plant biomass production, root total length, the ability of plants to rhizodeposit C and the C and N content of plant tissues were the main explicative factors. This study also shows that N and C nutrient supplies positively contribute to nutritional requirements and the growth of microorganisms and P availability in soil.

An evaluation of nitrogen indicators for soil health in long‐term agricultural experiments

“…That SOC and TN are strongly correlated should not come as a surprise as there are extensive global datasets demonstrating this relationship (Xu, Thornton et al., 2013). While BG and NAG activity are suggested to be more related to C and N acquisition, respectively, and respond to different drivers of substrate availability, they are typically correlated when examined across multiple sites (Waring et al., 2014) or when management within a site varies (Kanté et al., 2021). Much less is known about WEOC and WEON in cropland soils across sites, but the limited evidence suggests they are correlated (R. Haney et al., 2012).…”

Rhizodeposition through root senescence and root exudation of atmospheric C and N by legumes is controlled by traits indicative of resource acquisition and root development

“…Pasture plants are described to allocate more of their assimilated C to the below-ground, especially to store reserves for regrowth, compared to field crops, which export to the above-ground organs (Grayston et al, 1997;Kuzyakov & Domanski, 2000;Pausch & Kuzyakov, 2018). The high amounts of soluble C observed for both clover species during reproductive growth may also have contributed to this high rhizodeposition of C. We have recently shown that this large rhizodeposition by forage species may stimulate soil microbial communities (Kanté et al, 2021). The allocation of biologically fixed N to the below-ground compartment varied strongly from 11% for crimson clover to 24% for white clover.…”

“…This process has been found to induce an acceleration of mineralization of native soil organic matter (SOM) by stimulating microbial activity, a phenomenon called the rhizosphere priming effect (Cheng, 2009; Cheng et al, 2014). This increases the availability of mineral nutrients such as N and P for plant growth (Henneron, Cros, et al, 2020; Henneron, Kardol, et al, 2020; Kanté et al, 2021; Paterson, 2003; Paterson et al, 2007). Legumes induce high rhizosphere priming, even if substantial variation between species can be observed (Henneron, Kardol, et al, 2020).…”

Visual evaluation of soil structure is a reliable method to detect changes in the soil quality of Colombian Amazon pasturelands

“…These indicators are widely utilized to assess the soil's capacity to support and sustain plant growth (Lardy et al, 2022;Rabot et al, 2018 to their sensitive response to environmental changes. While SOC is a primary energy source for soil microorganisms and plays an important role in soil aggregation (Gayan et al, 2023;Hoffland et al, 2020), GMea reflects the efficiency of soil enzymes involved in nutrient cycling (Kanté et al, 2021;Kaur & Singh, 2021;Silva-Olaya, Mora-Motta, et al, 2021).…”