Appropriate N addition improves soil aggregate stability through AMF and glomalin‐related soil proteins in a semiarid agroecosystem

Abstract

Soil aggregation and structural stability play a crucial role in soil organic carbon (SOC) sequestration. However, the underlying mechanisms of arbuscular mycorrhizal fungi (AMF) and glomalin-related soil protein (GRSP) responses to N addition and their impacts on soil aggregation and organic carbon stability remain unclear. Hence, a 16-year field N addition experiment on winter wheat (Triticum aestivum L.) was conducted to investigate the effects on the stability of soil structure and SOC fractions via AMF and GRSP. Overall, N addition increased the soil aggregate mean weight diameter (MWD), which exhibited an increase in the proportion of large macroaggregates and a decrease in the proportion of silt-clay fractions. Appropriate N (180 kg N ha À1 ) input increased SOC stability and total SOC stock, while excessive N (360 kg N ha À1 ) input increased labile organic carbon fractions, and active C index and decreased the C stock. The concentrations of SOC, total GRSP (T-GRSP), and easily extractable GRSP (EE-GRSP) showed the largest increases in small macroaggregates, and GRSP was significantly correlated with SOC, recalcitrant organic carbon, and MWD (p < 0.05). These results indicated that appropriate N addition promoted AMF to secrete GRSP, which in turn favoured large macroaggregation and enhanced the physical protection of SOC. Meanwhile, the increased GRSP stimulated the accumulation of recalcitrant C, thus improving soil organic carbon stability and carbon sequestration capacity. The study suggested that appropriate N addition (180 kg N ha À1 ) should be used to improve the carbon sequestration potential of farmland on the Loess Plateau.

Effects of Natural Succession and Forest Landscape Restoration on Soil C and Aggregate-Associated C in the Central Loess Plateau, China

“…Numerous studies have demonstrated a significant increase in the proportion of macroaggregates after vegetation restoration (Wilpiszeski et al 2019; Rong et al 2020; Dong et al 2022a). This occurs because tillage practices break down soil aggregates and remove plant debris from the soil surface, thus inhibiting soil agglomeration (Zhang et al 2022). However, after restoring vegetation on cropland, human activities no longer destroy the soil structure, so large amounts of litter, root exudates, and dead root inputs are left untouched, which is conducive to the formation of macroaggregates (Six et al 2001; Six et al 2004; Wilpiszeski et al 2019).…”

“…1). First, during tillage, the remaining crops were removed, resulting in no organic matter being added to the soil (Zhang et al 2022). However, large amounts of roots and litters were input after vegetation restoration (see Table 1).…”

“…2). Macroaggregates can provide physical protection of the C in the soil and reduce the mineralization of organic C by microorganisms (Zhang et al 2022; Liu et al 2023). Moreover, an increase in the proportion of macroaggregates also indicates an increase in soil structural stability, namely soil resistance to erosion, which reduces the loss of topsoil C due to migration (Zheng et al 2021; Dong et al 2022b).…”

Soil Management Practices to Enhance Carbon Sequestration Rates- A Review

“…Its inherent stability in the soil means that it does not decompose rapidly, thereby sequestering carbon directly. Additionally, biochar influences the soil's physical and chemical properties, improving soil aggregation and porosity, which indirectly supports the stabilization of additional SOC by enhancing the physical protection of soil organic matter and promoting conditions conducive to increased microbial activity [43]. Manure, derived from animal excreta, often combined with bedding materials, is a traditional soil amendment that supplies not only organic carbon but also nutrients, particularly nitrogen, phosphorus, and potassium.…”

Reducing mineral fertilizer use for sustainable agriculture: The influence of seed coating with arbuscular mycorrhizal fungal spores and Leifsonia bacteria on maize (Zea mays L.) and sorghum (Sorghum bicolor (L.) Moench) production

“…They are well known for assisting host plants with phosphorus uptake (Smith and Read, 2008;Lu et al, 2023), but can also provide other benefits such as protection from pathogens (Cardoso and Kuyper, 2006;Sharma et al, 2023), assistance with the uptake of other nutrients such as nitrogen and copper, and improved water relations (Smith and Read, 2008;Sene et al, 2010;Lu et al, 2023;Sharma et al, 2023). AMF hyphae also play a role in the formation and structural stability of soil aggregates (Zhang et al, 2023) and contribute to the composition of plant community structures (Chen et al, 2023). On the other hand, plant growth promoting rhizobacteria (PGPR), isolated as free-living soil bacteria from the use rhizosphere of plants, can help reduce mineral fertilizer and increase plant growth and yield (Swarnika et al, 2022;Bhanse et al, 2022;Dhawi, 2023).…”