Soil degradation regulates the effects of litter decomposition on soil microbial nutrient limitation: Evidence from soil enzymatic activity and stoichiometry

Abstract

Soil microorganisms could obtain energy and nutrients during litter decomposition with the help of soil extracellular enzymes. The litter types were among the most critical factors that affect soil extracellular enzyme activities. However, how litter types modulate the soil extracellular enzyme activity with grassland gradation is unclear. Here, we conducted a 240-day experiment of two different types of litter decomposition on soil extracellular enzyme activity and stoichiometry in different degraded grasslands. We found that C-acquiring enzyme activity and the enzyme stoichiometry of C/N were higher in Chloris virgata litter than in Leymus chinensis litter at lightly degraded level and C-acquiring enzyme activity in C. virgata was 16.96% higher than in L. chinensis. P-acquiring enzyme activity had the same trend with litter types in moderately and highly degraded levels and it was 20.71% and 30.89% higher in C. virgata than that in L. chinensis, respectively. The change of the enzyme stoichiometry with litter types was only showed in the enzyme stoichiometry of C/N at lightly degraded level, suggesting that litter types only affected the microbial C limitation in lightly degraded grassland. Almost all soil extracellular enzyme activities and extracellular enzyme stoichiometry, except the enzyme stoichiometry of N/P, decreased with grassland degraded level increasing. All vector angles were less than 45° suggesting that soil microorganisms were limited by N rather than by P during the decomposition process. Enzyme vector analysis revealed that soil microbial communities were co-limited by C and N during litter decomposition. Moreover, based on Random Forest (explaining more than 80%), we found that soil total nitrogen, total carbon, total phosphorus, dissolved organic C, pH and EC were important factors affecting soil enzyme activities by degradation levels. Our results emphasized that degradation levels could modulate the influences of litter types on soil extracellular enzyme activity. Our study enhanced our understanding in resource requirements for microbial communities to litter resources in degraded grassland and helped us to provide new ideas for improving degraded grassland ecosystems.

Land Use Change from Natural Tropical Forests to Managed Ecosystems Reduces Gross Nitrogen Production Rates and Increases the Soil Microbial Nitrogen Limitation

“…In our study, the Vector-TER model results showed that the tropical soils were N-limited, which was intensified after converting the natural forest to the managed ecosystems (Figure b and Figure S3). Moreover, the Vector-TER revealed that the tropical soils were generally C-limited, as most ecosystems. , Based on our results and the comparison of different nutrient limitation models, we recommend the Vector-TER model as an indirect measure for assessing nutrient limitations in tropical soils. However, nutrient limitation prediction based on enzymatic theory still needs to be used with caution.…”

“…Moreover, the Vector-TER revealed that the tropical soils were generally C-limited, as most ecosystems. 93,94 Based on our results and the comparison of different nutrient limitation models, we recommend the Vector-TER model as an indirect measure for assessing nutrient limitations in tropical soils. However, nutrient limitation prediction based on enzymatic theory still needs to be used with caution.…”

Effects of different botanical oil meal mixed with cow manure organic fertilizers on soil microbial community and function and tobacco yield and quality

“…The activity mainly derived from the secretions of soil animals, plants, and microorganisms as well as the decomposition of various residues. To some extent, soil enzyme activity participate in the occurrence and development of soil and the formation and evolution of soil fertility ( Li et al, 2023 ). Yang et al (2022) found that deep tillage accompanied by the application of organic fertilizer increased the activities of sucrase, cellulase, and urease in wheat fields; furthermore, Liu et al showed that the application of organic fertilizer, chemical fertilizer (nitrogen fertilizer), and organic fertilizer combined with chemical fertilizer increased the activities of sucrase in soil by 124.1, 80.9, and 145.6%, respectively, while urease and alkaline phosphatase were also increased to varying degrees ( Liu et al, 2021 ).…”

Effect of forest planting patterns on the formation of soil organic carbon during litter lignocellulose degradation from a microbial perspective

“…Lignocellulose-degrading enzymes are encoded by diverse lignocellulose-degrading genes, which act in synergistic action to degrade lignocellulose (Wang et al, 2022 ; Li et al, 2023 ). Litter substrate composition was the most critical factor affecting the variations in soil extracellular enzymes, functional genes, and microbial community composition, resulting in differences in lignocellulose-degrading products and SOC formation (Wang W. et al, 2020 ; Li et al, 2023 ).…”

“…Lignocellulose-degrading enzymes are encoded by diverse lignocellulose-degrading genes, which act in synergistic action to degrade lignocellulose (Wang et al, 2022 ; Li et al, 2023 ). Litter substrate composition was the most critical factor affecting the variations in soil extracellular enzymes, functional genes, and microbial community composition, resulting in differences in lignocellulose-degrading products and SOC formation (Wang W. et al, 2020 ; Li et al, 2023 ). The relative abundance of cellulose-degrading genes and hemicellulose-degrading genes (GHs and PLs family genes) in BP forest litter was the highest, whereas the relative abundance of lignin-degrading genes (AAs family genes) in CP forest litter was the highest ( Figure 2 ).…”