Spatial variability of soil carbon to nitrogen ratio and its driving factors in Ili River valley, Xinjiang, Northwest China

Abstract

Soil carbon to nitrogen (C/N) ratio is one of the most important variables reflecting soil quality and ecological function, and an indicator for assessing carbon and nitrogen nutrition balance of soils. Its variation reflects the carbon and nitrogen cycling of soils. In order to explore the spatial variability of soil C/N ratio and its controlling factors of the Ili River valley in Xinjiang Uygur Autonomous Region, Northwest China, the traditional statistical methods, including correlation analysis, geostatistic alanalys and multiple regression analysis were used. The statistical results showed that the soil C/N ratio varied from 7.00 to 23.11, with a mean value of 10.92, and the coefficient of variation was 31.3%. Correlation analysis showed that longitude, altitude, precipitation, soil water, organic carbon, and total nitrogen were positively correlated with the soil C/N ratio (P < 0.01), whereas negative correlations were found between the soil C/N ratio and latitude, temperature, soil bulk density and soil pH. Ordinary Cokriging interpolation showed that r and ME were 0.73 and 0.57, respectively, indicating that the prediction accuracy was high. The spatial autocorrelation of the soil C/N ratio was 6.4 km, and the nugget effect of the soil C/N ratio was 10% with a patchy distribution, in which the area with high value (12.00-20.41) accounted for 22.6% of the total area. Land uses changed the soil C/N ratio with the order of cultivated land > grass land > forest land > garden. Multiple regression analysis showed that geographical and climatic factors, and soil physical and chemical properties could independently explain 26.8%and 55.4% of the spatial features of soil C/N ratio, while human activities could independently explain 5.4% of the spatial features only. The spatial distribution of soil C/N ratio in the study has important reference value for managing soil carbon and nitrogen, and for improving ecological function to similar regions.

Microenvironment heterogeneity affected by anthropogenic wildfire-perturbed soil mediates bacterial community in Pinus tabulaeformis forests

“…Even modest increases in soil pH, which often result from the deposition of ash, can enhance microbial activity. This leads to increased decomposition rates of organic matter, reducing the C/N ratio by promoting the mineralization of organic carbon and nitrogen into more readily available inorganic forms ( Sun et al, 2017 ). Other researchers observed similar patterns, noting that higher pH levels, even within a neutral to slightly acidic range, can lead to a decrease in the C/N ratio due to the enhanced breakdown of organic materials ( Tahmasbian et al, 2019 ; Zema and Lucas-Borja, 2023 ).…”

How are C, N, and P Distributed in Soils of the Caatinga Dryforest?

“…The C/N ratio re ects the quality and ecological function of the soil, being an important indicator of the nutritional balance of carbon and nitrogen in soils [73,74]. Its variation is directly linked to the cycling of these elements in the soil [74] and is generally inversely proportional to the decomposition rate of organic matter [75]. Furthermore, the C/N ratio is one of the main factors for variations in the composition of the soil microbial community [72,76].…”

Exploring the optimal sampling density to characterize spatial heterogeneity of soil carbon stocks in a Karst Region

“…Under large-scale sampling conditions, small-scale structural characteristics will be obscured and many details will be omitted, which will hinder the in-depth analysis of the structural characteristics of spatial variability; small-scale sampling is labor intensive and requires considerable material and financial resources (Kerry & Oliver, 2007). In addition, if the sampling distance is too small, the large-scale variability will be neglected as "random variation" due to its weakness or deducted through dimensionality reduction, and the research will be conducted from a local point of view rather than from the overall point of view (Wei, Xiao, Zhang, Li, & Li, 2006). As for the spatial variability in soil properties, large-scale spatial variability is generally related to regional environmental elements (such as soil quality, soil parent material, topography, and climate), whereas small-scale spatial variability is, in general, closely related to human factors (such as land use type and agricultural production measures) (Liu, Chang, Qi, Liu, & Chen, 2014).…”