Search

[Objective] Soil organic carbon (SOC) is not only an indicator of soil health but also plays a crucial role in feedback interaction between global warming and carbon stock in terrestrial ecosystems. Its dynamics is modulated by a multitude of interactive abiotic and biotic factors. In this paper, we analyze the spatial distribution of SOC in the plough layer and its correlation with soil texture and other geochemical properties in the region of Zhengzhou in Henan province. [Method] Soil samples were taken from a grid network in the region. SOC, bulk density, soil texture and other geochemical properties in each soil sample were measured. The correlation between SOC and soil nutrients, including nitrogen, phosphorus, potassium and micronutrients in the soil, was analyzed using the GeoChemStudio software. [Result] The calcareous skeletol soil in the region has the highest SOC, reaching 2.307%. The SOC content varied from 0.1%-11.6% across the region, and was normally distributed with a mean of 1.134%. The SOC was positively correlated with N, P2O5, Fe, Mn, Zn, Cu, Mo and B, and their associated correlation coefficients were 0.804 5, 0.223 0, 0.156 3, 0.119 1, 0.223 8, 0.263 4, 0.162 8 and 0.191 1, respectively. Negative correlations were found between SOC and K2O and pH, and their associated correlation coefficients were -0.088 8 and -0.195 7, respectively. The average SOC content in the plough layer in the region was 1.09%. Spatially, SOC was rich in Xinmi, Dengfeng and Gongyi in the southwest of the region. In terms of soil texture, SOC is higher in skeletol soil and calcareous cinnamon soil than in other soils. SOC stored in the topsoil in the whole region was 1 012.87x104 t, with 523.13x104 t stored in the cinnamon soils and calcareous cinnamon soils, accounting for 51.64% of the total topsoil SOC in the region. [ABSTRACT FROM AUTHOR]

Due to the scarcity of biological resources, desert areas are unable to achieve long-term carbon sequestration. Biological crust is a pioneer organism in desert areas and plays an important role in long-term carbon sequestration. However, the development of natural biological crust is slow. Clay plays an important role in the formation and development of biological crusts, and has a strong protective effect on soil organic carbon. Therefore, this paper explores the impact and mechanism of adding kaolin on the organic carbon of soil biological crust system, aiming to provide new solutions for the long-term carbon sink in desert areas. Through testing particle size, specific surface area and pore volume, chlorophyll a, chlorophyll fluorescence, microbial community, and soil organic carbon (SOC), it has been found that the addition of kaolin changed the physicochemical properties and microbial community structure of the system, promoted the growth of biochar, and strengthened the protective effect of the system on SOC. After 112 days of cultivation, the results show that the accumulation of SOC in the kaolin-based biological crust system increases to 145% of the algae inoculation group. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to study the effects of exogenous straw carbon addition on the organic carbon composition and rice growth characteristics of calcareous paddy soil in karst area, providing reference basis for exploring the changes in carbon composition of alcareous paddy soil in karst areas. 【Method】The rice pot experiment was carried out in the greenhouse of Yanshan Campus of Guilin University of Technology in March 2023, and the experiment period was 120 d. A total of 19 treatments were set up in the pot experiment. In the treatment that only added straw carbon, 0.5%, 1.0% and 3.0% （dry soil mass ratio） crushed straw, straw compost and straw biochar were added, respectively. In the treatment of adding straw carbon and calcium carbonate, the carbon content of the three kinds of straw was 1.0%, and on this basis, 0, 10.0% and 20.0% （dry soil mass ratio） calcium carbonate were added, respectively. At the same time, the control （CK） treatment without adding any substances was set up. The growth characteristics of rice and the changes of soil organic carbon components microbial biomass carbon （MBC), dissolved organic carbon （DOC), granular organic carbon （POC） and their influencing factors were analyzed.【Result】The type and amount of straw carbon had an impact on the content of organic carbon components in the soil. Adding 0.5% straw compost resulted in the highest MBC content in soil （235.73 mg/kg), while adding 1.0% straw compost resulted in the highest DOC content in soil （221.50 mg/kg). The soil treated with 3.0% straw biochar had the highest POC content （36.20 mg/kg). The content of calcium carbonate in soil also affected the composition of soil organic carbon. When the content of calcium carbonate was 20.0%, the soil MBC contents in the treatments adding three straw carbons were the highest. The soil with 10.0% calcium carbonate+1.0% straw compost had the highest DOC content （195.60 mg/kg). The effects of adding three kinds of straw carbon on the growth of rice were as follows: straw biochar ＞ straw compost ＞ broken straw. Among them, the rice with 0.5% straw biochar added had the best growth, with an average plant height of 102 cm and root length of 50 cm. Addition 3.0% crushed straw had the strongest inhibitory effect on rice growth. With the increase of calcium carbonate addition, the rice plant height treated by straw compost increased first and then decreased, and the addition of 10.0% calcium carbonate had a stronger effect on plant height. The correlation analysis results showed that the amount of straw biochar was significantly negatively correlated with soil DOC content （P ＜ 0.05, the same below), and extremely significantly positively correlated with soil POC content （P ＜ 0.01). There was a significant positive correlation between calcium carbonate addition and soil DOC content.【Conclusion】Exogenous straw carbon has a positive excitation effect on the active organic carbon components in calcareous paddy soil, which can greatly increase the contents of MBC, DOC and POC in soil, and the addition of straw carbon and calcium carbonate has a synergistic effect on the increase of soil active carbon components. Adding low amount of straw carbon can promote rice growth, and straw biochar has the most obvious promoting effect. Adding straw compost and straw biochar to soils with 10.0% and 20.0% calcium carbonate concentrations can promote rice growth [ABSTRACT FROM AUTHOR]