Abstract
The organic carbon mineralization process reflects the release intensity of soil CO2. Therefore, the study of organic carbon mineralization and particle composition analysis of soft rock and sand compound soil can provide technical support and a theoretical basis for soil organic reconstruction (soil structure, materials and biological nutrition). Based on previous research, four treatments were selected: CK (soft rock:sand=0:1), C1 (soft rock:sand=1:5), C2 (soft rock:sand=1:2) and C3 (soft rock:sand=1:1), respectively. Specifically, we analyzed the organic carbon mineralization process and soil particle composition by lye absorption, laser granulometer, and scanning electron microscope. The results showed that there was no significant difference in organic carbon content between C1, C2 , and C3 treatments, but they were significantly higher than in the CK treatment (P < 0.05). The organic carbon mineralization rate in each treatment accords with a logarithmic function throughout the incubation period (P < 0.01), which can be divided into a rapid decline phase in days 1 to 11 followed by a steady decline phase in days 11 to 30. The cumulative mineralization on the 11th day reached 54.96%–74.44% of the total mineralization amount. At the end of the incubation, the cumulative mineralization and potential mineralizable organic carbon content of the C1, C2 and C3 treatments were significantly higher than those of the CK treatment. The cumulative mineralization rate was also the lowest in the C1 and C2 treatment. The turnover rate constant of soil organic carbon in each treatment was significantly lower than that of the CK treatment, and the residence time increased. With the increase of volume fraction of soft rock, the content of silt and clay particles increased gradually, the texture of soil changed from sandy soil to sandy loam, loam , and silty loam, respectively. With the increase of small particles, the structure of soil appear ed to collapse when the volume ratio of soft rock was 50%. A comprehensive mineralization index and scanning electron microscopy analysis, when the ratio of soft rock to sand volume was 1:5–1:2, this can effectively increase the accumulation of soil organic carbon. Then, the distribution of soil particles was more uniform, the soil structure was stable (not collapsed), and the mineralization level of unit organic carbon was lower. Our research results have practical significance for the large area popularization of soft rock and sand compound technology.
Highlights
The farmland soil organic carbon pool plays an important role in the process of global carbon circulation and as the most important material base for soil fertility [1], and has a decisive role in the maintenance of cultivated land productivity, the prevention and treatment of soil erosion, the spatial and temporal variation of soil respiration and its stability, etc [2]
There were a large number of active organic substances such as sugars and proteins which were decomposed in the soil, which provided abundant carbon sources and nutrients for soil microorganisms and promote microbial activity
Kemmitt et al [21] studied the mineralization process of a small number of microorganisms and found that after fumigation with chloroform reduced the number of microorganisms by 90%, the mineralization rate of organic carbon among all treatments had no significant difference compared with the control treatment
Summary
The farmland soil organic carbon pool plays an important role in the process of global carbon circulation and as the most important material base for soil fertility [1], and has a decisive role in the maintenance of cultivated land productivity, the prevention and treatment of soil erosion, the spatial and temporal variation of soil respiration and its stability, etc [2]. Soil organic carbon mineralization is an important part of the carbon cycle in terrestrial ecosystems. The change of land resources caused by human activities often cause changes in atmospheric CO2 concentration through the effects on terrestrial ecosystems, which in turn affects the carbon cycle and the climate change process [4]. Soil organic carbon mineralization is a process in which organic substances are decomposed into inorganic substances under the action of microbial degradation, providing nutrient content for crop growth and releasing greenhouse gases such as CO2 to the outside world [5]. Studies have shown that arid and semi-arid regions account for 41% of the global land area, carrying 38% of the population and are sensitive to global climate change and human activities [6]. Han et al [8] studied the structure and physicochemical properties of sandstone and sand, and analyzed that the two resources can be mixed into different proportions to form “new soil”, and suggested that the optimum proportion of crops suitable for planting was range between
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
