The mineralization characteristics of organic carbon and particle composition analysis in reconstructed soil with different proportions of soft rock and sand

AbstractThe organic carbon mineralization process can reflect 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 theoretical basis for the theory of soil organic reconstruction. Based on the previous research, this paper mainly selected four typical treatments of 0:1 (CK), 1:5 (C1), 1:2 (C2) and 1:1 (C3), respectively, and analyzed the soil organic carbon mineralization process and particle composition by lye absorption method, laser particle size meter 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 CK treatment (P < 0.05). The organic carbon mineralization rate of each treatment accords with a logarithmic function throughout the culture period (P < 0.01), which can be divided into a rapid decline phase of 1-11 days and a steady decline phase of 11-30 days. The cumulative mineralization amount on the 11th day reached 54.96%-74.44% of the total mineralization amount. At the end of the culture, the cumulative mineralization and potential mineralizable organic carbon content of C1 and C2 treatments were significantly higher than those of CK treatment, and the cumulative mineralization rate was also the lowest with C1 and C2 treatment. The turnover rate constant of soil organic carbon in each treatment was significantly lower than that of CK treatment, and the residence time increased. With the increase of volume fraction of soft rock, the content of silt and clay particles increases gradually, the texture of soil changes from sandy soil to sandy loam, loam and silty loam, and because of the increase of small particles, the structure of soil appears to collapse when the volume ratio of soft rock was 50%. In summary, the ratio of soft rock to sand volume was 1:5-1: 2, which can effectively increased the accumulation of soil organic carbon. At this time, the distribution of soil particles was more uniform, the soil structure was stable, and the mineralization level of unit organic carbon was lower. The research results have practical significance for the large area popularization of soft rock and sand compound technology.

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The mineralization characteristics of organic carbon and particle composition analysis in reconstructed soil with different proportions of soft rock and sand

PeerJ ◽

10.7717/peerj.7707 ◽

2019 ◽

Vol 7 ◽

pp. e7707 ◽

Cited By ~ 1

Author(s):

Zhen Guo ◽

Jichang Han ◽

Yan Xu ◽

Yangjie Lu ◽

Chendi Shi ◽

...

Keyword(s):

Organic Carbon ◽

Soil Structure ◽

Carbon Mineralization ◽

Soft Rock ◽

Composition Analysis ◽

Organic Carbon Content ◽

Mineralization Process ◽

Particle Composition ◽

Decline Phase ◽

Organic Carbon Mineralization

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.

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Response of organic carbon mineralization and bacterial communities to soft rock additions in sandy soils

PeerJ ◽

10.7717/peerj.8948 ◽

2020 ◽

Vol 8 ◽

pp. e8948 ◽

Cited By ~ 1

Author(s):

Zhen Guo ◽

Jichang Han ◽

Juan Li

Keyword(s):

Organic Carbon ◽

Sandy Soil ◽

High Throughput Sequencing ◽

Carbon Mineralization ◽

Soft Rock ◽

Available Phosphorus ◽

Organic Carbon Content ◽

K Value ◽

Organic Carbon Mineralization ◽

Richness Index

Bacteria play a vital role in biotransformation of soil organic carbon (SOC). However, mechanisms of bacterium and organic carbon mineralization remain unclear during improvement of sandy soil using soft rock additions. In this study, four treatments with differing ratios of soft rock to sand of 0:1 (CK), 1:5 (C1), 1:2 (C2) and 1:1 (C3) were selected for mineralization incubation and high-throughput sequencing. The results showed that SOC, total nitrogen (TN), available phosphorus (AP), nitrate nitrogen (NO${}_{3}^{-}$-N), and mass water content (WC) of sandy soil increased significantly after addition of soft rock (P < 0.05). Compared with the CK treatment, cumulative mineralization and potential mineralized organic carbon content of C1, C2 and C3 increased by 71.79%–183.86% and 71.08%–173.33%. The cumulative mineralization rates of organic carbon treated with C1 and C2 were lower, 16.96% and 17.78%, respectively (P > 0.05). The three dominant bacteria were Actinobacteria, Proteobacteria and Chloroflexi, among which Proteobacteria was negatively correlated with mineralization of organic carbon (P < 0.01). The mineralization rate constant (k) was positively correlated and negatively correlated with Cyanobacteria and Nitrospirae, respectively. Under C2 treatment, Proteobacteria and Nitrospirae had the largest increase, and Cyanobacteria had the largest decrease. Compared with other treatments, C2 treatment significantly increased bacterial diversity index, richness index and evenness index, and the richness index had a negative correlation with k value. In conclusion, when the ratio of soft rock to sand was 1:2, the k of SOC could be reduced. In addition, the retention time of SOC can be increased, and resulting carbon fixation was improved.

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