Soil Region Of China Research Articles

Effect of Long-Term Fertilization Practices on the Stability of Soil Organic Matter in the Northeast Black Soil Region in China

Soil organic matter (SOM) is an important carbon pool in terrestrial ecosystems and plays a key role in soil functions. Nevertheless, the effects of fertilization practices on the physical, chemical, biological, and comprehensive stability of SOM are still unclear. We carried out a long-term field experiment in the northeast black soil region in China with four different fertilization practices: no fertilizer (CK), single chemical fertilizer (NPK), chemical fertilizer + straw (NPKJ), and chemical fertilizer + organic manure (NPKM). The content of particulate organic matter (POM) and mineral-associated organic matter (MAOM), compound composition of SOM, carbon mineralization characteristics, active soil organic matter (ASOM), and inert soil organic matter (ISOM) were tested. The results showed that the application of fertilizers significantly increased the contents of POM and MAOM to 2.59–4.65 g kg−1 and 32.69–34.65 g kg−1 (p < 0.05), but decreased the MAOM/POM values by 37.8–42.4%, indicating reduced the physical stability of SOM. Fertilization practices increased the contents of aromatic, nitrogen-containing compounds and decreased the oxygen compounds of SOM, representing enhancement of the chemical stability. The contents of ASOM and ISOM increased in fertilization practices, while the biological stability index (BSI) under the NPKJ and NPKM treatments was lower than the CK treatment, suggesting that the biological stability decreased under the manure and straw application. In addition, the comprehensive stability of SOM increased by 26–116% through a reduction in the physical and biological stability, coupled with an increase in the chemical stability. Collectively, our study demonstrated that the application of manure and straw enhanced both the comprehensive stability and content of SOM and reduced the physical and biological stabilities while increasing the chemical stability, which made the largest contribution to the comprehensive stability.

Pesticides trapping performance of vegetative filter strips in black soil region, Northeast China: controlled experiments and VFSMOD-W modeling

The Northeast black soil region in China is an important grain-producing area where various pesticides are extensively used to increase grain yields. However, this practice poses serious risks to the ecological health of soil and water systems, necessitating effective measures. Vegetative filter strips (VFS) are commonly used to mitigate agricultural diffuse pollutants, but their efficiency varies across different regions, requiring assessment. This study employed flume experiments, the VFSMOD-W model, and redundancy analysis (RDA) to evaluate the efficacy of VFS in runoff, sediment, and pesticide removal, as well as influencing factors. The results showed that VFS reduced outflow rate of runoff by 8 %–64 % and sediment by approximately 90 %, achieving load removal rates of 61 % and 95 % respectively. Pesticide load removal efficiency ranged from 37 % to 94 %, with higher efficiency for adsorbed pesticides like chlorpyrifos compared to water-soluble ones like atrazine. Interflow and vertical seepage were significant pathways for pesticide transport in VFS, with chlorpyrifos concentrations at 4 %–26 % and atrazine at 20 %–37 % of inflow concentrations. The VFSMOD-W model accurately predicted VFS efficiency (NSE > 0.90), and RDA results indicated that environmental factors could explain 86.7 % of the variation in VFS performance, with soil vertical saturated hydraulic conductivity (VKS) being the most influential factor, followed by rainfall intensity (T), saturated soil water content (OS), initial soil water content (OI), and filter slope for each segment (SOA). Optimizing soil moisture characteristic factors and increasing infiltration are crucial for VFS performance. Applying VFSMOD-W for precise VFS design can help reduce construction costs. In the future, long-term field monitoring and evaluation of VFS efficiency after implementation should be conducted in the black soil region of Northeast China to provide data supporting the improvement of VFSMOD-W simulation accuracy. This will also offer recommendations for the government in formulating VFS configuration schemes.

Spatial distribution and ecological-health risks associated with herbicides in soils and crop kernels of the black soil region in China

Herbicides are vital inputs for food production; however, their associated risks and hazards are pressing concerns. In black soil, the cumulative toxic effects of compound herbicides and potential risks to humans are not yet fully understood. Thus, this study conducted a comprehensive investigation to assess herbicide residue characteristics and the associated ecological health risks in representative black soil regions where major food crops (maize, soybean, and rice) are cultivated. Findings revealed that the soil harbored a collective presence of 29 herbicides, exhibiting total concentrations ranging from 111.92 to 996.14 μg/kg dry weight (dw). This can be attributed to the extensive use of herbicides over the years and their long half-lives, which results in the accumulation of multiple herbicide residues in the soil. Similarly, the total herbicide levels in maize, soybean, and rice kernels were 1173–61,564, 1721–9342, and 3775–8094 ng/kg dw, respectively. Multiple herbicide residues at all monitored sites were attributed to continuous crop barriers in soybean fields and the adoption of soybean and maize crop rotations. Notably, herbicides pose ecological risks in the black soil region, exhibiting high-risk levels of 79 %, 24 %, and 14 % at the sites monitored for oxyfluorfen, clomazone, and butachlor, respectively. Carcinogenic atrazine exhibited low- and medium-risk levels in 34 % and 63 % of soil samples, respectively. These results can serve as a scientific basis for establishing herbicide residue thresholds in agricultural soils within black soil areas and for implementing effective control measures to prevent herbicide contamination in agricultural ecosystems.

Responses of Soil Collembolans to Land Degradation in a Black Soil Region in China

Land degradation in black soil regions has a significant effect on belowground systems, and Collembolans can adequately indicate environmental changes in the soil. However, there is currently a knowledge gap in the literature regarding the responses of soil Collembolans to land degradation. In order to better understand this issue, in this study, a total of 180 soil Collembolan samples were collected from four habitats with varying degrees of land degradation in the Songnen Plain, namely a no land-degradation habitat (NLD), light land-degradation habitat (LLD), moderate land-degradation habitat (MLD) and severe land-degradation habitat (SLD). The results reveal that the different degrees of land degradation caused some differences in the taxonomic composition of the Collembolans; however, the majority of the Collembolan species are distributed relatively evenly. Proisotoma minima are always a dominant species during the study period. Seasonal variations are observed in the abundance, richness and diversity levels. In the severe land-degradation habitats (SLD), the abundance, richness, diversity and community complexity of the Collembolans are aways at the lowest levels. In addition, Proisotoma minima is negatively correlated with a majority of the species of Collembolans in the low levels of the land-degradation habitats, whereas they are positively correlated with most of the other species in the high levels. Epedaphic and euedaphic Collembolans responded to land degradation more obviously. The structural equation model (SEM) displays that soil Collembolan communities respond negatively to land degradation. Overall, our results provide implications that soil Collembolan communities are affected by land degradation, and that different taxa of soil Collembolans respond to degradation in numerous ways.

Does the Agricultural Productive Service Embedded Affect Farmers’ Family Economic Welfare Enhancement? An Empirical Analysis in Black Soil Region in China

The modernization of agriculture in China has begun to take shape, but some groups of farmers still have relatively weak access to welfare and live in poverty, which is closely related to national food security and sustainable agricultural development. Based on survey data from northeastern China, this study analyzes the logical framework of “Agricultural Productive Services (APS) Embedded—Farmers’ Family Economic Welfare Enhancement” by the endogenous switching regression model. The main findings are as follows. First, the purchase of APS brings a significant positive impact on farmers’ family economic welfare improvement, mainly through the income effect and the substitution effect. Second, with the income effect, there are significant differences in the strength of the “pulling power” of different forms of APS for farmers’ family economic welfare. Compared with farmers who purchase APS for the entire production chain, farmers who purchase only some of the services are more likely to increase their welfare in the later stages. Third, with the substitution effect, the re-employment behavior of the rural surplus laborers who are “squeezed out” under the embedding of APS is promoted, which makes farmers’ income channels, income types, and income opportunities diversify, and their welfare will be more obviously strengthened after purchasing services. In order to enhance farmers’ welfare more efficiently and meet their needs for a better life, this study suggests a combination of farmer information archiving and labor market information transparency to reduce service risks, expand employment channels, and enhance the effectiveness of the linkage between farmers and service providers.

Remote estimates of soil organic carbon using multi-temporal synthetic images and the probability hybrid model

Soil organic carbon (SOC) plays a key role in soil function, ecosystem services, and the global carbon cycle. Digital SOC mapping is essential for agricultural production management. Digital SOC mapping based on multi-source remote sensing data has been integrated well into prediction models and methodological approaches on different mapping scales. However, the mixed use of synthetic images and the application of the hybrid model considering the soil classification probability are rare. Here, we propose a probability hybrid model to estimate and map SOC content and distribution. Multi-temporal synthetic images were used to build the probability hybrid model. One hundred forty topsoil samples were collected in Suihua, a city in a typical black soil region in China. Cloud-free Sentinel-2 images were acquired from the bare soil periods between 2018 and 2021. Minimum, maximum, mean, and median synthetic images were calculated using single images from the same period. The random forest and support vector machine models were used for discriminating soil class and calculating soil classification probability, and then random forest regression model was applied to SOC mapping. Soil class mapping and classification probability were performed for Phaeozems, Chernozems, and Cambisols of the World Reference Base for Soil Resources (WRB) based on soil texture, climatic factors, and the normalized differential vegetation index (NDVI). Based on soil class mapping results, global models using single temporal images and multi-temporal images, the hybrid model using multi-temporal images for the three soil classes as well as a probability hybrid model using multi-temporal images were built and compared their SOC predictions. Our study showed that (1) Phaeozems, Chernozems and Cambisols could be classified accurately, and the overall validation accuracy of random forest model was 91.67%. (2) The correlations of SOC with bands and band indices improved using multi-temporal images, and the use of mixed synthetic images was better than the use of only one synthetic image. (3) The hybrid model performed far better than the global models, and the probability hybrid model led to the highest prediction accuracy, a validation R2 of 0.77 and an RMSE of 2.30 g kg−1. (4) The probability hybrid model was more accurate than the original hybrid model for digital SOC mapping, and the SOC distribution in boundary regions was smoother and more continuous. Our results suggest that the probability hybrid model has a large potential for SOC prediction and mapping.

Study on the Influencing Factors of Farmers' Adoption of Conservation Tillage Technology in Black Soil Region in China: A Logistic-ISM Model Approach.

The adoption of conservation tillage technology can improve the production efficiency of black soils (mollisols), and it has great significance to ensure the sustainable development of agriculture. This paper takes farmers in the black soil region of Jilin Province as the research object, uses 442 survey data of farmers in seven municipal areas in the black soil region of Jilin Province, constructs a logistic-ISM model, first determines the influencing factors of farmers’ adoption of conservation tillage technology, and then analyzes the hierarchical structure of each influencing factor. The results show that: (1) among the eight significant influencing factors of farmers’ adoption of conservation tillage technology, age, whether they know the government’s subsidies for conservation tillage and the number of labor force are the deep-rooted factors; (2) Education level, whether you know that the government is promoting conservation tillage, and the planting area are intermediate level factors; (3) whether they have received the technical services of conservation tillage and whether the cultivated land is scattered is the direct factors. Based on the significance analysis of the influencing factors of farmers’ adoption of conservation tillage technology and the research on the action mechanism of the influencing factors of farmers’ adoption of conservation tillage technology, this paper puts forward policy suggestions to improve the extension system of conservation tillage technology, improve the implementation of land transfer and subsidy policies, strengthen the ability of rural socialized services, and strengthen the publicity of black soils protection.

Stability Satisfied Design and Construction of Excavated Soil Dumps in a Soft Soil Region in China

Dumping is the main disposal method of the excavated soil from underground engineering in China; however, due to a lack of construction experiences and technical standards, landslide disasters often occurred during rapid dumping of excavated soil in soft soil regions. In this paper, geotechnical tests were conducted on the excavated soil from a foundation engineering site in Hangzhou, where the excavated soil would be used to construct a piled mountain. On this basis, a numerical study was carried out to investigate the effects of the design parameters (heap height, slope gradient) and construction parameters (layer thickness, heap speed) on the dump stability and failure mode. The results show that the safety factor of the excavated soil dump decreases with increasing heap height, slope gradient, layer thickness, and heap speed. The potential slide surfaces are toe circle, and compared to layer thickness and heap speed, the heap height and slope gradient have more remarkable influence on the depth and area of potential slide mass. The heap height limit increases with a decrease in slope gradient, and the heap speed limit decreases with an increase in layer thickness. Under the premise of ensuring the slope stability, the optimal design and construction parameters were obtained, i.e., heap height 28 m, slope gradient 1:2.75, layer thickness 1.0 m, and heap speed 0.50 m/day. Compared to the original design scheme, the storage capacity increases by 20.01%, and the construction duration decreases by 30.25% in the optimal design.

Navel orange fine root nutrient content and rhizosphere effects varied with tree ages and soil depths in a hilly red soil region of China

ABSTRACT Root nutrients are required for the growth and development of roots and shoots, which are closely related to soil quality and fruit productivity. In this study, trees of contrasting stand ages, including young, middle-aged, and old trees, were selected in field sites with common management practices in the navel orange (Citrus sinensis) orchards of Southern China. The fine root N decreased with soil depth and the fine root P was higher of old trees (1.82 g kg-1) than young (1.57 g.kg-1) and middle-aged trees (1.37 g. kg-1). Soil organic C, total N, and P generally increased with plant age in the rhizosphere and bulk soils, while reverse trend was found for sucrase and urease activities. Interestingly, acid phosphatase activity was much higher at a lower depth (202 and 82 g.kg-1 OC d-1 for rhizosphere and bulk soils, respectively) than at an upper depth (46 and 43 g.kg-1 OC d-1 for rhizosphere and bulk soils, respectively). In conclusion, root and soil nutrients generally increased with plant growth. Fine root N decreased while fine root P remained unchanged with soil depth due to the content and rhizosphere effect of index at different soil layers related to N and P, respectively.

Effects of Rainfall-Induced Topsoil Structure Changes on Root-Zone Moisture Regime during the Dry Period

Rainfall erosion and subsequent intermittent drought are serious barriers for agricultural production in the subtropical red soil region of China. Although it is widely recognized that rainfall-induced soil structure degradation reduced soil water storage and water-holding capacity, the effects of variation of the rainfall-induced topsoil structure on the subsequent soil water regime during the dry period is still rarely considered. The objective of this study was to ascertain the way of rainfall-induced topsoil structure changes on the subsequent soil water regime during the dry period. In a three-year-long experiment, six practices (CK, only crop; SM, straw mulching; PAM, polyacrylamide surface application; B, contour Bahia-grass strip; SPAM, straw mulching and polyacrylamide surface application; and BPAM, contour Bahia-grass strip and polyacrylamide surface application) were conducted at an 8° farmland with planting summer maize resulting in different topsoil structure and root-zone moisture, to establish and reveal the quantitatively relationship between the factors of topsoil structure and soil drought. Rainfall erosion significantly increased the soil crust coverage, and decreased the WSA0.25, 0–30 mm soil porosity and mean pore size. There was no significant difference during the raining stage of root-zone water storage between CK and other practices. An index of soil drought intensity (I) and degree (D) was established using soil water loss rate and soil drought severity. The larger value of I means a higher rate of water loss. The larger value of D means more severe drought. During the dry period, I and D were significantly higher in CK than in other practices. I and D had significantly positively correlation with the crust size and crust coverage, and negatively with WSA0.25, 15–30 mm soil porosity and mean pore size. Among of soil structure factors, the soil porosity had the largest effect on I and D. The rainfall-induced topsoil structure changes greatly deteriorated the root-zone regime during the dry period mainly due to significant increasing soil water loss but little improving the raining stage of soil water storage. Straw mulching had greater effects than other practices in alleviating rainfall-induced erosion and intermittent drought, and could be a better strategy applied for this region.

Comparison of sampling schemes for the spatial prediction of soil organic matter in a typical black soil region in China

Data on the spatial distribution of soil organic matter (SOM) are important for the spatio-temporal modeling of soil organic carbon dynamics and soil carbon sequestration potential estimates. A total of 175 topsoil samples (0–20 cm) were collected from a typical black soil area in central Hailun County in northeastern China. Seven sampling design schemes, ordinary kriging (OK), and regression kriging (RK) were applied to the re-sampled SOM data for predicting the spatial distribution of SOM. The results showed that single sampling designs, such as simple random, stratified random (STR), and conditional Latin hypercube (CLH), produced poor estimates of SOM, while hybrid sampling designs, such as uniform distribution of point pairs for variogram estimation combined with spatial coverage, STR combined with spatial coverage (STRC), and CLH combined with spatial coverage (CLHC), had a higher predicting accuracy when the sample size was relatively small (≤262). For square grid sampling, a higher predicting accuracy could be achieved only when the sample size was sufficiently large (i.e., ≥402). The inclusion of prior knowledge or SOM-related secondary data in the sampling design and the trade-off between the even and uneven distribution of sampling points are especially important for designing a small-size sampling scheme. Moreover, although the SOM-predicting accuracy of RK was not as good as OK in this study, increasing the sample size may improve the predicting accuracy of SOM. Therefore, the optimal sampling design and spatial predicting method are both important for the predictive mapping of SOM spatial distribution in this area.

Response of soil nematode community structure and diversity to long‐term land use in the black soil region in China

AbstractSoil nematodes are sensitive to environmental changes and are used widely as indicators of soil conditions. The community structure and diversity of soil nematodes were studied in different long‐term land use regimes in the black soil area in Northeast China. The land use regimes were maintained for 22 years, and included crop land (CL), grass land (GL) and bare land (BL). Soil samples were taken throughout the growing season, and nematodes were extracted and identified. A total of 39 nematode genera with relative abundance over 0.1 % were identified. Heterodera was the dominant genus in CL; Boleodorus was the dominant genus in GL, and Boleodorus, Eucephalobus and Filenchus were the dominant genera in BL. Land use had a significant effect on abundance of all soil nematode tropic groups and ecological indices. Sampling time had an effect on soil nematode abundance, but only on three of the eight nematode ecological indices MI (maturity index of free‐living nematode), CI (channel index) and EI (enrichment index). SR (species richness index) was highest in GL where plant species diversity was also high. The CI was the highest in BL among three land uses, which means the soil food web dominated, with fungal decomposition channels in BL. Soil nematode community structure and diversity was shown to be an effective and informative tool for analyzing ecological aspects of land use in black soil regions. The data are inconclusive as to whether the effect of land use on soil nematode parameters is direct, or indirect via inducing changes in soil physicochemical properties.

Bearing Capacity Prediction of Building Pile in Soft Soil Region in China by Using Support Vector Regression

The common determination method of pile point and pile bearing capacity always depends on the practical experiences. The accuracy of pile survey data should be verified in the field. To predict the pile point and pile bearing capacity, a prediction model based on support vector regression algorithms has been developed. The friction resistance around piles and the static-load settlement are the inputs. The pile point bearing capacity characteristic value and the characteristic value of pile bearing capacity are the outputs. The prediction model is trained by the data in the adjacent block and validated by the field data in the project. The calculations of 40mm settlement and the prediction of other piles in the project can then be acquired. Compared to the survey data, the predicted values has 16% surplus. This will be beneficial to reduce construction work significantly and to save about 5% foundation cost.

Long-Term Application of Chemical Fertilizers and Rice Straw on Soil Aluminum Toxicity

The red soil region in China is very important to agriculture. However, soil aluminum (Al) toxicity often occurs as a result of the high soil acidity. In a long-term experiment, we analyzed soil samples to determine the effect of fertilization on soil acidity and potential Al toxicity. The results showed that after 12 years of utilization, Al toxicity occurred in the soil of the control plot. Chemical fertilizer further decreased soil pH and intensified Al toxicity. However, rice straw effectively improved soil pH and ameliorated soil Al toxicity from 0 to 50 cm deep, which may be attributed to the accumulated soil organic matter (SOM) and the decomposition of the rice straw. Corresponding to the lower Al content in soil, peanut crops grew healthier with greater yields in the rice straw plot, indicating that returning crop stalks to the field should be a feasible fertilization strategy in the region.

Sediment flow behavior in agro-watersheds of the purple soil region in China under different storm types and spatial scales

Bedload sediment is not only a major pollutant, but can also act as a transporter of pollutants. Sediment flow behavior often reflects the characteristics of a watershed, such as land use and management. To clarify the behavior of sediment flow under different spatial scales and storm types in the Chinese purple soil area, the sediment flow behavior in three small agro-watersheds with different catchment areas, physical characteristics and land use types was investigated during natural rainfall events from 1999 to 2000. The results showed that there were three types of sediment hydrographs, waveform or linear with a low sediment concentration (1.13 ± 0.58 g l −1), logarithmic decrease (3.41 ± 4.13 g l −1), and compound linear and logarithmic decrease (9.58 ± 10.90 g l −1). During PP-type rainfall events (high-intensity rainfall occurred during the prophase of the rainfall process) and ML-type rainfall events (high intensity rainfall occurred during the middle of the rainfall event), the waveform or linear type sediment hydrographs or the logarithmic decrease type hydrographs were generated in each of the three agro-watersheds. However, sediment hydrographs produced by IM-type rainfall events (discontinuous rainfall with obvious segments) depended on the spatial scale of the watershed. As the spatial scale decreased, the hydrographs were transformed from the logarithmic decrease type to the compound type. In addition, it was found that the S = aQ b model could effectively simulate the sediment hydrologic process of a single rainfall event. The information provided in this study will help evaluate and prevent soil and water loss and non-point source pollution in the purple soil region.

The Soil Regions of China

The Soil Regions of China

The Soil Regions of China (Part 2)

The Soil Regions of China (Part 2)