Search Results (16)

Sustainable cropland management is essential in maintaining national food security. In the black soil regions of China, which are key areas for commercial grain production, sustainable land use must be achieved urgently. To address the absence of integrated, large-scale, remote sensing-based sustainability frameworks in China’s black soil zones, we developed a comprehensive evaluation system with 13 indicators from four dimensions: the soil capacity, the natural capacity, the management level, and crop productivity. With this system and the entropy weight method, we systematically analyzed the spatiotemporal patterns of cropland sustainability in the selected black soil regions from 2010 to 2020. Additionally, a diagnostic model was applied to identify the key limiting factors constraining improvements in cropland sustainability. The results revealed that cropland sustainability in Heilongjiang Province has increased by 7% over the past decade, largely in the central and northeastern regions of the study area, with notable gains in soil capacity (+15.6%), crop productivity (+22.4%), and the management level (+4.8%). While the natural geographical characteristics show no obvious improvement in the overall score, they display significant spatial heterogeneity (with better conditions in the central/eastern regions than in the west). Sustainability increased the most in sloping dry farmland and paddy fields, followed by plain dry farmland and arid windy farmland areas. The soil organic carbon content and effective irrigation amount were the main obstacles affecting improvements in cropland sustainability in black soil regions. Promoting the implementation of technical models, strengthening investment in cropland infrastructure, and enhancing farmer engagement in black soil conservation are essential in ensuring long-term cropland sustainability. These findings provide a solid foundation for sustainable agricultural development, contributing to global food security and aligning with SDG 2 (zero hunger). Full article

Soil erosion has caused the loss of black soil and exposed the soil parent material in the cultivated layer of sloping farmland in Northeast China. Straw return (STR) and manure fertilization (MF) are critical measures to improve soil quality and crop yield. However, the effect of STR and MF on the soil properties of the parent material remains unclear. We conducted a 1-year pot experiment in the field using the soil parent material of degraded black soil to evaluate the effects of STR and MF on soil nutrients, microbial community, and soybean yield. We analyzed these effects using two treatments (STR and MF) in three soybean growth stages (seedling, flowering, and maturity) and a control group (CK). The MF treatment had higher α and β diversity of soil microbial than the CK during all soybean growth stages. Similarly, STR had higher soil microbial α diversity at the maturity stage and lower diversity at the seedling stage. Co-occurrence network analysis suggested that STR and MF increased the proportion of positively correlated edges in soil bacterial and fungal networks compared to the CK. Notably, the treatments enriched beneficial taxa, such as Schizothecium (fungi) and Massilia (bacteria), which are associated with organic matter decomposition and nitrogen cycling. STR and MF significantly improved soil organic matter, total nitrogen, and carbon-nitrogen ratio (p < 0.05). Structural equation modeling (SEM) revealed that STR and MF directly increased soybean yield. This effect was primarily mediated by the significantly higher soil organic matter, total carbon, total nitrogen, and carbon-to-nitrogen ratio in the treatments than in the CK (p < 0.05). In summary, STR and MF improved soil fertility and soil microbial community diversity of degraded black soil. This study provides scientific methods to improve the fertility of degraded black soil and increase soybean production in the short term. Full article

Black soil with high fertility is a valuable soil resource, which plays an important role in guaranteeing regional food security and ecological security. Straw return is also a widely recognized way of straw resource utilization. However, it is still not clear which corn straw return method is more suitable for the Chinese black soil region with cold characteristics. The objectives of this study were to classify rainfall patterns (I—light rain with long duration, II—heavy rain with short duration, III—moderate rain with moderate duration; T1 and T2—special rains) and reveal the effects of furrow corn straw mulch—a new straw return—on soil erosion and organic carbon loss. Natural runoff plots (a planned size of 100 m² and dimensions of 20 m × 5 m for each one) with or without the furrow corn straw mulch, which had slope gradients of 3°, 6° and 9°, were applied for natural rainfalls. Runoff and sediment samples were collected after each erosive rainfall to measure runoff, sediment, and organic carbon concentration. The results showed that when comparing treatments with the furrow corn straw mulch to control treatments, runoff coefficients, sediment concentration, and mean ratios of organic carbon loss in sediment to total carbon loss decreased by 48.0–97.7%, 45.6–99.7%, and 4.7–12.9%, respectively. Furthermore, the ratios of <0.053 mm sediment increased but the ratios of >0.25 mm sediment generally decreased. The mean organic carbon concentration both in runoff and sediment decreased in the following order: II > III > I > T1 > T2. Rainfall pattern II induced greater ratios of organic carbon loss. Therefore, the furrow corn straw mulch measure, which effectively decreased soil erosion and regulated organic carbon loss from the black soil, is suitable for the farmlands in the black soil regions. Full article

The black soil region of Northeast China is the largest commercial grain production base in China, accounting for about 25% of the total in China. In this region, the water erosion is prominent, which seriously threatens China’s food security. It is of great significance to effectively identify the erosion-prone points for the prevention and control of soil erosion on the slope of the black soil region in Northeast China. This article takes the Tongshuang small watershed (Heilongjiang Province in China) as an example, which is dominated by hilly landforms with mainly black soil and terraces planted with corn and soybeans. Based on the 2.5 cm resolution Digital Elevation Model (DEM) reconstructed by unmanned aerial vehicles (UAVs), we explore the optimal resolution for hydrological simulation research on sloping farmland in the black soil region of Northeast China and explore the critical water depth at which erosion damage occurs in ridges on this basis. The results show that the following: (1) Compared with the 2 m resolution DEM, the interpretation accuracy of field roads, wasteland, damaged points, ridges and cultivated land at the 0.2 m resolution is increased by 4.55–27.94%, which is the best resolution in the study region. (2) When the water depth is between 0.335 and 0.359 m, there is a potential erosion risk of ridges. When the average water depth per unit length is between 0.0040 and 0.0045, the ridge is in the critical range for its breaking, and when the average water depth per unit length is less than the critical range, ridge erosion damage occurs. (3) When local erosion damage occurs, the connectivity will change abruptly, and the remarkable change in the index of connectivity (IC) can provide a reference for predicting erosion damage. Full article

Soil aggregates are important indicators of soil structure stability and quality. The black soil region of northeast China, known for its high agricultural productivity, faces significant challenges due to soil erosion. This study investigates the impact of terracing on the stability and erodibility characteristics of soil aggregates in sloped farmlands, which is crucial for this important agricultural area. Three research sites with the same basic management modes were selected along a latitudinal gradient, from the mid-temperate zone to the cold temperate zone, in the black soil region of northeast China. The Savinov method was used to analyze the differences in soil aggregate size distribution, stability characteristics, and soil erodibility between terraced and non-terraced slopes at each research site. The results showed that terracing increased the content of large soil aggregates (>0.25 mm) by 5.38–6.35%, with the increase becoming more pronounced from north to south. The improvement in soil structure varied by location and slope position, with the most significant improvement at the middle slope position. Terracing enhanced soil aggregate stability, reduced soil erodibility, and improved soil structure by increasing clay and soil organic matter (SOM) content and reducing soil bulk density (BD), promoting the conversion of small aggregates to large aggregates. Soil stability indicators such as water-stable aggregates (WSAs), mean weight diameter (MWD), and geometric mean diameter (GMD) were dominated by aggregates > 5 mm, while erodibility indicators such as fractal dimensions (Ds) and the soil erodibility factor (K values) were mainly influenced by aggregates < 0.25 mm. Terraces can improve the soil structure and stability of sloping farmland by increasing the content of large soil aggregates and enhancing overall soil quality. The benefits of these improvements increase with latitude. These findings provide critical insights for determining effective management practices for sloped farmlands in the black soil region under various site conditions. They offer scientific evidence for preventing soil erosion and improving soil quality, thus supporting the sustainable development strategy for protecting black soil and ensuring long-term agricultural productivity. Full article

To explore the spatial distribution characteristics of soil physical properties and soil erosion in sloping farmland with ridges in the black soil areas of northeast China, sloping farmland with ridges built with woven bags (RW) along the contour lines was selected as the research object, and another sloping farmland was selected as the control (CK). Soil samples were collected from both RW and CK at uniform spatial intervals to measure key indicators of soil properties in the surface layer (0–15 cm), including soil water-holding capacity, soil structure, and annual average soil loss (A). The results showed that: (i) RW exhibited a significantly higher overall field water-holding capacity compared to CK, with soil moisture characteristics more evenly distributed spatially. Soil bulk weight, fractal dimension, and soil aggregate destruction in RW were reduced by 1.09%, 0.65%, and 4.61%, respectively, compared to CK. Additionally, soil total porosity, capillary porosity, mean weight diameter (MWD), and geometric mean diameter (GWD) were more evenly distributed spatially in RW. (ii) On the up-slope, soil water content and DR_>0.25 in RW had a higher increase than those of CK. On the mid-slope, soil field water-holding capacity, capillary porosity, MWD, and GWD in RW had a higher increase than those in CK. On the down-slope, RW had a 7.67–10.79% increase in soil water content, saturated water-holding capacity, field water-holding capacity, and capillary water-holding capacity compared to CK, with total soil porosity and soil capillary porosity increasing by 2.84% and 15.51%, respectively. (iii) Annual average soil loss (A) of RW was reduced by 61.85–99.64% compared to CK, based on the China Soil Loss Equation (CSLE). (vi) Soil water-holding capacity and soil structure characteristics of RW showed benefits compared to CK, with the benefits ranging from 1.01 to 1.09, while the benefit of A reached 2.46. This study is significant for understanding the spatial distribution of soil erosion on sloped farmland in black soil areas and for the effective application of soil and water conservation measures. Full article

This study investigates the spatial and temporal heterogeneity of soil moisture on slopes of China’s northeastern black soil region, focusing on the effects of terrain adjustment and vegetation. Soil moisture dynamics in the 0–60 cm soil layer were measured at 10 cm intervals using the TRIME-PICO64 TDR^® device on slopes with similar gradients representing three land use types: transverse ridge tillage (TRT) farmland, terraced fields (TFs) farmland, and pure forest woodland (WL). The results indicate significant variations in soil moisture content and water storage across different land use types in the order of TF > TRT > WL. The study further identified that soil bulk density, porosity, and water-holding indicators were in the order of WL > TF > TRT, inconsistent with the soil moisture results, indicating that soil quality cannot be the sole reason for the differences in moisture. The moisture differences between farmland types (TRT and TF) and WL are substantial, especially during the rainy season. In the rainy season (0–60 cm) and the dry season (30–60 cm), significant differences in moisture content are observed (p < 0.05). Significant differences in moisture content between farmland types are found at 0–40 cm during the rainy season and at 0–10 cm during the dry season. In the rainy season, soil moisture for TRT and TFs first decreases from 26.76% and 30.85% to 22.44% and 25.38%, then slightly increases to 27.01% and 27.07% along the slope. Meanwhile, WL displays the opposite pattern on upper, relatively steep slopes, with soil moisture increasing from 16.66% to 17.81%, and exhibits a pattern of change similar to TRT and TFs on lower, gentler slopes. TFs consistently show higher soil moisture and water storage at all slope positions than TRT and WL. TFs improve soil quality, reduce erosion and sedimentation, and shift the lowest soil moisture content to a lower slope position. During the dry season, soil moisture differences between slope positions for TRT and WL were small. In general, terracing can effectively modulate moisture distribution along slopes, increasing moisture by an average of 0.26~12.43%, while afforestation, despite improving soil quality, leads to an 18.14~31.13% reduction in soil moisture content, with the impact being particularly significant during the rainy season. These findings provide important insights for optimizing land use and ecological construction, including keeping the balance between soil and water conservation, especially for sub-humid slope terrain areas. Full article

Pingliang City has a complex topography and diverse soil types. To realize the improvement of soil according to local conditions and the reasonable and sustainable use of soil resources, an evaluation of soil quality in Pingliang City was carried out, based on the soil distribution situation in Pingliang City, adopting a method combining fuzzy mathematics and cluster analysis of the main evaluation factors, such as soil organic matter, topsoil depth, soil erosion intensity, soil moisture regime, effective soil thickness, soil texture, soil profile structure, soil nutrient status and topographical parts, to carry out a comprehensive evaluation. A comprehensive evaluation of soil quality was conducted in seven counties under the jurisdiction of Pingliang City, and the evaluation results were compared and analyzed against the national standard, “Cultivated land quality grade”, to provide a basis for the selection of scientific soil improvement methods. The results of the arable land quality grades indicate that the quality of farmland in Pingliang City is divided into three to ten grades, and the average quality grade of farmland is 6.83, which is in the middle–lower level, and the overall grade distribution shows the characteristics of low in the middle and high in the east and west. The results of fuzzy mathematics combined with cluster analysis indicated the following trends in soil quality for the 12 soil genera: Chuan black gunny soil > yellow moist soil > sandy soil > silt soil > mulching helilu soil> loessal soil> loamy soil > slope loessal soil > arenosol > tillage leaching gray cinnamon soil > calcareous gray cinnamon soil > red clay soil. The results of the combination of fuzzy mathematics and clustering were significantly correlated with the results of the evaluation of the soil quality of arable land; the correlation coefficient was 0.884. This indicates that the method can accurately and objectively review the advantages and disadvantages of arable land soil and can be effectively applied to the evaluation of the soil quality of agricultural soils in other regions. It is a complement to the existing evaluation of the soil quality of arable land and at the same time provides a reference for the improvement of soil quality in agricultural regions. Full article

The Northeast black soil region is China’s vital commercial grain base. However, severe soil erosion on slope farmland poses a significant threat to this region’s sustainable agricultural productivity. The transition from traditional downslope ridging to contour ridging (briefly referred to as “contour ridging”) is one of the primary sustainable measures for preventing soil erosion on slope farmland. By integrating high-precision Digital Elevation Models (DEMs) and design standards, ArcMap can plan the orientation and position of contour ridgelines and estimate the reduction in soil erosion on slope farmland after implementing contour ridging. Therefore, the degree of discrepancy between the designed and implemented positions of the contour ridgelines directly affects the effectiveness of contour ridging and the precision in evaluating its impacts and benefits. This study aims to assess the position accuracy of contour ridgelines designed by ArcMap 10.5 (here after ArcMap) using high-precision DEMs obtained from unmanned aerial vehicles (UAV). For this purpose, three fields where contour ridging had already been implemented were selected in the Sanjiang Plain of Heilongjiang Province, China. CORS RTK was used to measure the XYZ coordinates of verification points along implemented ridges precisely. Those measured coordinates were compared with the designed ridgeline positions to analyze the positional discrepancies between the designed and implemented ridgelines. The results indicated the following: (1) The average slope gradient along contour ridgelines measured in the field (0.5~0.6°) was relatively close to that along the ridgelines designed using ArcMap (0.6°), and the elevation changes along most of the contour ridgelines showed a pattern of being higher in the middle and lower on both sides. (2) The positional offset between most of the measured and designed ridgelines was less than the width of a single ridge (1.3 m), and the median offset was one-third of the width of a single ridge. (3) The positional offset caused by the movement of ridging machinery could be larger than the offset resulting from the baseline setup, and verification points with larger positional offsets were often located at the edges of the plots as well as turns of the ridgelines. Therefore, during the designing ridgelines process, the turns should be made as smooth as possible. During ridging, reducing the speed at these turns to minimize errors and maintain the accuracy of the ridgeline was recommended. The findings of this study can provide a scientific basis to improve contour ridging design and effect prediction in slope farmland to control soil erosion and enhance agricultural sustainability. Full article

The impact of terracing construction on the soil moisture content of slope farmland was analyzed at three sites in northeast China’s black soil region, across a range of latitudes and hydrological, temperature and soil quality conditions. At each research site, slope farmland with terracing was compared to unterraced slope farmland with a similar shape and gradient. During the wet crop growth period (July) and dry postharvest period (October) of 2022, the TRIME-PICO64TDR soil moisture measuring instrument was used to measure the soil moisture content at depths of 0–60 cm. Terracing increased soil moisture content by up to 2.83 percentage points during the crop growth period and by up to 1.69 percentage points during the postharvest period. Terracing had a significant impact on the volumetric soil moisture content of the shallower soil layer (0–30 cm) during the growing period, and on the volumetric soil moisture content of the deeper soil layer (30–60 cm) during the postharvest period. Terracing weakens the effect of slope position on volumetric soil moisture, reducing differences in volumetric soil moisture content among different slope positions. The difference in the water conservation benefit of terracing among the sites is mainly related to soil quality: the lower the soil bulk density and the higher the silt clay content is, the greater the benefit of terracing for retaining moisture. The findings of this study can be beneficial for guiding management measures for slope arable soil in black soil regions around the world. Full article

Snowmelt erosion could cause serious damage to soil quality and agricultural production conditions of slope farmland in the black soil region of northeast China. Contour ridge tillage is a traditional and effective measure to mitigate soil loss on slope farmland. However, the characteristics and influence factors of snowmelt erosion of slope farmland with contour ridge culture and the effect of this measure on the snowmelt process have not been comprehensively investigated, especially at the field scale. To bridge the gap, in situ observation was conducted on the snowmelt erosion process of a typical farmland in Baiquan County, Heilongjiang Province, China. The results revealed that during the snowmelt erosion period, the average daily snowmelt runoff volume and sediment concentration exhibited a trend of first increase and then a subsequent decrease. In the early stage, although the sediment concentration was large, limited discharge and soil thaw depths led to minimal soil loss. In the following stage, due to increased runoff and thaw depths, 94% of the total soil loss amount was obtained with an obvious erosion path formed. For each event, when soil thaw depths were shallow, sediment concentration had a high and early peak, whereas a reverse trend was observed when thaw depths increased. The hysteresis relationship of discharge–sediment indicated that the location where snowmelt erosion primarily occurred would change, under the influence of variations in runoff, freeze and thaw action, thaw depths, and micro-topography. The results could provide a guide in the control of soil erosion in seasonal snowmelt-erosion-prone areas. Full article

The black soil region in Northeast China is one of the major grain-producing areas of China. Soil erosion in the black soil region caused by natural factors and anthropic activities has attracted much attention, especially in a rolling hilly region. Compared with natural factors, the land use factor of cropland encompasses the most easily optimized measures. Jiutai County of Changchun City, located in the hilly areas of Northeast China, was taken as an example to calculate the soil erosion modulus using the Revised Universal Soil Loss Equation model. The overall soil erosion status of cultivated land in the study area was mainly slight and light, the proportion of cultivated land affected by extremely intensive and severe erosion was relatively small, and the average soil erosion modulus was 7.09 t·hm⁻²·a⁻¹ in 2019. In view of spatial distribution characteristics of soil erosion revealed by the spatial aggregation and hot spot analysis, the most serious soil erosion intensity was concentrated in the southeast and northeast sloping farmland over 8°. With the increase in elevation and topographic slope, the proportion of slight and light soil erosion gradually decreased, which was closely related to the increase in soil erodibility caused by the space–time migration of soil organic carbon caused by the interaction of hydraulic and tillage erosion in complex topographic areas. The Geographically Weighted Regression model was introduced to explore the driving factors and superposition mechanism of farmland soil erosion in the hilly region of Northeast China. Based on the relationship between soil erosion and landscape fragmentation, landscape fragmentation was an important driving force promoting soil erosion, sediment yield, and sediment transport. This paper is committed to providing a basis for accurately deploying regional soil and water conservation measures and formulating macro land management policies. Full article

This research explored the effects of biochar on slope runoff and sediment transport processes and the hydrodynamic mechanism of rill erosion under the seasonal freeze–thaw climate in the black soil area of Northeast China. The four slopes of 1.8, 3.6, 5.4 and 7.2° were set, corn straw biochar was used, and three biochar contents of 0 kg m⁻² (B0 treatment), 6 kg m⁻² (B6 treatment) and 12 kg m⁻² (B12 treatment) were applied. The experimental plot was placed outdoors to simulate the freeze–thaw cycle of sloping farmland under natural conditions. Three artificial simulated rainfall tests were carried out before the end of seasonal freeze–thaw cycles and spring sowing date (May) in 2018 and 2019. The sediment transport process of runoff and the variation of hydrodynamic parameters in rills were analyzed under one and two seasons of freezing and thawing in natural outdoor conditions. The results show that biochar has a positive effect on reducing rainfall runoff and soil loss after one year and two years of seasonal freezing and thawing. The effect of biochar on the sediment concentration of slope runoff increased with increasing application time; in the second year, the B6 and B12 treatments reduced the sediment concentration by 5.5–14.8% and 3.3–13.6%, respectively, compared with the values of the first year. The Reynolds number (Re) in the rill flow after the B6 and B12 treatments decreased with increasing duration, which effectively reduced the turbulence degree of the flow on the rill of the slope. With the increase in duration, the rill critical erosion power increased; in 2018 and 2019, the critical shear force, critical runoff power and critical unit runoff power were 0.403 Pa, 0.098 m s⁻¹, and 0.002 N m⁻¹ and 0.497 Pa, 0.124 m s⁻¹, and 0.003 N m⁻¹, respectively. This result indicates that increasing the duration and number of seasonal freeze–thaws can promote the development of biochar control of the runoff and sediment processes on slope and rill development. Full article

Black soil is fertile, abundant with organic matter (OM) and is exceptional for farming. The black soil zone in northeast China is the third-largest black soil zone globally and produces a quarter of China’s commodity grain. However, the soil organic matter (SOM) in this zone is declining, and the quality of cultivated land is falling off rapidly due to overexploitation and unsustainable management practices. To help develop an integrated protection strategy for black soil, this study aimed to identify the primary factors contributing to SOM degradation. The geographic detector, which can detect both linear and nonlinear relationships and the interactions based on spatial heterogeneous patterns, was used to quantitatively analyze the natural and anthropogenic factors affecting SOM concentration in northeast China. In descending order, the nine factors affecting SOM are temperature, gross domestic product (GDP), elevation, population, soil type, precipitation, soil erosion, land use, and geomorphology. The influence of all factors is significant, and the interaction of any two factors enhances their impact. The SOM concentration decreases with increased temperature, population, soil erosion, elevation and terrain undulation. SOM rises with increased precipitation, initially decreases with increasing GDP but then increases, and varies by soil type and land use. Conclusions about detailed impacts are presented in this paper. For example, wind erosion has a more significant effect than water erosion, and irrigated land has a lower SOM content than dry land. Based on the study results, protection measures, including conservation tillage, farmland shelterbelts, cross-slope ridges, terraces, and rainfed farming are recommended. The conversion of high-quality farmland to non-farm uses should be prohibited. Full article

Biochar, as a kind of soil amendment, has attracted wide attention from scholars in various countries, and the effects of biochar on soil and water loss have been well reported. However, soil erosion is significantly affected by geographical conditions, climate, and other factors, and research on the characteristics of soil erosion and the effects of biochar application in seasonally frozen soil areas is currently unclear. The purpose of this study was to explore the effect of corn straw biochar application on soil and water conservation during the spring thawing period. Specifically, through field experiments, the addition of 0, 6, and 12 kg m⁻² biochar on slopes of 1.8, 3.6, 5.4, and 7.2° and the effects on runoff and the soil erosion rate of farmland were analyzed. The results showed that in the 6 and 12 kg m⁻² biochar addition treatments, the saturated water content of the soil increased by 24.17 and 42.91%, and the field capacity increased by 32.44 and 51.30%, respectively. Compared with the untreated slope, with an increase in biochar application rate, runoff decreased slightly, and soil erosion decreased significantly. This study reveals that biochar can be used as a potential measure to prevent soil and water loss on sloping farmland in cold regions. Full article