Cropland Soil Erosion Research Articles

Ecological unequal exchange: Evidence from imbalanced cropland soil erosion and agricultural value-added embodied in global agricultural trade

The cropland soil erosion (CSE), a major driver of land degradation and water pollution, is directly caused by agricultural production processes driven by food demand in a globalized food market. However, it is essential to determine what role global trade and agricultural value chains play in regional CSE, especially when imbalanced erosion is embodied in global agricultural trade. In this study, the Revised Universal Soil and Water Loss Equation and the Environment Expanded Multi Region Input-Output Model were used to quantify the global distribution of CSE and the value added in global agricultural value chains to identify trade imbalances. We introduce the Local Environmental Coefficient, the Regional Environmental Coefficient, and the Agricultural Trade Environment Inequality (AEI) index, which were used to analyze the overall and bilateral inequalities in agricultural trade among the world’s regions. The results showed that 34.65 % of the global CSE was embodied in international trade, whereas the ratio of the value added was 30.80 %. The global trade in agricultural products is generally unbalanced, as indicated by the AEI index of developed regions such as Norway and Japan, which is more than 30 times higher than that of regions such as China and Brazil, and more than 20 times higher than the global average. In terms of bilateral trade, China, the United States, and Brazil face more prominent imbalances in their international trade. Major agricultural producers generally bear more environmental costs with less value-added benefits in trade. This study quantifies, for the first time, the implied imbalances of CSE transfer in agricultural trade. Global ecological governance thus requires accountability from all regions, especially in an era of increasing globalization of agricultural trade. Timely adoption of ecological compensation and technology transfer for both large agricultural producers and less-developed regions are key to achieving sustainable global agricultural production.

Temporal Variation in Soil Resistance to Rill Erosion in Cropland of the Dry—Hot Valley Region, Southwest China

In croplands, soil erosion resistance varies with both natural processes and human disturbances. To clarify the temporal variation in soil erosion resistance, nine cropland plots with three treatments (continuous fallow, fallow after tillage and tillage with corn) were established in the dry–hot valley region of China. A total of 144 field runoff simulation experiments were conducted from May to October to measure the soil detachment rate (Dc), rill erodibility (Kr) and critical shear stress (τc). The results revealed that the natural dry—wet alternation had little influence on the continuous-fallowed soil erosion resistance. On the other hand, the tillage disturbance that occurred in May sharply increased the Dc and Kr to 2.24 and 3 times that of the continuous-fallow treatment, respectively. Then, the erosion resistance could be enhanced with surface consolidation for the fallow-after-tillage treatment. However, after three months of fallow, the Kr was still 89.5% of the fresh tilled soil. In contrast, crop growth could significantly improve aggregate stability and reduce the Kr to 38.2% in August and even further to 23.7% in October compared to the fresh tilled soil. It could be concluded that crop growth is more efficient in enhancing erosion resistance than the mechanical effect. The above results would benefit from the accurate modeling of cropland soil erosion dynamics and guide agricultural management in dry–hot climate regions.

Mismatch between provincial grain production and consumption increased cropland soil erosion in China

Cropland soil erosion is primarily caused by agricultural production and indirectly altered by consumption patterns. A well-developed grain trade system transfers grain products to distant locations, away from their place of origin where soil erosion may have occurred. Evidence-based policies to control soil erosion can be developed by holding consumers responsible for the soil erosion caused by their consumption. However, there have been few systematic studies on cropland soil erosion that is embodied in grain trade. In this study, we estimated the soil erosion intensity (SEI) of grain production in each province of China from 1990 to 2020 by combining the Revised Universal Soil Loss Equation and socio-economic statistics. We also constructed an interprovincial grain trade network using linear programming techniques and analyzed the cropland soil erosion associated with the interprovincial grain trade. The results showed a rise in national cropland soil erosion attributed to grain production from 5.36×108 t in 1990 to 7.56×108 t in 2020. In particular, those embodied in interprovincial grain trade increased from 0.94×108 t in 1990 to 3.52×108 t in 2020. Nationally, about 10.72% of soil erosion exports in 2020 was from provinces with lower-than-average SEI, compared to 18.42% in 1990, indicating that current patterns of grain production and consumption are unfavorable for erosion control. Accordingly, measures have been proposed to build a soil erosion control system that includes consumers, such as changing farming practices, optimizing agricultural layout, promoting technology export and establishing a provincial compensation mechanism.

Spatial Quantification of Cropland Soil Erosion Dynamics in the Yunnan Plateau Based on Sampling Survey and Multi-Source LUCC Data

The mapping and dynamic monitoring of large-scale cropland erosion rates are critical for agricultural planning but extremely challenging. In this study, using field investigation data collected from 20,155 land parcels in 2817 sample units in the National Soil Erosion Survey, as well as land use change data for two decades from the National Land Use/Cover Database of China (NLUD-C), we proposed a new point-to-surface approach to quantitatively assess long-term cropland erosion based on the CSLE model and non-homologous data voting. The results show that cropland in Yunnan suffers from serious problems, with an unsustainable mean soil erosion rate of 40.47 t/(ha·a) and an erosion ratio of 70.11%, which are significantly higher than those of other land types. Engineering control measures (ECMS) have a profound impact on reducing soil erosion; the soil erosion rates of cropland with and without ECMs differ more than five-fold. Over the past two decades, the cropland area in Yunnan has continued to decrease, with a net reduction of 7461.83 km2 and a ratio of −10.55%, causing a corresponding 0.32 × 108 t (12.12%) reduction in cropland soil loss. We also quantified the impact of different LUCC scenarios on cropland erosion, and extraordinarily high variability was found in soil loss in different basins and periods. Conversion from cropland to forest contributes the most to cropland erosion reduction, while conversion from grassland to cropland contributes 56.18% of the increase in soil erosion. Considering the current speed of cropland regulation, it is the sharp reduction in land area that leads to cropland erosion reduction rather than treatments. The choice between the Grain for Green Policy and Cropland Protecting Strategy in mountainous areas should be made carefully, with understanding and collaboration between different roles.

Compound erosion effect of snowmelt, wind, and rainfall on sloping farmlands of Chinese typical Mollisol region.

Research on the processes and mechanisms of compound soil erosion by multiple forces can provide scientific guidance for precisely controlling cropland soil erosion. Based on the seasonal alternation of freezing-thawing, snowmelt, wind, and rainfall erosion forces on sloping farmlands under natural conditions from November to next October of each year, we used a set of indoor simulation experiments of multi-force superimpositions to analyze the compound soil erosion processes of snowmelt (1 and 2 L·min-1), wind (12 m·s-1), and rainfall (100 mm·h-1). We further discussed the erosion effects of multi-force superimpositions. The results showed that, under single snowmelt erosion, an increase in snowmelt flow had a greater effect on sloping snowmelt erosion intensity than that of sloping runoff rate. When sloping snowmelt flow increased from 1 L·min-1 to 2 L·min-1, sloping runoff rate and erosion intensity increased by 2.7 and 4.0 times, respectively. Under snowmelt-wind superimposition erosion, previous sloping snowmelt erosion inhibited late wind erosion occurrence. As sloping snowmelt flow increased from 1 L·min-1 to 2 L·min-1, the inhibiting action subsequently increased and wind erosion intensity caused by previous snowmelt reduced by more than 50%. Both wind erosion and snowmelt-wind superimposed erosion intensified late rainfall erosion. The early wind erosion increased rainfall erosion by 24.5%. The snowmelt-wind superimposed effect increased the later slope rainfall erosion by 132.8% and 465.4% under 1 and 2 L·min-1 snowmelt runoff rates, respectively. The compound soil erosion amount driven by multiple force superimposition was not the sum of the corresponding erosion amount caused by single erosion force, with promoting or inhibiting effects of erosion force superimposition. The erosion effect of snowmelt-wind superposition was negative, but that of wind-rainfall superposition and snowmelt-wind-rainfall superpositions were positive.

A GIS-based approach for estimating fallow-season cropland soil erosion based on rainfall erosivity

ABSTRACT Rainfall erosivity describes the capability of rainfall to cause soil erosion from a surface during a storm. Currently, the average long-term annual and monthly rainfall erosivity for a location may be obtained from isoerodent maps using a sample of climate stations across the United States (US). However, at the state-scale these measures are sporadic, using rainfall data from an increasingly outdated period, which may not reflect possible changing rainfall erosivity. Focusing on the state of Kentucky, US, we developed rainfall erosivity grids from the state Mesonet system to determine if erosivity has changed spatially and temporally between the original erosivity datasets from the latter twentieth-century and 2011–2020. We further used the Mesonet-derived dataset to develop a GIS-based model to estimate potential soil erosion for croplands during the fallow-season when soil is most prone to erosive storms. Results indicated that monthly erosivity increased across the state between the two periods. Larger increases in erosivity during the latter part of the fallow-season resulted in higher estimated soil erosion from croplands, particularly to the west. These findings may provide guidance in identifying and targeting croplands at greatest potential risk of soil erosion during the fallow-season for additional monitoring, mitigation and management practices.

Multiple perspective accountings of cropland soil erosion in China reveal its complex connection with socioeconomic activities

Cropland soil erosion is a major threat to global agricultural sustainability. Compared with the well-studied natural factors of soil erosion, socioeconomic factors have just begun to be considered. The major obstacle is that the soil erosion of different crops has not been accounted for and connected to socioeconomic activities. This study adopted the revised universal soil loss equation (RUSLE) and the environmentally extended multiregional input-output (EE-MRIO) model to account for soil erosion on cropland from the production, consumption, and income perspectives at the provincial and sectoral levels in China. The results showed the major responsible agents in a synthetic view. On the production side, the Yunnan-Kweichow Plateau and surrounding hills of the Sichuan Basin, the Chinese grain bases located in northeastern and central China, and the Loess Plateau were the major regions that caused the most cropland soil erosion. On the consumption side, the national final demand for Sichuan, Yunnan, Shandong, Henan, and other provinces with high production-based cropland soil erosion (PBE) values per se pulled remarkable cropland soil erosion. On the income side, the crucial provinces into which the national primary input enabled notable cropland soil erosion were still those areas with serious cropland soil erosion. From the industrial perspective, the direct effects of human primary inputs into agriculture and the demand for agricultural products played the dominant role. In addition, Cereal and BOP (beans, oil and potatoes) were the most important among the agricultural sectors. The effects of the nonagricultural sectors, especially the manufacture of foods and tobacco (MFT) and the chemical industry (CI), on cropland soil erosion also cannot be ignored. Our results indicated that accounting from multiple perspectives could inform the better management of cropland soil erosion from a more comprehensive perspective. To the best of our knowledge, this study is the first to consider the accounting of cropland soil erosion in China from multiple perspectives. Tailored packages of measures should be established based on different patterns of areas with serious cropland soil erosion.

Production-Based and Consumption-Based Accounting of Global Cropland Soil Erosion.

The effective control of cropland soil erosion is urgent for all countries because of its threat to global food security. Cropland soil erosion is caused by agricultural production and driven indirectly by consumption. Analyzing the causes and preventive strategies from the consumption side is essential for soil erosion control. However, there is not yet sufficient research or practice. In this study, we estimated global cropland soil erosion with the revised universal soil loss equation, allocated it to specific types of crops, and quantified the cropland soil erosion footprint of the economies with a multiregional input-output analysis model. Our results showed that developed economies, usually importing cropland soil erosion from developing or agriculturally developed economies, are the beneficiaries in the current crop trading system. The European Union is the largest net importer, while Brazil is the largest exporter. The indirect and induced sectors are the main contributors, consuming approximately 70.48% of the total cropland soil erosion. Our results revealed the region- and product-specific contributors that could inform the reduction of global cropland soil erosion for sustainable food production and consumption.

Multiple Perspective Accountings of Cropland Soil Erosion in China Reveal its Complex Connection with Socioeconomic Activities

Multiple Perspective Accountings of Cropland Soil Erosion in China Reveal its Complex Connection with Socioeconomic Activities

Telecoupling cropland soil erosion with distant drivers within China

Soil erosion on cropland is a result of the interaction between nature and human activities. The socioeconomic influencing factors of soil erosion have been less studied than the biophysical processes and previous studies have mainly focused on the impacts of local socioeconomic factors on soil erosion in the same region. However, since agricultural activities are densely connected to other socio-economic activities, the need for agricultural products from distant regions could potentially drive local soil erosion accompanying agricultural production. To the best of our knowledge, these telecoupling effects have not been studied. Here, we combined the Revised Universal Soil Loss Equation (RUSLE) and multiregional input-output analysis (MRIO) models to quantify the contribution of China's cross-provincial economic demand to local soil erosion at the provincial, sectoral, and supply chain levels. Our results show that a large amount of soil erosion in the southwest, northeast, and central regions is linked to the economic needs across provinces. Agriculture and food processing are the most important distant driving sectors. The driving effect of household consumption on soil erosion mainly occurs on shorter supply chains, while exports and capital formation drive soil erosion through longer chains. Our results indicate that local soil erosion management must consider the impact of distant agricultural product needs and coordinate food production and supply on a national scale to protect the ecological function of the land.

Changes in soil erosion in cropland in northeastern China over the past 300 years

Accelerated soil erosion in cropland is a major threat to food production. However, northeastern China (NEC) is one of the most important food production areas in China, and soil erosion in this region has attracted little attention because of its flatter terrain and smaller sediment load than other regions in China. To obtain a clear understanding of cropland soil erosion in northeastern China on a historical basis, data on cropland area over the past 300 years and a 2012 national water conservancy survey were used to quantify the temporal and spatial changes in cropland soil erosion in northeastern China from 1653 to 2012. From 1653 to 2012, a total of 44.28 Gt of soil eroded from cropland in northeastern China at an average rate of 0.12 Gt yr−1, and 53% of this erosion occurred after 1950. Controlled by the intensity of the opening up of waste land, the average cropland erosion rate was low from 1653 to 1949, it increased dramatically between 1950 and 1980, and it decreased after the implementation of ecological policies after 1999. The annual soil loss was 0.01 Gt yr−1 for 1653–1739, 0.04 Gt yr−1 for 1740–1791, 0.09 Gt yr−1 for 1792–1910, and 0.15 Gt yr−1 for 1911–1949, whereas the values were 0.37 Gt yr−1 for 1950–1999 and 0.46 Gt yr−1 for 2000–2012. Cropland erosion mainly occurred in Liaoning (Liao) Province before 1780 but has expanded to Jilin (Ji) and Heilongjiang (Hei) Provinces since then. By 1980, 42% of the land in NEC had been cultivated, and 78% of that land was being eroded at an erosion rate higher than the tolerance soil loss (T); these proportions became 46% and 82%, respectively, by 2012. Hei Province contained the largest eroded cropland area after 1950. The exponential increase in the cropland soil loss resulted from the increase in the cropland acreage in the steep slope area.

The effects of tillage on sheet erosion on sloping fields in the wind-water erosion crisscross region of the Chinese Loess Plateau

Tillage complicates erosion on sloping fields, especially in regions of combined wind and water erosion. The wind-water erosion crisscross region of the Chinese Loess Plateau is an example of such a region wherein erosion is caused by the stimulating effects of tillage, rainfall, and wind. Sheet erosion is an important form of cropland soil erosion and is closely correlated to the productive capacity of land. It is important to better understand the influence of tillage on soil sheet erosion in order to estimate the loss of fertile surface soil and to provide suitable tillage recommendations for the cultivation of sloping cropland in this region, which is susceptible to multiple erosion factors. This study aims to clarify spatial distribution and variation of sheet erosion rates as affected by different tillage patterns on sloping cropland under different slope conditions. We applied beryllium-7 measurements and sediment collection methods to estimate sheet erosion rates to reveal the distribution of sheet erosion on bare sloping fields, to determine correlations between sheet erosion rates and slopes (0°, 5°, 10°, 15°, 20°, and 25°), and to analyze variation in sheet erosion affected by tillage patterns on a plot scale. Results show that sheet erosion increased in a top-down direction and achieved maximum values at the mid- or lower-mid section of slopes, then erosion rates decreased or sediment deposition occurred at the base of slopes. Sheet erosion intensified with an increase in slope gradient fitting to linear or exponential functions regardless of the tillage pattern used (i.e., whether solely applying autumn plowing or a combination of autumn and spring plowing). However, tillage patterns had an obvious effect on sheet erosion. Differences in sheet erosion caused by tillage patterns increased from 5° to between 15° and 20° before decreasing at 25°. This demonstrates that steep slope gradients will weaken tillage pattern effects on sheet erosion, thus becoming a significant impacting factor on sheet erosion. Based on sheet erosion rates, we recommend that cropland be converted to grassland or shrubland when slope gradients are greater than 20° in the study region. Notably, a decrease in tillage intensity (frequency) helped in the reduction of sheet erosion on sloping croplands, and further tillage practices associated with conservation tillage should be applied on sloping cropland to obtain better soil erosion control results.

The influence of tillage practices on soil detachment in the red soil region of China

Intensive cropland soil erosion can be caused by disturbance activities. However, conservation measures have been reported to increase soil resistance and decrease erosion. Hydraulic flume experiments were conducted to measure the detachment rate of disturbed soil samples from a peanut field with five tillage practices. Hydraulic variables were adopted to estimate the soil detachment rate and to quantify the rill erodibility parameter. The disturbed soil detachment rates are substantially greater than those for comparable undisturbed soil experiments. The average disturbed soil detachment rates for the 5 different tillage treatments, from lowest to highest, are as follows: straw mulch (PC) < manure (PM) < peanut and orange intercropping (PO) < peanut and radish crop rotation (PR) < conventional downslope furrows (PF). The conservation measures (PC, PM and PO) have a limited effect on increasing the disturbed soil resistance under low flow energy conditions. Thus, the average rill erodibility is lower, and the critical shear stress is higher for the PC, PM and PO treatments than those of the PR and PF treatments. With a slope gradient steeper than 17.6%, there is no significant difference among the detachment rates of all treatments. A linear function of both flow rate and slope gradient can be used to estimate the disturbed soil detachment rate. Both stream power and flow shear stress are more effective than the unit stream power in predicting soil detachment rates. The stream power is the most effective predictor among the three hydraulic parameters studied. Instead of the power functions, the linear functions of the hydraulic parameters are suggested to quantify the disturbed soil detachment rates.

Cropland physical disturbance intensity: plot-scale measurement and its application for soil erosion reduction in mountainous areas

Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation. Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of biophysical conditions and differences in farmers' management behavior. The main purpose of this paper is to develop a composite index of cropland physical disturbance intensity (CLDI) to reflect the plot-scale discrepancy of potential soil erosion in mountainous areas. The study was based on both plot survey and household interview data, collected from six typical catchments in mountainous areas of southwestern China. Four kinds of physical disturbance practices and two kinds of conservation practices during one crop rotation period were synthesized to develop the CLDI index. The rough set theory was referenced to avoid subjectivity during weight allocation. The results show that conventional tillage, deep fertilization, and manual weeding are the main causes of cropland soil erosion, whereas manure application in combination with seasonal fallow reduces soil erosion. Different crop types as well as cropland location factors determine the spatial pattern of CLDI. Crop rotation modes with major crops of tobacco and maize resulted in a maximal CLDI, and cropland plots with a distance radius of 150 meters away from households received the most intensive physical disturbance. These results are critical to help better protect rural environments in mountainous areas. Based on the results, methods to reduce cropland soil erosion are suggested.

Extent of Cropland and Related Soil Erosion Risk in Rwanda

Land conversion to cropland is one of the major causes of severe soil erosion in Africa. This study assesses the current cropland extent and the related soil erosion risk in Rwanda, a country that experienced the most rapid population growth and cropland expansion in Africa over the last decade. The land cover land use (LCLU) map of Rwanda in 2015 was developed using Landsat-8 imagery. Based on the obtained LCLU map and the spatial datasets of precipitation, soil properties and elevation, the soil erosion rate of Rwanda was assessed at 30-m spatial resolution, using the Revised Universal Soil Loss Equation (RUSLE) model. According to the results, the mean soil erosion rate was 250 t·ha−1·a−1 over the entire country, with a total soil loss rate of approximately 595 million tons per year. The mean soil erosion rate over cropland, which occupied 56% of the national land area, was estimated at 421 t·ha−1·a−1 and was responsible for about 95% of the national soil loss. About 24% of the croplands in Rwanda had a soil erosion rate larger than 300 t·ha−1·a−1, indicating their unsuitability for cultivation. With a mean soil erosion rate of 1642 t·ha−1·a−1, these unsuitable croplands were responsible for 90% of the national soil loss. Most of the unsuitable croplands are distributed in the Congo Nile Ridge, Volcanic Range mountain areas in the west and the Buberuka highlands in the north, regions characterized by steep slopes (&gt;30%) and strong rainfall. Soil conservation practices, such as the terracing cultivation method, are paramount to preserve the soil. According to our assessment, terracing alone could reduce the mean cropland soil erosion rate and the national soil loss by 79% and 75%, respectively. After terracing, only a small proportion of 7.6% of the current croplands would still be exposed to extreme soil erosion with a rate &gt;300 t·ha−1·a−1. These irremediable cropland areas should be returned to mountain forest to foster environmental sustainability or further sustainable alternative erosion control techniques may be applied, such as applying Vetiver Eco-engineering Technology due to its economical soil erosion control and stabilization of steep slopes and the construction of erosion control dams to absorb and break down excess runoff from unusually intense storms in various parts of the watersheds.

Use of magnetic tracer and radio-cesium methods to determine past cropland soil erosion amounts and rates

Abstract The primary objective of this research was to determine the soil erosion rates in cropland of west central Illinois using a magnetic tracer (fly ash) and radio-cesium (cesium-137). The fly ash and cesium-137 accumulation on a stable cropland/hayland summit was determined using a spiral transect. This reference site was used as a baseline and then compared with the fly ash and cesium-137 levels in adjacent cropland landscape positions to estimate loss from erosion. The cesium-137 and fly ash data suggests that cropland lost significant sediment, fly ash and cesium-137 to erosion process especially from the upper and lower backslopes and footslope. The amount and rate of erosion predicted for each cropland landscape position using the fly ash and cesium-137 methods were determine for the 1910 to 1960, 1960 to 2009 and for the entire 100-year time periods. The fly ash and cesium-137 determined erosion amounts and annual soil erosion rate for cropland landscapes positions were highest for the upper and lower backslopes. Past backslope annual erosion rates for three different time periods were 51 Mt ha− 1 yr− 1 or less and above the tolerable soil loss rate of 11 Mt ha− 1 yr− 1 for Hickory soils. However, the predicted fly ash annual erosion rates for the last for the last 50 years using cesium-137 deposition was higher than annual erosion rates for the 1910 to 1960 time period using the difference between the two methods. The reason for the higher erosion rates for the 50 years after 1960 than before was most likely the continued use of moldboard plowing, up and down the slope plowing and the more intensive corn–soybean rotation without forages and small grains. These methods provide a way to document past cropland soil erosion amount and rates for three different time periods (1910 to 1960, 1960 to 2009 and 1910 to 2009).

Strategies to Rehabilitate Lake Simcoe – Modelling Phosphorus Loads, Remedial Measures and Control Options

ABSTRACT Average annual total phosphorus loads to Lake Simcoe are estimated at 100 metric tons. Urban sources of phosphorus such as water pollution control facilities and urban stormwater runoff account for approximately 30% of the total loading. Rural sources such as runoff from agricultural lands, leachate from septic systems, atmospheric deposition and soil erosion contribute the remaining 70%. A target load of 75 metric tons per year has been proposed to ensure an end-of-summer deep water dissolved oxygen concentration of 5.0 mg/L. To achieve the target load, it is necessary to reduce the export of phosphorus from the major controllable sources by 25 metric tons per year. Remedial measures and phosphorus control options to reduce point and non-point sources include controlling agricultural runoff, and erosion and urban stormwater runoff. Several management strategies have been evaluated using a GIS-assisted computer model called HYDROSIM which predicts changes in phosphorus loading in response to implementation of remedial measures within the Lake Simcoe watershed. Management scenarios examined the effectiveness of remedial options based on present and future conditions to ensure that the target load is achievable and sustainable. Modelling results indicate that the most substantial loading reductions can be achieved by controlling urban stormwater runoff and cropland soil erosion. Based on the implementation of an aggressive management program, the target load of 75 metric tons per year is considered to be achievable and can be maintained into the future.