Reduction In Sediment Loss Research Articles

The impact of vegetation reconstruction on soil erosion in the Loess plateau

Vegetation restoration not only extensively reshapes spatial land use patterns but also profoundly affects the dynamics of runoff and sediment loss. However, the influence of vegetation restoration on runoff and sediment yield from a regional perspective are scarce. This study therefore focused on 85 sites within the “Grain for Green” Project (GGP) region on the Loess Plateau, to investigate the impacts of the GGP on soil erosion. The results revealed a notable reduction in sediment loss and runoff due to vegetation restoration. Since the inception of the GGP in 1999, approximately 4.1 × 106 ha of degraded lands have been converted into forestlands, shrublands, and grasslands, resulting in an average annual reduction of 1.4 × 109 m3 in runoff and a decrease of 3.6 × 108 t in annual sediment loss on the whole Loess Plateau, with the GGP contributing approximately 26.7% of the sediment reduction in the Yellow River basin. The reduced soil erosion has mainly been regulated by vegetation cover, soil properties (clay, silt, and sand), slope, and precipitation on the Loess Plateau. The insights gained offer valuable contributions to large-scale assessments of changes in soil erosion in response to vegetation reconstruction and enhance our understanding of the spatial configurations associated with soil erosion control measures.

Assessing the watershed-scale effects of tillage management on surface runoff and sediment loss using a Curve Number-precipitation relationship based approach

Poor soil management limits the soil functions of water infiltration and storage and enhances water and soil losses. Adoption of improved soil management practices is thus vital to protecting agricultural soils amid recurring droughts and declining water availability. Although the benefits of adopting soil health promoting practices such as no-tillage (NT) have been extensively investigated at field scale, studies quantifying the watershed-scale impacts of such practices are lacking. This study aims to address this gap by quantifying soil and water conservation benefits of adopting NT over conventional tillage (CT) on all croplands in the Brushy Creek Watershed in the Texas Blackland Prairies using the Agricultural Policy/Environmental eXtender (APEX) model. Most hydrologic and water quality models often fall short in accurately simulating the effects of management practices since they are not capable of simulating changes in soil and hydrologic properties that result from changes in soil management. This study proposed a novel framework to translate field-scale rainfall and runoff relationships into a watershed-scale parameterization tool that can be used for any agricultural watershed where measured rainfall and runoff data are available. Curve Number–Precipitation (CN-P) relationships were first defined based on field observations of rainfall and runoff from paired CT and NT fields. The CT and NT APEX models were then trained to follow the defined CN-P relationships to reflect the associated changes in hydrologic properties. Changing management from CT to NT on all croplands in the study watershed (i.e., in 35% of the watershed area) resulted in a 25% (38 mm year−1) reduction in average annual runoff and a 57% (1.13 t ha -1year−1) reduction in average annual sediment loss at the outlet of the watershed. The reduction in sediment loss from individual subareas with NT management was found to be sensitive to subarea physical properties such as slope and channel depth to width ratio, but the reduction in runoff was not sensitive to those properties. Results from this study are useful to natural resource conservationists and watershed managers in effectively implementing improved soil management practices.

A perennial living mulch substantially increases infiltration in row crop systems

Poor infiltration in annual row crop systems can cause a range of problems, including sediment and nutrient loss in runoff, diminished trafficability, anaerobic soil conditions, and reduced precipitation use efficiency. Soils covered by perennial vegetation generally sustain much higher infiltration rates, and consequently are less prone to these problems. Kura clover (<i>Trifolium ambiguum</i> Bieb.) living mulch (KCLM) is a management system that seeks these environmental benefits of perenniality, while allowing continued production of annual row crops like maize (<i>Zea mays</i> L.) and soybean (<i>Glycine max</i> [L.] Merr.). This is done by planting them into tilled or killed strips within a perennial stand of kura clover. Our objective was to compare the hydrologic performance of long-term KCLM systems (in place for at least five years) against adjacent fields or plots in conventional row crop production on the same soil types. Measured variables included field-saturated hydraulic conductivity (K_fs), moisture release curves, and bulk density. K_fs was measured with a constant head single ring infiltrometer, and moisture release curves were determined with the evaporation method. Bulk density was measured on 5 cm diameter cores extracted from the surface horizon of each treatment. None of the long-term sites contained appreciable sloped land, so supporting runoff measurements were made on a third field in Minnesota where the KCLM had only been in place for two years, using lined plots with flumes and tipping buckets. Results revealed substantial and significant differences in K_fs at the long-term sites. At one site the mean value was 11 times greater in the living mulch than in the conventional fields, while at the other site it was 19 times greater. The runoff plots showed a 93% reduction in sediment loss for the KCLM relative to conventional production over the course of a year that included 10 runoff-inducing storms. These results suggest that KCLM may confer similar hydrologic benefits to prairie strips if strategically placed in fields or watersheds.

Rye cover crop increases earthworm populations and reduces losses of broadcast, fall-applied, fertilizers in surface runoff

Corn (Zea mays L.) silage and soybean [Glycine max (L.) Merr.] rotations in the US Upper Midwest leave minimal amounts of surface residues, which can contribute to soil degradation, increased surface runoff, and reduced water quality. Planting cover crops after harvest can reduce these concerns, but their effectiveness in reducing nutrient losses in surface runoff shortly after fall planting and fertilization has not been thoroughly investigated. Therefore, we applied 65 mm of simulated rainfall in 60 min to five replicate, 1.5 by 3.0 m, field plots in a no-till, corn silage-soybean rotation into which a rye (Secale cereale L.) cover crop was planted for 14 consecutive years and to five replicate plots with no cover crop history. Natural slope of the plots ranged from 0.1 to 2.7%. The study was conducted in October 2014, about one month after corn silage harvest and rye planting and ∼1 h after broadcast application of monoammonium phosphate and potassium chloride fertilizers. The living rye cover crop significantly (P ≤ 0.05) delayed surface runoff by 5.7 min and decreased total runoff by 65% compared to plots with no cover crop. This resulted in a significant 68% reduction in sediment loss and even greater significant reductions in fertilizer nutrient losses (i.e., NH4-N - 86%; total P - 83%; total dissolved P - 84%; K - 91%). Earthworm population and biomass, measured using electrical extraction shortly after the rainfall simulations, were 1.2 and 1.4 times greater in cover crop plots than in no cover plots and 3.2 and 2.5 times greater the following spring. Our results suggested that a living cover crop and their long-term usage can contribute to improvements in soil structure and increased earthworm populations that can substantially reduce sediment and nutrient losses in surface runoff due to a severe storm shortly after post-harvest broadcast application of fertilizer.

Effects of different spatial distributions of physical soil crusts on runoff and erosion on the Loess Plateau in China

AbstractThe response of runoff and erosion to soil crusts has been extensively investigated in recent decades. However, there have been few attempts to look at the effects of spatial configuration of different soil crusts on erosion processes. Here we investigated the effects of different spatial distributions of physical soil crusts on runoff and erosion in the semi‐arid Loess Plateau region. Soil boxes (1.5 m long × 0.2 m wide) were set to a slope of 17.6% (10°) and simulated rainfall of 120 mm h−1 (60 minutes). The runoff generation and erosion rates were determined for three crust area ratios (depositional crust for 20%, 33%, and 50% of the total slope) and five spatial distribution patterns (depositional crust on the lower, lower‐middle, middle, mid‐upper, and upper slope) of soil crusts. The reduction in sediment loss (‘sediment reduction’) was calculated to evaluate the effects of different spatial distributions of soil crusts on erosion. Sediment yield was influenced by the area ratio and spatial position of different soil crusts. The runoff rate reached a steady state after an initial trend of unsteadily increasing with increasing rainfall duration. Sediment yield was controlled by detachment limitation and then transport limitation under rainfall. The shifting time of erosion from a transport to detachment‐limiting regime decreased with increasing area of depositional crust. No significant differences were observed in the total runoff among treatments, while the total sediment yield varied under different spatial distributions. At the same area ratio, total sediment yield was the largest when the depositional crust was on the upper slope, and it was smallest when the crust was deposited on the lower slope. The sediment reduction of structural crust (42.5–66.5%) was greater than that of depositional crust (16.7–34.3%). These results provide a mechanistic understanding of how different spatial distributions of soil crusts affect runoff and sediment production. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Polyacrylamide efficacy for reducing soil erosion and runoff as influenced by slope

Anionic polyacrylamide (PAM) can reduce soil erosion. Slope is an important factor determining erosion rate; however, PAM guidelines have not been well developed for different slopes. The objective of this study was to evaluate the extent which 20 kg ha⁻¹ (18 lb ac⁻¹) PAM (20P) and 40 kg ha⁻¹ (36 lb ac⁻¹) PAM (40P) increase the time to initial runoff (TRO), decrease cumulative runoff (RO), and decrease cumulative sediment loss (SL) on a Mexico silt loam soil adjusted to slopes of 10%, 20%, and 40%. Soils were packed to a bulk density of 1.3 Mg m⁻³ (81 lb ft⁻³) in test beds 0.3 × 0.3 × 0.15 m (12 × 12 × 6 in) and were subjected to a 61 mm h⁻¹ (2.4 in hr⁻¹) simulated rainfall with a kinetic energy of 1.5 kJ m⁻² h⁻¹ (103 ft lb ft⁻² hr⁻¹) for 1 h. Differences in TRO and SL for all slopes and PAM rates were all highly significant, as were all two-way interactions (<i>p</i> &lt; 0.01). Applications of 20P and 40P significantly increased TRO compared to the untreated control (0P) at slopes 20% and greater but not at a 10% slope. No difference in TRO was found for soils at slopes up to 20% between 20P and 40P. The TRO was significantly greater at 40% slope for the 40P compared to the 20P application. Values of TRO with 20P and 40P were not increased at a 10% slope compared to 0P. Slope was not a factor in reducing RO. Applications of 40P for all slopes had significantly greater RO than either 0P or 20P. Polyacrylamide reduced SL for all slopes. A higher rate of PAM (40P) had less SL than a lower rate of PAM (20P) at slopes of 20% and 40%. With 40P, the reduction in SL was 72% greater than 0P at 40% slope. Therefore, slope is a critical factor in determining a PAM rate for reducing soil erosion and should be considered for proper application.

Will nutrient-efficient genotypes mine the soil? Effects of genetic differences in root architecture in common bean ( Phaseolus vulgaris L.) on soil phosphorus depletion in a low-input agro-ecosystem in Central America

Crop genotypes with root traits permitting increased nutrient acquisition would increase yields in low fertility soils but have uncertain effects on soil fertility in the long term because of competing effects on nutrient removal vs. the soil conserving effects of greater crop biomass. This study evaluated the relative importance of phosphorus loss in crop extraction vs. phosphorus loss in soil erosion as influenced by genetic differences in root shallowness and therefore phosphorus uptake in common bean ( Phaseolus vulgaris L.). Six recombinant inbred lines of varying root architecture and two commercial genotypes of bean were grown in unfertilized, steeply sloped (32%), low phosphorus (5.8 mg kg −1, Fe-strip) Udults in Costa Rica. Fertilized (60 kg total phosphorus ha −1) plots of commercial genotypes were also included in the study. Runoff was monitored throughout the bean growing season in 2005 and 2006, and in 2006, monitoring continued through the maize growing season. Phosphorus removed in plant biomass at harvest through the 2006 bean–maize crop cycle averaged 7.3 kg ha −1 year −1, greatly exceeding phosphorus loss due to erosion (0.15–0.53 kg ha −1 year −1) in unfertilized plots. In fertilized bean plots, total biomass phosphorus averaged 6.32 kg ha −1 year −1 and total eroded phosphorus averaged 0.038 kg ha −1 year −1, indicating rapid sorption of fertilizer phosphorus. Shoot growth of several recombinant inbred lines under low phosphorus was comparable to that of fertilized commercial genotypes, illustrating the effectiveness of selection for root traits for improving plant growth in low-phosphorus soils. Genotypic differences in root architecture of recombinant inbred lines led to 20–50% variation in groundcover by shoots, which was associated with 50–80% reduction in sediment loss. This study demonstrates that root architecture traits can affect nutrient cycling at the agro-ecosystem level, and that integrated nutrient management strategies are necessary to avoid soil nutrient depletion.

The potential impact of projected change in farming by 2015 on the importance of the agricultural sector as a sediment source in England and Wales

Abstract In association with a major initiative aimed at identifying policy packages for inclusion in the Programmes of Measures (POM's) comprising EU Water Framework Directive (WFD) River Basin Management Plans (RBMP's), recent work has evaluated the gap between current and compliant suspended sediment losses due to farming across England and Wales. The work required national scale sediment source apportionment to assess the current contributions of diffuse agricultural and urban sector losses, channel bank erosion and point source discharges to the total suspended sediment loads delivered to all rivers. Results suggested that the agricultural sector dominates present day (year 2000) sediment inputs to rivers (1929 kt = 76%) compared to eroding channel banks (394 kt = 15%), diffuse urban sources (147 kt = 6%) and point source discharges (76 kt = 3%). Projected change in farming by 2015, represented by the Business as Usual forecast of structural developments and predicted uptake of sediment mitigation methods, suggested an overall 9% reduction in sediment loss from the agricultural sector across England and Wales. The projected reduction is unlikely to deliver sediment compliance in all catchments. Key limitations of the integrated modelling approach are discussed.

Predicting potential change in agricultural sediment inputs to rivers across England and Wales by 2015

Recent work has evaluated the gap between current and compliant suspended sediment losses due to farming across England and Wales and the potential for change by 2015. The study adopted the guideline annual average sediment threshold of 25 mg L–1 cited by the European Union Freshwater Fish Directive. Compliance testing required national scale sediment source apportionment to assess the current contributions of diffuse agricultural and urban sector losses, channel bank erosion and point source discharges to the total suspended sediment loads delivered to all rivers. Results suggested that the agricultural sector dominates present day (year 2000) sediment inputs to rivers (1929 kt = 76%) compared with eroding channel banks (394 kt = 15%), diffuse urban sources (147 kt = 6%) and point source discharges (76 kt = 3%). Projected change in farming by 2015, represented by the Business As Usual forecast of structural developments and predicted uptake of sediment mitigation methods, suggested a 9% reduction in sediment losses from the agricultural sector across England and Wales. Further mitigation of diffuse agricultural sediment transfers to watercourses will therefore be necessary to ensure ‘good ecological status’ in some catchments. A similar modelling framework could be applied in other countries.

Cumulative Sediment, Nitrogen and Phosphorus Losses From Bare and Compost-Amended Fill Slopes

Constructed slopes are often amended with compost in order to reduce erosion and improve vegetation establishment. These composts can contain soluble nutrients which may become a source of pollution to nearby water bodies. This study examined annual sediment and nutrient losses in surface runoff from nine potential types of compost treatments. These included treatments that tested differences between two types of compost (mature and immature) as well as various methods of compost application, including surface blankets and incorporation. Over an entire rain season, there were no significant differences in sediment and nutrient (NO3−, NH4+ and P) losses between the two compost types when they were applied as surface blankets. In treatments where a compost blanket was applied over the top of compost tilled into the soil there was a significant reduction in sediment loss compared to treatments where compost was just tilled into the soil, without a blanket overlay. This treatment reduced sediment loss to a level that was comparable to vegetated treatments. Although this treatment had twice the amount of compost as the treatments with just a surface blanket of compost, it lost less than a fourth as much nitrate in its runoff over the year as either compost type when they were applied as a blanket over bare soil. The greatest sediment loss came from treatments in which compost was tilled into the soil with no additional compost surface blanket. Effects of different treatments were confounded by a gradient in slope hydrology that resulted in a relationship between runoff volume and plot position along the slope. Our statistical analysis took this into account and the data presented represent our attempt to control for this nuisance variable. Our findings suggest that compost can be used as a soil amendment and as an erosion control measure on constructed slopes at a minimal risk of nutrient loss if it is done in the proper manner. We recommend that compost be incorporated into the soil to facilitate greater infiltration and that a blanket of compost or woody mulch be placed over the soil to provide surface erosion protection.

Evaluation of the AnnAGNPS Model for prediction of runoff and sediment yields in St Lucia watersheds

The Annualised Agricultural Non-Point Source Pollution Model (AnnAGNPS) was used to predict runoff and sediment losses from a forested and an agricultural watershed of St. Lucia Island in the Caribbean. Digital elevation models (DEM) of the agricultural and forested watersheds were generated from digitised topographic data. Based on the critical source area (CSA) and minimum source channel length (MSCL) specifications, the agricultural watershed was discretised into eight cells and three channel reaches, and the forest watershed into 12 cells and five channel reaches. The weighted curve numbers (CNs) were used for the cells with multiple land uses. The CN was observed to be the most sensitive parameter in the prediction of runoff and was adjusted during calibrations. The calibration runs of the AnnAGNPS resulted in errors between observed and simulated values of 0–33% for the agricultural watershed and 3.3–46.2% for the forested watershed for runoff prediction. The sediment yield prediction error percentage during the calibration run varied from 18.2% to 40.5% for the agricultural watershed and 9.1% to 50% for the forest watershed. However, validation of the calibrated model for different rainfall events resulted in errors of 6.7–36% and a value for the coefficient of prediction (CP′A) of 0.028 (agricultural watershed) and 3.4% to 36% with a value for the CP′A of 0.23 (forested watersheds) for runoff prediction. Validation of sediment loss for both the watersheds resulted in higher errors (23% to 55%) and CP′A value of 0.341 for both the watersheds. Also, the model prediction of average annual runoff and sediment loss revealed that the agricultural watershed sediment loss (73.3 t ha−1 year−1) was significantly higher than for the forest watershed (7.2 t ha−1 year−1). Further, the validated model was used to simulate the runoff and sediment losses under a recommended land management regime for the agricultural watershed, which resulted in an 18.5% reduction in runoff and a 63% reduction in sediment loss as compared to the current management practice. This study revealed that the AnnAGNPS can be successfully applied for assessment of runoff and sediment losses and subsequent land use planning to conserve the natural resources in the watersheds of St. Lucia.

Corn Yield, Runoff, and Sediment Losses from Manure and Tillage Systems

AbstractOne challenge in land application of manure is to maximize its benefit to crops without harming the environment. Our objective was to evaluate the impact of manure addition on corn yield, and sediment losses in snowmelt and rainfall runoff under moldboard plow (MP) and ridge tillage (RT) systems. Corn (Zea mays L.) grain yield and sediment losses in surface runoff after a one‐time spring application of (16.2 dry Mg ha−1) solid beef (Bos taurus) manure on a 12% slope Forman (fine‐loamy, mixed Udic Argiborolls)‐Buse (fine‐loamy, mixed Udorthentic Haploborolls) complex were measured from 1992 through 1994. In 1993, there was no effect of manure on grain yield irrespective of tillage because of high rainfall. Under average rainfall conditions in 1994, grain yield (10.2 Mg ha−1) in the manure RT treatment was 1.0, 0.9, and 0.7 Mg ha−1 greater than that in no‐manure RT, manure MP, and no‐manure MP treatments, respectively. Snowmelt runoff was not affected by manure application and it transported &lt;0.1 Mg sediment ha−1. Manure reduced rainfall runoff by 10 mm in 1993 and 3.2 mm in 1994, which led to reduction in sediment loss of 2.5 and 0.2 Mg ha−1, respectively. The RT system resulted in lower rainfall runoff compared with the MP system for all 3 yr. Onetime manure application reduced rainfall runoff and associated sediment loss in both tillage systems. However, manure application was more effective in minimizing runoff and sediment losses during intense rainfall in the RT than in the MP system.

Runoff and Sediment Losses from Tall Fescue under Simulated Rainfall

AbstractA study was initiated to examine runoff volume and sediment loss from various density tall fescue (Festuca arundinacea Schreb.) turf stands. Plots were established with seeding rates of 0, 98, 244, 390 and 488 kg ha−1 and allowed to mature for 9 months. Three different rainfall intensities (76, 94, and 120 mm h−1) were applied to the plots using a variable intensity rainfall simulator. Results indicate that there were significant differences in runoff volume and sediment load as affected by rainfall intensity. The runoff initiation time for the 0 kg ha−1 seeding rate was the only seeding rate that was significantly different from all others. Mean runoff rates over time were significantly different for the first 5‐min time interval of the 30‐min storm for all three intensities. There was a significant difference in total sediment load for all three rainfall intensities. At the high (120 mm h−1) rainfall intensity, there was over a sixfold reduction in sediment loss when comparing the 0 kg ha−1 seeding rate to the 98 kg ha−1 seeding rate. Greater sediment loss reductions were observed at the lower rainfall intensifies when comparing the same seeding rates. Sediment loss rates did not differ for the 98, 244, 390, and 488 kg ha−1 seeding rates at the low (76 mm h−1) and medium (94 mm h−1) rainfall intensities. At the high (120 mm h−1) rainfall intensity, significant differences were detected between the 0 kg ha−1 and the 488 kg ha−1 seeding rate. The 98, 244, and 390 kg ha−1 seeding rates were not statistically different at this intensity. These results indicate that even low density turfgruss stands significantly reduce sediment loss.

The effect of forestry drainage operations on upland sediment yields: A study of two peat‐covered catchments

AbstractThe suspended sediment yields of two adjacent, paired, catchments on blanket peat in mid‐Wales were compared before and after preafforestation drainage works. Catchment A was ploughed whilst an adjacent catchment (B) was left unploughed. After eight months Catchment B was also ploughed. The ploughing strategy in both catchments was designed to minimize sediment loss. However, suspended sediment loss increased 2·5 times following ploughing in Catchment A, whilst no such increase occurred at this time in Catchment B. Subsequently, suspended sediment yields in Catchment B increased 4·8 times after it was ploughed. Organic sediment was lost mainly from furrow sides, and erosion pins showed maximum ground recession in summer, due to peat wastage. Summer desiccation prepared sediment for transport, and organic suspended sediment loads were highest in the autumn. Sediment loads were limited by vegetation colonization and some reduction in sediment loss was due to the presence of unploughed strips adjacent to stream courses.

Effect of Mulch Rate on Soil Loss by Raindrop Splash1

An experiment consisting of 50 rainfall simulator events of 76 mm/hour intensity for 30 minutes was run to examine the effect of oat straw (Avena barbata Brot.) on splash detachment and transport of soil. Soil available for transport by interrill flow is a function of soil detached by interrill flow, direct splash impact, and secondary splash impact. Soil transported by interrill flow was measured separately from soil transported by rain splash. The small 30 by 30 cm plot minimized overland flow soil detachment because interrill (not rill) flow occurred. Soil transported by interrill flow was measured. Soil transported by splash and by the interrill flow is decreased as straw mulch cover increases from 0 to 96%. The amount of soil moved by rain splash and by interrill flow is linearly correlated with cover level when both processes are considered. At 96% cover, soil loss by splash transport is reduced to < 8% of the bare soil loss, and interrill transport is reduced to 24% of the bare soil loss. The amount of interrill flow of water was not reduced under the experimental conditions which implies that the reduction in sediment loss by interrill flow is the result of reduced detachment by rain splash.

Evaluation of Agricultural Sediment Control Practices Relative to Water Quality Planning

Control of sediment has become increasingly important as an element of many water quality improvement programs. An analytical method using the universal soil loss equation and linear programming to determine the cost-effectiveness of alternative sediment control practices is developed. Applications of this method to four case study farms and a hypothetical watershed are analyzed. The analyses illustrate the need for developing priorities so as to achieve greatest reduction in sediment losses per dollar of cost. The costs per unit of sediment reduction vary greatly with area, soil, and strategy or technique used.