Highest Soil Loss Research Articles

Effects of three tillage treatments on seasonal runoff and soil loss in the Peace River region

Three tillage treatments were evaluated over a 4-yr period for their effects on runoff and soil loss under natural precipitation on a Donnelly silt loam soil (Solonetzic Gray Luvisol) near Dawson Creek in the Peace River region of British Columbia. Conventional-tilled (CT) plots (spring or fall cultivation) received twice the amount of tillage as the reduced-tilled (RT) plots, while the zero-tilled (ZT) plots were only disturbed at seeding once a year. The plots were seeded to barley (Hordeum vulgare L.). Rainfall and snowmelt runoff were collected throughout the year to determine seasonal runoff and soil losses. The effects of the tillage treatments on runoff and soil loss depended on the season (whether caused by rainfall or snowmelt) and the crop year. Mean snowmelt runoff was ZT > CT > RT. Conventional tillage had significantly higher rainfall runoff and soil loss from snowmelt than the other two tillage treatments, with no significant differences between RT and ZT. Mean rainfall-induced soil loss was significantly different for each tillage treatment, with CT > RT > ZT. Soil losses from snowmelt were low, less than 30% of those from rainfall, since snowfall was 45% below normal. Soil losses from rainfall were consistently higher than from snowmelt for each tillage treatment in each of the four crop years and provided over 75% of the 4-yr total annual soil loss. Tillage effects were more pronounced in years with low runoff and soil loss than in years with high runoff and soil loss. Zero tillage and RT are effective in reducing average annual soil losses by 81 and 53%, respectively, of those observed under conventional tillage. Key words: Runoff, soil loss, erosion plots, seasons, tillage

Soil erosion management on arable lands of submontane Punjab, India: A review

Abstract Soil erosion, a serious problem in Submontane Punjab, India, has been intensively studied by a number of investigators. Various soil management practices, such as the use of diverse crops, strip cropping, increasing crop cover, multiple cropping, agroforestry, mulching, conservation tillage, ridging, and furrowing have decreased erosion. Maize at a spacing of 60 cm x 22.5 cm showed minimum soil loss by runoff. Crops with erect growth and limited tilling allowed for high runoff and soil loss. The intercropping of groundnut with maize gave the highest net return with the least amount of soil loss by erosion; maize with urd (Vigna mungo L.) gave the second highest net return with the least amount of soil loss by erosion. Maize and guar (Cyamopsis tetragonoloba L.) in alternating strips of 9‐m width showed minimal runoff (9%) and soil loss (3.3 Mg ha‐1). The agroforestry practice of growing Leucaena leucocephala Lam. intercropped with maize, guar, or urd also was effective in reducing runoff and soil...

The potential of agroforestry methods for erosion control in Rwanda

Based on four years of plot measurements in Butare (Rwanda), the potential of agroforestry practices for soil conservation was analysed. The agroforestry system investigated is based on Grevillea robusta planted at a density of 200 trees per hectare. Supplementary erosion control measures consisted of hedgerows planted on microterraces (two species of leguminous shrubs: Calliandra calothyrsus and Leucaena leucocephala as well as the fodder grass Setaria splendida). On the agroforestry plots, crop management was in accordance with the principles of appropriate (“ecologic”) agriculture, including practices such as mixed cropping, the use of green manure, composting, and integration of livestock. Comparative measurements were carried out on bare fallow and on “traditional farming” plots with monocropped cassava. With a mean annual precipitation of 1279 mm, a rainfall erosivity factor of R = 385 , and a slope of 28 percent, high annual soil losses were recorded on the bare fallow plot (557 tons per hectare per year) as well as on the cassava plot (303 t·ha −1 · y −1). The high soil losses recorded on the Grevillea plot (111 t · ha −1 · y −1) demonstrate that the problem of accelerated erosion on steep slopes cannot be solved by simply planting trees and by introducing management practices that provide a a better ground cover for only part of the year. In contrast, on agroforestry plots with supplementary erosion control hedges, erosion rates lower than 12,5 t · ha −1 · y −1 were measured. Agroforestry systems that include the integration of leguminous perennials as contour hedges offer a promising method for soil conservation even on slopes threatened by severe erosion.

The Hydrological Effects of a Wildfire in a Eucalypt Afforested Catchment

SYNOPSIS A high-intensity wildfire through a humid, upland catchment which was partially afforested to Eucalyptus fastigata, markedly increased stormflows and caused high soil losses off the afforested slopes. Total streamflow yield was unchanged but baseflow was reduced after the fire. The change in stormflow generation was caused by increased overland flow which resulted in shorter times of concentration and higher peak discharges during storms. Increased overland flows are linked to the widespread presence of water repellency in the plantation soils. The fire also increased the erodibility of the surface soils which were readily entrained by the overland flow, hence the accelerated soil erosion. Measured soil losses on the afforested slopes (55 t/ha) were roughly five times higher than those estimated from sediment in the stream (10 t/ha). The difference is attributed in large part to a healthy riparian buffer zone which was observed to have trapped large amounts of eroded soil and ash. The potential loss of site fertility and the threat of downstream flooding and sedimentation after such wildfires, lead us to advise forest managers to adopt a more positive approach to forest fuel management.

The effects of wildfire on soil wettability and hydrological behaviour of an afforested catchment

A wildfire in February 1986 destroyed most of an afforested research catchment in the southwestern Cape region of South Africa. The hydrological consequences of the fire were quantified using monitored pre-fire and post-fire stream flow and sediment data from the burned catchment and a nearby control catchment. Soil loss and soil wettability were also measured. In the first year after the fire, weekly stream flow totals increased by 12%, quick flow volumes increased by 201%, peak flow rates increased by 290% and catchment response ratio increased by 242%. Soil loss on overland flow plots ranged from 10 to 26 t ha −1, and suspended sediment and bedload yields each increased roughly four-fold following the fire. Wettability of the soils was greatly reduced by the passage of fire. Surface soil layers (0–10 mm) were burned clean of any inherent water repellency by the passage of a hot fire, but more severe repellency, in broader bands, was induced in deeper soil levels by the heating of the soil. It is postulated that the widespread development of water repellency in the soil led to overland flow during larger rainstorms, which in turn caused the markedly altered hydrological behaviour of the catchment and the high soil losses relative to the unburned condition.

Tillage and Canopy Cover Effects on Interrill Erosion from First‐Year Alfalfa

AbstractAlfalfa (Medicago sativa L.) establishment techniques commonly produce a soil surface susceptible to high runoff and soil losses prior to crop canopy development. Limited data are available on the erodibility and productivity of alfalfa seedbeds established with conservation tillage systems. Four alfalfa establishment techniques were investigated for runoff, erosion, and forage yield over two growing seasons on a Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudoll) with a 5% slope in south‐central Wisconsin. Alfalfa seedbeds were established on cropland previously in no‐till (NT) corn (Zea mays L.). Five simulated rainfalls were applied to moldboard (MB), moldboard‐nurse crop (MB/nc), chisel (CH), and NT alfalfa seedbeds. An additional seedbed investigated was no‐till with surface residue removed (NT/wo) immediately prior to rainfall simulation. Relative to MB, CH treatments reduced runoff volumes by 23 to 72% and NT treatments reduced volumes 59 to 100%. Soil‐loss reductions of 24 to 64% from CH and 71 to 100% from NT relative to MB were observed. Runoff volumes from NT/wo were the largest of all treatments for four of the five rainfall simulations. Soil losses from NT/wo were statistically similar (P = 0.05) to MB for all rainfall simulations. Comparisons of MB to MB/nc runoff volumes did not indicate an influence of canopy cover on runoff. A MB/nc soil loss of 87% less than MB at a rainfall simulation with MB/nc canopy cover of 93% relative to MB canopy cover of 47% did indicate a canopy effect on soil loss. No significant influence of canopy development on runoff volumes from similar treatments over time was evident. Canopy development contributed to reduced soil losses within all treatments, with a maximum reduction of 96% observed for MB/nc canopy cover of 93% relative to MB/nc soil loss at 0% canopy. Establishment year alfalfa yield and quality did not vary among MB, CH, and NT treatments at a significance level of P = 0.05.

Soil Loss Under Row Cropping of Sweet Potato, Soybean and Two Small Fruit Crops in Northern Alabama

Research was undertaken to evaluate the feasibility of utilizing vegetable and small fruit crops as a means of controlling soil erosion on a limited-resource farm. The crops selected were sweet potato (Ipomoea batatas , two small fruit crops of brambles / (Rubus spp.), and soybean (G ycine mar). Soybean was used as a control crop to compare the effectiveness of these crops in controlling erosion and their financial potential since most of the farmers used soybean in their farmin operations. Runoff was collected from P nineteen and eleven rainfal events from May through September 1986 and 1987, respectively, usin a modified Gerlach trough method. The runoff was analyzed to f etermine soil loss, particle size fractions of the eroded sediment, and organic matter [hat was removed with the soil particles. In addition, the duration and intensity of rainfall and percent vegetative cover were recorded for each rain-fall event. Soil and organic matter losses were significantly affected by crop type, canopy cover, rainfall duration, and the month in which the rainfall occurred. Sweet potato was most effective and ras berry the least effective in reducing soil loss and runoff. The re l uced soil loss and runoff from the sweet potato plots were attributed to higher percentage of ground cover and the ridge-planting technique used. The high soil loss and runoff from the raspberry plots were attributed to poor stand development and low percentage of ground cover. The article size fractions of the eroded sediments were enerally not af ected by crop type but b rainfall intensity. P P The b ackberry crop appeared to be more suite (Y for north Alabama than raspberry based on the ield produced. Even though the labor and cost of production of t i e vegetable and bramble crops were higher than for soybean, the net return was also higher.

Landscape Change and Man-Accelerated Soil Loss: The Case of the Sagarmatha (Mt. Everest) National Park, Khumbu, Nepal

Popular and policy-influencing hypotheses concerning historical, post-1950, and current landscape degradation within the Sagarmatha (Mt. Everest) National Park, Khumbu, Nepal, were tested through a number of complementary measures. Historical perspectives were provided by the assessment of soil profiles, pollen analysis of stratified soil samples, and the identification and 14C dating of charcoal samples found at various soil depths. Repeat photography, combined with ground-truth verification, enabled an assessment of existing claims that large-scale vegetation and geomorphic change had occurred in the Park during the past 29-34 years. Soil-loss study plots were installed on a stratified and replicated basis throughout the Imja Khola valley and monitored on a weekly basis between 6 April and 1 November 1984. Results suggested that man may have been frequenting and modifying the Khumbu landscape for considerably longer than the 400-year period generally assumed, and that substantial climatic change has occurred during the past 4,000 years. Since the 1950s, far less forest removal and geomorphic damage has occurred in the Khumbu than has been hitherto assumed; most shrub/grassland and forested slopes below 4,000 m are surficially stable, but high soil loss occurs in certain degraded alpine summer settlement areas because of continued shrub harvesting for fuelwood, grazing pressures, and natural freeze-thaw processes. Project results suggest that previous claims of serious landscape degradation in the Khumbu have been overstated. Similar mis- understandings are likely to exist for other regions of Nepal and contain the potential for adversely affecting development and land management policies there. Long-term, region-specific, and quantitative research is suggested to facilitate the better understanding, and thus better management, of the diverse environments characteristic of Nepal, the Himalaya, and the mountain world in general.

Simplified Process Model for Water and Sediment Yield from Single Storms Part II — Performance

ABSTRACT THE performance of a simplified process (SP) model for water and sediment yield from single storms was analyzed and compared to USLE performance using rainfall simulator and natural rainfall plot data. SP and USLE provided soil loss estimates with approximately equal accuracy on the rainfall simulator plots. Neither method was able to predict the extremely high soil losses which occurred on one of the sandy soil treatments. On steep slopes, the SP model performed much better than the USLE. The superiority of SP estimates for the steep slope plots was probably a result of distinct differences in the formulation of the two methods. Optimization of SP infiltration parameters generally improved both runoff and soil loss estimates. This underscores the importance of site-specific infiltrometer data in the estimation of infiltration parameter values.

Simulated Rainfall Duration and Sequencing Affect Soil Loss

ABSTRACT SOIL loss from 99-mm diameter laboratory samples of Hagerstown silty clay loam soil was measured under 55 mm/h simulated rainfall. The soil losses from two aggregate size distributions of the same soil were compared. When rain was applied in different durations, soil loss rates increased rapidly during the period when surface soil aggregates were being broken down by the rain drops. After the period of aggregate breakdown, the soil loss rates decreased and approached a long term constant rate as the soil surface was puddled and compacted by the rain drops. For sequenced rainfall events separated by 24-h drying periods, a series of twelve 5-min rainfall events on the coarse aggregates produced soil loss rates which were 86% greater than the soil loss rates measured from six 10-min rainfall events. Cumulative soil loss from the coarse aggregates which had received twelve 5-min rainfalls was 4.5 kg/m^, compared to 2.8 kg/m^ from the coarse aggregates which had received six 10-min rainfalls. In a series of storms, each event produces an initial high soil loss rate. When each storm is short this initial effect, repeated many times, produces greater soil losses than during longer storms which have fewer initial precipitation periods.

Soil organic matter dynamics in paired rangeland and cropland toposequences in North Dakota

The effects of cultivation and erosion on organic matter transformations were studied by systematically sampling slope positions on three paired rangeland and cropland toposequences. The toposequences were on differing parent materials, sandstone, siltstone and shale in southwestern North Dakota. Soils weathered from the three parent materials were all Haploborolls or Argiborolls but differed in texture and solum depth. Carbon, nitrogen, phosphorus and soil loss have been previously measured. Microbial biomass C and N by chloroform fumigation, mineralizable C and N during 10, 20 and 60 day incubations, and organic C and N content were measured. Decreases in the above soil properties occurred in cropland soils, but the proportion of organic N mineralized increased. Biomass and mineralizable C and N concentrations were correlated with organic C and N concentrations, rather than with total accumulation in the profile. Total accumulation and proportion of N mineralized were correlated with clay content. Changes in respiration:mineralization, mineralization:biomass and microbial C:N ratios suggested differences in substrate and microbial population composition between rangeland and cropland. Microbial biomass and mineralization rates did not vary with slope position, but parent material had significant effects. The siltstone site which had the highest soil losses began with the highest microbial biomass and mineralizable C and N concentrations and had the highest losses. The sandstone site suffered high soil but low OM constituent losses whereas the shale site suffered low soil and OM constituent losses. The sites can be classified in terms of their response to perturbation using concepts of “resistance” and “resilience” from ecosystem theory. The sandstone and shale sites may both be considered “resistant” with respect to agricultural perturbation, whereas the siltstone site was not.

Assessing Soil Loss in Kiambu and Murang'a Districts, Kenya

Soil loss was measured in Kiambu District during the long rainy season, 1982. From the data gathered during this period, the USLE was calibrated for the agro-ecologic conditions existing in the area. During 1983, soil loss measurements were collected in Murang'a District for the two growing seasons. Using the Kiambu calibrated USLE values, soil loss was estimated also for Murang'a. The significant correlation between the estimated and measured soil loss values indicates that the USLE, as calibrated for Kiambu, gives meaningful estimates in this area of Kenya. Nevertheless, the estimation of the erosivity values at the field level as well as the assessment of the conservation practices need further refinement.The measured soil loss values in both districts indicate that fields in annual crops, especially cotton and maize, result in the highest soil losses; perennial cash crops result in the lowest soil losses. It appears that approximately 25 % of the sampled fields are undergoing land degradation solely due to excessive soil losses. This is especially true in areas of recent agricultural expansion as they generally have higher soil losses than the established farming areas.

Runoff and Soil Loss in Trinidad under Different Crops and Soil Management

AbstractErosion caused by some of the farming practices on the major soil type (Orthoxic Tropudult) in the northern mountain range in Trinidad was assessed by measuring the runoff and soil loss from maize (Zea mays L.) and cowpea (Vigna unguiculata L. Walp) plots on 11, 22, and 52% slopes with and without tillage during the wet seasons in 2 consecutive years. The total rainfall for each of the three periods over which the experiments were conducted was 38.8, 22.4, and 82.5 cm, respectively.At the lower levels of rainfall there was generally a significant increase in soil loss (but not runoff) from the bare plots with an increase in slope from 11 to 22 to 52%; but a nonsignificant increase in both runoff and soil loss from the cropped plots. At the higher rainfall level, there were significant increases in soil loss from the bare and both of the cropped plots with an increase in slope from 11 to 22% only.The effect of tillage of the 22% slope on runoff and soil loss seems to have depended on the level and distribution of the rainfall and on the crop type. When rainfall is low, no‐tillage does not significantly affect runoff or soil loss, but it significantly (P = 0.05) reduces soil loss from bare plots if there are intense storms. At the highest rainfall level, no‐tillage still resulted in high soil losses (28 to 55 t/ha) and maize and cowpea (particularly maize) were less effective than at lower rainfall in reducing soil loss. Because of the high level of rainfall experienced in these hills the bare soil should not be exposed in the wet season and the clean cultivation of maize and cowpea in the wet season should not be recommended for slopes >11%.