Concentrations In Runoff Water Research Articles

Effects of Mechanical Harvest plus Chipping and Prescribed Fire on Sierran Runoff Water Quality

Fire suppression in Sierran ecosystems creates a substantial wildfire hazard and may exacerbate nutrient inputs into Lake Tahoe by allowing the buildup of O horizon material, which serves as a source for high N and P concentrations in runoff water. The purpose of this study was to evaluate the effects of biomass reduction using cut-to-length mechanical harvest followed by chipping and controlled burning on surface runoff volume and water quality. Based on previous findings regarding N and P leaching flux and soil solution concentrations, we hypothesized that controlled burning and/or mechanical harvest with residue chipping does not increase inorganic N, P, and S concentrations in overland flow. Runoff, snowmelt, and rainfall were collected, volume measurements were taken, and samples were analyzed for NO(3)-N, NH(4)-N, PO(4)-P, and SO(4). Runoff volume, season, and year were identified as important parameters influencing overland flow nutrient concentrations and loads. Higher nutrient concentrations were commonly associated with summer rather than winter runoff, but the opposite was true for nutrient loads due to the higher runoff volumes. Treatment (unharvested, harvested, unburned, burned) effect was a strong predictor for discharge loads of NO(3)-N and SO(4) but was a weak predictor for PO(4)-P. Discharge loads of NO(3)-N and SO(4) were greater for the unburned harvested and the burned unharvested treatments than for the unburned, unharvested control sites or the burned and harvested combined treatment. Although mechanical harvest and/or controlled burning had a small initial impact on increased nutrient loading, the effects were minimal compared with background levels. Hence, these management practices may have the potential to improve forest health without the danger of large-magnitude nutrient mobilization and degradation of runoff water quality found with wildfire.

Apatite Control of Phosphorus Release to Runoff from Soils of Phosphate Mine Reclamation Areas

Phosphorus (P) in runoff can pose a water quality risk in phosphate mine reclamation areas. High dissolved P (DP) concentrations (about 0.4–3.0 mg L−1) in runoff from these areas and high equilibrium P concentrations for the soils led us to hypothesize that P release is controlled by dissolution of apatite rather than by desorption mechanisms. Objectives were to (a) verify via chemical- and solid-state assessments that P in the reclamation soils is mainly in the form of apatite and (b) examine evidence that DP concentrations in runoff water from these soils is controlled by apatite dissolution. Soil analyses included total P (TP), P sorption isotherms, P fractionation, mineralogy, and P distribution by particle size classes. Runoff samples were chemically characterized and modeled for speciation. Results showed high TP concentrations and the presence of apatite. The Ca- and Mg-bound P accounted for about 95% of TP. Runoff samples were undersaturated with respect to apatite. A strong relationship between calculated apatite specific surface area and measured DP concentration in water extracts is supportive of other evidence that apatite dissolution is a major factor controlling P release from these soils. Data indicate that these soils will be a long-term P source rather than sink. Results are applicable to other phosphate mine reclamation sites and illustrate the need to account for compositional differences between reconstructed soils on reclaimed mining sites and their indigenous soil analogues.

Soil Nutrient and Sediment Loss as Affected By Erosion Barriers and Nutrient Source in Semi-Arid Burkina Faso

In semi-arid Sahel, soil erosion by water is one major factor accounting for negative nutrient balances in agricultural systems. A field experiment was conducted on a Ferric Lixisol in Burkina Faso to assess the effects of soil and water conservation barriers (stone rows or grass strips of Andropogon gayanus), the sole use of organic (compost) or mineral (urea) source of nitrogen (N), and the combined use of barriers and compost or urea nitrogen on soil nutrient and sediment erosion. The run-off barriers were put along contours. Organic carbon (OC) and nutrients losses through run-off and sediments were monitored during 2001 and 2002. Carbon and nutrient concentrations of generated sediments were very high, of 14–29 g kg−1 OC, 1.0–3.7 g kg−1 N and 0.32–0.71 g kg−1 total P. concentration in run-off water reached 0.023 g L−1 in stone rows treatments compared to only 0.002 g L−1 with treatments without barriers. Annual losses of organic C, N, P, and K were high and greatly dependant on soil loss magnitude. Compared to the control plots, soil losses were reduced on average by 84% during the 2 years with stone rows treatments, while by 71% with grass strips treatments. Compost application reduced soil loss by 75% in plots without barriers and by 89% in plots with stone rows as compared to control plots. With urea application, soil loss was on average 13% lower than in plots with compost. Integrated water and nutrient management can effectively alleviate soil, carbon, and nutrients losses by water erosion, therefore may contribute to intensifying crop production in Sahelian smallholder farming.

Soil Dissipation and Runoff Losses of the Herbicide Pendimethalin in Tobacco Field

The loss of pendimethalin, a selective herbicide, was determined in runoff water from loamy soil plots of various surface slopes cultivated with tobacco, over a period of 193 days. Conditions were selected to simulate agricultural practices employed in the Mediterranean region. The surface slopes of plots were 0%, 2.5%, 5%, 7.5%, and 10% and both cultivated and uncultivated (control) areas were simultaneously monitored. The cumulative losses of pendimethalin in surface runoff, as percentage of the initial applied active ingredient, were 0.067% for tilled and 0.098% for untilled soil of 10% slope, while for the plots of 0% slope they were ten times lower, 0.006% and 0.009% respectively. The maximum concentrations in runoff water reached 15.87 μg L−1 and were detected after the second run off event. The dissipation in top soil was studied for a period of 129 days. The half-lives that were calculated using first order kinetics ranged from 23 to 27.2 days in non-cropped soil and from 22.3 to 26.2 in tobacco plots.

Land Application of Sugar Beet By‐products: Effects on Runoff and Percolating Water Quality

Water quality concerns, including greater potential for nutrient transport to surface waters resulting in eutrophication and nutrient leaching to ground water, exist when agricultural or food processing industry wastes and by-products are land applied. Plot- and field-scale studies were conducted to evaluate the effects of sugar beet by-products on NO3-N and P losses and biochemical oxygen demand (BOD) in runoff and NO3-N concentrations in percolating waters. In the runoff plot study, treatments in the first year included two rates (224 and 448 Mg ha(-1) fresh weight) of pulp and spoiled beets and a nonfertilized control. In the second year, no by-products were applied on the treated plots, the control treatment was fertilized with N fertilizer, and an additional treatment was added as a nonfertilized control in buffer areas. Wheat (Triticum aestivum L.) was grown in the year of by-product application and sugar beet (Beta vulgaris L.) in the following year. In the percolation field study, the treatments were the control, pulp (224 Mg ha(-)(1)), and spoiled beets (224 Mg ha(-1)). Results from the runoff plot showed that both by-products caused immobilization of soil inorganic N and thus reduced NO3-N losses in runoff and soil waters during the first growing season. There was some risk of NO3-N exceeding the drinking water limit of 10 mg L(-1), especially between the period of wheat harvest and soil freezing in fall when pulp was applied at 448 Mg ha(-1). The field-scale study showed that by-product application at 224 Mg ha(-1) did not result in increased ground water NO3-N concentrations. Application of spoiled beets at both rates caused significantly higher BODs in runoff in the first year of application. The concentrations of total and soluble reactive P (SRP) were also higher from both rates of spoiled beet application and from the higher application rate of pulp during the 2-yr study period. These high BODs and total P and SRP concentrations in runoff waters from land application of sugar beet by-product suggest that application rates should not be higher than 224 Mg ha(-1). Best management practices that prevent runoff from entering surface waters directly from these fields are warranted.

Characteristics of Nutrient Transport from Tate's Hell State Forest into East Bay in Florida

From 1988 to 1998, silvicultural activities impacted 5,856 km of rivers and streams in the southern United States. Internal cycling of nutrients from the water column and sediment in a forest can be an important contribution to the nutrient load of aquatic ecosystems. Therefore, understanding nutrient transport in forests can aid efforts to protect aquatic resources. Two watersheds in Tate's Hell State Forest in northwest Florida were selected to conduct a study of silvicultural impacts on surface water quality. Of the two sites one had been impacted with ditching and fertilization while the other site was not. From June 2003 to May 2005 a field study determined nutrient [nitrate-nitrogen (NO3-N); ammonia-nitrogen (NH3-N) and ortho-phosphate (PO4−)] concentrations in run-off water and sediment in these watersheds. Results showed NO3-N, NH3-N and ortho-phosphate concentrations in water and sediment, were higher at the impacted site verses the non-impacted site. At the impacted site NO3-N, NH3-N and ortho-phosphate concentrations in the water column were 16% to 33%, 39% to 47% and 66% higher, respectively. Nutrient concentrations in sediment from the impacted site were significantly (p< 0.05) higher than those from the un-impacted site and ranged (in mg kg−1) from 0.25 ± 0.01 to 0.44 ± 0.03 for NO3-N; 6.41 ± 0.19 to 12.77 ± 0.45 for NH3-N; and 1.01± 0.02 to 1.50 ± 0.02 for PO4−. In this ecosystem sediment acted as a source of NH3-N and ortho-phosphate and as a sink for NO3-N. These results indicate that proper management of inactive silvicultural sites is necessary to mitigate nutrient transport to aquatic systems.

PHOSPHORUS IN RUNOFF FROM TWO WATERSHEDS IN LOST RIVER BASIN, WEST VIRGINIA

The loss of nutrients in runoff from soils treated with heavy manure application is a major cause of poor surface water quality in the United States. Poultry production in the Hardy County, West Virginia, has increased considerably since the early 1990s. The Lost River basin contains the highest density of poultry houses in the county. Most of phosphorus (P)-rich manure produced is land applied, and concerns over water quality impacts are widespread. The objectives of this study were to apply the Natural Resources Conservation Service technique on two watersheds (Cullers Run and Upper Cove Run) in the Lost River basin to predict the loss of water and P from soils by runoff and to estimate the impact on water quality. The predicted average runoffwas 4374 m 3 /ha per year, and agreed with the observed average runoff of 4267 m 3 /ha per year. This gives an annual runoff of 74.6 million m 3 for the two watersheds. The average P loss by runoffwas 0.57, 1.98, and 5.51 kg/ha per year from soils under forest, pasture, and crop, respectively. The high P loss by runoff was probably associated with application of P fertilizer or poultry manure to cropped soils. The total annual loss of P from soils by runoff was estimated at 16,435 kg. The predicted P concentration varied widely in runoff water generated from different soils and land covers. The average P concentration in runoff water was 133, 432, and 1146 μg/L for forestland, pastureland, and cropland, respectively. The predicted average P concentration in runoff was 224 μg/L for the two watersheds. However, the observed P concentration was very low (1.3-13.3 μg/L) in the monthly water samples (January-December 2006) collected from the Lost River, where the pH ranged between 7.6 and 8.4. The average pH in soils was 4.22, 5.42, and 6.15 for forest-land, pastureland, and cropland, respectively. Changing the pH of runoff water from acidic (soils) to the alkaline range in the Lost River could precipitate calcium phosphates and decrease P concentration in water. The technique predicted P concentration in runoff at the edge of field. The increase in water pH as well as P removal by aquatic weeds and algae could be the cause of the low P concentration observed in the Lost River.

Rethinking the Contribution of Drained and Undrained Grasslands to Sediment‐Related Water Quality Problems

Grass vegetation has been recommended for use in the prevention and control of soil erosion because of its dense sward characteristics and stabilizing effect on the soil. A general assumption is that grassland environments suffer from minimal soil erosion and therefore present little threat to the water quality of surface waters in terms of sediment and sorbed contaminant pollution. Our data question this assumption, reporting results from one hydrological year of observations on a field-experiment monitoring overland flow, drain flow, fluxes of suspended solids, total phosphorus (TP), and molybdate-reactive phosphorus (<0.45 mum) in response to natural rainfall events. During individual rainfall events, 1-ha grassland lysimeters yield up to 15 kg of suspended solids, with concentrations in runoff waters of up to 400 mg L(-1). These concentrations exceed the water quality standards recommended by the European Freshwater Fisheries Directive (25 mg L(-1)) and the USEPA (80 mg L(-1)) and are beyond those reported to have caused chronic effects on freshwater aquatic organisms. Furthermore, TP concentrations in runoff waters from these field lysimeters exceeded 800 mug L(-1). These concentrations are in excess of those reported to cause eutrophication problems in rivers and lakes and contravene the ecoregional nutrient criteria in all of the USA ecoregions. This paper also examines how subsurface drainage, a common agricultural practice in intensively managed grasslands, influences the hydrology and export of sediment and nutrients from grasslands. This dataset suggests that we need to rethink the conceptual understanding of grasslands as non-erosive landscapes. Failure to acknowledge this will result in the noncompliance of surface waters to water quality standards.

Soil and water environmental effects of fertilizer-, manure-, and compost-based fertility practices in an organic vegetable cropping system

Degraded soil quality, which decreases agricultural productivity and increases nonpoint source pollution of surface water, may be ameliorated by employing soil organic matter enhancing management, such as practiced by compost use in organic farming. The value of compost applied at rates lower than those required to supply crop nutrient needs requires investigation because applying compost at agronomic nitrogen rates may not be economically feasible for organic vegetable producers. We conducted field research during 2000–2002 on a Luvisol to compare the nutrient and non-nutrient effects of various rates and timings of mixed poultry litter-yard waste compost with a traditional organic fertilizer (poultry litter) and inorganic fertilizer on environmental soil attributes and water quality in an organic vegetable crop rotation. Soil organic C, total N, and available P increased 60%, 68%, and 225%, respectively, above the control with the application of 144 Mg ha −1 compost (dry wt.) during the 3-year study, but the low rate of compost (31 Mg ha −1) did not affect soil C or N. Compost N mineralization was not synchronous with sweet corn N assimilation, resulting in excess root zone nitrate that would have posed a leaching risk without the use of a winter rye N-scavenging cover crop. The concentrations of nitrate N that leached below the tillage zone occasionally exceeded the 10 mg L −1 health standard but were not different among the agronomic rates of compost, poultry litter, fertilizer, and control treatments for nearly every sampling event. Despite increasing runoff water concentrations of N and P, the high compost rate reduced the amounts of N and P that were transported from the soil surface by five-fold and four-fold, respectively, compared to the inorganic fertilizer due to a four-fold reduction in runoff volume. Crop yields did not benefit from low compost rates during the 3-year duration of the study; however, improvements in some bulk density and porosity indicated that benefits of longer term, low compost rate additions may accrue over time.

Ion enrichment of snowmelt runoff water caused by basal ice formation

AbstractOnce meltwater reaches the base of a snowpack it can infiltrate the underlying stratum, runoff, or refreeze and form a basal ice layer. Basal ice formation is most common early in melt over saturated or very cold frozen soils. Initial meltwater becomes enriched in ion concentrations compared to the parent snow due to ion fractionation during thaw and percolation through the snowpack. If ion exclusion occurs during basal ice formation, further enrichment of initial runoff water ion concentrations might occur. The influence of basal ice formation on runoff water chemistry was examined by comparing ion concentrations in runoff water that had sustained basal ice contact, to meltwater before basal ice contact. A series of experiments, involving melting a snowpack in a large insulated box over a cold impermeable substrate in a temperature‐controlled room, were carried out. A cooling system at the chemically inert base ensured formation of basal ice during snowmelt. Meltwater samples were collected throughout melt from within the snowpack using an extraction tube; runoff water was collected at the base. All samples were analysed for major anions and cations. Results showed that formation of basal ice layers can sometimes enrich the initial runoff water compared to meltwater before basal ice contact. Ion concentrations in basal ice contact runoff water were up to sixteen times greater than those in no‐contact meltwater; however, on average, basal ice contact runoff water showed 1·5 times the ion concentrations of the no‐contact meltwater. Enrichment was greatest with the rapid formation of a thick basal ice layer. The implications are that basal ice formation alters both meltwater ion pathway and concentration. When no basal ice is present, enhanced infiltration of meltwater ion load can cause relatively dilute runoff water. When basal ice is present all meltwater runs off and further ion‐concentration enrichment occurs. Copyright © 2008 John Wiley &amp; Sons, Ltd.

인공강우와 콩재배 포장 라이시메타를 이용한 endosulfan의 유출량 평가

강우에 의한 경사지 토양으로부터의 농약 유출양상을 파악하고 그에 대한 농약의 특성, 환경적 요인 및 영농방법 등의 영향 정도를 평가하기 위하여 토양흡착실험과 인공강우유출 실험 및 콩 재배 lysimeter 포장에서 유출실험을 수행하였다. Endosulfan의 흡착법에 의한 흡착계수 (K)는 <TEX>$77{\sim}131$</TEX>이었으며, 탈착법에 의한K값이 흡착법으로 구한 값보다 높았다. 영국 SSLRC의 이동성 분류기준에 의하면 endosulfan은 Koc 4,000을 초과하여 non-mobile 등급에 속하였다. 인공강우 처리구의 유출수 및 유실토양에 의한 endosulfan의 유실율은 <TEX>$3.4{\sim}5.6%$</TEX> 및 <TEX>$4.4{\sim}15.6%$</TEX>이었다. 인공강우실험 후 토심별 분포를 살펴 본 결과 대부분의 endosulfan 잔류분은 토심 5 cm 이내에 잔류하였다. 경사도 30%의 경우가 10%에 비하여 각 농약의 유실량이 <TEX>$0.6{\sim}0.9$</TEX>배 많았는데 유출수에 의한 농약의 유실량 차이는 유출수 중 농도 차이로 볼 수 있으며, 유실토양에 의한 농약 유실량 차이는 토양 유실량과 관계되는 것으로 생각되었다. Lysimeter 포장유출실험 결과 경사도 및 경사장별 endo-sulfan 유실량은 살포량 대비 <TEX>$5{\sim}35%$</TEX> 수준이었다. 콩재배구의 유실율은 나지구의 유실율에 비하여 평균 66% 수준이었다. 경사조건의 영향을 살펴보면 유출수의 경우에는 그 차이가 크지 않았으나 유실토양에 의한 유실율은 경사도와 경사장 증가에 따라 <TEX>$4{\sim}12$</TEX>배까지 증가하는 것으로 나타났다. 한편 유출수 중 농약성분의 최고농도는 콩재배구 및 나지구 각각 <TEX>$8{\sim}10{\mu}gL^{-1}$</TEX> 및 <TEX>$7{\sim}9{\mu}gL^{-1}$</TEX> 수준으로 작물 재배 여부에 따른 유출수 중 농도의 차이는 크지 않은 것으로 나타났다. Three different experiments were carried out to investigate the runoff and erosion losses of endosulfan from sloped-field by rainfall. The mobility of endosulfan and which phase it was transported by were examined in adsorption study, the influence of rainfall pattern and slope degree on the pesticide loss were evaluated in simulated rainfall study, and the pesticide losses from soybean-grown field comparing with bare soil were measured in field lysimeter study. Adsorption parameter (K) of endosulfan ranged from 77 to 131 by adsorption method and K values by the desorption method were higher than those by the adsorption method. By the SSLRC's classification for pesticide mobility endosulfan was classified as non-mobile class (<TEX>$K_{oc}>4,000$</TEX>). Runoff and erosion loss of endosulfan by three rainfall scenarios ranged from 3.4 to 5.6%and from 4.4 to 15.6%of the amount treated. Endosulfan residues were mainly remained at the top 5 cm of soil depth after the simulated rainfall study. Pesticide loss in case of 30%-slope degree ranged from 0.6 to 0.9 times higher than those in case of 10%-slope degree. The difference of pesticide runoff loss was related with its concentration in runoff water and the difference of pesticide erosion loss would related closely with the quantity of soil eroded. Endosulfan losses from a series of lysimeter plots in sloped land by rainfall ranged from 5 to 35% of the amount treated. The erosion rate of endosulfan from soybean-plots was 66% of that from bare soil plots. The effect of slope conditions was not great for runoff loss, but was great for erosion loss as increasing to maximum <TEX>$4{\sim}12$</TEX> times with slope degree and slope length. The peak runoff concentration of endosulfan in soybean-plots and bare soil plots ranged from 8 to 10 and from 7 to <TEX>$9{\mu}gL^{-1}$</TEX> on nine plots with different slope degree and slope length. Therefore the difference of the peak runoff concentrations between bare soil plots and soybean-plots were not great.

Nitrogen and Phosphorus Runoff Losses from Orchard Soils in South China as Affected by Fertilization Depths and Rates

Fertilizers are heavily applied in orchards of the hilly and mountainous topography of South China and may increase nutrient loadings to receiving waters. A simple runoff collecting system was used to measure the effects of different fertilization treatments on total N and P concentrations of surface runoff in a Chinese chestnut ( Castanea mollissima Blume) orchard in Dongyuan County, Guangdong Province, China, fn such orchards, fertilizer was typically applied in two short furrows or pits on either side of each tree. Treatments included three application depths (surface, 10 cm and 20 cm), and three application rates (low, median and high). Results showed that 90.5% of the runoff water samples had a total N concentration higher than 0.35 mg L −1 and 54.2% had a total P concentration higher than 0.1 mg L −1. Fertilizer application at all depths and at all but the lowest rate significantly increased total N and P concentrations in runoff water. Fertilization with chemical compound fertilizer at a soil depth of 20 cm produced significantly lower ( P < 0.05) total N concentration in runoff than both surface and 10-cm depth fertilization, and significantly lower ( P < 0.05) total P concentration in runoff than surface fertilization. Total N and P concentrations in runoff significantly increased with the application rate of organic fertilizers. With the exception of total P concentrations, which were not significantly different between the control and fertilization at a rate of 119 kg P ha −1 in organic form, all the other fertilization treatments produced significantly higher total N and total P concentrations in runoff than the control. A fertilization depth ≥ 20 cm and an application rate ≤ 72 kg N ha −1 or 119 kg P ha −1 for compound organic fertilizer was suggested to substantially reduce N and P runoff losses from hillslope orchards and to protect receiving waters in South China.

제주 화산회토양에서 돈분액비 시용이 유거수의 특성에 미치는 영향

제주지역에서 사료작물 작부체계에 있어 여름철에 주로 재배되고 있는 수수<TEX>$\times$</TEX>수수 교잡종을 공시하여 lysimeter에 돈분액비 시용수준이 유거수의 특성에 미치는 영향을 구명하기 위하여 무비구, 화학비료구(200kg N/ha), 돈분액비 시용구(200, 400, 600kg N/ha) 등 5처리를 두어 난괴법 3반복으로 수행하였다. 돈분액비의 시용 초기에 유거수내 BOD 및 COD는 돈분액비 600kg N/ha 시용구가 다른 처리구에 비해 유의적으로 높았다(p<0.05). 또한 돈분액비 시용량이 증가할수록 유거수의 T-N는 증가하였다. 그러나 유거수 중의 T-P 농도는 돈분액비 시용수준에 대한 영향은 크게 나타나지 않았다. 유거수 중의 <TEX>$NO_3-N$</TEX> 및 <TEX>$NH_4-N$</TEX> 농도는 돈분액비 시용수준이 증가할 수록 높았다(p<0.05). 결론적으로 제주 화산회토양에서는 돈분액비 시용량이 증가할 수록 수수<TEX>$\times$</TEX>수수 교잡종의 건물수량은 높일 수 있으나 유거수에 의한 환경오염이 우려된다. 따라서 제주 화산회토양에서 화학비료를 대체하기 위한 돈분액비 이용은 200kg N/ha 시용하는 것이 환경 오염방지 측면에서 안전할 것으로 판단된다. This study was conducted to determine the effects of application levels of pig slurry on the characteristics of runoff water in volcanic ash soil in Jeju, Korea. This study was arranged in randomized complete block design. The data represent the means of the three experiments. Experimental plots were consisted of five treatments such as no fertilizer, chemical fertilizer at 200kg N/ha/year and pig slurry levels at 200, 400 and 600kg N/ha/year. The concentrations of BOD and COD in 600kg N/ha pig slurry were significantly higher (p<0.05) than those of the other treatments at initial sampling at 12 days after application. The total nitrogen concentration in runoff water increased with increasing pig slurry. The total phosphorous concentration in runoff water was hardly influenced by application levels of pig slurry since there were no significant difference among the treatments. The concentrations of <TEX>$NO_3-N\;and\;NH_4-N$</TEX> were raised (p<0.05) in proportion to application levels of pig slurry. In conclusion, pig slurry usage at 200kg N/ha to the volcanic ash soil in Jeju area can replace the chemical fertilizer. However, more than 200kg N/ha of pig slurry may not be appropriate, because it may contaminate the water environment.

Impact of fertilization on chestnut growth, N and P concentrations in runoff water on degraded slope land in South China

Growing fruit trees on the slopes of rolling hills in South China was causing serious environmental problems because of heavy application of chemical fertilizers and soil erosion. Suitable sources of fertilizers and proper rates of applications were of key importance to both crop yields and environmental protection. In this article, the impact of four fertilizers, i.e., inorganic compound fertilizer, organic compound fertilizer, pig manure compost, and peanut cake (peanut oil pressing residue), on chestnut (Castanea mollissima Blume) growth on a slope in South China, and on the total N and total P concentrations in runoff waters have been investigated during two years of study, with an orthogonal experimental design. Results show that the organic compound fertilizer and peanut cake promote the heights of young chestnut trees compared to the control. In addition, peanut cake increases single-fruit weights and organic compound fertilizer raises single-seed weights. All the fertilizers increased the concentrations of total N and total P in runoff waters, except for organic compound fertilizer, in the first year experiment. The observed mean concentrations of total N varied from 1.6 mg/L to 3.2 mg/L and P from 0.12 mg/L to 0.22 mg/L, which were increased with the amount of fertilizer applications, with no pattern of direct proportion. On the basis of these experiment results, organic compound fertilizer at 2 kg/tree and peanut cake at 1 kg/tree are recommended to maximize chestnut growth and minimize water pollution.

인공강우에 의한 alachlor, ethalfluralin, ethoprophos 및 pendimethalin의 토양표면 유출

Two different experiments, adsorption/desorption and runoff by rainfall simulation of four pesticides, such as alachlor, ethalfluralin, ethoprophos and pendimethalin were undertaken their runoff and erosion losses from sloped land and to assess the influence of their properties and environmental factors on them. The mobility of four pesticides and which phase they were transported by were examined in adsorption study, and the influence of rainfall pattern and sloping degree on the pesticide losses were evaluated in simulated rainfall study. Freundlich adsorption parameters (K) by the adsorption and desorption methods were 1.2 and 2.2 for ethoprophos, 1.5 and 2.6 for alachlor, respectively. And adsorption distribution coefficients (Kd) by the adsorption and desorption methods were 56 and 94 for ethalfluralin, and 104 and 189 for pendimethalin, respectively. K or Kd values of pesticides by the desorption method which were desorbed from the soil after thoroughly mixing, were higher than these ones by the adsorption method which pesticides dissolved in water were adsorbed to the soil. Another parameter (1/n), representing the linearity of adsorption, in Freundlich equation for the pesticides tested ranged from 0.96 to 1.02 by the desorption method and from 0.87 to 1.02 by the adsorption method. Therefore, the desorption method was more independent from pesticide concentration in soil solution than the adsorption method. By Soil Survey and Land Research Center (SSLRC)'s classification for pesticide mobility, alachlor and ethoprophos were classified into moderately mobile $(75{\leq}Koc 4000). Runoff and erosion loss of pesticides by three rainfall scenarios were from 1.0 to 6.4% and from 0.3 to 1.2% for alachlor, from 1.0 to 2.5% and from 1.7 to 10.1% for ethalfluralin, from 1.3 to 2.9% and from 3.9 to 10.8% for pendimethalin, and from 0.6 to 2.7% and from 0.1 % 0.3% for ethoprophos, respectively. Distribution of pesticides in soil profile were investigated after the simulated rainfall study. Alachlor and ethoprophos were leached to from 10 to 15 cm of soil layer, but ethalfluralin and pendimethalin were mostly remained at the top 5 cm of soil profile. The losses of the pesticides at 30% of sloping degree were from 0.2 to 1.9 times higher than those at 10%. The difference of their runoff loss was related with their concentration in runoff water while the difference of their erosion loss must be closely related with the quantity of soil eroded.

Aging Effects on the Availability of Herbicides to Runoff Transfer

Realistic estimation of sorption parameters is essential to predict long-term herbicide availability in soils and their contamination of surface water and groundwater. This study examined the temporal change of an effective partition coefficient Kd(eff) for the herbicides simazine, diuron, and oryzalin from a 0.12 ha field experiment during 7 vineyard growing seasons. Kd(eff) is the ratio of solvent extractable herbicide concentrations in the top soil (0-2 cm) to the average concentrations in runoff water and is considered to assess the effective availability of herbicides to runoff transfer. Kd(eff) increased largely with aging time since application, from values similar to those of the literature (determined in 24 h batch conditions, Kd(ref)), up to 88, 164, and 30 times these initial values for simazine, diuron, and oryzalin respectively. The seasonal variation of Kd(eff) values between years and compounds could be adequately described by a unique model, taking into account the cumulative rainfall since application and Kd(ref) of each compound. This simple model was able to represent the influence of the soil moisture content and its changes in the different biological and physicochemical processes that may contribute to the (bio)available, sorbed, or entrapped state of any of the studied herbicides with aging time under Mediterranean climate.

Phosphorus, potassium and organic carbon concentrations in runoff water and sediments under different soil tillage systems during soybean growth

Runoff transports nutrients and impoverishes agricultural soils, causing off-site environment contamination. The objective of this study was to quantify P, K and organic carbon concentrations in runoff under different soil tillage systems. The experiment was carried out in the field, under simulated rainfall, during soybean growth, from April 2003 to May 2004, in the Santa Catarina highlands, Southern Brazil, on a typical Hapludox. The evaluated soil tillage treatments (which were replicated) were: (i) continuous bare soil (BS), (ii) conventional tillage on a desiccated residue (CT), (iii) no till on a burned residue, in a never-tilled soil (BNT), (iv) no till on a desiccated residue, in a never-tilled soil (DNTnt) and (v) no till on a desiccated residue, in soil tilled 4 years before (DNTt). Fodder radish ( Raphanus sativus) residues were managed as indicated prior to planting soybean crop. As a result, no-till treatments have higher P, K and organic carbon concentrations in the superficial 0–0.025 m soil layer and in runoff sediments than CT. The highest enrichment ratios were of 0.90, 1.34 and 1.17 for P, K and organic carbon, and occurred in burned no till, bare soil and conventional treatments, respectively. P and K concentrations in runoff water reached in the first rainfall test 1.0 and 15.8 mg L −1 in the no-till treatments, and were higher than in the CT treatment, where these contents were only of 0.09 and 1.9 mg L −1, respectively. Crop residue burning increased P and K and reduced organic carbon levels in the topsoil layer compared to other non-burned treatments. In the runoff water, burning increased P and K concentrations, while in sediments, it presented higher P and organic carbon contents and reduced K levels, in relation to non-burned plots. Positive linear correlations were obtained between P and K in runoff water and P, K and organic carbon in sediments, and their respective levels in the 0–0.025 m soil layer. P and K concentrations in runoff water decreased exponentially in the no-till treatments, and linearly in CT and BS with the number of rains applied. P contents in sediments exponentially decreased, while K potentially increased with the size of the particles in the sediments transported in runoff. There was no relationship between organic carbon content in runoff sediments loss and sediment size.

The effect of fertiliser and grazing on nitrogen export in surface runoff from rain-fed and irrigated pastures in south-eastern Australia

Nutrients, including nitrogen (N), exported from agricultural systems contribute to eutrophication and the development of algal blooms. Understanding the relative effect of farm management on nutrient export will indicate the extent to which farmers can potentially mitigate this process. Six years of monitoring surface runoff from rain-fed and irrigated dairy pastures was carried out in south-eastern Australia. Over the monitoring period, the flow-weighted mean annual total N (TN) concentrations in runoff varied between 8.2 and 29 mg/l for rain-fed pasture and 8.7 and 58 mg/l for irrigated pasture. An additive component model describing N concentrations separated the management (grazing and fertiliser) and year effects from other processes. The model accounted for 40 and 47% of the variation in N concentrations for the rain-fed and irrigated pastures, respectively. While fertiliser application, grazing and year had a significant effect on concentrations, other variables that are not necessarily under management control significantly affected N export. With current knowledge, improved management of pasture-based systems such as improved timing of fertiliser application and grazing relative to runoff may only result in a small decrease in N export. The remainder of the variability was attributed to environmentally mediated changes of N concentrations in runoff water. The collection of more detailed information on environmental parameters including soil moisture and soil temperature is proposed, to enable a better prediction of N concentrations and therefore improved understanding of potential management strategies.

Effect of Chemical and Microbial Amendment on Phosphorus Runoff from Composted Poultry Litter

Environmental impacts of composting poultry litter with chemical amendments at the field scale have not been well quantified. The objectives of this study were to measure (i) P runoff and (ii) forage yield and N uptake from small plots fertilized with composted and fresh poultry litter. Two composting studies, aerated using mechanical turning, were conducted in consecutive years. Composted litter was collected at the completion of each study for use in runoff studies. Treatments in runoff studies included an unfertilized control, fresh (uncomposted) poultry litter, and litter composted with no amendment, H3PO4, alum, or a microbial mixture. An additional treatment, litter composted with alum plus the microbial mixture, was evaluated during the first year. Fertilizer treatments were applied at rates equivalent to 8.96 Mg ha(-1) and rainfall simulators were used to produce a 5 cm h(-1) storm event. Composted poultry litter, regardless of treatment, had higher total P concentrations than fresh poultry litter. Composting poultry litter resulted in reductions of N/P ratios by as much as 51%. Soluble reactive P concentrations were lowest in alum-treated compost, which reduced soluble P concentrations in runoff water by as much as 84%. Forage yields and N uptake were greatest from plots fertilized with fresh poultry litter. Composting poultry litter without the addition of C sources can increase P concentrations in the end product and surface runoff. This study also indicated that increased rates of composted poultry litter would be required to meet equivalent N rates supplied by fresh poultry litter.

Determining Phosphorus Release Rates to Runoff from Selected Alberta Soils Using Laboratory Rainfall Simulation

Phosphorus losses from agricultural land can cause accelerated eutrophication of surface water bodies. This study evaluated the use of soil test phosphorus (STP) levels to predict dissolved inorganic phosphorus (DIP) concentrations in runoff water from agricultural soils using laboratory rainfall simulation. The objectives of this study were to determine (i) to what extent STP concentrations can be used as a basis to predict P losses from Alberta soils and (ii) how extended rainfall simulation run times affected DIP losses. Soil samples collected from a total of 38 field sites, widely scattered throughout the southern half of Alberta, were subjected to rainfall simulation in the laboratory. The STP concentrations were determined using Miller-Axley, Norwest, Kelowna, Modified Kelowna Mehlich-III, and distilled water extraction methods. Each rainfall simulation event lasted for at least 90 min. Runoff samples were collected in time series for the duration of each simulation, during two distinct runoff intervals: (i) for the first 30 min of continuous runoff (T30) and (ii) for 40 min during runoff equilibrium (Teq). For all the STP extractants and both runoff intervals, the relationship with DIP-flow-weighted mean concentration (FWMC) was linear and highly significant with r2 values ranging from 0.74 to 0.96. However, the slopes of the resulting regression lines were, on average, 1.85 times greater for the T30 runoff interval over those computed for the Teq interval. Thus experimental methodology greatly influenced regression parameters, suggesting that more work was needed to verify these relationships under natural conditions. In addition, with many of the r2 values greater than 0.90 there would be little, if any, benefit derived by including soil properties in regression analysis.