Water Infiltration Capacity Research Articles

Struktur Komunitas Mesofauna Tanah dan Kapasitas Infiltrasi Air setelah diberi Perlakuan Biostarter Pengurai Bahan Organik

Research about the biostarter application on the biopori concept through parameter of soil mesofauna community structure and water infiltration capacity was aimed to investigate the effect of biostarter product on soil mesofauna community structure and water infiltration rate at Lubang Resapan Biopori (LRB) aged 30 days and 50 days, also the correlation between mesofauna community structure and soil infiltration capacity. This study uses a single factor completely randomized design, which has 5 treatments including control, EM4, Bioklin, Mig Dec, and Orgadec. The results showed that the addition of biostarter affects soil mesofauna community structure, particularly positive effect on the abundance of Oribatida and Mesostigmata. Products Orgadec was able to increase faster the abundance of mesofauna both at the age of LRB 30 days and 50 days, whereas Mig Dec and EM4 starting to show its influence on the LRB after 50 days. Infiltration rate LRB age of 30 days showed a significant difference in treatment of Orgadec only, whereas at the age of 50 days, the significant difference is indicated in the treatment EM4​​, Mig Dec and Orgadec. Based on the Spearman correlation test, the total number of individuals and number of Oribatida. Both showed significant positive correlation with the infiltration rate. Keywords: biostarter, community structure, soil mesofauna, infiltration rate, LR

Effects of sodium polyacrylate on water retention and infiltration capacity of a sandy soil

Based on the laboratory study, the effects of sodium polyacrylate (SP) was investigated at 5 rates of 0, 0.08, 0.2, 0.5, and 1%, on water retention, saturated hydraulic conductivity(Ks), infiltration characteristic and water distribution profiles of a sandy soil. The results showed that water retention and available water capacity effectively increased with increasing SP rate. The Ks and the rate of wetting front advance and infiltration under certain pond infiltration was significantly reduced by increasing SP rate, which effectively reduced water in a sandy soil leaking to a deeper layer under the plough layer. The effect of SP on water distribution was obviously to the up layer and very little to the following deeper layers. Considering both the effects on water retention and infiltration capacity, it is suggested that SP be used to the sandy soil at concentrations ranging from 0.2 to 0.5%.

Enhancement of Artificial Infiltration Capacity in Low Permeability Soils for Gaza Coastal Aquifer

Water is a key component in determining the quality of our lives. Today, people are concerned about the quality of the water they drink. Groundwater aquifer is considered the main and the only water supply source for all kinds of human usage in the Gaza Strip which is severely deteriorated in-terms of quality and quantity in the past two decades. In the past years, several researches have been conducted on the enhancement of the role of storm water infiltration system aimed mainly at improving the quality and the availability of water. This paper investigates methods to enhance the storm water infiltration capacity of Sheikh Radwan Reservoir by using soil column pilot experiment of specific sand media and simulating the real situation using the MODFLOW groundwater flow model. The sample of storm water was collected from the reservoir in the wet season, and was allowed to infiltrate through the soil column of 170 cm depth in the soil experiment. The results of soil experiment showed that the quality of infiltrated water (BOD, COD, Suspended Solid, Ammonia) was found to conform to Palestinian standard for aquifer infiltration with 90% percent removal of contaminants, which indicate the effectiveness of the used soil media. The simulation of MODFLOW model was done considering different number and distribution of infiltration wells. The results showed an increase of water quantity in groundwater aquifer with maximum water level mound of 6 m beneath the reservoir after 3 months of flooding, and started to decrease gradually to reach -2 m to -3 m in the dry season which reflect the normal situation. The results of the study showed that 33 infiltration wells are needed to evacuate the collected storm water at the reservoir within 10 days which satisfy the function of the reservoir as flood relief and infiltration. Also it is recommended by the study to increase the sand filter depth to 2 m, in order to improve the removal percentage of contaminants to reach 100%.

Wheat yield and physical properties of a brown latosol under no-tillage in south-central Paraná

Soil management influences the chemical and physical properties of soil. Chemical conditions have been thoroughly studied, while the role of soil physical conditions regarding crop yield has been neglected. This study aimed to analyze the wheat yield and its relationship with physical properties of an Oxisol under no-tillage (NT). The study was carried out between 2010 and 2011, in Reserva do Iguaçu, State of Paraná, Brazil, on the Campo Bonito farm, after 25 years of NT management. Based on harvest maps of barley (2006), wheat (2007) and maize (2009) of a plot (150 ha), zones with higher and lower yield potential (Z1 and Z2, respectively) were identified. Sampling grids with 16 units (50 x 50 m) and three sampling points per unit were established. The wheat grain yield (GY) and water infiltration capacity (WIC) were evaluated in 2010. Soil samples with disturbed and undisturbed structure were collected from the 0.00-0.10 and 0.10-0.20 m layers. The former were used to determine soil organic carbon (Corg) levels and the latter to determine soil bulk density (BD), total porosity (TP), macroporosity (Mac), and microporosity (Mic). Soil penetration resistance (PR) and water content (SWC) were also evaluated. The wheat GY of the whole plot was close to the regional average and the yield between the zones differed significantly, i.e. 22 % higher in Z1 than in Z2. No significant variation in Mic was observed between zones, but Z1 had higher Corg levels, SWC, TP and Mac and lower BD than Z2 in both soil layers, as well as a lower PR than Z2 in the 0.00-0.10 m layer. Therefore, soil physical conditions were more restrictive in Z2, in agreement with wheat yield and zone yield potential defined a priori, based on the harvest maps. Soil WIC in Z1 was significantly higher (30 %) than in Z2, in agreement with the results of TP and Mac which were also higher in Z1 in both soil layers. The correlation analysis of data of the two layers showed a positive relationship between wheat GY and the soil properties TP, SWC and WIC.

A New Model on the Hydraulic Conductivity of Asphalt Mixtures

It is well known that asphalt mixtures with different air void contents will present different drainage capacity, but until now there is not a model that evaluates its water infiltration capacity considering its air void content value. For this reason, a new model to predict the hydraulic conductivity (permeability) of asphalt mixtures as a function of its air void content has been proposed in this paper. Additionally, this paper presents the laboratory results and procedures used to measure the hydraulic conductivity of asphalt mixtures with a wide range of air void content. With this purpose, four types of asphalt mixtures with different aggregate distribution (dense, semidense, discontinuous and porous), amounts of bitumen (from 4.5 to 5.2%) and air void content (from 4 to 20%), have been tested. The average hydraulic conductivity of the asphalt mixtures analyzed ranged from 5.2×10^(-6) to 3.0×10^(-2) cm/s. Besides, it has been found that the hydraulic conductivity model is valid for all ranges of air void content existing in the compacted asphalt mixture. In addition, the model has been checked through experimental and literature data, presenting a good fit to data. Therefore, the results of this study can be used as reference values of the hydraulic conductivity of asphalt mixtures used in the road pavement construction.

Influencia de los tipos de vegetación y la cubierta de tierra en la capacidad de infiltración del agua en el suelo en un ecosistema de páramo de gran altitud

Los ecosistemas de montaña están recibiendo mucha atención debido a su importancia en la provisión y regulación de los recursos hídricos, un fenómeno que es especialmente importante en los ecosistemas de altura de los Andes del norte (páramos). Si bien es ampliamente aceptado que la capacidad de los suelos para regular los flujos hidrológicos está básicamente dada por su estructura y su contenido de materia orgánica, esta capacidad también podría estar influenciada por las diferencias en la naturaleza y espesor de la cobertura del suelo en diferentes tipos de vegetación. Mediante una serie de ensayos de infiltración de agua en el suelo en localidades con diferentes tipos de vegetación o usos del suelo en un páramo ecuatoriano, evaluamos la contribución relativa de la cobertura de vegetación rastrera a la capacidad de infiltración de agua en el suelo. Las tasas de infiltración fueron extremadamente altas en las zonas arbustivas y en el bosque de Polylepis, pero decrecieron marcadamente en los pajonales, los bosques de pino y los senderos de paso de ganado. En todos los casos, la capa de vegetación rastrera contribuyo significativamente a la capacidad total de infiltración, como se demuestra por la disminución de las tasas de infiltración que reportamos cuando esa capa fue removida experimentalmente. El manejo y la restauración de los ecosistemas de montaña se debería concentrar en la recuperación de la heterogeneidad a nivel del paisaje y en la protección de las capas vegetales rastreras que regulan los microclimas del suelo y proveen una mayor capacidad de infiltración de agua.

Relationships Between Plant Spatial Patterns, Water Infiltration Capacity, and Plant Community Composition in Semi-arid Mediterranean Ecosystems Along Stress Gradients

Water redistribution from bare soil to vegetation patches is a key feature of semi-arid ecosystems, and is responsible for their patchy vegetation patterns. The magnitude of water redistribution depends on the properties of the bare soil (which determine the amount of water run-off) and the capacity of vegetation patches to trap water run-on. We examined the relationships between plant spatial patterns, water infiltration into bare soil, and plant community composition in semi-arid sites with different hydro-physical properties (silty and gypseous soils) in NE Spain. We also studied the effect of two stressors, aridity and grazing, on water infiltration and plant spatial patterns. Our results indicate a negative correlation of bare soil sorptivity (the capacity to absorb water by capillarity) and vegetation aggregation. There was a strong positive correlation between perennial grass cover and the spatial aggregation of vegetation, but aggregation was not associated with positive associations of different plant types. The aggregation of vegetation was positively correlated with species richness and the overall extent of vegetation cover. Grazing reduced water infiltration into silty soils, which are prone to compaction. In contrast, soil crust affected the hydrology of gypseous soils, especially in the most arid sites, where grazing increased infiltration, reducing surface sealing due to breaking of the soil crust. Together, our results suggest that biotic and abiotic factors affect the hydro-physical properties of soils in the semi-arid ecosystems of NE Spain, which is linked to the plant communities through the spatial distribution of plants.

Simulation of Hydrological Functions of Typical Vegetations in Poyang Lake Basin

Vegetation influences the runoff through affecting rainfall interception, soil water infiltration capacity and surface evaporation and other factors etc. In this paper, remote sensing data is used to analyze the major vegetation types of Poyang Lake Basin, and then a hydrological model (VIC model) is employed to simulate and compare runoff under different vegetation type scenarios. The simulation results show that the presence of vegetation will reduce the runoff and rate of decrease varies according to vegetation type: runoff reduction reaches the maximum when the vegetation type were mixed forest, followed by evergreen coniferous forest follows, and reaches the lowest when the evergreen broad-leaved forest predominates.

Twenty two years of tillage and mulching impacts on soil physical characteristics and carbon sequestration in Central Ohio

Knowledge about the changes in carbon (C) concentration and mechanical and hydrological properties under different tillage and mulch treatments is necessary to assess the feasibility of adoption of conservation practices for sustaining productivity and protecting the environment. It is widely recognized that no-till (NT) farming conserves soil and water, saves energy, improves the environment and enhances soil quality. However, the magnitude and direction of tillage and mulch-induced changes are soil and site specific. Therefore, a field study was conducted on a long-term on-going experiment to evaluate the effects of three tillage {NT, ridge till (RT) and plow till (PT)} and three mulch rates (0, 8 and 16Mgha−1yr−1) on soil physical properties and total C concentrations in macro (250–2000μm) and micro (<250μm) aggregates. The experiment was initiated in 1989 on a Crosby Silt Loam (Stagnic Luvisol) in Central Ohio. The data show positive effects of mulch rate on soil physical attributes and total C concentration under NT. Significant (P<0.05) variations in bulk density (ρb) and penetration resistance (PR) along with their interactions were observed among tillage and mulch treatments. The water infiltration capacity (ic) ranged from 1.2cmh−1 (PT) to 4.6cmh−1 (NT). With increase in mulch rate from 0 to 16Mgha−1, saturated hydraulic conductivity (Ks) for 0–10cm depth increased from 1.78 to 3.37, 1.57 to 2.95 and 1.37 to 2.28 (×10−2cmh−1) under NT, RT and PT, respectively. Analyses of variance indicate significant interaction between tillage, mulch and soil depth for the Ks. Similarly, the mean weight diameter (MWD, mm) increased from 0.36 to 1.21, 0.29 to 0.84, 0.25 to 0.62 under NT, RT and PT, respectively, with increase in mulch rate from 0 to 16Mgha−1. Total C (%) increased from 1.26 to 1.50, 1.20 to 1.47 and 0.95 to 1.10 under NT, RT and PT, respectively, with increase in mulch rate from 0 to 16Mgha−1. Macro-aggregates (250–2000μm) contained 30% more total C and N concentrations than microaggregates (<250μm). Under NT, the soil showed a higher structural stability than PT with significantly lower compaction values. Further, with NT the soil showed a higher capacity to retain C than PT. Thus, long term use of NT along with mulch application enhances soil quality with respect to soil mechanical, hydrological properties along with carbon concentration in the soil.

Groundwater vulnerability assessment and sensitivity analysis in Nong Rua, Khon Kaen, Thailand, using a GIS-based SINTACS model

The SINTACS approach was used to evaluate intrinsic groundwater vulnerability within Nong Rua District, Khon Kaen Province, Thailand. The approach is based on seven environmental variables prepared in the form of GIS data layers. These variables are depth to water level, infiltration capacity, unsaturated zone, soil type, aquifer media, hydraulic conductivity, and slope. The resulting vulnerability map depicts the spatial extent of six classes of vulnerability ranging from very low to extremely high. High and moderate level classes of vulnerability dominated most of the study area. The northwestern, southwestern and central parts of the study area fell under the very high and extremely high vulnerability levels according to this approach. These regions displayed characteristics that indicated their vulnerability such as a high infiltration rate, coarse-texture soil, and shallow depth to groundwater. The statistical correlation coefficient between the nitrate concentration in 87 wells and the SINTACS vulnerability levels was 0.51. Both map removal and single variable sensitivity analyses were performed to observe the influence of specific variables on the model result. The result of this study is useful for guiding strategic planning of groundwater quality management.

The impact of subterranean termite activity on water infiltration and topsoil properties in Burkina Faso

ABSTRACTFew quantitative experimental studies have been carried out on the influence of subterranean termite activity on the water infiltration capacity of crusted soils in the semi‐arid Sahelian region. These studies found increased infiltration rates on soils that were affected by foraging galleries of subterranean termites. In this paper, remarkable results are presented from crusted agricultural fields in the Sanmatenga region in Burkina Faso with clear termite activity compared to reference fields without termite activity. Fine‐scale rainfall experiments were carried out and general topsoil (upper 5 cm) characteristics were measured. Infiltration rates were found to be significantly slower on plots affected by subterranean termite activity. These results are contradictory to the findings reported in general literature. On the basis of topsoil property measurements, the reduced infiltration rates cannot be indisputably explained, and we suggest that the main responsible factor for a reduction of infiltration was related to differences in topsoil surface (upper 3 mm) properties. Two hypotheses are formulated in an attempt to explain the reduced water infiltration rates on termite plots. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Environmental factors controlling temporal and spatial variability in the soil‐atmosphere exchange of CO2, CH4 and N2O from an Australian subtropical rainforest

AbstractThe temporal variations in CO2, CH4 and N2O fluxes were measured over two consecutive years from February 2007 to March 2009 from a subtropical rainforest in south‐eastern Queensland, Australia, using an automated sampling system. A concurrent study using an additional 30 manual chambers examined the spatial variability of emissions distributed across three nearby remnant rainforest sites with similar vegetation and climatic conditions. Interannual variation in fluxes of all gases over the 2 years was minimal, despite large discrepancies in rainfall, whereas a pronounced seasonal variation could only be observed for CO2 fluxes. High infiltration, drainage and subsequent high soil aeration under the rainforest limited N2O loss while promoting substantial CH4 uptake. The average annual N2O loss of 0.5 ± 0.1 kg N2O‐N ha−1 over the 2‐year measurement period was at the lower end of reported fluxes from rainforest soils. The rainforest soil functioned as a sink for atmospheric CH4 throughout the entire 2‐year period, despite periods of substantial rainfall. A clear linear correlation between soil moisture and CH4 uptake was found. Rates of uptake ranged from greater than 15 g CH4‐C ha−1 day−1 during extended dry periods to less than 2–5 g CH4‐C ha−1 day−1 when soil water content was high. The calculated annual CH4 uptake at the site was 3.65 kg CH4‐C ha−1 yr−1. This is amongst the highest reported for rainforest systems, reiterating the ability of aerated subtropical rainforests to act as substantial sinks of CH4. The spatial study showed N2O fluxes almost eight times higher, and CH4 uptake reduced by over one‐third, as clay content of the rainforest soil increased from 12% to more than 23%. This demonstrates that for some rainforest ecosystems, soil texture and related water infiltration and drainage capacity constraints may play a more important role in controlling fluxes than either vegetation or seasonal variability.

Stream recession curves and storage variability in small watersheds

Abstract. The pattern of streamflow recession after rain events offers clues about the relationship between watershed runoff (observable as river discharge) and water storage (not directly observable) and can help in water resource assessment and prediction. However, there have been few systematic assessments of how streamflow recession varies across flow rates and how it relates to independent assessments of terrestrial water storage. We characterized the streamflow recession pattern in 61 relatively undisturbed small watersheds (1–100 km2) across the coterminous United States with multiyear records of hourly streamflow from automated gauges. We used the North American Regional Reanalysis to help identify periods where precipitation, snowmelt, and evaporation were small compared to streamflow. The order of magnitude of the recession timescale increases from 1 day at high flow rates (~1 mm h−1) to 10 days at low flow rates (~0.01 mm h−1), leveling off at low flow rates. There is significant variability in the recession timescale at a given flow rate between basins, which correlates with climate and geomorphic variables such as the ratio of mean streamflow to precipitation and soil water infiltration capacity. Stepwise multiple regression was used to construct a six-variable predictive model that explained some 80 % of the variance in recession timescale at high flow rates and 30–50 % at low flow rates. Seasonal and interannual variability in inferred storage shows similar time evolution to regional-scale water storage variability estimated from GRACE satellite gravity data and from land surface modeling forced by observed meteorology, but is up to a factor of 10 smaller. Study of this discrepancy in the inferred storage amplitude may provide clues to the range of validity of the recession curve approach to relating runoff and storage.

Practical Guidelines for Water Percolation Capacity Determination of the Ground

Determination of water infiltration capacity of ground soils and rocks represents important part of design and construction procedures of the facilities for the infiltration of clean precipitation water. With their help percolation capacity of ground as well as response of the infiltration facilities to the inflowing precipitation water is estimated. Comparing to other in situ hydrogeological tests they can be understood as simple. However, in every day's practice several problems during their on site application and desk interpretation can arise. Paper represents review of existing practical engineering procedures during the performance of percolation tests. Procedures are described for the borehole and shaft percolation tests execution and calculation theory for stationary and non-stationary percolation tests are given. Theory is illustrated with practical exercises. Interpretations of typical departures from theoretical presumptions according to Hvorslev test of non-stationary test are illustrated.

Erosion control and protection from torrential floods in Serbia-spatial aspects

Torrential floods represent the most frequent phenomenon within the category of ?natural risks? in Serbia. The representative examples are the torrential floods on the experimental watersheds of the rivers Manastirica (June 1996) and Kamisna (May 2007). Hystorical maximal discharges (Qmaxh) were reconstructed by use of ?hydraulics flood traces? method. Computations of maximal discharges (Qmaxc), under hydrological conditions after the restoration of the watersheds, were performed by use of a synthetic unit hydrograph theory and Soil Conservation Service methodology. Area sediment yields and intensity of erosion processes were estimated on the basis of the ?Erosion Potential Method?. The actual state of erosion processes is represented by the coefficients of erosion Z=0.475 (Manastirica) and Z=0.470 (Kamisna). Restoration works have been planned with a view to decreasing yields of erosive material, increasing water infiltration capacity and reducing flood runoff. The planned state of erosion processes is represented by the coefficients of erosion Z=0.343 (Manastirica) and Z=0.385 (Kamisna). The effects of hydrological changes were estimated by the comparison of historical maximal discharges and computed maximal discharges (under the conditions after the planned restoration). The realisation of restoration works will help decrease annual yields of erosive material from W?=24357 m3 to W?=16198.0 m3 (Manastirica) and from W?=19974 m3 to W?=14434 m3 (Kamisna). The values of historical maximal discharges (QmaxhMan=154.9 m3?s-1; QmaxhKam=76.3 m3?s-1) were significantly decreased after the restoration (QmaxcMan=84.5 m3 ?s-1; QmaxcKam=43.7 m3?s-1), indicating the improvement of hydrological conditions, as a direct consequence of erosion and torrent control works. Integrated management involves biotechnical works on the watershed, technical works on the hydrographic network within a precisely defined administrative and spatial framework in order to achieve maximum security for people and their property and to meet other requirements such as: environmental protection, sustainable soil usage, drinking water supply, rural development, biodiversity sustaining, etc. The lowest and the most effective level is attained through PAERs (Plans for announcement of erosive regions) and PPTFs (Plans for protection from torrential floods), with HZs (Hazard zones) and TAs (Threatened areas) mapping on the basis of spatial analysis of important factors in torrential floods formation. Solutions defined through PAERs and PPTFs must be integrated into Spatial Plans at local and regional levels.

Maximum entropy production allows a simple representation of heterogeneity in semiarid ecosystems

Feedbacks between water use, biomass and infiltration capacity in semiarid ecosystems have been shown to lead to the spontaneous formation of vegetation patterns in a simple model. The formation of patterns permits the maintenance of larger overall biomass at low rainfall rates compared with homogeneous vegetation. This results in a bias of models run at larger scales neglecting subgrid-scale variability. In the present study, we investigate the question whether subgrid-scale heterogeneity can be parameterized as the outcome of optimal partitioning between bare soil and vegetated area. We find that a two-box model reproduces the time-averaged biomass of the patterns emerging in a 100 x 100 grid model if the vegetated fraction is optimized for maximum entropy production (MEP). This suggests that the proposed optimality-based representation of subgrid-scale heterogeneity may be generally applicable to different systems and at different scales. The implications for our understanding of self-organized behaviour and its modelling are discussed.

Effect of the settlement of sediments on water infiltration in two urban infiltration basins

The sealing of surfaces in urban areas makes storm water management compulsory. The suspended solids from surface runoff water accumulate in infiltration basins and may impact on water infiltration. This paper describes a study of the effect of the settlement of sedimentary layers on the water infiltration capacity of two urban infiltrations basins. In situ water infiltration experiments were performed (1) to quantify the effect of sediment on water infiltration at local scale and (2) to derive the complete characterization of the unsaturated hydraulic properties of sediments and subsoils by using the BEST algorithm. These properties were used to model the effect of sediments on 1D water infiltrations at basin scale, simulating real operating conditions for three model rainfalls (shower, rainfall and light rainfall) and the full year 2008. The results clearly prove that sediments reduce local water infiltration capacities, due to their lower saturated hydraulic conductivities ( K s ). Moreover, numerical results have shown that this finding could have a drastic impact on water infiltration at the basin scale through increasing the number and duration of water pondings. From the technical point of view, this study underlines the need for efficient monitoring of infiltration basin sedimentation and its impact on water infiltration capacity.

Avaliação de parâmetros fisico-hídricos de Latossolo Vermelho sob pastejo e sob cerrado

O objetivo primeiro neste trabalho foi avaliar a qualidade fisico-hídrica do solo em áreas sob pastejo, em relação a um cerrado natural. Os tratamentos foram: cerrado natural, cerrado antropizado (pastejado na estação seca) e três pastagens cultivadas, com diferentes graus de cobertura do solo. O estudo foi realizado na Embrapa Cerrados em um Latossolo Vermelho, nas camadas de 0-5, 10-15, 40-55 e 70-80 cm, cujos parâmetros avaliados foram condutividade hidráulica saturada (Ks), capacidade de água disponível (CAD), densidade do solo (Ds) e macroporosidade (Ma). A qualidade fisico-hídrica do solo nas áreas sob pastejo foi analisada tendo-se como referência os parâmetros medidos no cerrado natural. Observou-se semelhança estatística da CAD na camada 0-5 cm para todas as áreas mas ocorreu drástica redução da saturação efetiva nas áreas sob pastejo, explicada principalmente pela queda na macroporosidade. A redução média da Ma foi de 70,8%, ocasionando um decréscimo da ordem de 73,6% da Ks nos primeiros 15 cm das áreas sob pastejo, podendo-se concluir que a camada superficial do solo foi a mais afetada pelo pastejo, com perda significativa da qualidade fisico-hídrica e previsível redução na capacidade de infiltração da água no solo.

Impact of organic farming systems on runoff formation processes—A long-term sequential rainfall experiment

Nearly 50% of the agricultural used areas of the European Union can be classified as having a high or very high risk for soil surface sealing and erodibility. The objective of this long-term sequential experimental rainfall study was to identify the soil surface aggregation and crusting as well as runoff and infiltration effects of organic management systems (with different dates of conversion from conventional to organic farming) in comparison to a conventional management system. The experimental data received from the rainfall experiment showed that the soil surface crusting process started earlier in the conventionally managed soil than in the soils from the organic farm. Additionally the soil surface of the conventional and organic managed soils was similarly sealed, but the well-established organic farming management showed lower runoff than the recently established organic farming management. Both organic farming systems showed lower surface runoff and higher water infiltration capacity than the conventional management system. The conversion from conventional to organic farming resulted in lower soil surface runoff and higher infiltration which is a benefit of long-term organic farming systems to reduce erosion hazards and floods.

Características de solos construídos após mineração de carvão relacionadas ao processo de construção e à composição do material utilizado

A mineração de carvão a céu aberto envolve a remoção do solo e de camadas geológicas, que devem ser repostos na seqüência original, visando a reabilitação das áreas mineradas. Este processo altera as características originais do solo e da paisagem. Neste sentido, perfis de solos construídos há 24 e 2 anos, em duas áreas mineradas no município de Minas do Leão (RS), foram avaliados quanto ao processo e à composição dos materiais utilizados na construção. Quanto ao processo de construção, foram determinadas as características morfológicas, a densidade, a condutividade hidraulica saturada e a capacidade de infiltração de água no solo. Em relação à composição dos materiais, determinaram-se granulometria, capacidade de traoca de cátions (CTC), teor de carbono orgânico (CO) e potenciais de neutralização e acidificação. Em ambas as áreas reconstituídas, o processo de construção aumentou a densidade e diminuiu a condutividade hidráulica saturada e a capacidade de infiltração de água no solo. A granulometria, a CTC e o teor de CO foram similares nas duas áreas amostradas, indicando que o processo de construção e os materiais utilizados foram semelhantes. A diminuição dos potenciais de neutralização e acidificação nos perfis de solos construídos há 24 anos indicou um avanço da sulfurização com o tempo de construção dos solos. Os solos em ambas as áreas apresentam sérias limitações para o desenvolvimento de vegetação, influindo negativamente para a recuperação dessas áreas e de áreas adjacentes.