Norton Lloyd Darrell

• PhD
• Professor (Associate) at Purdue University West Lafayette

Improving soil structure, a central feature of soil health, is associated with land use and soil type, and takes long-term period. The objective of this study was to evaluate the water retention or structural condition of soils exploited under different long-term land use (> 20 years) in competition with one-time anionic polyacrylamide (PAM) applic...

Enhancing soil structure is vital for sustainable land management. We evaluated the effects of long-term land use (no-till, NT; conventional-till, CT; grass, and forest), and that of adding polyacrylamide (PAM = 25, 50, 100 and 200 mg/L) to CT soil, on a silty loam soil quality indices, pore size distribution and structural stability (IN, USA). For...

Efficacy of polyacrylamide (PAM), a water-soluble soil conditioner, prepared with poor quality water (low salinity, higher sodicity) commonly available to farm managers, is unknown. We studied the effects of treating aggregates of four soils with predominant smectitic or kaolinitic clay mineralogy with PAM solution prepared with poor quality water...

Naturally dense soils have been commonly managed for coffee plantations in Vertentes Fields physiographic zone of Minas Gerais state, Brazil. Such dense soils in association with the irregular rainfall in recent years have increased risks for crop productivity. Therefore, management practices aiming at improving subsoil root exploration have been r...

Core Ideas One‐time tillage increased soybean yield as a result of improving soil physical properties. Penetration resistance, air capacity, macroporosity, relative field capacity, and S index were the soil physical properties that best predicted soybean yield. The most sensitive soil physical properties for detecting structural related alterations...

Water determines the success of coffee farming, since it influences the phenology of the plant and, consequently, its productivity, product quality and commercial viability. The Least Limiting Water Range (LLWR) associated with the monitoring of soil water content (θ) distinguishes management systems as to their effectiveness in supplying water to...

Gypsum has a long history as a soil amendment. Information on how flue gas desulfurization (FGD) gypsum affects soil, water, and plant properties across a range of climates and soils is lacking. We conducted a meta‐analysis using data from 10 field sites in the United States (Alabama, Arkansas, Indiana, New Mexico, North Dakota, Ohio, and Wisconsin...

Heavy rainfall in conjunction with an increase in population and intensification of agricultural activities have resulted in countless problems related to flooding in watersheds. Among the techniques available for direct surface runoff (DSR) modeling and flood risk management are the Unit Hydrograph (UH) and Instantaneous Unit Hydrograph (IUH). Thi...

Humic acid (HA) may reduce adsorption and increase soil P availability, however, the magnitude of this effect is different when Ca2+ prevails over Mg2+ in limed soils. The objective of this study was to evaluate the effects of HA rates and carbonate sources on the adsorption, phosphate maximum buffering capacity (PMBC), and P availability in two co...

The Mantiqueira Range region is one of the most important headwaters in southeastern Brazil. In this context, the relationship between pedology and hydrology has been debated and analyzed in recent years, contributing to the creation of a multidisciplinary science call hydropedology. Therefore, the aim of this study was to evaluate the hydropedolog...

In Brazil, the Mantiqueira Range, southeastern region, shelters the last remnants of the ecologically important Upper Montane Tropical Forest. since extensive exploration that has been taking place in this biome for decades, the influence of land-use changes on hydropedology in these areas must be investigated once major land-use changes have been...

Soil degradation by water erosion has been accelerated by human activities. This process is aggravated in the Andes region due to steep slopes, sparse vegetation cover, and sporadic but high intensity rainfall, which together with a shallow soil depth, increases soil erosion risk. The objective of this study was to analyze the soil erosion risk, as...

Phosphorus is a key-nutrient in the fertility management of highly weathered tropical soils. So, this work was carried out with the objective of evaluating the influence of the interaction between P doses, mycorrhizal inoculation and historical land use on soybean growth and P uptake in five Latosols (Oxisols) with contrasting chemical, physical an...

Modelos têm sido usados pelo homem há milhares de anos para controlar seu ambiente de uma maneira favorável para melhores condições de vida para os humanos. O uso de modelos hidrológicos tem sido uma ferramenta muito eficaz para apoiar os decisores que lidam com as bacias hidrográficas para subsidiar diversas atividades econômicas e sociais, como o...

Understanding soil formation processes across different landscapes is needed to predict how soil properties will respond to land use change. This study aimed to characterize mountainous Inceptisols (Cambisols) under high altitude subtropical climate in southeastern Brazil, by soil physical, chemical and micromorphological analyses, under native for...

Mantiqueira Range is the most important headwater region in southeastern Brazil, being responsible for streamflows that feed a significant part of Brazilian hydroelectric energy production. This region is extremely fragile with endemic species like those that compose the upper mountain cloud forest (UMCF), and the dominant soils are typical Incepti...

Climate change is always occurring. Its impacts on the environment are still uncertain, especially due to the difficulty of simulating the earth’s climate accurately. However, the global circulation climate models have been the only scientific tool to assess such impacts and their results have been well accepted. This study aimed to analyze the pos...

Soil surface roughness is identified as one of the controlling factors governing runoff and soil loss. Yet, most studies pay little attention to soil surface roughness. In this study, we analyzed the influence of surface roughness on runoff and soil erosion rates. Bulk samples of a silt loam soil were collected and sieved to 4 aggregate sizes: 0.00...

This study was conducted in a rural region where there are conventional and organic farms, the agricultural production includes more than 20 million people, and the effect on environmental quality is still poorly known in terms of indicators. Our objectives were: (1) compare soils attributes to reference areas, (2) verifying if cultivated areas und...

Land-use changes affect soil water balance. The Upper Grande River Basin (UGRB) headwaters have undergone intense modifications in land use. This study was conducted to simulate, using the LASH model, the impacts on the hydrological regime in the UGRB with five land-use trends: S-1 and S-2 - reforestation with eucalyptus covering 20 % and 50 %, res...

Eucalyptus plantations are normally found in vulnerable ecosystems such as steep slope, soil with low natural fertility and lands that were degraded by agriculture. The objective of this study was to obtain Universal Soil Loss Equation (USLE) factors and use them to estimate water erosion risk in regions with eucalyptus planted. The USLE factors we...

Mined gypsum has been beneficially used for many years as an agricultural amendment. A large amount of flue gas desulfurization (FGD) gypsum is produced by removal of SO2 from flue gas streams when fuels with high S content are burned. The FGD gypsum, similar to mined gypsum, can enhance crop production. However, information is lacking concerning t...

The Lavras Simulation of Hydrology (LASH) hydrological model is classified as a deterministic, semiconceptual, and spatially distributed model. This model was developed to make available a tool for hydrological analysis in watersheds with a limited database, and it has presented good streamflow predictions. The aim of this study was to calibrate an...

Hydrological models have been used in many places of the world in order to support practitioners with respect to watershed management actions. The goal of this research was to apply the Lavras Simulation of Hydrology (LASH model) to a Brazilian tropical watershed dominated by Oxisols, to estimate maximum, minimum and mean stream flows for both curr...

The process of water erosion occurs in watersheds throughout the world and it is strongly affected by anthropogenic influences. Thus, the knowledge of these processes is extremely necessary for planning of conservation efforts. This study was performed in an experimental forested watershed in order to predict the average potential annual soil loss...

Wind-driven rain (WDR) experiments were conducted to evaluate the interrill component of the Water Erosion Prediction Project model with a two-dimensional experimental set-up in a wind tunnel. Synchronized wind and rain simulations were applied to soil surfaces on windward and leeward slopes of 7, 15 and 20%. Since WDR fall trajectory varied with h...

The vector physics of wind-driven rain (WDR) differs from that of wind-free rain, and the interrill soil detachment equations in the Water Erosion Prediction Project (WEPP) model were not originally developed to deal with this phenomenon. This article provides an evaluation of the performance of the interrill component of the WEPP model for WDR eve...

Soil surface roughness is commonly identified as one of the dominant factors governing runoff and interrill erosion. The objective of this study was to compare several existing soil surface roughness indices and to test the use of the revised triangular prism surface area method (RTPM) to calculate the fractal dimension as a roughness index. A silt...

For soils and conditions outside the USA, input parameters for physically based soil erosion models, such as the WEPP model, are usually not available, particularly for tropical soils. In a laboratory study, small erosion pans and a programmable rain simulator were used to determine interrill erodibility, whereas in the field, rills were physically...

The loss of N and P by leaching is an important issue, especially on agricultural fi elds with subsurface tile drainage. The objective of this study was to evaluate how gypsum amendment and soil exchangeable Ca2+ and Mg2+ could affect the movement of P, NH4–N, and NO3–N in infi ltrated water and soil. A column experiment was performed using a Miami...

Relationships between regional climates and oceanic and atmospheric anomalies are important in understanding the rainfall regime of a given region. This work aimed to analyze rainfall erosivity in the Upper Grande River Basin, Southern Minas Gerais State, Brazil; namely the two most representative environments, the Mantiqueira Range (MR) and the Pl...

Relationships between regional climate and oceanic and atmospheric anomalies are important tools in order to promote the development of models for predicting rainfall erosivity, especially in regions with substantial intra-annual variability in the rainfall regime. In this context, this work aimed to analyze the rainfall erosivity in headwaters of...

Conceptual rainfall-runoff models at the watershed scale are useful tools for assisting in managing and planning water resources, making it possible to estimate streamflow and to predict hydrologic impacts due to land-use changes. The objective of this study was to calibrate and to validate the LAvras Simulation of Hydrology (LASH Model) (Beskow, 2...

To better assess the impacts of conservation buffers and grasslands on water quality at large spatial scales, development and integration of novel approaches are crucial to ensure that these land management practices are functioning properly and meeting their original goals. Recent developments in remote sensing technology have greatly enriched the...

Many hydrologic models have been developed to help manage natural resources all over the world. Nevertheless, most models have presented a high complexity regarding data base requirements, as well as, many calibration parameters. This has brought serious difficulties for applying them in watersheds where there is scarcity of data. The development o...

Soil water content is essential to understand the hydrological cycle. It controls the surface runoff generation, water infiltration, soil evaporation and plant transpiration. This work aims to analyze the spatial distribution of top soil water content and to characterize the spatial mean and standard deviation of top soil water content over time in...

The objective of this work was to evaluate the aggregate stability of tropical soils under eucalyptus plantation and native vegetation, and assess the relationships between aggregate stability and some soil chemical and physical properties. Argisols, Cambisol, Latosols and Plinthosol within three eucalyptus-cultivated regions, in the states of Espí...

Water erosion has been considered as the most important worldwide environmental problem, being especially caused by intense rainfall events. The potential of rain to generate soil erosion is known as rainfall erosivity and its estimation is fundamental for the understanding of climatic vulnerability of a given region. This work aims to develop mode...

Flue Gas Desulfurization Gypsum (FGDG) is produced from pollution control systems reducing sulfur dioxide emissions from thermo-electric coal-fired power plants. Natural gypsum and FGDG both have been shown to be useful in control of soil erosion. However, concerns have been raised recently by environmental groups as to the fate of trace elements i...

Soil surface roughness is commonly identified as one of the dominant factors governing runoff and interrill erosion. Yet, because of difficulties in acquiring the data, most studies pay little attention to soil surface roughness. This is particularly true for soil erosion models which commonly don't include a roughness factor, or use a simplified,...

Flue gas desulfurization (FGD) gypsum from modern fossil fuel combustion systems has many potential uses in agriculture. One concern is its elevated mercury (Hg) concentration, which varies based on the operating configuration. The wet limestone scrubbing process that removes sulfur from flue gas (and produces gypsum) is also effective in removing...

Adding anionic polyacrylamide (PAM) to soils stabilizes existing aggregates and improves bonding between and aggregation of soil particles. However, the dependence of PAM efficacy as an aggregate stabilizing agent with soils having different clay mineralogy has not been studied. Sixteen soil samples (loam or clay) with predominantly smectitic, illi...

Knowledge on the factors influencing water erosion is fundamental for the choice of the best land use practices. Rainfall, expressed by rainfall erosivity, is one of the most important factors of water erosion. The objective of this study was to determine rainfall erosivity and the return period of rainfall in the Coastal Plains region, near Aracru...

Because of wind erosion during the dust bowl era of the early 1930s in the central United States, Congress appropriated federal funding to study the problem and find ways that protect the land from all forms of erosion. Afterwards, a series of erosion stations were established across the eastern United States, and natural rainfall-runoff plots were...

Different tillage intensities may influence soil physical and chemical properties, distribution of nutrients and organic carbon between and within the aggregates. We studied the effect of long term (25 years) conservation tillage on structure stability and the total C and N distribution in Miami silt loam aggregates sampled from the upper 0-5 cm la...

Mapping and assessment of erosion risk is an important tool for planning of natural resources management, allowing researchers to modify land-use properly and implement management strategies more sustainable in the long-term. The Grande River Basin (GRB), located in Minas Gerais State, is one of the Planning Units for Management of Water Resources...

Mechanisms of aggregate disruption and the measurement techniques used to quantify them for different aggregate sizes affect the relation of aggregate stability to soil erodibility and to basic soil properties. We evaluated two different techniques of aggregate stability analysis that gave either a settling velocity or stability of aggregates param...

Soil erosion studies are usually implemented to collect data for specific processes, surface conditions or treatments. The ease of conducting the proposed erosion study, the associated quality of the data, and the confidence level of the findings, are generally related to the degree of the control on the experimental variables. With a proper experi...

Soil-structural stability (expressed in terms of aggregate stability and pore size distribution) depends on (i) soil inherent properties, (ii) extrinsic condition prevailing in the soil that may vary temporally and spatially, and (iii) addition of soil amendments. Different soil management practices alter shrinking and swelling stresses and may enh...

Soil moisture is an important hydrological variable that characterizes the soil water dynamics influencing surface runoff generation and consequently sediment transport. This work aimed to analyze the spatial patterns of surface soil moisture, to identify the elements that exert the most influence in the context of its spatial distribution on surfa...

Physically based hydrologic models for watersheds are important tools to support water resources management and predict hydrologic impacts produced by land-use change. Grande River Basin is located in southern Minas Gerais State, and the Grande River is the main tributary of Basin which has 2080 km2 draining into the Camargos Hydropower Plant Reser...

No-till agriculture has been proven to reduce soil erosion. However, its effects on runoff quantity and quality vary depending on soil type and conditions. Given the fact that chemicals are applied at or near the soil surface, a potential exists for adverse water quality impacts. We found that using surface-applied gypsum soil amendment to no-tille...

In general, increasing the concentration of one cation species in soil solution can decrease levels of other cations in plants. It is not clear whether adjusting soil cation ratios or adding gypsum will improve plant growth. We studied the effect of adding gypsum to unleached soil, and the effect of changing soil-exchangeable Ca/Mg ratios on corn r...

Physically based hydrologic models for watershed are important tools to support water resources management and predict hydrologic impacts produced by land-use change. Rio Grande Basin is located in south of Minas Gerais State, and the Rio Grande is the main tributary of basin which has 2080 km2 draining into the Camargos Hydropower Plant Reservoir...

Soil erosion has been studied from different perspectives. This paper presents results on interrill erosion for three different application methods of Polyacrylamide (PAM) and Gypsum. Small interrill plots (0.74 m2) were packed with a highly erodible sieved soil and surface was prepared for it to have a geometrically ordered rough (GOR) surface. So...

One of the major factors contributing to surface water contamination in agricultural areas is the use of pesticides. The Soil and Water Assessment Tool (SWAT) is a hydrologic model capable of simulating the fate and transport of pesticides in an agricultural watershed. The SWAT model was used in this study to estimate stream flow and atrazine (2-ch...

Erosion control can be achieved by reducing runoff volume using soil amendments that improve infiltration and prevent particle detachment and transport. Effective soil erosion control can be achieved by a number of means, however, water quality may still be impaired by removal of soluble nutrients and pesticides. We hypothesized that addition of an...

Loss of N and P from soil to water is not only an agronomic but also an environmental and human health problem. The main objective of this study was to evaluate the effect of gypsum amendment and soil-exchangeable Ca and Mg on the concentration and loss of nutrients in runoff, sediment, and soil. The experiment was performed in the laboratory using...

Soil aggregate breakdown and dispersibility under rain depends on clay mineralogy. Little is known about effects of mineralogy on aggregate stability for long-term cultivated soil which was the objective of our study. Soil samples representing a range of agricultural soils (no-till and tilled) of humid and semi-arid zones with predominantly kaolini...

Applications of animal manures have increased soil test P values in many parts of the USA and thus increased the risk that soil P will be transferred to surface water and decrease water quality. To continue farming these areas, landowners need tools to reduce the risk of P losses. A field experiment was conducted near Kurten, TX, on a Zulch fine sa...

Anhydrous ammonia is a widely used N fertilizer and its interactions with soils and soil clays play an important role in its environmental fate. This study was conducted to determine the quantity and forms of ammonia adsorbed by clay-sized fractions of soils as a function of water content, exchangeable cation, and organic matter (OM). Fourier trans...

Wind movement and velocity can have a profound effect on some aspects of the soil erosion process. In the case of wind-driven rain, differences in raindrop trajectory are expected: wind-driven raindrops achieve some degree of horizontal velocity, which increases their resultant impact velocity and they strike the soil surface at an angle deviated f...

Sandy soil, prone to intense soil erosion, is used for agriculture in the subtropics of Brazil. This study was conducted to determine whether soil amendments are effective for conserving topsoil by preventing water-induced erosion on a Brazilian sandy Alfisol soil (coarse-loamy, mixed, thermic Typic Paleudalf). A programmable rainfall simulator was...

Determining the amount of sediment being transported by rivers is fundamental to determine the environmental impact on reservoirs, as well as to estimate their life span. This monitoring is particularly important for large hydroelectric dams such as the Itaipu hydroelectric facility on the Parana River, which provides over 24% of the electricity ne...

Phosphorous (P) and nitrogen (N) in runoff from agricultural fields are key components of nonpoint-source pollution and can accelerate eutrophication of surface waters. A laboratory study was designed to evaluate effects of near-surface hydraulic gradients on P and N losses in surface runoff from soil pans at 5% slope under simulated rainfall. Expe...

In wind-driven rains, wind velocity and direction are expected to affect not only energy input of rains but also shallow flow hydraulics by changing roughness induced by raindrop impacts with an angle on flow and the unidirectional splashes in the wind direction. A wind-tunnel study under wind-driven rains was conducted to determine the effects of ho...

Soil sealing and erosion on agricultural fields is a severe problem that often leads to increased runoff and decreased soil quality. Much research has been conducted using polyacrylamide (PAM) to control soil sealing and reduce erosion, yet few studies have attempted to determine the most effective molecular formulation(s) of PAM. Our objective was...

The interaction of water with the clay fractions (<2 micrometer) from two midwestern soils was studied using Fourier transform infrared (FTIR) spectroscopy and gravimetric methods. The soil clay fractions were obtained from a Blount loam (fine, illitic, mesic Aeric Epiaqualfs) and a Fayette silty clay loam (fine-silty, mixed, mesic, superactive Typ...

It is usually recognized that relatively large amounts of soil particles cannot be transported by raindrop splashes under windless rain. However, the splash-saltation process can cause net transportation in the prevailing wind direction since variations in splash-saltation trajectory due to the wind are expected in wind-driven rain. Therefore, dete...

In attempts to better manage soil and water resources, soil erosion models have received increasing attention. Until recently, the Universal Soil Loss Equation (USLE) has been used as a soil erosion model on the field scale. Since then, more process-based soil erosion models have been developed such as the Water Erosion Prediction Project (WEPP) mo...

One goal of the Everglades Restoration Plan in south Florida is to increase water flow to the Everglades National Park, which may result in an elevated water table in parts of Miami-Dade County. Useful hydrologic data concerning rainfall-runoff relations, soil erosion, and water holding capacity are limited for this county. The objective of this st...

Use of anionic polyacrylamide (PAM) as an erosion control soil amendment has been studied at the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), National Soil Erosion Research Lab since the early 1990s. An initial field experiment in Indiana using simulated rainfall on a sloping silt loam soil found that 20 kg ha-1 of PAM c...

In nature, erosive rainstorms are usually associated with high winds. Therefore, a quantification of wind and rain interactions and the effects of wind on detachment and transport processes provides a great opportunity for a given prediction technology to improve the estimation of erosion. This paper presents experimental data obtained on interrill...

Many arid or semiarid countries experience significant problems with water for rainfed crop production. Semiarid regions may receive sufficient rainwater to support crops, but it is distributed so unevenly in time and/or space that rainfed agriculture is not always successful. Developing technologies to increase agricultural water use efficiency th...

In wind-driven rains, variations in raindrop trajectory and frequency are expected due to the changes in the angle of raindrop incidence. This article presents experimental data on the effects of horizontal wind velocity on rainsplash detachment. In a wind tunnel facility equipped with a rainfall simulator, windless rains and rains driven by horizo...

Soil amendments, runoff, soil productivity.

Steep slopes consisting of disturbed soil are very often found in construction, landfill, and surface mining situations. Although legislation and economics dictate that vegetative cover be established on these slopes as rapidly as possible, the occurrence of large rainfall events during critical periods of vegetation establishment can frequently ca...

Soil erosion by water involves the processes of detachment, transport and deposition of soil materials by the erosive forces of raindrops and surface flow of water. The redistribution of sediment within a field-sized area is important in estimating the effect of erosion and deposition on productivity, in helping the conservation planner to target e...

A wind tunnel study under wind-driven rains was conducted to determine the combined effect of rain and wind on the rainsplash transport process. The rains driven by horizontal wind velocities of 6, 10 and 12 m s−1 were applied to three agricultural soils packed into a 20×55-cm soil pan placed at both windward and leeward slopes of 4.0°, 8.5° and 11...

Soils of the US Corn Belt often experience surface sealing, low infiltration, and erosion under rainfall, all of which result in economic loss. This study seeks to establish if high Mg content in these soils can have an adverse effect on soil structure, clay dispersability, water intake rate, and erosion as a result of the greater hydration radius...

Different opinions exist regarding the specific effect of Mg on soil physical and chemical properties. We hypothesized that Mg(2+), compared with Ca(2+), reduces saturated hydraulic conductivity (K(s)) via promoting clay swelling, disaggregation, and clay dispersion. Two soils (mixed, mesic Typic Hapludalfs) in packed soil columns were leached with...

Disturbed areas especially as they occur on sloping land are highly erodible in humid environments until vegetation can be established. These critical areas produce considerable amounts of sediment and pollutants that can be carried either attached to the sediment or in soluble forms. The cost of many "engineering based" erosion control strategies...

Soil loss from embankments at highway construction sites, sanitary landfills, and elsewhere can be extremely large due to the loosened state of the soil and very steep slope gradients (typically 2:1 to 3:1). Soil amendments have the potential to protect the soil during critical periods of vegetation establishment, thus reducing on-site damages and...

Most existing soil loss data are spatially-averaged, though various tracing techniques have been used for obtaining spatially-distributed data. Spatially-distributed soil erosion data are needed for validating physically-based erosion prediction models and for better understanding soil erosion dynamics. The objectives of this study were to evaluate...

Fragipan horizon strength, which has been attributed to Si cementation, limits soil productivity by restricting the depth of root growth and water movement. Fluidized bed combustion (FBC) ash, a high pH material, was evaluated as a potential amendment to dissolve the cementing agent and decrease the strength of the horizon. Fragipan horizon samples...

O objetivo deste trabalho foi avaliar o efeito de parcelas de erosão com seções transversais da superfície do solo retangular (STR) e triangular (STT) na perda de solo e água e na erodibilidade, em sulcos e entressulcos. O experimento foi conduzido em 1998, em um Argissolo Vermelho-Amarelo distrófico arênico, preparado convencionalmente. As dimensõ...

Soil erosion is commonly measured as the quantity of sediment leaving a plot or watershed. The techniques for measuring soil erosion patterns and sediment redistribution within plots or watersheds by direct monitoring are very limited. The objective of this study was to develop a direct and non-intrusive tracer method to study the sources, patterns...