Phillip R. Owens

Solum depth spatial prediction comparing conventional with knowledge-based digital soil mapping approaches

Solum depth and its spatial distribution play an important role in different types of environmental studies. Several approaches have been used for fitting quantitative relationships between soil properties and their environment in order to predict them spatially. This work aimed to present the steps required for solum depth spatial prediction from knowledge-based digital soil mapping, comparing the prediction to the conventional soil mapping approach through field validation, in a watershed located at Mantiqueira Range region, in the state of Minas Gerais, Brazil. Conventional soil mapping had aerial photo-interpretation as a basis. The knowledge-based digital soil mapping applied fuzzy logic and similarity vectors in an expert system. The knowledge-based digital soil mapping approach showed the advantages over the conventional soil mapping approach by applying the field expert-knowledge in order to enhance the quality of final results, predicting solum depth with suited accuracy in a continuous way, making the soil-landscape relationship explicit.

Digital soil mapping approach based on fuzzy logic and field expert knowledge

In Brazil, soil surveys in more detailed scale are still scarce and necessary to more adequately support the decision makers for planning soil and environment activities in small areas. Hence, this review addresses some digital soil mapping techniques that enable faster production of soil surveys, beyond fitting continuous spatial distribution of soil properties into discrete soil categories, in accordance with the inherent complexity of soil variation, increasing the accuracy of spatial information. The technique focused here is knowledge-based in expert systems, under fuzzy logic and vector of similarity. For that, a contextualization of each tool in the soil types and properties prediction is provided, as well as some options of knowledge extraction techniques. Such tools have reduced the inconsistency and costs associated with the traditional manual processes, relying on a relatively low density of soil samples. On the other hand, knowledge-based technique is not automatic, and just as the traditional soil survey, the knowledge of soil-landscape relationships is irreplaceable.

Transport and Fate of Phosphorus during and after Manure Spill Simulations

Animal manure spills contribute to P loading of surface waters and little is known about the effectiveness of the current manure spill clean-up methods to mitigate P contamination. Manure spill clean-up consists of containing, removing, and land applying the contaminated water column, while P-enriched fluvial sediments remain in place. Therefore, the objectives of this study were to (i) understand how P partitions between the water column and fluvial sediments during a manure spill, and (ii) evaluate the efficacy of current manure spill clean-up methods to remediate manure contaminated sediments. Manure spill simulations were conducted using fluvarium techniques and sediments collected from three drainage areas of two drainage ditches. Sediments with the greatest clay content (33%) resulted in a significantly greater P buffering capacity (10.3 L kg(-1)) and removed P from the water column at the greatest rate during the manure spill simulation relative to sediments with < 6% clay. Phosphorus uptake length for all sediments ranged from 574 to 815 m and the adsorption flux ranged from 8.9 to 16.7 mg m(-2) h(-1). After simulating the current manure spill remediation methods, P desorbed to the water from all sediments exceeded the Environmental Protection Agency total P criteria (0.076 mg L(-1)) for the region by at least 67%. Furthermore, results from this study suggest that the current manure spill remediation method needs refining to mitigate P from the total fluvial system water column and sediment following a spill.

Steepland resources: characteristics, stability and micromorphology

Abstract Steeplands of Central America are a major land resource, but due to population pressures they are rapidly being deforested leading to landscape instability. Microwatersheds of Southern Honduras were examined to correlate soil type, landform, slope gradient and slump potential. Soils most susceptible to slumping were moderately deep (0.5–1 m) Haplustalfs and Haplustepts. These soils occupy about 25% of the landscape, and have slope gradients of 45–90%. Soils are developed on plagioclase-rich andesitic parent material, are loam to clay loam in texture and have high base status. However, due to weathering of parent material, sand and silt fractions are dominated by quartz with smaller amounts of plagioclase, vermiculite and kaolinite. The A and B horizons have an open porphyric related distribution with plagioclase as the coarse fraction in a fine-grained groundmass. The andesitic parent rock contains abundant hydrothermally altered plagioclase phenocrysts in a single-spaced porphyric-related (c/f5μm ratio of 4:1) distribution. Some feldspars are partially to completely altered to clay pseudomorphs, probably vermiculite. Microfabric analysis of soil and pararock did not show any striated b-fabric indicative of shear failure. However, microfabrics do confirm translocated clay into the subsoil as typic pore coatings indicating long-term landscape stability prior to deforestation.

Role of Inceptisols in the Hydrology of Mountainous Catchments in Southeastern Brazil

AbstractMantiqueira 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 Inceptisols. These forest environments are rapidly disappearing in Brazil. The changing land use combined with shallow Inceptisols lead to important effects on hydrology. Therefore, studies addressing streamflow behavior in these landscapes are urgently needed for understanding the groundwater recharge process. The objectives of this study were to investigate the role of shallow Inceptisols linked to the land use changes in the streamflow behavior of the Mantiqueira Range region and to understand the mechanisms of water flow into the saturated zone. To validate the study, a comparative analysis was developed for a representative watershed of Mantiqueira Range, ...

MICROMORPHOLOGY AND PEDOGENESIS OF MOUNTAINOUS INCEPTISOLS IN THE MANTIQUEIRA RANGE (MG)

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 forest and pasture. The soil under pasture had a greater bulk density than under forest, resulting in a severe reduction of macroporosity. At two depths, coarse quartz grains are angular, suggesting absence of transportational processes, thus confirming an autochthonous pedogenesis from the underlying gneissic rock. Most feldspars were weathered beyond recognition, but mineral alteration was commonly seen across cleavage plans and edges of micas. The micromorphological results suggest an intermediate stage of mineral weathering and soil development, which is in accordance with properties expected to be found in Inceptisols.

Spatial prediction of soil properties in two contrasting physiographic regions in Brazil

This study compared the performance of ordinary kriging (OK) and regression kriging (RK) to predict soil physical-chemical properties in topsoil (0-15 cm). Mean prediction of error and root mean square of prediction error were used to assess the prediction methods. Two watersheds with contrasting soil-landscape features were studied, for which the prediction methods were performed differently. A multiple linear stepwise regression model was performed with RK using digital terrain models (DTMs) and remote sensing images in order to choose the best auxiliary covariates. Different pedogenic factors and land uses control soil property distributions in each watershed, and soil properties often display contrasting scales of variability. Environmental covariables and predictive methods can be useful in one site study, but inappropriate in another one. A better linear correlation was found at Lavrinha Creek Watershed, suggesting a relationship between contemporaneous landforms and soil properties, and RK outperformed OK. In most cases, RK did not outperform OK at the Marcela Creek Watershed due to lack of linear correlation between covariates and soil properties. Since alternatives of simple OK have been sought, other prediction methods should also be tested, considering not only the linear relationships between covariate and soil properties, but also the systematic pattern of soil property distributions over that landscape.

Interpolation methods for improving the RUSLE R-factor mapping in Brazil

Methods for Revised Universal Soil Loss Equation (RUSLE) rainfall erosivity factor (R-factor) predictions have been useful for land use planning in agricultural areas related to soil erosion risk map assessment, which is crucial at the regional scale. Many studies have focused on the R-factor prediction in Brazil and have utilized ordinary kriging and other methods, especially inverse square distance weighted (ISDW) predictions. For large regions with sparse sample rain-gauge network and complex atmospheric systems, such as Brazil, regression-kriging method arises as one that can produce reliable and improved results. The objective of this study was to compare the performance of (1) ordinary kriging; (2) co-kriging taking altitude as spatially distributed covariate; (3) ISDW; (4) multivariate regression model for R-factor as function of latitude, longitude, and altitude; and (5) regression-kriging. Daily pluviometric data sets from 928 rain gauges were used, considering the Modified Fournier Index (MFI) methodology for estimating the mean annual R-factor values for each rain gauge. From these stations, 155 were extracted randomly and used exclusively for statistical comparison of the methods. Regression-kriging method has demonstrated higher performance than the others, with mean absolute error of 11% compared to 15.8%, 16.2%, 19%, and 19.5%, respectively, for co-kriging, ordinary kriging, regression model, and ISDW. In addition, Willmotts index D for regression-kriging was higher than 0.94 while for the others lower than 0.90, proving its greater prediction accuracy. Thus, regression-kriging method was the most reliable, producing the best practical map. With regard to other methods, co-kriging also produced acceptable results for developing R-factor maps for Brazil.

Impact of Time to First Rainfall Event on Greenhouse Gas Emissions Following Manure Applications

Use of inorganic fertilizers and manures are known to result in the release of greenhouse gases (GHG) to the atmosphere, and rainfall events can also increase GHG emissions from soils. The objective of this study was to examine how the time between fertilizer or manure application and the first rainfall event affects carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) fluxes. Swine manure, poultry litter, and urea were surface applied to plots. Rainfall was simulated 1, 4, 8, 15, or 29 days after application. Gas fluxes were determined before and after each rainfall simulation. Postrain CO2 fluxes were the greatest from poultry litter at 4 to 8 days after fertilization, and all fertilizer treatments produced similar N2O emissions with a peak 4 days after fertilization. These data seem to indicate that if manures are applied during drier periods of the year, GHG emissions can be minimized, in addition to reducing nutrient runoff losses.

Manure Spills and Remediation Methods to Improve Water Quality

Within the last 2 decades the transition in livestock production technology and intensity has resulted in an increase in annual livestock production and a drastic decrease in the number of livestock operations. Consequently, the susceptibility of current livestock operations to experience manure spills is far greater relative to livestock farms 20 years ago, due to increased herd size per farm. Therefore, manure spills in agricultural communities have become a pervasive issue and have led to the catastrophic contributions of nutrients and pathogens to surface and groundwaters, human health issues, and large fish kills. Furthermore, the current remediation methods for manure spills that reach surface waters focus on mitigating contaminants in the water column and give no attention to the manure-exposed ditch sediments that remain in the fluvial system and continue to impair the water column. Therefore, this chapter addresses the causes, environmental impacts, and current and alternative remediation methods for manure spills in agricultural streams. Geographic data suggest that the location of animal-feeding operations and the occurrence of manure spills were highly correlated with the location of tile-drained agriculture fields. In addition, at least 14% of reported manure spills were separately attributed to the failure in waste storage equipment and over-application of manure in the states of Iowa and Ontario, Canada. Evaluations of the downstream impacts of manure spills have reported ammonia, total phosphorus, and total N concentrations that were at least 28 times the average upstream concentrations before the spill occurred. Studies have also determined that the current manure spill remediation method results in soluble phosphorus and nitrogen concentrations significantly greater than the Environmental Protection Agency total phosphorus nutrient critical limit, 24 h after the plume of the spill has passed. However, supplemental treatment of manure exposed sediments resulted in at least a 50% decrease in the soluble phosphorus concentrations which was in compliance with the phosphorus nutrient criteria.