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Richard J. Heck

Other affiliations: Ontario Agricultural College
Bio: Richard J. Heck is an academic researcher from University of Guelph. The author has contributed to research in topics: Soil structure & Soil water. The author has an hindex of 23, co-authored 63 publications receiving 1778 citations. Previous affiliations of Richard J. Heck include Ontario Agricultural College.


Papers
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Journal ArticleDOI
TL;DR: In this paper, X-ray computed tomography (CT) has been used to investigate the hydro-physical characteristics of the soil, in a functional and temporal manner, and a dynamic approach has also been utilized in the evaluation of the biotic factor influence on soil.
Abstract: The study of the spatial configuration of soil, in its complexity, requires an understanding of the interrelations and interactions between the diverse soil constituents, at various levels of organization. Investigations of the spatial arrangement of the mineral and organic components of soil have benefited from the development of techniques for structural analysis. X-ray computed tomography (CT) is a non-destructive and non-invasive technique that has been successfully used for three-dimensional (3D) examination of soil. Valuable information has been obtained by the application of CT for the description and quantitative measurements of soil structure elements, especially of soil pores and pore network features. In many studies, X-ray CT has been used to investigate the hydro-physical characteristics of the soil, in a functional and temporal manner. A dynamic approach has also been utilized in the evaluation of the biotic factor influence on soil. The analysis of soil solid phases, by X-ray CT, has been c...

266 citations

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TL;DR: In this paper, a 30-year old long-term rotation and tillage treatment experiment on a Canadian silt loam soil was conducted and the results showed that a diverse crop rotation was needed for an optimal performance of NT for the studied soil.
Abstract: Tillage and rotation are fundamental factors influencing soil quality and thus the sustainability of cropping systems. Many studies have focused on the effects of either tillage or rotation, but few have quantified the long term integrated effects of both. We studied the issue using a 30-year old long-term rotation and tillage treatment experiment on a Canadian silt loam soil. Topsoil measurements were carried out for three different rotations: R1, (C–C–C–C) continuous corn (Zea mays L.), R6, (C–C–O(RC), B(RC)) corn, corn, oats (Avena fatua L.) and spring barley (Hordeum vulgare L.) and R8, (C–C–S–S) corn, corn, soybean (Glycine max L.), soybean. A red clover (Trifolium pretense L.) cover crop was under seeded in oats and spring barley in R6. In 2010, first year corn was grown in R6 and R8. The tillage treatments included no tillage, NT and mouldboard ploughing, MP. Topsoil structural quality was visually evaluated in early June and mid October. Minimal disturbed soil cores collected in early June were used for X-ray CT scanning and to quantify water content and porosity. Soil friability was determined on the soil samples using a drop shatter test. Crop yield was determined and correlated to the soil quality estimates. We found significant effect of both rotation and tillage on visual soil structure at both times of assessment. Poor soil structure was found for NT except when combined with a diverse crop rotation (R6). The soil core pore characteristics data also displayed a significant effect of tillage but only a weak insignificant effect of rotation. The drop shatter results were in accordance with the visual assessment data. Crop yield correlated significantly with the visual soil structure scores. We conclude that a diverse crop rotation was needed for an optimal performance of NT for the studied soil.

231 citations

Journal ArticleDOI
TL;DR: In this article, a detailed analysis of changes in the soil structure induced by conventional (CT) and no-tillage (NT) systems was carried out for three different soil depths (0-10, 10-20 and 20-30 cm).
Abstract: Structure represents one of the main soil physical attributes indicators. The soil porous system (SPS) is directly linked to the soil structure. Water retention, movement, root development, gas diffusion and the conditions for all soil biota are related to the SPS. Studies about the influence of tillage systems in the soil structure are important to evaluate their impact in the soil quality. This paper deals with a detailed analysis of changes in the soil structure induced by conventional (CT) and no-tillage (NT) systems. Three different soil depths were studied (0–10, 10–20 and 20–30 cm). Data of the soil water retention curve (SWRC), micromorphologic (impregnated blocks) (2D) and microtomographic (μCT) (3D) analyses were utilized to characterize the SPS. Such analyses enabled the investigation of porous system attributes such as: porosity, pore number and shape, pore size distribution, tortuosity and connectivity. Results from this study show a tri-modal pore size distribution (PSD) at depths 0–10 and 10–20 cm for the soil under CT and a bi-modal PSD for the lower layer (20–30 cm). Regarding the soil under NT, tri-modal PSDs were found at the three depths analyzed. Results based on the micromorphologic analysis (2D) showed that the greatest contribution to areal porosity (AP) is given by pores of round (R) shape for CT (52%: 0–10 cm; 50%: 10–20 cm; 67%: 20–30 cm). Contrary to the results observed for CT, the soil under NT system gave the greatest contribution to AP, for the upper (0–10 cm) and intermediate (10–20 cm) layers, due to the large complex (C) pore types. For the μCT analysis, several types of pores were identified for each soil tillage system. Small differences in the macroporosity (MAP) were observed for the 0–10 and 20–30 cm between CT and NT. A better pore connectivity was found for the 0–10 cm layer under NT.

177 citations

Journal ArticleDOI
01 Jul 2012-Geoderma
TL;DR: In this article, a high-resolution X-ray CT scanner was used to quantify soil pore characteristics on undisturbed field moist soil and link these results to soil friability assessed using the drop-shatter method.

118 citations

Journal ArticleDOI
01 Sep 2006-Geoderma
TL;DR: In this paper, the authors examined pedogenesis, as well as the clay mineralogy of soil and rock samples obtained from a transect of gypsiferous and calcareous materials, using XRD, TEM and EDX analyses.

102 citations


Cited by
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Journal ArticleDOI
TL;DR: X-ray microtomographic imaging is a non-destructive technique for quantifying these processes in three dimensions within individual pores, and as reported here, with rapidly increasing spatial and temporal resolution.

968 citations

Journal ArticleDOI
15 Mar 2018-Geoderma
TL;DR: In this paper, the potential of observable soil structural attributes to be used in the assessment of soil functions is evaluated and discussed from a methodological point of view and with respect to their relevance to soil functions.

602 citations

Journal ArticleDOI
TL;DR: In this paper, the applicability of various thresholding and locally adaptive segmentation techniques for industrial and synchrotron X-ray CT images of natural and artificial porous media was investigated.
Abstract: [1] Nondestructive imaging methods such as X-ray computed tomography (CT) yield high-resolution, three-dimensional representations of pore space and fluid distribution within porous materials. Steadily increasing computational capabilities and easier access to X-ray CT facilities have contributed to a recent surge in microporous media research with objectives ranging from theoretical aspects of fluid and interfacial dynamics at the pore scale to practical applications such as dense nonaqueous phase liquid transport and dissolution. In recent years, significant efforts and resources have been devoted to improve CT technology, microscale analysis, and fluid dynamics simulations. However, the development of adequate image segmentation methods for conversion of gray scale CT volumes into a discrete form that permits quantitative characterization of pore space features and subsequent modeling of liquid distribution and flow processes seems to lag. In this paper we investigated the applicability of various thresholding and locally adaptive segmentation techniques for industrial and synchrotron X-ray CT images of natural and artificial porous media. A comparison between directly measured and image-derived porosities clearly demonstrates that the application of different segmentation methods as well as associated operator biases yield vastly differing results. This illustrates the importance of the segmentation step for quantitative pore space analysis and fluid dynamics modeling. Only a few of the tested methods showed promise for both industrial and synchrotron tomography. Utilization of local image information such as spatial correlation as well as the application of locally adaptive techniques yielded significantly better results.

510 citations

Journal ArticleDOI
TL;DR: Current and potential applications of thermal RS in agriculture discussed here include irrigation scheduling, drought monitoring, crop disease detection, and mapping of soil properties, residues and tillage, field tiles, and crop maturity and yield.

357 citations

Journal ArticleDOI
TL;DR: It is concluded that CT is well placed to contribute significantly to unravelling the complex interactions between roots and soil.
Abstract: The need to observe roots in their natural undisturbed state within soil, both spatially and temporally, is a challenge that continues to occupy researchers studying the rhizosphere. This paper reviews how over the last 30 years the application of X-ray Computed Tomography (CT) has demonstrated considerable promise for root visualisation studies. We describe how early CT work demonstrated that roots could be visualised within soils, but was limited by resolution (ca. 1 mm). Subsequent work, utilising newer micro CT scanners, has been able to achieve higher resolutions (ca. 50 μm) and enhance imaging capability in terms of detecting finer root material. However the overlap in the attenuation density of root material and soil pore space has been a major impediment to the uptake of the technology. We then outline how sophisticated image processing techniques, frequently based on object tracking methods, have demonstrated great promise in overcoming these obstacles. This, along with the concurrent advances in scan and reconstruction times, image quality and resolution (ca. 0.5 μm) have opened up new opportunities for the application of X-ray CT in experimental studies of root and soil interactions. We conclude that CT is well placed to contribute significantly to unravelling the complex interactions between roots and soil.

354 citations