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Akira Yamauchi - One of the best experts on this subject based on the ideXlab platform.
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plasticity in nodal root elongation through the Hardpan triggered by rewatering during soil moisture fluctuation stress in rice
Scientific Reports, 2018Co-Authors: Roel Rodriguez Suralta, Jonathan Manito Niones, Mana Kanonakata, Thiem Thi Tran, Shiro Mitsuya, Akira YamauchiAbstract:Rainfed lowland (RFL) rice fields have Hardpans and experience soil moisture fluctuations (SMF) stress, which influence root system development. Here, we clarify the expression and timing of the plasticity in nodal root elongation through the Hardpan under SMF and its contribution to shoot growth using a shallow-rooting IR64 and its deep-rooting introgression line, YTH304. Under SMF, soil moisture content had negative relationship with soil penetration resistance, regardless of Hardpan bulk densities. YTH304 had greater root system below the Hardpan than IR64 in Hardpan with 1.50 but not in 1.70 g cm−3 bulk density (BD). YTH304 had greater plasticity in nodal root elongation through the Hardpan than IR64 under SMF, which was clearly expressed during rewatering. YTH304 also had greater soil water uptake below the Hardpan during drought and greater shoot growth than IR64. The results imply that deep root system development during SMF was due to the plasticity in nodal root elongation through the Hardpan expressed during rewatering rather than during drought periods. This is against the long standing belief that active root elongation through the Hardpan happens during drought. This also implies a need to revisit current root screening methods to identify rice lines with good Hardpan penetration ability.
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genotypic variations in the plasticity of nodal root penetration through the Hardpan during soil moisture fluctuations among four rice varieties
Plant Production Science, 2018Co-Authors: Dinh Thi Ngoc Nguyen, Roel Rodriguez Suralta, Mana Kanonakata, Shiro Mitsuya, Stella Owusunketia, Akira YamauchiAbstract:AbstractRainfed lowland rice fields are characterized by soil moisture fluctuations (SMF) and the presence of Hardpan that impedes deep rooting and thus limits water extraction from deep soil layer during the periods of drought. In this study, we used rootboxes with three layers; shallow layer, artificial Hardpan, and deep and wet layer below the Hardpan, to evaluate differences in the plasticity of nodal roots elongation through the Hardpan and promote root branching below the Hardpan in response to SMF among four rice varieties; Sasanishiki, Habataki, Nipponbare, and Kasalath. Experiments were conducted during the summer and autumn seasons. Plasticity was computed as the difference in root traits within each variety between the SMF and continuously well-watered treatments. In both experiments, Habataki consistently tended to exhibit higher root plasticity than the other three varieties by increasing number of nodal roots that penetrated the Hardpan during rewatering period in SMF, when the soil moisture...
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hydrogen isotope composition of soil water above and below the Hardpan in a rainfed lowland rice field
Field Crops Research, 2006Co-Authors: Katsuya Yano, Akira Yamauchi, Nobuhito Sekiya, Benjamin K Samson, M A Mazid, Yasuhiro Kono, L J WadeAbstract:Abstract In rainfed lowland rice fields, developing Hardpan soil layers must be important to pool rainfall, but during drought that also restricts water movement from below it. We investigated whether the Hardpan can maintain a contrast of deuterium/hydrogen isotopic composition (δD) in soil water under field condition. The experimental site was at Rajshahi in north-west Bangladesh. The Hardpan soil layers had developed around 0.2 m soil-depth in the field. Soil water from either above or below the Hardpan was collected non-destructively with porous cups installed into the field. Using an isotopic ratio mass spectrometer, δD value of each water sample was determined. During the sampling period, the field surface varied from water-saturated to unsaturated status with rainfall event. While the δD values fluctuated by the influence of rainfall, significant differences in the δD values were always detected between above and below the Hardpan, revealing heterogeneity in the δD values persisted with the Hardpan. The effect of Hardpan on retention of the δD signature was further confirmed in a laboratory experiment using intact soil columns collected from a paddy field at Nagoya University. The natural δD signature in rainfed lowland rice field may be useful to identify certain genotypes that demonstrate in situ capability of water acquisition from below the Hardpan through δD analysis of the xylem sap.
Longbin Huang - One of the best experts on this subject based on the ideXlab platform.
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rhizosphere modifications of iron rich minerals and forms of heavy metals encapsulated in sulfidic tailings Hardpan
Journal of Hazardous Materials, 2020Co-Authors: Songlin Wu, Tuan A H Nguyen, Gordon Southam, Tingshan Chan, Yingrui Lu, Felipe Saavedramella, Longbin HuangAbstract:Abstract Hardpan caps formed after extensive weathering of the top layer of sulfidic tailings have been advocated to serve as physical barriers separating reactive tailings in depth and root zones above. However, in a Hardpan-based root zone reconstructed with the soil cover, roots growing into contact with Hardpan surfaces may induce the transformation of Fe-rich minerals and release potentially toxic elements for plant uptake. For evaluating this potential risk, two representative native species, Turpentine bush (Acacia chisholmii, AC) and Red Flinders grass (Iseilema vaginiflorum, RF), of which pre-cultured root mats were interfaced with thin discs of crushed Hardpan minerals in the rhizosphere (RHIZO) test. After 35 days, the surface dissolution of Hardpan minerals occurred and Fe-rich cement minerals were transformed from ferrihydrite-like minerals to goethite-like and Fe(III)-carboxylic complexes, as revealed by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) and synchrotron-based X-ray absorption fine structure spectroscopy (XAFS) analysis. This transformation may result from the functions of root exudates. The transformation of Hardpan cement minerals caused the co-dissolution of Cu and Zn initially encapsulated in the cements and their uptake by plants. Nevertheless, only was the minority of the plant Cu and Zn transported into shoots.
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Zinc and lead encapsulated in amorphous ferric cements within Hardpans in situ formed from sulfidic Cu-Pb-Zn tailings.
Environmental Pollution, 2019Co-Authors: Songlin Wu, Tuan A H Nguyen, Gordon Southam, Peter M. Kopittke, David J. Paterson, Longbin HuangAbstract:Abstract Hardpans are massively indurated layers formed at the top layer of sulfidic tailings dams, which develop cementation structures and result in heavy metal immobilization. However, the micro-structural and complex forms of the cementing materials are not fully understood, as well as the mechanisms by which Zn and Pb are stabilized in the Hardpans. The present study deployed synchrotron-based X-ray fluorescence microscopy (XFM) to have characterized the cementing structures, examined the distribution of Fe, Zn and Pb, and obtained laterally-resolved speciation of Zn within the Hardpans using fluorescence X-ray absorption near-edge structure (XANES) imaging. The XFM analyses revealed that the Fe-rich cement layers consisted of Fe (oxyhydr)oxides coupled with amorphous Si materials, immobilizing Zn and Pb. Through laterally-resolved XANES imaging analyses, Zn-ferrihydrite-like precipitates were predicted to account for >76% of the total Zn within the Fe-rich cement layers. In contrast, outside of the cement layers, 9–63% of the Zn was estimated as labile ZnSO4.7H2O, with the remainder in the form of Zn-sulfide. These findings demonstrated that the Fe-rich cement layers were critical in immobilizing Zn and Pb within Hardpans via mineral passivation and encapsulation, as the basis for long-term geochemical stability in the Hardpan layer of sulfidic mine tailings.
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microstructural characteristics of naturally formed Hardpan capping sulfidic copper lead zinc tailings
Environmental Pollution, 2018Co-Authors: Songlin Wu, Tuan A H Nguyen, Gordon Southam, Tingshan Chan, Yingrui Lu, Longbin HuangAbstract:A massive and dense textured layer (ca. 35–50 cm thick) of Hardpan was uncovered at the top layer, which capped the unweathered sulfidic Cu-Pb-Zn tailings in depth and physically supported gravelly soil root zones sustaining native vegetation for more than a decade. For the purpose of understanding functional roles of the Hardpan layer in the cover profile, the present study has characterized the microstructures of the Hardpan profile at different depth compared with the tailings underneath the Hardpans. A suit of microspectroscopic technologies was deployed to examine the Hardpan samples, including field emission-scanning electron microscopy coupled with energy dispersive spectroscopy (FE-SEM-EDS), X-ray diffraction (XRD) and synchrotron-based X-ray absorption fine structure spectroscopy (XAFS). The XRD and Fe K-edge XAFS analysis revealed that pyrite in the tailings had been largely oxidised, while goethite and ferrihydrite had extensively accumulated in the Hardpan. The percentage of Fe-phyllosilicates (e.g., biotite and illite) decreased within the Hardpan profile compared to the unweathered tailings beneath the Hardpan. The FE-SEM-EDS analysis showed that the fine-grained Ca-sulfate (possibly gypsum) evaporites appeared as platelet-shaped that deposited around pyrite, dolomite, and crystalline gypsum particles, while Fe-Si gels exhibited a needle-like texture that aggregated minerals together and produced contiguous coating on pyrite surfaces. These microstructural findings suggest that the weathering of pyrite and Fe-phyllosilicates coupled with dolomite dissolution may have contributed to the formation of Ca-sulfate/gypsum evaporites and Fe-Si gels. These findings have among the first to uncover the microstructure of Hardpan formed at the top layer of sulfidic Cu-Pb-Zn tailings, which physically capped the unweathered tailings in depth and supported root zones and native vegetation under semi-arid climatic conditions.
Mostafa Redwan - One of the best experts on this subject based on the ideXlab platform.
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application of mineral liberation analysis in studying micro sedimentological structures within sulfide mine tailings and their effect on Hardpan formation
Science of The Total Environment, 2012Co-Authors: Mostafa Redwan, Dieter Rammlmair, Jeannet A MeimaAbstract:Abstract In this paper, mineral liberation analysis (MLA) was applied as a new approach to elucidate and quantify textural, mineralogical, and chemical variations on a μm/mm scale to understand the alteration processes relevant for Hardpan formation at the Davidschacht mine tailings in Freiberg, Germany. Additionally, the bulk mineralogical, geochemical, and physical properties were investigated in detail. Within the upper 1.5 m of this impoundment, a repetition was observed of oxidized sediments with pH values between 2 and 3, and of unoxidized sulfide/carbonate bearing sediments with pH values around 7.0. The alteration process was not homogeneous, as even within the same lamina different stages of oxidation were observed. According to the MLA measurements, the 2D pore area decreased from about 43 area-% in the unoxidized layers to 10.5–24.0 area-% in the Hardpan layers, which is due to the accumulation of secondary precipitates. This clogging of pores was localized at the contact zone between two graded layers. The upper part of the lower layer consisted of very fine grained mica and chlorite fragments, which have a relatively high water retention capacity. This lamina was overlain by the bottom part of the next graded layer, which was characterized as relatively coarse grained with coarse open pores and an elevated content of primary reactive sulfides. This lamina provides access to oxygen and rain water to stimulate reactions, eventually supported by microbiological activity. Since graded layers might be amputated at top or bottom, the above described assemblage was not ubiquitous, but nevertheless multiple repetitions were encountered even at thin section level. The occurrence of these repetitions of slightly inclined tile like Hardpans may reduce rain water and oxygen input at the rim of the impoundment. The application of MLA has opened up new opportunities for a better understanding of the sedimentological and mineralogical setup in relation to oxidation, transport, and precipitation processes on a μm scale within tailings impoundments.
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Influence of climate, mineralogy and mineral processing on the weathering behaviour within two, low-sulfide, high-carbonate, gold mine tailings in the Eastern Desert of Egypt
Environmental Earth Sciences, 2011Co-Authors: Mostafa Redwan, Dieter RammlmairAbstract:Despite its importance within environmental management strategies, little concern is shown to sulfide oxidation and/or Hardpan formation at neutral pH where dry condition prevails. Two gold mine tailings in Egypt, El Sid and Barramiya, were studied for their geochemical/mineralogical properties, and climate influence on Hardpan formation. The tailings are characterised by homogeneous silt-sized sediments (>42%), have high carbonate, predominantly as calcite for El Sid and dolomite-ankerite for Barramiya, and low-sulfide contents, chiefly as pyrite, galena and sphalerite for El Sid, and arsenopyrite–pyrite for Barramiya. El Sid is characterised by high average concentrations of Pb (2,758 mg/Kg) and Zn (2,314 mg/Kg), its lower part dominated by mafics, overlaid by granitoids. Barramiya has higher As (average 2,836 mg/Kg) content and represents a mixture of mica-schists/mafics-ultramafics. During field investigations, no Hardpans were identified, only bassanite and gypsum were found at the surface of El Sid tailings, forming thin layers and desiccation crack fillings. Column experiments showed a thin crust consisting of gypsum, halite and sodium sulfate formed at the top of the column of El Sid tailings after 2 weeks, this was not recognized in the column from Barramiya. The homogenous thickened tailings deposition in both areas did not favour Hardpan formation, since the critical amounts of reacting sulfides were never achieved in individual lamina, due to missing mineral/grain size fractionation. The high-temperature/low-water availability, characteristic for desert climate regions did not allow significant sulfides oxidation. Therefore, both tailings will suffer from continuous erosion and spreading out of contaminants to the environment for a prolonged period of time by sporadic flash floods.
Jeannet A Meima - One of the best experts on this subject based on the ideXlab platform.
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application of mineral liberation analysis in studying micro sedimentological structures within sulfide mine tailings and their effect on Hardpan formation
Science of The Total Environment, 2012Co-Authors: Mostafa Redwan, Dieter Rammlmair, Jeannet A MeimaAbstract:Abstract In this paper, mineral liberation analysis (MLA) was applied as a new approach to elucidate and quantify textural, mineralogical, and chemical variations on a μm/mm scale to understand the alteration processes relevant for Hardpan formation at the Davidschacht mine tailings in Freiberg, Germany. Additionally, the bulk mineralogical, geochemical, and physical properties were investigated in detail. Within the upper 1.5 m of this impoundment, a repetition was observed of oxidized sediments with pH values between 2 and 3, and of unoxidized sulfide/carbonate bearing sediments with pH values around 7.0. The alteration process was not homogeneous, as even within the same lamina different stages of oxidation were observed. According to the MLA measurements, the 2D pore area decreased from about 43 area-% in the unoxidized layers to 10.5–24.0 area-% in the Hardpan layers, which is due to the accumulation of secondary precipitates. This clogging of pores was localized at the contact zone between two graded layers. The upper part of the lower layer consisted of very fine grained mica and chlorite fragments, which have a relatively high water retention capacity. This lamina was overlain by the bottom part of the next graded layer, which was characterized as relatively coarse grained with coarse open pores and an elevated content of primary reactive sulfides. This lamina provides access to oxygen and rain water to stimulate reactions, eventually supported by microbiological activity. Since graded layers might be amputated at top or bottom, the above described assemblage was not ubiquitous, but nevertheless multiple repetitions were encountered even at thin section level. The occurrence of these repetitions of slightly inclined tile like Hardpans may reduce rain water and oxygen input at the rim of the impoundment. The application of MLA has opened up new opportunities for a better understanding of the sedimentological and mineralogical setup in relation to oxidation, transport, and precipitation processes on a μm scale within tailings impoundments.
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formation of sequences of cemented layers and Hardpans within sulfide bearing mine tailings mine district freiberg germany
Applied Geochemistry, 2007Co-Authors: Torsten Graupner, Jeannet A Meima, Andrea Kassahun, Dieter Rammlmair, Dagmar Kock, Markus Furche, Adrian Fiege, Axel Schippers, Frank MelcherAbstract:Abstract The roles of mineral dissolution, precipitation, transformation and mass transport processes related to formation of characteristic cemented layer–Hardpan sequences were studied in low sulfide and low carbonate Freiberg polymetallic mine tailings. Using high resolution profiling, combined geochemical, geomicrobiological and geophysical methods allowed description of the process of weathering of reactive mineral phases and the position of the oxidation front in detail, as well as revealing the mechanisms of cementation of tailings predominantly by the formation of gels/poorly crystalline phases. Autochthonous and allochthonous gels reduced the porosity of cemented layers to values ⩽1%, whereas secondary crystalline phases were less efficient in filling the pore space. Electron microprobe analysis of cemented tailings showed that common jarosite-group minerals contained up to about 8 wt.% PbO and 0.2–1.9 wt.% As 2 O 5 . Iron–As–Si gels reached contents of up to ∼44 wt.% As 2 O 5 in gel-rich cemented layers. Zinc was below the detection limit in the studied secondary phases. Sequential extraction of cemented and related oxidized brown silt layers confirmed that the bulk of As was bound to amorphous/poorly crystalline hydrous oxides of Fe, whereas Pb was often bound to jarosite. Zinc was found preferentially in the water-soluble and the exchangeable fractions. In the grey silt and the sand directly underlying the oxidized layers, As, Pb and Zn occurred as sulfide minerals. The main effects of the cemented layer–Hardpan sequences at the studied site are (1) a temporary natural attenuation of the toxic compounds, (2) a restriction of the downward movement of the oxidation front, and (3) a reduction of the extent of the erosion of the surface of the tailings impoundment by wind and water. The potential of a heap to form cemented layers and Hardpans is greatly increased by a heterogeneous distribution of grain sizes and reactive materials in the topmost zone, as well as by the occurrence of sulfide-rich tailings on top of layers with low permeability.
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geochemical modelling of Hardpan formation in an iron slag dump
Minerals Engineering, 2007Co-Authors: Jeannet A Meima, Simona Regenspurg, Andrea Kassahun, Dieter RammlmairAbstract:Abstract The geochemical processes underlying Hardpan formation in an alkaline iron slag dump containing up to 30 cm thick Hardpans were investigated. A modelling approach has been developed to simulate mineral precipitation sequences upon pore water evaporation with PHRQPITZ and PHREEQC. This modelling approach follows the thermodynamic reaction path in which reaction products, except for calcite, may react again with the aqueous phase and form new products as evaporation proceeds. Phases that were allowed to precipitate include am-SiO 2 , am-Al(OH) 3 , ferrrihydrite, calcite, and salts that are known to occur in natural evaporites. The predicted results were compared with the observed mineralogy of evaporites and Hardpans as analysed by XRD, FTIR-spectroscopy, and/or SEM–EDS. The evaporites precipitating from relatively unweathered iron slag were found to consist mainly of sodium salts (mirabilite, trona, glaserite) and to a smaller extent of calcite and gel-like phases of in particularly Si, but also Al and Fe. After 10 years of weathering, amorphous Si-gels and calcite were found to be most abundant. These results are based on model predictions as well as on observations. This silica gel phase, which actually consists of heterogeneous Ca- and Fe-rich silica gels, covers particles and fills micropores and -cracks in the Hardpan. Hardpans formed by gel-like phases may hold rain water by their swelling properties.
Randy L. Raper - One of the best experts on this subject based on the ideXlab platform.
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Measurement and Variation of Site-specific Hardpans
2001 Sacramento CA July 29-August 1 2001, 2020Co-Authors: Randy L. Raper, E.b. Schwab, Seth M. DabneyAbstract:Cone index profiles taken in several Southeastern U.S. fields with upland soils were used to measure the Hardpan depth and to predict their spatial variation. Continuous treatments of these fields for several years included conventional tillage, no-tillage, segregated traffic, and random traffic. Conventional tillage systems were found to bring the Hardpan significantly closer to the soil surface, even in no-trafficked row middles and directly beneath the rows. Little difference in depth of Hardpan was found between a no-till field subjected to random traffic and a field where traffic was segregated. The least amount of variation in Hardpan depth was found in trafficked row middles in a no-till field.
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Site-specific subsoiling: benefits for Coastal Plain soils.
2020Co-Authors: Randy L. Raper, D. W. Reeves, Joey N. Shaw, E. Van Santen, P. L. Mask, D. L. Jordan, D. F. CaldwellAbstract:The negative impacts of soil compaction on crop yields can often be alleviated by subsoiling. However, this subsoiling operation is often conducted at unnecessarily deep depths where it wastes energy and disturbs surface residue necessary for erosion control and soil quality. A corn (Zea mays L.)-cotton (Gossypium hirsutum L.) rotation experiment was conducted for four years on a Coastal Plain soil with a Hardpan in east-central Alabama to evaluate the potential for site-specific subsoiling (tilling just deep enough to eliminate the Hardpan layer) to improve crop yields and conserve energy. Both crops showed benefits of subsoiling as compared to the no-subsoiling treatment. Site-specific subsoiling produced yields equivalent to deep subsoiling treatment while not excessively disturbing surface soil and residues. INTRODUCTION The depth and degree of soil compaction has been found to vary greatly throughout Southern U.S. fields. Subsoiling at a uniform depth has been found to be particularly effective in reducing the effect of compaction on crop yields (Campbell et al., 1974). However, subsoiling at a depth deeper than necessary wastes subsoiling energy and unnecessarily disturbs excessive amounts of soil and crop residue. Also, subsoiling at a depth shallower than necessary wastes subsoiling energy without eliminating the compacted soil condition. Adjusting the depth of subsoiling to match the Hardpan depth throughout a field, i.e., site-specific subsoiling, was investigated as a potential method for soil compaction management. Measurements of the Hardpan depth taken in the Southeastern U.S. indicate that between 25 and 75% of subsoiling energy could be saved if some form of site-specific subsoiling could be developed and used (Fulton et al., 1996; Raper, 1999). Also, some data indicate that subsoiling deeper than necessary may reduce yields (Raper et al., 2000). Therefore, this study was initiated to evaluate whether the concept of site-specific subsoiling was viable. METHODS AND MATERIALS A 20-ac field from the Alabama Agricultural Experiment Station’s E.V. Smith Research and Education Center in east-central Alabama, USA was used for this experiment. The coastal plain field was comprised of a Toccoa fine sandy loam (coarse-loamy, mixed, active, nonacid, thermic Typic Udifluvents) that had excessive soil strength and required annual subsoiling. A complete set of soil cone penetrometer measurements (ASAE, 1999a; ASAE, 1999b) were obtained with the Multiple-Probe Soil Measurement System (Raper et al., 1999) on an approximate 300-ft grid. Cone index measurements were analyzed to determine depth to the Hardpan over the entire field.
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Site-Specific Subsoiling Benefits for Cotton Production
2005 Tampa FL July 17-20 2005, 2020Co-Authors: Randy L. Raper, D. W. Reeves, Joey N. Shaw, E. Van Santen, P. L. MaskAbstract:The negative impacts of soil compaction on crop yields can often be alleviated by subsoiling. However, this subsoiling operation is often conducted at unnecessarily deep depths where it wastes energy and disturbs surface residue necessary for erosion control and improved soil quality. A corn (Zea mays L.)-cotton (Gossypium hirsutum L.) rotation experiment was conducted over four years on a Coastal Plain soil with a Hardpan in east-central Alabama to evaluate the potential for site-specific subsoiling (tilling just deep enough to eliminate the Hardpan layer) to improve crop yields while conserving energy. Seed cotton yield showed benefits of subsoiling compared to the no-subsoiling treatment. Site-specific subsoiling produced yields equivalent to deep subsoiling while not excessively disturbing surface soil and residues. Significant reductions in draft force and drawbar power were found for site-specific subsoiling as compared to uniform deep subsoiling. Producers in the Coastal Plains who can determine the depth of their root-impeding layer and can provide site-specific subsoiling to loosen compacted soil profiles should have comparable yields and reduced energy requirements as those producers implementing uniform deep subsoiling.
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Design and evaluation of ground-driven rotary subsoilers
Soil & Tillage Research, 2012Co-Authors: Ahmet Çelik, Randy L. RaperAbstract:Abstract Compacted soil Hardpans restrict crop growth by limiting root access to moisture and nutrients in the subsoil. Mechanically disrupting this Hardpan profile is necessary in many soils to promote proper root elongation and crop growth. Subsoiling is the primary deep soil tillage practice which needs to be done once every two to three years depending on soil type and conditions. To maintain an adequate amount of residue for conservation systems, subsoiling should be performed without excessively disturbing the soil surface. However, most subsoilers disrupt the soil surface excessively and cover valuable crop residues. The objective of this study was, therefore, to design an alternative subsoiler for conservation tillage systems that minimized soil disturbance and energy requirements while adequately disrupting compacted soil profiles. Ground-driven rotary subsoilers were designed and manufactured by dividing a 1.2 m diameter coulter into multiple blades. Minimizing the sliding soil resistance on the side of the coulter was one of the main considerations in forming the shape and number of blades. An experiment was conducted in the soil bins of the USDA-ARS National Soil Dynamics Laboratory in Auburn, AL, USA to determine the effects of ground-driven rotary subsoilers on soil disturbance and energy requirements compared with a large coulter and a typical subsoiler. Treatments were four different types of subsoilers (coulter-no-blade, coulter-5-blade normal direction, coulter-5-blade reverse direction, and shank-type) and two tillage depths (25 and 38 cm). Soil disturbance, cone index, bulk density and draft were measured and statistical analyses conducted to determine the differences between subsoilers. The coulter-5-blade normal direction and coulter-5-blade reverse direction subsoilers required considerably less draft power (from 10 to 68%) for both operation depths than coulter-no-blade and shank type subsoilers. Coulter subsoilers minimized soil disturbance and required higher draft energy (from 22.5 to 33.5%) per volume of disturbed soil than the shank-type subsoiler. The soil disruption paths of coulter-5-blade subsoilers have an advantage for row crops due to limited above-ground disturbance if seeds can be placed in the middle of the disrupted zone.
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Benefits of site-specific subsoiling for cotton production in Coastal Plain soils.
Soil & Tillage Research, 2007Co-Authors: Randy L. Raper, D. W. Reeves, Joey N. Shaw, E. Van Santen, P. L. MaskAbstract:The negative impacts of soil compaction on crop yields can often be alleviated by subsoiling. However, this subsoiling operation is often conducted at unnecessarily deep depths wasting energy and excessively disturbing surface residue necessary for erosion control and improved soil quality. A corn (Zea mays L.)-cotton (Gossypium hirsutum L.) rotation experiment was conducted over 4 years on a Coastal Plain soil with a Hardpan in east-central Alabama to evaluate the potential for site-specific subsoiling (tilling just deep enough to eliminate the Hardpan layer) to improve crop yields while conserving energy. Seed cotton yield showed benefits of subsoiling (2342 kg/ha) compared to the no-subsoiling treatment (2059 kg/ha). Averaging over all years of the study, site-specific subsoiling produced cotton yields (2274 kg/ha) statistically equivalent to uniform deep subsoiling at a 45 cm depth (2410 kg/ha) while not excessively disturbing surface soil and residues. Significant reductions in draft force were found for site-specific subsoiling (59% and 35%) as compared to uniform deep subsoiling at a 45 cm depth in shallow depth Hardpan plots (25 cm) and medium depth Hardpan plots (35 cm), respectively. Calculated fuel use for site-specific subsoiling was found to be reduced by 43% and 27% in the shallow and medium depth Hardpan plots, respectively, as compared to uniform deep subsoiling in these same plots. Producers in the Coastal Plains who can determine (or who know) the depth of their root-impeding layer and perform site-specific subsoiling can have comparable cotton yields to traditional uniform depth subsoiling with reduced energy requirements.
