Showing papers in "Soil Science in 1981"
1,157 citations
504 citations
Abstract: A root-soil model developed previously has been extended to predict the amount of increase in soil shear resistance (root reinforcement) produced by stretching, slipping, and breaking roots of various sizes. We measured Young's moduli, tensile strengths, and diameters of pine and barley root
348 citations
TL;DR: In this paper, the authors present a survey of Soil and Water Conservation Agencies in the United States and around the world, with a focus on land use planning, water conservation, and watershed management.
Abstract: 1. Conserving Soil and Water. 2. Soil Erosion and Civilization. 3. Geologic Erosion and Sedimentation. 4. Water Erosion and Sedimentation. 5. Wind Erosion and Deposition. 6. Predicting Soil Loss. 7. Soil Surveys as a Basis for Land Use Planning. 8. Cropping Systems. 9. Tillage Practices for Conservation. 10. Conservation Structures. 11. Vegetating Mining and Construction Sites. 12. Vegetating Other Areas of High Erosion Hazard. 13. Pastureland, Rangeland, and Forestland Management. 14. Water Conservation. 15. Soil Drainage. 16. Irrigation and Reclamation. 17. Soil Pollution. 18. Water Quality and Pollution. 19. Economics of Soil and Water Conservation. 20. Soil and Water Conservation Agencies in the United States. 21. Soil and Water Conservation Around the World. Appendix A. Conversion Factors. Appendix B. Common and Scientific Names of Plants Mentioned in the Text. Index.
260 citations
TL;DR: In this paper, the retention of arsenate by four soils of Saskatchewan, Canada, and its relation to selected soil properties and anionic environments were studied, and the data indicate that As retention by the soils at the dilute, As concentration range studied does not proceed through the precipitation of sparingly soluble arsenate compounds.
Abstract: The retention of arsenate by four soils of Saskatchewan, Canada, and its relation to selected soil properties and anionic environments were studied. The data indicate that As retention by the soils at the dilute, As concentration range studied does not proceed through the precipitation of sparingly soluble arsenate compounds. Arsenate retention evidently proceeds through adsorption mechanisms. The adsorption maxima of the soils are not related to acidity and the contents of inorganic C, but are linearly related to amounts of ammonium oxalate-extractable Al and, to a lesser extent, to the contents of clay and ammonium oxalate-extractable Fe. Chloride, nitrate, and sulfate present at concentrations usually present in saline soils have little effect on the adsorption of As. Phosphate substantially suppresses As adsorption by the soils, and the extent of the suppression varies from soil to soil.
258 citations
118 citations
TL;DR: Moisture content measured in the soil correlated strongly with the curvature of the soil surface, and grain yields were as high as 1734 kilograms per hectare at the concave parts of the landscape, while at the convex parts, the moisture content was higher as discussed by the authors.
Abstract: Moisture content measured in the soil correlated strongly with the curvature of the soil surface. At the concave parts of the landscape, the moisture content was as high as 14 percent, and grain yields were as high as 1734 kilograms per hectare. At the convex parts, the moisture content was
109 citations
TL;DR: In this article, the adsorption of selenite and selenate selenium and desorption by sulfate and phosphate in normal, calcareous, high organic carbon saline, and alkali soils were studied.
Abstract: In the laboratory, we studied the adsorption of selenite and selenate selenium and desorption by sulfate and phosphate in normal, calcareous, high organic carbon saline, and alkali soils. Initial selenium solutions contained 5 to 150 μmole Se/g soil, and desorbing solutions contained 500 μmo
92 citations
TL;DR: In this paper, the authors evaluated selected data describing complexation (including adsorption) of cadmium and other trace metals by natural solid and soluble soil components, using a consistent format to demonstrate the conditional nature of reported selectivity coefficients.
Abstract: We reevaluated selected data describing complexation (including adsorption) of cadmium and other trace metals by natural solid and soluble soil components, using a consistent format to demonstrate the conditional nature of reported selectivity coefficients. In all cases, the determined selectivity values increased substantially as the concentration of trace metals decreased with respect to the concentration of other competing cations. This dependence upon relative metal concentrations is apparently due to the heterogeneous composition of complexing sites in most soil systems and competition among the various cations present for these sites. Most selectivity coefficients have been obtained after the introduction of metal concentrations well above those normally encountered in natural systems, with little attention paid to the concentration and composition of competing cations. Under such conditions, the metal occupied not only the most specific sites, but a large portion of the more numerous nonspecific sites. The use of selectivity values obtained under such conditions, in predictive models, will greatly underestimate metal complexation in natural systems. This demonstrates the importance of determining selectivity coefficients under conditions comparable to those existing in nature, if results are to be applicable to real systems.
81 citations
TL;DR: In this article, the authors studied the release of fixed NH4+ by clay minerals under field conditions on two representative arable sites, one on loess and the other on alluvial soil.
Abstract: We studied the release of fixed (nonexchangeable) NH4+ by clay minerals under field conditions on two representative arable sites, one on loess the other on alluvial soil. The nonexchangeable NH4+ content of soil from three depths was determined at five dates during the growing season in fields carrying winter barley (loess) or spring oats (alluvial soil). There were significant changes in the content of nonexchangeable NH4+ during the growing period. Early in crop growth particularly, the upper soil layers (0 to 60 cm) were depleted of nonexchangeable NH4+; later, nonexchangeable NH4+ declined at the depth of 60 to 90 cm. The nonexchangeable NH4+ content of alluvial soil recovered to approximately its original level at the end of the growing season. There was a substantial net loss on nonexchangeable NH4+ from the loess soil of about 40 ppm, equivalent to 500 kg N/ha assuming a soil depth of 90 cm. Soil samples labeled with nonexchangeable 15NH4+ and placed back into the field under sugar beet at the depths from which the samples had been taken, released, between May and October, significant quantities of labeled nonexchangeable NH4+, which, on the basis of a soil depth of 75 cm, were equivalent to about 350 kg N/ha in the loess and 150 kg N/ha in the alluvial soil. It is suggested that in these soil types, which are representative of many arable soils in central Europe, the so-called fixed NH4+ is involved in the general soil N cycle.
TL;DR: In this article, a study was conducted at the boreal forest and alpine tundra transition at Walker Lake, Alaska, to determine whether the lichen-mixed-heath assemblage of the Tundra was capable of producing Podzols.
Abstract: On well-drained sites in northern locations, Podzols have traditionally been observed in association with forest vegetation and the less leached Arctic Brown soils with tundra vegetation. The present study shows that this vegetation-soil association is not a ubiquitous feature in northern Alaska, suggesting that Podzol occurrence beyond the modern tree line is not sufficient evidence to infer past forest expansion. This study was initiated at the boreal forest and alpine tundra transition at Walker Lake, Alaska, to determine whether the lichen-mixed-heath assemblage of the tundra was capable of producing Podzols. Morphologically, soils developed under lichen-heath cover could not be distinguished from those under spruce trees. Standard pedologic parameters, such as pH, CEC, and dithionite (Fed) and pyrophosphate (Fep) extractable iron, also failed to distinguish between these soils. An altitudinal trend unrelated to vegetation cover was apparent in these data. The Fep:Fed ratio, as well as Fep and organic carbon in the B2hir, decreases with altitude. Both stable carbon isotopes and lignin oxidation products were used to investigate the plant sources of carbon in the B horizons. Altitudinal increases of both B horizon 13C/12C and present day plant cover 13C/12C indicate that morphologically similar soils may have developed under isotopically and taxonomically different plant communities. The lignin oxidation products from the B2hir of the forest soil are consistent with the prevailing gymnosperm trees growing on the site, and the oxidation products of the B2hir of the tundra soil are consistent with the angiosperm species that predominate at the tundra site. These results and other field evidence suggest that trees have not been more extensive in the past at Walker Lake. Albic horizons in the Arctic are, therefore, not conclusive evidence of a forest environment. Additional evidence, such as relict arboreal material, is needed before inferring tree line fluctuations and associated climatic change.
TL;DR: In this article, the effect of flooding of Pahokee muck (a drained, cultivated Histosol) on nitrous oxide emissions from the soil was determined by measuring field N/sub 2/O fluxes and produced in soil samples incubated under controlled laboratory conditions.
Abstract: To determine the effect of flooding of Pahokee muck (a drained, cultivated Histosol) on nitrous oxide emissions from the soil, we measured field N/sub 2/O fluxes and N/sub 2/O produced in soil samples incubated under controlled laboratory conditions. During the first 5 days of flooding of a field that had previously been cropped to sweet corn (Zea mays L. rugosa), the NO/sub 3//sup -/-N levels declined from 68 to <0.1 microgram nitrogen per cubic centimeter. Similarly, the N/sub 2/O flux decreased from 174 g N/ha/d prior to flooding to approximately 0 after flooding. Comparing the flux values and the N/sub 2/O concentrations in the flood water suggested that the flooded field may have acted as a sink for atmospheric N/sub 2/O. In laboratory-incubated samples of the preflood and flooded soils, the potential denitrification rates increased from 16.2 ..mu..g N/cm/sup 3//day prior to flooding to 31.2 ..mu..g N/cm/sup 3//d after flooding. Whereas N/sub 2/O was the major product of denitrification in soil samples collected prior to flooding, very little N/sub 2/O accumulated in samples collected from the flooded field. Nitrous oxide was readily reduced in the flooded soil in the presence of NO/sub 3//sup -/-N and NO/sub 2//sup -/-N concentrations ofmore » 100 and 3 mg/liter, respectively.« less
TL;DR: In this paper, the authors measured carbon dioxide production in Yolo silt loam amended with alfalfa meal and sewage sludge after the addition of solutions of chromium, cadmium, copper, lead, manganese and zinc at concentrations ranging from 0 to 400 parts per million.
Abstract: We measured carbon dioxide production in Yolo silt loam amended with alfalfa meal and sewage sludge after the addition of solutions of chromium, cadmium, copper, lead, manganese, and zinc at concentrations ranging from 0 to 400 parts per million. Quantities of these metals extractable with water, KNO/sub 3/, DTPA, and HNO/sub 3/ were determined at the end of the experiment. Threshold concentrations of metals, defined as the concentration required for 10 percent inhibition of CO/sub 2/ production, were in the sequence Pb>Cd>Cu>Mn = Zn. An addition of only 8.6 ppm of Cr to this soil is sufficient to inhibit CO/sub 2/ evolution by 10 percent, whereas the addition of about 27 ppm of Pb would be required to produce the same effect.
TL;DR: In this paper, the analytical constant-flux solution to Burgers' equation is presented, which is applicable to infiltration into soils with a constant diffusivity and quadratic conductivity-water content relationship.
Abstract: We present the analytical constant-flux solution to Burgers' equation. Burgers' equation is a minimally nonlinear Fokker-Planck diffusion equation, applicable to infiltration into soils with a constant diffusivity and quadratic conductivity-water content relationship. Field Bungendore fine sand has a near-constant diffusivity-water content relationship, and analytical solutions of Burgers' equation are in good agreement with field profiles of water content obtained in situ with a rainfall simulator. The solutions and experimental data all relate to nonponding infiltration with fluxes less than the saturated hydraulic conductivity; however, a wide range of elapsed times and flux rates are covered. Predicted wet-front penetration is in good agreement with the field experimental data. The complete analytical solution can be evaluated using a programmable hand calculator. The simpler “profile-at-infinity” solution is shown to be surprisingly accurate over a wide range of times, giving useful results easily. An expression for the time to ponding is also presented.
TL;DR: In this paper, the order of reaction of sulfide formation was found to be ill defined and the optimum pH for both sulfide and methane formation was 6.5 to 8.7.
Abstract: In suspensions of Crowley soil, and under conditions of controlled pH and redox potential, sulfide formation took place in the pH range 5.5 to 8.5 and in the redox potential range −175 to −350 mV. At each pH tested, the rate of sulfide formation increased with a decrease of the redox potential. The order of reaction of sulfide formation was found to be ill defined. The optimum pH for both sulfide and methane formation was 6.7. Empirical data were in agreement with thermodynamically predicted values. Nitrate reduction, manganous and ferrous ion, and sulfide and methane formation occurred sequentially according to thermodynamic principles. However, some overlap did occur in the later stages of the formation of manganous, ferrous, and sulfide ions, possibly due to delayed dissolution of manganese and iron compounds. A small amount of methane was formed at redox potentials as high as −120 mV. Nitrate and sulfate or their reduction products repressed methane formation. The effect of nitrate appeared to be twofold: first, it delayed methane formation until the reduction of nitrate was complete and the redox potential was lowered sufficiently for further anaerobic reactions to proceed. Secondly, it exerted a toxic effect on methane formation. The major effect of sulfate appeared to be toxic, although a slight increase of the redox potential did occur at high sulfate concentrations.
TL;DR: In this article, the natural terrestrial gamma radiation flux near the soil surface is used to infer areal soil moisture, and airborne gamma radiation data are collected over a network of 240 flight lines (each approximately 6 square kilometers) in the upper Midwest and used to calculate real-time soil moisture.
Abstract: Measurements of the natural terrestrial gamma radiation flux near the soil surface are used to infer areal soil moisture. Airborne gamma radiation data are collected over a network of 240 flight lines (each approximately 6 square kilometers) in the upper Midwest and used to calculate real-ti
TL;DR: The authors compared the physical and chemical properties of worm casts with the properties of the surface 0 to 10 centimeters of six soils along a toposequence developed on basement complex rocks in southwestern Nigeria.
Abstract: We compared the physical and chemical properties of worm casts with the properties of the surface 0 to 10 centimeters of six soils along a toposequence developed on basement complex rocks in southwestern Nigeria. Casts contained less sand and more silt and clay than the surface soil. Bulk de
TL;DR: In this paper, a numerical model was developed to simulate water and nitrogen transport and transformations through water-unsaturated, multilayered soil profiles, and the nitrogen transformation processes considered were nitrification, denitrification, immobilization, mineralization, and ionic exchange of ammonium.
Abstract: We developed a numerical model to simulate water and nitrogen transport and transformations through water-unsaturated, multilayered soil profiles. The nitrogen transformation processes considered were nitrification, denitrification, immobilization, mineralization, and ionic exchange of ammonium. Plant uptakes of water and nitrogen were also included. We used an explicit-implicit finite difference approximation method to solve the nitrogen transport and transformation equations simultaneously with the water flow equation. Model evaluation and sensitivity analysis for a wide range of values for the rate of nitrification, distribution coefficient for ammonium exchange, and rate of N uptake were investigated.
TL;DR: In this paper, the authors studied the properties of termite mounds built by two closely related species of Macrotermes to assess whether the two species differed in sorting out soil constituents.
Abstract: We studied the properties of termite mounds built by two closely related species of Macrotermes to assess whether the two species differed in sorting out soil constituents.Both species selectively preferred fine soil separates to construct the main hive (central part of mound), which is buil
TL;DR: In this article, the authors determined the quantity of distribution of yellow organic acids in two forest soils and adjacent stream waters and determined the molecular weight distribution of these organic acids and found the major fraction, the mobile fulvic acid fraction, to have a molecular weight in the range of 810 to 930.
Abstract: Using gel filtration, we determined the quantity of distribution of yellow organic acids in two forest soils and adjacent stream waters. We also determined the molecular weight distribution of these yellow organic acids and found the major fraction, the mobile fulvic acid fraction, to have a molecular weight in the range of 810 to 930. To calibrate the gel columns, we used standards chemically similar to yellow organic acids, rather than dextrans, which had been used by previous authors. If the molecular weights of yellow organic acids determined previously are recalculated using the new standard curve, the previous gel-filtration values agree quite well with those reported in this paper. Gel filtration of soil solutions from two forest soils demonstrated that yellow organic acids originated in the upper soil profile and that soil permeability strongly influences their concentration in adjacent stream waters. Because yellow organic acids originate in the soil, they can be referred to as mobile fulvic acids. Soil solutions passing through the lower B horizons had decreased mobile fulvic acid concentrations; thus the deeper B horizons were able to absorb and decrease mobile fulvic acids in the solutions derived from the upper profile.
TL;DR: In this article, the authors extracted humic acid (HA) from an Encinillas soil, Xeroumbrepts, Inceptisols, and oxidized it with potassium persulfate for 2 hours at 140°C.
Abstract: We extracted humic acid (HA) from an Encinillas soil, Xeroumbrepts, Inceptisols, and oxidized it with potassium persulfate for 2 hours at 140°C. The oxidation products, after methylation, were analyzed by direct injection into a gas chromatographic-mass spectrometric computer system. The most abundant compounds isolated from the HA oxidation products were n-C16 and n-C18 fatty acids, followed by several benzenecarboxylic and phenolic acids. Dicarboxylic acids and dialkyl phthalates constituted only a relatively small proportion of the isolated compounds. No n-alkanes were detected. Persulfate degrades only 40 percent of total weight HA, leaving a residue that can easily be recovered for further structural investigations. Persulfate, therefore, may be used as first oxidant in a sequential HA degradation.
TL;DR: In this paper, the molar reactivity of aluminum and iron toward phosphate (P/Al or Fe) at 0.5 M increased in the order: (Al + Fe)dit-pyr (0.3) < Fepyr ( 0.4) < Alpyr(0.5) < P/Al/Fe (< 0.0, and (Al+ Fe)oxa < 0.6) at pH 8.0.
Abstract: We measured phosphate retention by 18 Ando soil samples at different pH values (4 to 8.5) and phosphorus concentrations (10-3 to 2 M). A general regression equation held for each soil: log Y = α pH + β log [C] + c, where Y = phosphorus retention and [C] = phosphorus concentration. By multiple regression analysis, the Y values were correlated with the status of aluminum and iron analyzed by selective dissolution using pyrophosphate, dithionite-citrate, and oxalate-oxalic acid as reagents. Aluminum bound with humus, Alpyr, reacted with phosphate depending little on pH and markedly on phosphorus concentration, whereas aluminum and iron in allophane, (Al + Fe)oxa, depending markedly on pH and moderately on phosphorus concentration. Aluminum and iron in allophanelike constituents (Al + Fe)dit-pyr showed features similar to aluminum bound with humus. The molar reactivity of aluminum and iron toward phosphate (P/Al or Fe) at 0.5 M increased in the order: (Al + Fe)dit-pyr (0.3) < (Al + Fe)oxa (0.4) < Alpyr (0.5) < Fepyr (0.8) at pH 5.0, and (Al + Fe)oxa (<0.1) < (Al + Fe)dit-pyr (0.3) < Fepyr (0.5) < Alpyr (0.6) at pH 8.0.
TL;DR: In this article, the authors monitored the composition of the soil air in native grassland and cultivated fields over several years on upper, middle, and lower slope sites on an Orthic Dark Brown Chernozemic soil.
Abstract: We monitored the composition of the soil air in native grassland and cultivated fields over several years on upper, middle, and lower slope sites on an Orthic Dark Brown Chernozemic soil. Soil carbon dioxide concentrations approximated 0.1 percent, volume per volume, in late April, started to increase in early May, reached maximum values of 1 to 2 percent, volume per volume, in June and July, and by late September had decreased to the same levels as in late April. The CO2 concentrations varied considerably from year to year and were affected more by slope position than by vegetative cover. Comparison between CO2 and O2 gradients indicated that anaerobic respiration rarely occurred. The annual course of CO2 evolution appeared related to climatic conditions during the growing season. Regression equations between CO2 evolution, and water content or temperature of the 0− to 10-cm soil layer were rarely significant, but monthly mean CO2 evolution correlated well with the mean temperature and total precipitation of that month. Carbon dioxide evolution increased markedly down the slope, reflecting increased productivity and possibly erosion, and was about twice as large under native grassland as on the cultivated fields that were fallowed every second year. Differences in CO2 evolution were small between cropped and fallowed sites on similar slope positions. Average CO2 evolution of the cultivated fields was estimated at 1900 kg C per hectare per year during the crop year and at 1800 kg C/ha/yr in the fallow year; the mean dry matter input was in the order of 1700 kg C/ha/yr. Accumulation of NO3-N in fallow fields was highest in the years with the lowest CO2 evolution. The low accumulation of NO3-N appeared mainly due to immobilization of mineral nitrogen during periods of high soil respiration rates.
TL;DR: The authors showed that sulfate has accumulated over the last 80 years, is now accumulating, and can continue to accumulate at higher input levels in this soil, and further research on the reasons for them is necessary.
Abstract: Previous laboratory studies on sulfate content and adsorption in an eastern Tennessee forested Ultisol showed that, although considerable amounts of adsorbed, insoluble sulfate were present in B horizon samples, further accumulations into this form could not be induced with additional inputs. These results posed two questions addressed in this paper: (1) what proportion, if any, of current adsorbed, insoluble sulfate is the result of modern inputs; and (2) are these soils capable of further accumulation of adsorbed, insoluble sulfate under field conditions. Field studies, including sampling beneath and adjacent to an old house, a lysimeter investigation, and sulfate salt application, showed that sulfate has accumulated over the last 80 years, is now accumulating, and can continue to accumulate at higher input levels in this soil. The discrepancies between laboratory and field results pose problems for easy estimation of sulfate adsorption capacity, and further research on the reasons for them is necessary.
TL;DR: When winter wheat straw was mixed with the soil, wheat plant yield decreased significantly, but the decrease was largely overcome by higher rates of N application; hence, in this case, N immobilization during straw decomposition, and not phytotoxicity, appeared to be a primary factor causing yield decreases.
Abstract: We measured the effects of winter wheat residue, residue placement, nitrogen fertilizer placement, and nitrogen rates on winter wheat growth in greenhouse pot and split root studies under conditions simulating cool-wet spring conditions in the Pacific Northwest. Phytotoxicity to winter wheat plants from decomposing winter wheat residue could not be demonstrated in these studies. When winter wheat straw was mixed with the soil, wheat plant yield decreased significantly, but the decrease was largely overcome by higher rates of N application; hence, in this case, N immobilization during straw decomposition, and not phytotoxicity, appeared to be a primary factor causing yield decreases.
TL;DR: In this paper, three intensities of tillage disturbance were imposed on a deep yellow loamy sand for three successive years, and differences in water release curves of the top 10 centimeters occurred in the first year and persisted through the three years.
Abstract: Three intensities of tillage disturbance were imposed on a deep yellow loamy sand for three successive years. Differences in water release curves of the top 10 centimeters occurred in the first year and persisted through the three years. Air permeability and soil water diffusivity measurements also reflected differences in pore geometry. The distribution of water down the first 70 cm of profile was found to reflect these surface soil differences, with the ploughed treatment having its maximum water content deeper in the profile early in the rainy season. We infer that difference in tillage treatment will continue to affect soil and crop water status in such weakly structured sands.
TL;DR: In this article, a two-dimensional numerical model for predicting the spatial soil temperature regime under transparent polyethylene mulch is developed, which takes into consideration weather conditions as well as soil characteristics.
Abstract: A two-dimensional numerical model for predicting the spatial soil temperature regime under transparent polyethylene mulch has been developed. The model takes into consideration weather conditions as well as soil characteristics. The results indicate that soil heating at the edges of the mulch is lower than at the center, and thus a narrow mulch provides less efficient heating than a wider mulch. The predicted results agree well with the observed data. This model enables us to determine the optimal size of mulch with respect to weather conditions, soil characteristics, and particular plant or agricultural requirements.
TL;DR: In this paper, the accuracy and useful range of six buffer-pH lime requirement (LR) tests, improved their accurate range, and select the best methods to determine the LR of acid mineral soils by routine analysis.
Abstract: In this experiment, we sought to determine the accuracy and useful range of six buffer-pH lime requirement (LR) tests, improve their accurate range, and select the best methods to determine the LR of acid mineral soils by routine analysis. Four single-buffer methods (Woodruff, Shoemaker et a