Showing papers on "Soil organic matter published in 1973"

Soils and soil fertility

Abstract: Preface.1 Soil.2 Soil Formation.3 Physical Properties of Soils.4 Soil Mechanics.5 Soil Water.6 Soil Organic Matter.7 Soil Mineralogy.8 Soil Chemistry.9 Amending the Soil.10 Fertilizers.11 Nitrogen.12 Phosphorus.13 Potassium.14 Calcium, Magnesium, and Sulfur.15. The Micronutrients.16. Variations in Plant Composition.17 Soil Classification and Survey.18 Land Use and Soil Management.19 Water Management.20 Soil Erosion and Its Control.21 Soil Pollution.Appendix.

The effect of superphosphate on the cadmium content of soils and plants

Abstract: The cadmium content of phosphatic fertilizers manufactured in New South Wales ranged from 18 to 91 p.p.m. and was closely correlated with phosphorus content. Superphosphate contained 38-48 p.p.m. cadmium. The evidence suggests that the rock phosphate raw material was the sole source of the fertilizer cadmium. The cadmium in superphosphate was soluble in water and was associated with both the phosphate and sulphate components of the fertilizer. It appeared to be as readily. available to plants as the cadmium in cadmium chloride. Cadmium impurities in superphosphate accumulated in the soil, mostly in the surface 10 cm, principally in a cation exchangeable form, and this increased the supply of available cadmium to plants. This accumulated cadmium was extracted from the soil by hydrochloric acid. Increases of up to five-fold in total soil cadmium were found in soils which had been fertilized with superphosphate, and in one soil there was a 12-fold increase in hydrochloric acid-soluble cadmium. Plant uptake of cadmium from soil was generally small and ranged from 0.4 to 7% of that available. Uptake was greatly influenced by soil type, and addition of calcium carbonate reduced the uptake by subterranean clover from cadmium residues in soil. Plant species differed greatly in their ability to take up cadmium, and the concentration of cadmium varied widely within the plant. Generally only 12-18 % of the cadmium in cereal plant tops was translocated to the grain which had a lower cadmium content than any other part of the plant. The addition of cadmium to soil, either as cadmium chloride or in superphosphate, always increased the cadmium content of the grain of cereals or the edible portion of vegetables. Top-dressing of improved pastures with superphosphate brought about considerable increases in the cadmium content of pasture species, especially that of subterranean clover. Analyses of wheat grain and cereal breakfast foods indicated that, although Australian cereal growing soils have long histories of superphosphate usage, the cadmium content of the grain produced is low, the range found being 0.012 to 0.036 p.p.m. Low values, < 0.010 to 0.015 p.p.m., were also found in processed green peas.

Cadmium, nickel, lead, and zinc in earthworms from roadside soil.

Abstract: Cd, Ni, Pb, and Zn in soils and earthworms along two Maryland highways decreased with increasing distance (10, 20, 40, 80, and 160 ft) from the roadway. Metals were quantified by atomic absorption spectrophotometry. Metal residues were higher at the location along each highway where traffic volume was greater. Correlations between residues in earthworms and soil decreased with decreasing atomic weights (Pb > Cd > Zn > Ni). Metal residues in soils were positively correlated with quantities of soil organic matter. Earthworms accumulated up to 331.4 ppm of Pb and 670.0 of Zn, concentrations which may be lethal to earthworm-eating animals.

The Role of Soil Invertebrates in Turnover of Organic Matter and Nutrients

Abstract: Substantial proportions of organic substances which originate in plants or animals eventually reach the soil, where they may remain for only a few hours or days if they are readily decomposable (Heath et al., 1966), or as long as several decades if they decay slowly (Kendrick, 1959). The plant material ranges from bacteria, fungal hyphae and soft leaf tissue to tough woody substances. Animal materials range from single-celled protozoa, nematodes, soft-bodied worms and insect larvae through arthropods with tough exoskeletons to large vertebrate animals and excreta.

Relationship between the carbon isotope composition of soil CO2 and dissolved carbonate species in groundwater

Abstract: To understand the carbonate geochemistry of an aquifer system, it is helpful to determine the sources of carbon in the dissolved carbonate species. Samples of ground litter, soil organic matter, soil CO2, and groundwater were collected in the area of recharge to the principal artesian aquifer of central Florida and were analyzed for 3C content. Analytical results yield consistent 3C/2C values for soil organic matter, $aCrDB = 23 4- l0o. TheaC/2C ratio of the litter samples ranges from $SCrDB of --18.2 to --29.500 and indicates the presence of both Calvin and Hatch-Slack cycle plants. The xaC/x2C of the soil CO2 ranges from -14.7 to -21.3o, which is consistent with the trend observed in the litter. The relationship between x3C/x2C of the dissolved carbonate and the percent calcite saturation indicates that the $aCDB of the source CO_ is within the range of -25 4- 5o, as is expected for a humid, subtropical environment. To understand the carbonate chemistry of an aquifer system, it is necessary to determine the various sources of carbonate in that system. One approach is the use of stable carbon isotopes. The use of stable carbon isotope analyses in conjunction with standard chemical analyses aids in determining the sources of carbon in ground- water, because the carbon isotope compositions of various components of the global carbon reservoir generally fall within distinct ranges (Table 1). Carbon isotope data are reported in the standard notation relative to the PDB standard,

Nutrient Availability in Desert Grassland Soils Under Mesquite (Prosopis juliflora) Trees and Adjacent Open Areas

Abstract: A pot-culture technique was used to calculate relative yields for N, P, K, and S as an index of availability of these nutrients in soil from under mesquite [Prosopis juliflora (Swartz.) DC] trees and from adjacent open areas on a desert grassland site. Arizona cottontop [Trichachne californica (Benth.) Chase], plains bristlegrass (Setaria macrostachya H.B.K.), and bush muhly (Muhlenbergia porteri Scribn.), all native perennial grasses which grow abundantly under mesquite, were used as test plants. Relative yields for N were up to 15 times higher in soil under mesquite trees than in nonmesquite soil, whereas the level of total N was only three times greater. The soil under mesquite trees apparently provides a more favorable environment for supply of N than nonmesquite soil. Relative yields for S in mesquite soil were three times greater than in nonmesquite soil and were proportional to the difference in total S between soils, indicating that S is supplied more slowly than N under mesquite trees. Phosphorus showed a slight, although significant, difference in availability between soils, but total P was the same in the two soils. A threefold higher level of organic matter in soil under mesquite probably contributes to increased availability of P. Differences in total potassium and its supply to test plants were not detected between the two soils.

Interaction of pesticide-derived chloroaniline residues with soil organic matter1

Abstract: Herbicide-derived chloroaniline residues are immobilized by physical absorption to both the organic and the inorganic fraction of the soil and, in addition, by chemical binding to the soil organic matter. In contrast to the polymerization reactions, the binding of the chloroanilines is strictly a physicochemical process; microbial activity is involved only in the liberation of the chloroanilines from the parent herbicides. The chemical attachment of chloroanilines to humic substances occurs by at least two mechanisms, in a hydrolyzable (probably anil and anilinoquinone) and in a nonhydrolyzable (probably heterocyclic rings and ether bonds) manner. In the test soil (Nixon sandy loam) these two types of bonds immobilized roughly equal amounts of chloroanilines. Free radicals have little or no role in these reactions. The binding of chloroanilines to the soil organic matter greatly increases the persistence of these herbicide-derived residues in the environment.

Decomposition of 14c-labelled plant material under field conditions

Abstract: Mature, uniformly labelled (14C, 15N), chopped, wheat straw incorporated in the plow layer of a Brown Chernozemic soil and a Gray Wooded soil was allowed to decompose in the field Labelled grass material (14C) was added to the surface of an adjacent virgin Brown Chernozemic soil After 4 yr of normal cropping practices, one-fifth of the C of added straw remained in the Brown soil and one-sixth in the Gray Wooded The initial decomposition rate of straw was retarded in plots under wheat as compared with those under fallow Decomposition of labelled grass was initially dependent on sufficient rainfall to compress it to the soil surface When winter periods are excluded from the time scale, the half-life of resistant straw components or soil organic matter derived from the straw was equivalent to 24 mo in Gray Wooded soil and 48 mo in Brown soil Resistant grass material decomposed more slowly with a half-life of 96 growing mo Distribution of labelled C among the various fractions of soil organic matter af

The sorption of iodide by soils as influenced by equilibrium conditions and soil properties

Abstract: The sorption of iodide was reduced when soil was dried before equilibration with an iodide solution. With undried soils, sorption continued for > 48 h, maximum sorption occurred at pH values < 5 but a secondary sorption peak occurred at pH 8.5 to 9.0, particularly with a soil containing a high level of organic matter. Temperature had only a small effect on sorption over the range 10 to 35 °C. Maximum values for the sorption of iodide by two surface soils (0 to 10cm) at pH 6.6 to 6.8, assessed with a soil: solution ratio of 1:10, an equilibrium time of 40 h and at room temperature, were 25 and 6 fig I/g soil, respectively. The amounts of iodide sorbed by these soils, and by soils taken from successive 10 cm layers to a depth of 40 cm at the same two sites, were closely related to the contents of organic matter in the soils but not to contents of iron or aluminium oxides or of clay. Treatment of the surface soils with hydrogen peroxide to destroy organic matter greatly reduced the sorption of iodide at the pH of about 5.5 that resulted from the treatment. The removal of iron and aluminium oxides with Tamm reagent also resulted in a marked reduction in sorption at pH < 5. The results indicate that sorption was due in part to soil organic matter and in part to iron and/or aluminium oxides. At pH > 6, organic matter appeared to be the major sorbing constituent but under more acid conditions the oxides appeared to be increasingly important.

Clay minerals as a factor influencing the biochemical activity of soil microorganisms

Abstract: The results of the study confirm the significance of clay minerals as a factor influencing the biochemical activity of soil microorganisms. The soil microflora is influenced both by the direct effect of clays on the microbial cells and indirectly, by their effect on the environment. The direct effect is projected into fundamental processes of the cycle of biogenic elements, including humification processes. The character and mechanism of the effect depend on the species of microorganism, on the quality and quantity of the mineral sorbents present in the soil and on other ecological factors. A further study will be carried out to investigate different aspects of the influence of clay minerals on the incidence, growth and biochemical activity of soil microorganisms.

Studies on iodine in british soils

Abstract: Summary A method for the determination of iodine in soils and other agricultural materials was developed on the basis of an existing Auto-analyser procedure for iodine in blood. Using this method, soils from twenty-three widely separated sites in the U.K. were found to have total iodine contents ranging from 2.7 to 36.9 mg/kg. Total iodine contents were not closely correlated with the distance of the site from the coast or with rainfall, indicating that these factors did not exert major effects on iodine content. When two soils derived from marine alluvium were excluded, total soil iodine contents were positively correlated with aluminium oxide extracted by Tamm's reagent (r= 0.88***), with ferric oxide extracted by citrate-dithionite (r= 0.64**), and with soil organic matter (r = 0.59**). Analysis of twenty-two fertilizer materials, and of the faeces and urine from sheep fed diets containing two levels of iodine, indicated that inputs of iodine to the soil from these sources were small. From the correlation between total soil iodine contents and other soil properties, together with the proportions of the total iodine extracted by various reagents including sodium hydroxide and oxalic acid, it is concluded that soil iodine is associated, in part, with sesquioxide material and, in part, with soil organic matter.

Contamination of soil with zinc, copper, lead, and cadmium in the Wollongong city area

Abstract: From a grid sampling procedure over 56 km2 of the Wollongong city area, levels of acetic acid-extractable soil zinc, lead, and cadmium, and EDTA-extractable soil copper, have been investigated. Mean levels of these metals in four groups of urban grassland, namely, farm land, recreational land, industrial land, and roadsides, are up to 10 times greater than those in a rural control area. Highest levels of all four metals are found in the Port Kembla industrial area, where 21 samples within 1 km of the main heavy metals smelting complex have mean values of 82 p.p.m. zinc, 343 p.p.m. copper, 21 p.p.m. lead (15 samples), and 2.8 p.p.m. cadmium (11 samples); mean levels in the rural area are 2.7 p.p.m. zinc, 5.3 p.p.m. copper, <1 p.p.m. lead, < 1 p.p.m, cadmium. Profile samples show that all four contaminants were very largely concentrated in the top 15 cm soil, confirming an airborne origin.

THE RELATIONSHIP BETWEEN SOIL pH, ORGANIC MATTER, AVAILABLE PHOSPHORUS, EXCHANGEABLE POTASSIUM, CALCIUM, MAGNESIUM, AND NINE ELEMENTS IN THE MAIZE TISSUE

Abstract: Simple and multiple correlation coefficient was run between soil pH, organic matter, available P, exchange K, Ca, Mg and nine other elements in the maize tissue sampled from four different soil zones of the Western and Lagos States of Nigeria. The results indicate that soil organic matter pl

Soybean Tolerance to Metribuzin

Abstract: Tolerance of greenhouse-grown soybean (Glycine max (L.) Merr.) to preemergence applications of 4-amino-6- tert-butyl-3-(methylthio)-as-triazin-5(4H)one (metribuzin) was greatly influenced by herbicide rate, soil organic matter, and simulated rainfall after treatment. Planting depth affected tolerance in cases where effects of the other variables were marginal. Severe injury was observed with 1.1 % soil organic matter except at the 0.56 kg/ha herbicide rate with no rainfall for 10 days after treatment. Tolerance increased with increas- ing soil organic matter to the point where no injury occurred at 16.8 or 40.0% organic matter, even at herbicide rates up to 1.68 kg/ha with 1.25 cm simulated rainfall immediately after treatment.

The mobilization and fixation of molybdenum, vanadium, and uranium by decomposing plant matter

Abstract: Summary Mo, V, and U are mobilized as anions by aerobically decomposing plant matter; the behaviour of the dissolved metals differs in several respects from what would be expected in inorganic systems With respect to dialysis through cellophane, between pH I and 4 the mobilized Mo is fixed by colloidal organic decomposition products, with maximum retention at pH 15; V is retained between pH 15 and 70, with a maximum at pH 3 The specific fixation of Mo and V by soil organic matter was considerably less, and persisted over wider pH ranges–15-65 and 10-90 respectively The fixation of U by both forms of humified organic matter increased sharply to a maximum around pH 4-5, and thereafter decreased slightly up to pH 8 The anionic forms of the three elements persisted when MOO:2-4, VO;-3 and UO, were incubated with anaerobically decomposing plant matter; under these conditions V(V) was probably reduced to V(IV), and it seems that an anionic V(IV) complex was formed Although the molecular size of the colloidal decomposition products of lucerne was somewhat less than that of organic matter extracted from Rothamsted top soil, acid hydrolysates of the two humic acids contained the same twenty-three amino acids, in much the same relative proportions

Factors affecting the distribution of proteoid roots within the root systems of two Hakea species

Abstract: The proteoid roots of Hakea prostrata and H. laurina are concentrated in the surface soil horizons, even though the root systems penetrate to much greater depths. The relationships of a number of soil and plant factors to proteoid root occurrence in a given portion of the root system were examined. Pockets of humus-rich soil in any part of the root system greatly increased the proteoid root concentration in that region. The following factors, listed in their apparent order of importance, were analysed: local concentration of parent roots, local level of soil organic matter, local nitrogen availability, shoot growth, nitrogen concentration of the shoots, vertical distance of the region from the soil surface, local availability of calcium, magnesium, and potassium, local bulk density and certain other physical factors, nutrient status of the rest of the root system, horizontal distance of the region from the centre of the plant, relative maturity of parent roots in the region, and local soil pH and certain other chemical factors. The nitrogen component of soil regions high in organic matter largely accounted for their higher non-proteoid root concentration, smaller proteoid root size, greater number of laterals, and longer roots per unit weight, but not their much greater number of proteoid roots per unit total root weight. This suggests that other factors are also involved in proteoid root formation.

The origin of soil polysaccharide: transformation of sugars during the decomposition in soil of plant material labelled with 14c

Abstract: Summary Incubation of soil with 14C-rye straw for 448 days resulted in the evolution of about 50 per cent of the carbon of the substrate as CO2 The two main sugars of the straw, glucose and xylose, were degraded to approximately the same extent (70 per cent). The same results were obtained whether the soil was derived from granitic or basic igneous parent material. There was very little transformation of the substrate to galactose, mannose, arabinose, rhamnose, or fucose, and a much slower rate of degradation than with soil incubated with 14C-glucose over a similar period. Hydrolysis of the soil samples by a preliminary treatment with 5 N H2SO4, before treatment with 24 N H2SO4, followed by heating with N H2SO4 did not release significantly greater amounts of sugar than treatment with 24 N H2SO4 and N H2SO4 alone. Separate analysis of the hydrolysates showed that 90 per cent of each of galactose, mannose, arabinose, xylose, rhamnose, or fucose had been extracted by 5 N H2SO4, but only 50 per cent of the glucose. Fractionation of the straw-soil mixture after 224 days incubation showed that the specific activity of the glucose was higher in the humin fraction than in the fulvic acid, as would be expected if the remaining 14C were still in the form of unchanged plant material. This evidence that plant polysaccharide persists in soil could explain the presence of much of the xylose in the soil organic matter.

Chemical Distribution of Residual Fertilizer Nitrogen in Soil as Revealed by Nitrogen-15 Studies

Abstract: Chemical distribution patterns were obtained for the residual N in field plots previously amended with ¹⁵N-labeled urea and oxamide. From 25 to 40% of the fertilizer N was present in the soil (0 to 25 cm) after the first growing season, about half of which still remained after 5 years. Essentially all of the fertilizer-derived N (97.0%) occurred in organic combination; only a small fraction (3.0%) was accounted for in inorganic forms, chiefly as fixed NH₄⁺. In comparison to the native humus N, higher percentages of the fertilizer N left after the first growing season occurred as amino acids (52.0 vs. 33.7%) and amino sugars (8.2 vs. 7.5%); lower percentages occurred in acid-insoluble forms (9.0 vs. 15.2%), as acid-hydrolyzable organic NH₃ (9.0 vs. 17.0%), and as unidentified acid-soluble N (8.8 vs. 20.3%). Considerable humification occurred during the subsequent 4 years with relocation of amino acids N (and possibly amino sugar-N) to more resistant humus forms. The findings suggest that fertilizer N, once incorporated into soil organic matter, becomes increasingly stable with time and is not readily mineralized or subject to leaching.

The comparative effects of exchangeable calcium, magnesium, and sodium on some physical properties of red-brown earth subsoils. I. Exchange reactions and water contents for dispersion of Shepparton soil

Abstract: The susceptibility to waterlogging of red-brown earth subsoils is discussed One of these, Shepparton, has been leached with chloride solutions of given SAR, in the range 0-7, the last solution being 1 mM in calcium or magnesium The soil was then extracted with neutral lM ammonium chloride and the displaced cations measured The exchange of sodium for both calcium and magnesium was similar, following the Gapon equation except at very low SAR values Some potassium and sodium was extracted from calcium and magnesium soils Shepparton soil of known SAR was remoulded over a range of water contents and synthetic aggregates formed The percentage of the clay fraction which dispersed from the aggregates was measured The water content for perceptible dispersion of magnesium soil was only about half that of calcium soil, the water contents being near the 15 bar and 01 bar values respectively for unsheared soil The water content for dispersion decreased sharply with increasing SAR of the soil Calcium-sodium soil with an ESP of 35 dispersed at the same water content as magnesium soil Possible reasons for the enhanced dispersion of sheared, wet magnesium soil compared with similar calcium soil are discussed

Aggregation in swelling clay soils

Abstract: Dry sieving, wet sieving, and aggregate bulk density measurements were used to study the mechanisms of dry aggregate formation in three swelling clay soils. These experiments showed that, for a given soil, a single probability function can be used for all dry aggregate fractions to predict their water stability and the distribution of water stable aggregates in their unstable portions. This result is explained in terms of the mode of formation of dry aggregates. Coarse aggregation in these soils was attributed to the binding action of dispersed clay. Soil disruption experiments showed that, above a certain moisture content, soil samples were susceptible to disruption by mechanical action. This moisture content is linearly related to the specific surface area of the soil, and agrees closely with the soil liquid limit. Aggregate disruption in the coarsely aggregated soil sample is explained in terms of soil mineralogy and electrolyte concentration. The effect of rate of reflocculation of disrupted clay on soil aggregation is considered.

A study of the mechanisms of aggregation in a krasnozem soil

Abstract: Dry sieving, wet sieving, and soil analytical techniques were used to study the levels of organization within dry aggregates of virgin and cultivated krasnozem soils. Three mechanisms of aggregation appeared to exist. In the c 0.5 mm size range, the mechanism was independent of cultivation and was connected with basic soil particle properties. In the 5.0-0.5 mm range the hydrophobic properties of organic matter are proposed as important in determining water stability. In the range > 5.0 mm, binding of roots in the virgin soil and clod formation by implements in the cultivated soils appeared to be operative. Reduction in clay crystal size and surface activity appeared to be connected with phosphate fertilizer application.

An introduction to the scientific study of the soil.

Abstract: An introduction to the scientific study of the soil , An introduction to the scientific study of the soil , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Soil Organic Matter Effect on Activity of Acetanilides, CDAA, and Atrazine

Abstract: Field and greenhouse studies were conducted to determine the influence of soil organic matter on herbicidal activity using four Pocomoke soils with organic matter contents of 4.8, 7.0, 11.9, and 17.0%. In field experiments, control of giant green foxtail [Setaria viridis var. major (Gaud.) Posp.] was greater than 75% from all treatments of 2-chloro-2′,6′-diethyl-N-(methoxymethyl) acetanilide (alachlor), 2-chloro-N-isopropylacetanilide (propachlor), and N,N-diallyl-2-chloroacetamide (CDAA) with no statistical differences between chemicals, rates, or organic matter levels. Control was statistically lower from all 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) treatments except 2.6 kg/ha at 7% organic matter and 4.4 kg/ha at 7 and 17% organic matter. Under greenhouse conditions, giant foxtail (Setaria faberi Hermm.) was used to establish GR50 values on soils or soil mixtures containing 0.8, 1.9, 3.9, 6.4, 11.0, and 18.7% organic matter for the herbicides used in the field study and for 2-chloro-N-(1-methyl-2-propynyl)acetanilide (prynachlor). Generally as organic matter levels increased, the GR50 values for herbicides increased; the rate of GR50 increase varied with herbicides. A ranking of herbicides from most toxic to least toxic is: propachlor>alachlor>prynachlor>CDAA. Atrazine GR50 values varied from a low similar to propachlor at 0.8% organic matter to 20 times greater than propachlor at 17% organic matter.

Soil organic matter and phosphorus relationships under tropical forests

Abstract: A positive correlation was detected between soil organic matter and acid-extractable P in the superficial soil horizons, but not in the subsoil, of secondary forests in the humid tropics. Clearing diminished the origial level of organic matter concomitantly with concentration of acid-extractableP.