Showing papers on "Soil organic matter published in 1983"

Changes in the Carbon Content of Terrestrial Biota and Soils between 1860 and 1980: A Net Release of CO"2 to the Atmosphere

Abstract: Changes in land use over the past two centuries have caused a significant release of CO2 to the atmosphere from the terrestrial biota and soils. An analysis of this release is based on amounts of organic carbon within an ecosystem following changes such as harvest of forests; it is also based on rates of changes, such as conversion of forest to agriculture, deduced from agricultural and forestry statistics. A model is used to calculate the net amount of carbon stored or released each year by the biota and soils of 69 regional ecosystems. Some of the changes, such as afforestation, the growth of harvested forests, and buildup of soil organic matter, result in a storage of carbon; others, such as harvest of forests and increase in pasture and agricultural areas, result in a loss of carbon to the atmosphere. According to this analysis, there has been a net release of carbon from terrestrial ecosystems worldwide since at least 1860. Until 1960, the annual release was greater than release of carbon from fossil fuels. The total net release of carbon from terrestrial ecosystems since 1860 is estimated to have been 180 x 1015 g (a range of estimates is 135-228 x 1015 g). The estimated net release of carbon in 1980 was 1.8-4.7 x 1015 g; for the 22 yr since 1958 the release of C was 38-76 x 1015 g. The ranges reflect the differences among various estimates of forest biomass, soil carbon, and agricultural clear- ing. Improvements in the data on the clearing of tropical forests alone would reduce the range of estimates for 1980 by almost 60%. Estimates of the other major terms in the global carbon budget, the atmospheric increase in C02, the fossil fuel release of C02, and the oceanic uptake of C02, are all subject to uncertainties. The combined errors in these estimates are large enough that the global carbon budget appears balanced if the low estimate for the biotic release of carbon given above is used (1.8 x 1015 g released in 1980) with the higher estimates of oceanic uptake. If higher estimates for biotic release are used, then the carbon budget does not balance, and the estimates of oceanic uptake or of other factors require revision.

Organic Carbon, Nitrogen, and Phosphorus Concentrations and pH in Soil Profiles as Affected by Tillage Intensity

Abstract: No-tillage (NT), minimum tillage (MT), and conventional tillage (CT) practices were continuously applied to a Hoy tville silty clay loam (Mollic Ochraqualf) soil (18 years) and a Wooster silt loam (Typic Fragiudalf) soil (19 years) in Ohio. The effect of the various tillage intensities on the profile (0-30 cm) distribution of organic C, N, and P concentrations and pH was investigated. Results showed that NT resulted in significantly (P < 0.05) higher organic C and N concentrations in the 0to 15-cm soil increment of the Hoy tville soil but significantly lower concentrations in the 15to 30-cm soil increment. For the Wooster soil, NT resulted in higher concentrations in the 0to 7.5-cm soil increment. No significant differences were observed among tillage intensities in the 7.5to 30-cm soil increment. Comparison of organic C concentrations in the plow layer (0-22.5 cm) of the soils at the beginning of the longterm tillage experiment and at present showed that concentrations remained constant or decreased 11 % under NT in the Hoytville and Wooster soils, respectively. Present organic C concentrations in the Hoytville 1 Contribution from the Dep. of Agronomy, Ohio Agric. Res. & Dev. Ctr., Wooster, OH 44691. Published with approval of the Director as Paper no. 72-82. Received 19 May 1982. Approved 24 Aug. 1982. * Assistant Professor, Dep. of Agronomy, The Ohio State University and The Ohio Agric. Res. & Dev. Ctr., Wooster, OH 44691. soil were decreased 12 to 14% by long term MT or CT while a 23 to 25% decrease was observed for the Wooster soil. Organic P concentrations under NT were significantly (P < 0.05) higher in the 0to 7.5cm increment of the Wooster soil and significantly lower in the 22.5to 30-cm soil increment. Organic C/N, C/P, and N/P ratios were calculated and higher ratios were observed under NT than under MT or CT in the surface soil increments. Tillage intensity, however, had little effect on the ratios averaged over the entire profile (0-30 cm). Soil pH was 0.1 to 0.3 units lower (P < 0.05) under NT in all soil increments except in the 22.5to 30-cm increment of the Wooster soil where no significant differences in pH were observed among the tillage intensities. Additional Index Words: no-till, zero tillage, minimum tillage, nutrient distribution, organic C/N/P ratios. Dick, W.A. 1983. Organic carbon, nitrogen, and phosphorus concentrations and pH in soil profiles as affected by tillage intensity. Soil Sci. Soc. Am. J. 47:102-107. A INCREASING NUMBER of farmers are changing to crop production methods which are less tillage-intensive. No-tillage, defined as a crop production system DICK: ORGANIC C, N, AND P CONCENTRATIONS AND PH IN SOIL PROFILES AFFECTED BY TILLAGE INTENSITY 103 where weed control is accomplished entirely by herbicides and tillage is limited to the opening of a small slot for seed placement, is a method rapidly being adopted by farmers throughout the U.S. This is because no-tillage reduces soil erosion and fuel use, conserves soil water, and allows row-crop production to be practiced on steeply sloping farmland. By the year 2000 an estimated 65% of the seven major crops (corn, soybeans, sorghum, wheat, oats, barley, and rye) in the U.S. will be grown by the no-tillage system and 78% by the year 2010 (Phillips et al., 1980). With no-tillage, mechanical incorporation of fertilizer within the soil plow layer is not possible and the nutrients taken up by plant roots from the subsoil and incorporated into the plant are subsequently deposited on the soil surface as plant residue. A few reports on changes in the distribution of organic matter, nutrients, and acidity (pH) in the soil profile as a result of no-tillage practices have been previously published (Van Doren et al., 1976; Blevins et al., 1977; Juo and Lal, 1979; Doran, 1980). These reports, however, dealt with studies on sites where continuous no-tillage crop production practices had been maintained for only 10 years or less and cannot describe longer-term effects of continuous no-tillage. In Ohio, experiments dealing with various tillage intensities (no-tillage, minimum tillage, and conventional tillage) were begun in 1962 and 1963 and have continued to the present. These 18and 19-year continuous tillage experiments have allowed a much greater time for changes in organic matter, nutrients, and pH to become established. The objectives of this study were to investigate changes in organic C, N, and P concentrations and pH as affected by tillage intensity in soil profiles collected from these long-term experimental plots. MATERIALS AND METHODS Experimentation on a Hoytville silty clay loam (fine, illitic, mesic Mollic Ochraqualf) soil and a Wooster silt loam (fine, mixed, mesic Typic Fragiudalf) soil concerning the effects of tillage intensity on crop production was begun in 1963 and 1962, respectively. This corresponds to an 18-year period where the various tillage intensities have been continuously applied at the Hoytville site and a 19-year period at the Wooster site. The complete history and the soil characteristics of these sites were described by Van Doren et al. (1976). Briefly, prior to the beginning of the tillage experiment, the Hoytville site (slope, < 1%) had been maintained for 6 years in a conventional tillage corn-oats-meadow rotation and a grass meadow had been maintained for 6 years at the Wooster site (slope, 2.5 to 4.0%). Soil characteristics observed at the two sites can be attributed primarily to parent material, topography, drainage, and shrinkswell potential. The Hoytville soil has poor surface and internal drainage when wet but cracks substantially when dry. In contrast, the Wooster soil has much better surface and internal drainage and little or no shrink-swell potential. At each site nine combinations of three levels of each of two variables in a complete factorial, randomized block design with three replications were established. The tillage variable is defined as follows: 1. No-tillage (NT)—planting was accomplished directly into the proceeding years crop residue by means of a coultertype planter. 2. Minimum tillage (MT)—moldboard plow 20 to 25 cm deep with no other tillage prior to planting. 3. Conventional tillage (CT)—moldboard plow 20 to 25 cm deep and at least two other 10-cm deep secondary tillage operations prior to planting. The rotation variable consisted of (i) continuous corn, (ii) corn and soybeans, and (iii) corn, oats, and alfalfa meadow in a 3-year rotation. Sufficient numbers of plots were established so that each crop in each of the nine treatments appeared each year. The same tillage treatments have been maintained on each plot to the present time. Tilled treatment plots were plowed in the spring 1 to 4 weeks before planting for the Wooster soil and in the fall for the Hoytville soil. The third year (meadow) of the corn-oatsmeadow rotation received no tillage prior to planting. Common management practices were maintained for the various rotations across the tillage treatments, i.e., the total amount of N, P, K, and lime applied was the same for the three tillage treatments and in all cases was broadcast-applied. Fertilizer was broadcast in the spring prior to planting and lime was broadcast in the winter as required to maintain a pH in the Ap horizon of the continuous corn plots at or above 6.0. Herbicide materials and rates varied with years but the total amounts added to the NT plots compared to the MT or CT plots was approximately one-third greater over the experimental time period. Soil samples (2.5-cm outer diameter soil cores) from 0 to 1.25 cm, 1.25 to 2.5 cm, 2.5 to 7.5 cm at 2.5-cm increments, and from 7.5 to 30 cm at 7.5-cm increments from the NT plots and from 0 to 30 cm at 7.5-cm increments from the MT and CT plots were collected prior to tillage in the fall of 1980. Samples were obtained after first removing from the soil surface easily identified plant materials, i.e., corn stalks and leaves. The soils were air-dried and ground to pass through a 60-mesh sieve. Soil pH was determined by a glass electrode (soil-to-water ratio, 1:1), organic C by the Walkley-Black method (Allison, 1965), organic N was determined by semimicro-Kjeldahl digestion as described by Bremner (1965), and organic P was obtained by subtracting the value of inorganic P (Olsen and Dean, 1965) from the value obtained for total P (Dick and Tabatabai, 1977). All concentrations reported for organic C, N, and P are expressed on a gravimetric basis. For the statistical analyses, the concentration of the various parameters measured in the 0to 7.5-cm soil increment for the NT plots was obtained by calculating a weighted average of the concentrations in the 0to 1.25-, 1.25to 2.5-, 2.5to 5.0-, and 5.0to 7.5-cm soil increments. Data were interpreted using analysis of variance and Duncan's Multiple Range Test. RESULTS AND DISCUSSION The main effect of tillage intensity on organic C, N, and P concentrations and on pH in soil profile samples will be the focus of this paper. No mention of rotation effects and interaction effects of tillage and rotation will be made. Data for all three tillage treatments will be presented but in most cases the results for the MT and CT treatments were similar.

Volatilization of ammonia

Abstract: Ammonia is ubiquitous in Nature, being formed from the biological degradation of proteins in soil organic matter, plant residues and animal wastes. Its presence is readily detectable near barns, stables and feedlots where plant and animal residues are concentrated but it is also formed in many other situations from less concentrated sources, e.g. in fields and forests (Lemon and Van Houtte 1980). It is constantly being formed in soils at rates which depend on the level of microbial activity and the susceptibility of organic N compounds to biological attack. It is also being added to soils in increasing amounts as fertilizer.

Changes in organic and inorganic phosphorus composition of two grassland soils and their particle size fractions during 60–90 years of cultivation

Abstract: Summary Changes are reported in the chemical and biological composition of soil phosphorus (P) in a Black Chernozemic silt loam (Blaine Lake Association) and a Dark Brown Chernozemic sandy loam (Bradwell Association) during 60–90 years of cultivation Cultivated and adjacent uncultivated soils were sampled, separated into particle size fractions by physical dispersion and the fractions subjected to a sequential chemical extraction to remove several forms of inorganic phosphorus (Pi) and organic phosphorus (Po) In the uncultivated Bradwell soil significant amounts (7%) of secondary (NaOH extractable) Pi forms were associated with high levels of labile (bicarbonate and resin extractable) Pi These secondary Pi forms, which were concentrated in the finer particle size fractions (<2μm), contributed to the P loss during cultivation of the coarse textured Bradwell soil, whereas all P loss in the Blaine Lake soils was due to Po losses alone Sulphuric acid extractable P (thought to be mainly apatites) accumulated in both soils under cultivation, particularly in the coarse silt (50–5 μm) fraction Labile P fractions were greatly reduced during cultivation, indicating a significant reduction in available P and P fertility of cultivated soils This reduction in P fertility was closely tied to soil organic matter losses

The influence of texture, structure and clay mineralogy on the soil moisture characteristic

Abstract: The relative importance of texture, structure, organic matter and clay mineralogy to the nature of the soil moisture characteristic is examined for an extensive group of Australian soils using numerical classification and diagnostic methods. The presence of pedality, particle size composition and grade of structure were the soil properties most consistently associated with differences between the groups of soils with similar moisture characteristics. By association, field texture was shown to be a useful property. Although the presence of pedality and grade of structure were important, the shape and size of ped had only weak associations with differences in the soil moisture retention. Montmorillonite, iron oxide, vermiculite and quartz were the minerals in the clay size fraction which appeared to be important if they were present. In contrast, the presence of illite did not show any strong associations with a particular position or form of the moisture characteristic. The soil moisture characteristic was successfully modelled as a power function. It appears that being able to group and classify the soil moisture characteristic and then to provide a description of these groups both in terms of soil properties and model parameters is a valuable means of developing simple predictive models for field soils. The error of our predictions for 44 horizons based on this simple approach appears to be only marginally larger than that encountered in conventional laboratory methods, and in view of soil heterogeneity it is argued that following further development these predictions may be adequate in many hydrological and agricultural applications.

The Mineralogy, Chemistry, and Physics of Tropical Soils With Variable Charge Clays

Abstract: This book is the culmination of an effort started in 1974 when the senior author started assembling information for a tropical soils course that he taught while on sabbatical leave at North Carolina State University. The literature cited throughout the book was current when the book went to press. Soil systems contain mineral and organic materials that have constant or permanent surface charges, such as montmorillonite, or constant surface potentials, usually referred to as variable charge materials. Most soil systems contain some of both kinds. In the tropics, most of the minerals with permanent charge have been severely weathered. Consequently, the surface charge of the remaining material results from adsorption of potential determining ions. This book treats the mineralogy, chemistry, and physics of the variable charge minerals and soil organic matter.

Leaf-litter production and soil organic matter dynamics along a nitrogen-availability gradient in Southern Wisconsin (U.S.A.)

Abstract: Annual net N mineralization in the 0–10 cm mineral soil zone of nine forest stands on silt–loam soils was measured using a series of insitu soil incubations from April 1980 through April 1981. Diff...

Relationships Among Iron, Aluminum, Carbon, and Sulfate in a Variety of Forest Soils1

Abstract: Among several soil properties tested, percent Fe/sub c/ (i.e., Fe by citrate-dithionite minus oxalate extraction) was the single parameter most closely related to SO/sub 4//sup 2 -/ adsorption properties in a variety of forest soils. There were exceptions to this general relationship, however, and a combination of percent C, citrate-dithionite, and oxalate extractions for both Fe and Al appear most promising in predicting sulfate adsorption. Percent clay, pH, and pyrophosphate-extractable Fe + Al were either insignificantly or inconsistently related to SO/sub 4//sup 2 -/ adsorption. Because organic matter had a decidedly negative influence upon SO/sub 4//sup 2 -/ adsorption, surface soils and B horizons of Spodosols (and highly podzolized soils) had relatively poor SO/sub 4//sup 2 -/ adsorption properties, even when their dithionite-extractable Fe values were high. Organic matter also reduced Fe crystallinity (i.e., increased Fe/sub c//Fe/sub d/, or the ratio of oxalate to dithionite Fe), and the results of this study suggest that crystalline rather than amorphous, inorganic Fe (i.e., oxalate minus pyrophosphate Fe) is most highly correlated with adsorbed, water-insoluble SO/sub 4//sup 2 -/.

Soil acidification induced by leguminous crops

Abstract: Solution culture and greenhouse studies have both clearly demonstrated the ability of legumes to acidify their rooting medium. Furthermore, research workers comparing the pH beneath undisturbed sites versus all-legume pastures or all-grass versus all-legume (or grass-legume) pastures have observed a lower soil pH under the leguminous pastures. The processes leading to legume-induced soil acidification are reviewed and discussed. The growth of legumes which are fixing atmospheric N2 involves the excess uptake of nutrient cations over anions from soil solution. This results in the net efflux of H3O+ ions from plant roots into the rhizosphere. When virgin lands are sown with legumes the accumulation of soil organic matter, with a consequent increase in cation exchange capacity and exchange acidity, is an important contributing factor to the long-term decline in surface soil (0–10 cm) pH. Nonetheless, such a phenomenon does not explain the decrease in pH below 10 cm soil depth nor the lower pH below leguminous than all-grass pastures. The efflux of H3O+ ions from the legume roots may have an important effect on the soil pH under such conditions. The loss of symbiotically fixed N; from the system through leaching of NO3− - N may also contribute to soil acidification under leguminous pastures.

Nitrogen and cation mobilization by soil fauna feeding on leaf litter and soil organic matter from deciduous woodlands

Abstract: Decomposing oak litter was incubated in laboratory microcosms and the effects of adding a variety of soil animals upon nitrogen and cation release were monitored. Various groups of macrofauna caused a marked increase in ammonium release with smaller increases in calcium, potassium and sodium leaching. Microfauna also had significant but much less marked effects upon nitrogen and cation release. The effects of different grazing intensities of the millipede Glomeris marginata on a variety of forest organic substrates show that the animals amplified existing patterns of nutrient release.

Aluminium chemistry and acidification processes in a shallow podzol on the Swedish westcoast

Abstract: Processes pertinent to soil acidification with special emphasis on the solution chemistry of A1, were studied in three adjacent small catchments on the Swedish westcoast, with mixed coniferous forest and shallow podzols (average soil depth 50 cm). Soil solution from different depths, groundwater and stream-water were sampled. Separation of organic and inorganic Al species was done with an ion exchange technique. The concentration of organic A1 species was linearly correlated with the concentration of dissolved organic C (r,2, varied from 0.38 to 0.69 with p, < 0.001). In the A horizon 83 to 97 % of the dissolved A1 consisted of organic species. The average concentration of total A1 varied from 3.3 to 9.8 μmole 1−1, in soil leachates collected below the A0, horizon, and from 29.3 to 47.0 pmole 1−1, in leachates collected below the A2, horizon. The organic Al species decreased in importance with increasing soil depth. Leachates collected below the B horizon had average total A1 concentrations ranging from 95.3 to 115 pmole 1−1, with a contribution of organic species varying between 8 and 20% of the total concentration.

Effect of Fire on Hydrophobic and Cementing Substances of Soil AGGREGATES1

Abstract: Many Italian soils over which fire has passed are intensely eroded. To clarify the effect of fire on some factors associated with the soil erodibility, such as soil organic matter content, aggregate stability, and hydrophobic and cementing substances, we performed an experimental burning in

The Biogeochemical Cycle of Silicon in Two Temperate Forest Ecosystems

Abstract: The biogeochemical cycle of silicon was modelled in two temperate forested ecosystems with the help of four natural reservoirs: vegetation, soil organic matter, soil minerals and soil solutions. Silicon, like potassium, calcium and manganese, is a very good tracer of the functioning of forest ecosystems: deciduous forest ecosystems are characterized by moderate weathering release and geo chemical drainage, and by a strong biological cycle (85 % of the soluble silicon is derived from the soil biogenic silica). In contrast, coniferous forest ecosystems have a weak biological cycle and a strong silicon weathering release flow (85 % of the soluble silicon is derived from the crystalline soil minerals).

Uptake of cadmium, zinc, lead, and copper by earthworms near a zinc-smelting complex: influence of soil pH and organic matter.

Abstract: Soil samples were taken from 31 sites near Eindhoven, The Netherlands, mainly along transects of 1 to 15 km from the nearest zinc smelter. Earthworms (Lumbricus rubellus) were taken from the upper 20 cm soil layer and analyzed from accumulation of Cd, Zn, Pb and Cu by atomic absorption spectrophotometry. Cd, Zn, and Pb appeared to be more strongly accumulated by L. rubellus when present in soil with a low pH value. Cu was the only exception in this regard; its uptake by L. rubellus was not significantly influenced by soil pH. The organic matter content of the soil played a significant role only in the worm uptake of Pb. Soil Pb content, soil pH, and soil organic matter content together accounted for almost 70% of the variance in worm Pb content. The results indicate that L. rubellus accumulates Pb more strongly in soil with a low pH and low organic matter content than in soil with higher values of these parameters. The demonstrated influence of pH and organic matter content on element concentration in earthworms emphasizes the importance of soil factors in governing the entrance of toxic metal elements into the food web. (JMT)

Relationship between intensity of phosphatase activity and physico-chemical properties in woodland soils

Abstract: The relationships between intensity of phosphatase activity and soil properties at two depths in some Lake District woodland soils have been examined. Significant relationships were found with soil organic matter, moisture, clay + silt, total nitrogen, isotopically-exchangeable phosphorus, extractable magnesium contents and soil pH. When data from all soils, both 0–5 and 10–15 cm depths, were pooled 66% of the total variation in intensity of phosphatase activity could be accounted for by these soil properties. However, covariance analysis showed that regressions between intensity of phosphatase activity and soil properties differed with soil depth, soil type, season, vegetation type and underlying rock type. When the effects of these interactions were taken into account, up to 99% of the variation in the intensity of phosphatase activity could be accounted for. The relative importance of these interactive factors appeared to be rock type = vegetation type > soil type = season > soil depth. The effects of the soil properties and the interacting factors on the intensity of phosphatase activity in these woodland soils are discussed.

Soil respiration in a chihuahuan desert rangeland

Abstract: Soil respiration of a desert soil was measured at the New Mexico State University Ranch in Southern New Mexico. Respiration rates were highest during late July and August after summer rains. Soil respiration data were used to estimate soil organic matter turnover which was 54 yr using summer data and 20 yr using both summer and winter data. The long turnover estimate for summer measurements resulted from temperatures above optimum in June and July. Diurnal soil respiration was also measured after a simulated 2.54 cm rain event. For both wetted and dry soils, temperature controlled the patterns of soil respiration with an optimum of near 41°C. Activation energy values decreased from 84.91 to 39.5 kJ mol −1 when the soil was wetted. A light-dark container method was tested as a possible means of estimating algal uptake of CO 2 , however, the method was not feasible for desert soils.

Processes of Soil Organic-Matter Accretion at a Mudfloe Chronosequence, Mt. Shasta, California

Abstract: Amounts of carbon and nitrogen were measured in bulk soils and compenent density fractions from four mudflows (A, B, D, E) of increasing age at Mt. Shasta, California, in order to gain insight into mechanisms of soil organic—matter accretion. Soil was divided into a light fraction (specific gravity 2mm) and a tree index (reflecting number and size of trees near each soil—sampling point and their proximity) accounted for 50—80% of the variability in light—fraction C and N at the D and E flows but not at the A and B flows, where all parameters were less variable. Rockiness and tree index accounted for little of the variability in heavy—fraction C and N, indicating that light— and heavy—fraction organic—matter accumulate in response to different factors. It appears that mass and composition of light—fraction organic matter correlate with short—term changes in biological activity, whereas heavy—fraction organic matter accumulates steadily and correlates with long—term processes such as mineral weathering and soil horizon formation.

Water retention equations and their relationship to soil organic matter and particle size distribution for disturbed samples

Abstract: Functional relationships between soil water content and water suction were examined and related to textural and organic carbon content data. Soil water retention curves between 5 and 10 000 kPa were determined on disturbed samples of 18 soils representing various soil Great Groups in the Canadian prairies. The best fit was obtained with a two-straight-line regression model. Correlation and regression analysis showed that texture was the main soil property influencing the shape and position of the water retention curve. Organic matter influenced primarily the water content at which a break in the curve occurred. Soil zone and cultivation history had little effect on water retention. Key words: Water retention, texture, organic matter, two-straight-line regression

Mapping soil erosion and accumulation with the fallout isotope caesium-137

Abstract: The fallout isotope 137Cs has been used to trace the redistribution of soil in a cultivated paddock, in an upland catchment on the Darling Downs. The areal concentrations (mCi km-2) have been used to construct a caesiographic map which illustrates the areas of 137Cs depletion and build-up and the major areas of soil erosion and deposition, respectively, in the paddock. These areas have been graded on the basis of apparent relative intensity of erosion or deposition. Therefore, this method allows retrospective, quantitative estimates to be made of the extent and degree of soil redistribution within the last 3 decades. In addition the 137Cs results will be used to test mathematical models of erosion/deposition processes.

Copper and zinc species in the soil solution and the effects of soil pH

Abstract: A scheme to distinguish various species of trace metals in the soil solution has been used to study the forms of copper and zinc in the soil solution of a sandy loam that had been limed to give a range of soil pH values. The scheme is based on the lability of the metal species and involves the use of anodic stripping voltammetry, atomic absorption spectroscopy, and equilibration with Chelex-100 exchange resin. The solubility of zinc in this soil decreased markedly with increasing soil pH, with most of the zinc being present as free metal ions or as labile complexes. In contrast, copper species were largely moderately labile and non-labile and the solubility of copper varied only slightly with soil pH. The effects of enriching the soil with the metals and organic matter on the species present were also investigated.

Studies of litter and acid insoluble soil organic matter fractions using 13C‐cross polarization nuclear magnetic resonance spectroscopy with magic angle spinning

Abstract: Summary Cross polarization carbon-13 nuclear magnetic resonance spectroscopy with magic angle spinning (CP-MASS) was used to analyse for various forms of carbon in soils, a moss peat, hydrochloric acid insoluble residues from soils and peat, and litter from beech and pine trees. The chemical composition of the litters was also investigated by conventional techniques. The results show that hydrolysis with hydrochloric acid extraction removes nearly all oxygenated alkyl carbon from the soils used. It is shown that humification pathways in which carbohydrates are incorporated into humic substances via nonhydrolysable linkages are not important for the soils investigated in this work. CP-MASS data suggest that the percentage of aromatic carbon in pine leaves increases with increase in ageing time. The results for the beech leaves are not sharply defined.

Protein Transformation in Soil

Abstract: Publisher Summary Protein degradation is carried out mostly by microorganisms in conjunction with mesofauna such as earthworms and insect larvae. The mineralization of protein has a considerable effect on soil fertility and soil scientists have been studying microbial proteolysis in situ and in vitro in order to understand the genesis of soil nitrogen. This chapter provides an evaluation of the work done in this area and to point out its significance in the study of soil dynamics. It also discusses the transformations proteins undergo in the presence of biotic and abiotic components, and how these reactions may influence protein decomposition and nitrogen availability. Most of the nitrogen present in unfertilized soils is organic in nature. This organic nitrogen represents an important nutrient reservoir and a large part of it appears to be derived from protein. Sulfur and nitrogen are added to soil through the decomposition of methionine and cysteine. Some research suggests that amino compounds contribute to the structure of soil by their incorporation into humic acid, from which they are slowly released by enzymes. After transformation, they are used as plant nutrients. The breakdown of protein is crucial for composting, the development of soils, the digestion of sewage sludge, and the biodegradation of solid waste.

Adsorption of prometryn and metolachlor by selected soil organic matter fractions

Abstract: We studied the adsorption of prometryn and metolachlor by different fractions of soil organic matter, including humic substances (humic and fulvic acids), humin, and nonoxidizable soil organic matter. As a measure for adsorption evaluation, we used a distribution coefficient (Kdfom), calcula

Influence of Soil Reaction and Organic Matter on The Solubility of Heavy Metals in Soils

Abstract: The solubility behaviour of heavy metals determines mobility, leaching, availability, and toxicity of these elements in soils. In model experiments the solubility of Cu, Zn, Cd and Pb was investigated in equilibrium solutions of different soil samples under varying conditions.

Effects of heavy metals on radicle growth of selected woody species germinated on filter paper, mineral and organic soil substrates

Abstract: Copper, nickel, and cobalt solutions were added to a variety of substrates to test the effects of these metals on the germination and radicle elongation of two deciduous and five coniferous woody species native to eastern North America. For species grown on filter paper, germination was little affected by metal concentrations of up to 100 ppm. Filter-paper tests showed that radicle elongation was reduced by 25% at concentrations that ranged from 1 to 5 ppm for Betulapapyrifera Marsh, to as much as 50 to 100 ppm for Pinusstrobus L. Concentrations causing similar effects on mineral and organic soil substrates were, respectively, 10 and 100 times greater than those for filter paper. For all species, toxicity followed the pattern Ni > Cu > Co for filter paper and for mineral and organic soils. Deciduous species were more readily damaged by these metals than were coniferous species.

Structural units in humic acids from South-Eastern Queensland soils as determined by 13C NMR spectroscopy

Abstract: Solution l3C Fourier transform nuclear magnetic resonance (FTNMR) spectra of six humic acids extracted from a range of soil types and a solid state, cross polarization/magic angle spinning (CP/MAS) 13C NMR spectrum of a lignin are reported. Quantifying specific regions of the spectra reveals the presence of alkyl, carbohydrate, aromatic and carboxyl carbons. Alkyl carbon is in general the ' major contributor to these spectra, averaging 38% of the total carbon. Long-chain units comprise a significant proportion of this group, although highly branched systems are also in evidence in two samples. Carbohydrate carbon is a major contributor in two samples, representing 27% and 28% of the total carbon nuclei measured. Aromatic carbon content shows the greatest variability, ranging from 10 to 45%. Humic acids from soils developed under rainforest show the lowest aromaticity, and it is suggested that aromatic structures are not integral building blocks of terrestrial humic acids. Little evidence was found for the presence of hydroxy- and methoxy-substituted aromatic carbons even in humic acids high in aromaticity.