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Showing papers on "Soil organic matter published in 1977"


Journal ArticleDOI
TL;DR: In this article, data from the Rothamsted classical field experiments on the effects of long-continued cropping and manuring on the amount of organic matter in soil, on the age of this soil organic matter, and on the number of microbial biomass in the soil.
Abstract: Data are assembled from the Rothamsted classical field experiments on the effects of long-continued cropping and manuring on the amount of organic matter in soil, on the age of this soil organic matter, on the amount of microbial biomass in the soil, and on the rate at which plant residues d

1,157 citations


Journal ArticleDOI
TL;DR: In this article, a review deals with methodological approaches, measured rates, and environmental control of two major interdependent processes regulating the structure and function of terrestrial ecosystems, viz., plant decomposition and soil respiration.
Abstract: This review deals with methodological approaches, measured rates, and environmental control of two major interdependent processes regulating the structure and function of terrestrial ecosystems, viz., plant decomposition and soil respiration. Both these processes have been evaluated through indirect assessments as well as through direct measurements under the field conditions. The techniques used suffer in general from difficulties in creating conditions of natural environment during the process of measurement. Generalizations regarding the magnitude of rates in different ecosystems are difficult because of limited results or non-comparability of results from different methods. Temperature and moisture and their interactions markedly influence both the processes. The surface feeders and soil animals have a marked influence on the decomposition. Partitioning of soil respiration into components due to live roots, microbes, and soil fauna has eluded a satisfactory solution so far.

734 citations


Book ChapterDOI
TL;DR: In this article, the mechanism of immobilization and mineralization of organic phosphorus in soil has been reviewed and two analytic techniques for the determination of the organic phosphorus content of soils: ignition and extraction.
Abstract: Publisher Summary This chapter reviews the mechanism of immobilization and mineralization of organic phosphorus in soil The chapter describes two analytic techniques for the determination of the organic phosphorus content of soils: ignition and extraction In the ignition method, the organic phosphorus is determined by measuring the differences in the acid-extractable phosphorus in soil samples before and after ignition In the extraction method, the organic phosphorus is determined by the difference between the inorganic and total phosphorus in the soil extracts Various factors that affect the organic phosphorus content of soils are rainfall, mean temperature, drainage, soil pH, cultivation, inorganic phosphorus content of the parent material, and sulfur content in areas of low atmospheric returns Investigations have been carried out on the accumulation of organic phosphorus under pasture and the incorporation of added inorganic phosphorus in soil organic matter The chapter also examines the chemical nature of organic phosphorus in soils and summarizes the phosphorus cycle of a native grassland ecosystem

605 citations


Journal ArticleDOI
TL;DR: In this paper, the role of organic ligands in metal complexing in natural waters has received little attention because of uncertainties regarding both the abundance and nature of dissolved organic carbon compounds, and it has been shown that the bulk of the dissolved organic matter in the natural waters consists of highly oxidized and chemically and biologically stable polymeric compounds closely resembling soil humic substances.

436 citations



Journal ArticleDOI
TL;DR: In this paper, the authors compared the performance of continuous cropping with those under planted fallows and natural bush regrowth for three years after forest clearing, and suggested that soils may be planted with a combination of Guinea grass and pigeon pea fallow for one or two years after three or four years.
Abstract: Soil properties under continuous cropping were compared with those under planted fallows and natural bush regrowth for three years after forest clearing. The cropping treatments consisted of continuous maize with and without stover returned as surface mulch, continuous soybean, and maize and cassava intercropped. The fallow treatments included pigeon pea, leucaena, Guinea grass and natural bush regrowth. In the continuous soybean and unmulched maize plots, soil organic matter and pH declined rapidly; whereas the mulched maize plots maintained a soil organic matter level comparable to the fallow treatments. To maintain soil organic matter in the surface soil at a level comparable to soil under secondary forest, two to three applications of a total amount of 16 MT/ha/annum of dry plant materials (maize stover or grass) are required when the material is applied as surface mulch. In the cropped plots, favorable physical characteristics in the surface soil were also maintained when sufficient plant residue was returned; whereas the deterioration of subsoil structure of the forest soil occurred in all cropping treatments. Guinea grass fallow has a distinct advantage in recycling mineral nutrients and maintaining soil physical properties and organic matter. It is suggested that soils may be planted with a combination of Guinea grass and pigeon pea fallow for one or two years after three or four years of arable cultivation.

193 citations


Journal ArticleDOI
TL;DR: In this article, the influence of the initial chemical composition of the roots of three grass species on decomposition was studied in a laboratory incubation experiment, and the results showed that the effect of soil in controlling decomposition may be as great as the impact of the substrate.
Abstract: Grass root production is a major source of C entering Chernozemic soils. The influence of the initial chemical composition of the roots of three grass species on decomposition was studied in a laboratory incubation experiment. Roots of Stipa comata Trin. and Rupr., Stipa spartea Trin. var. curtiseta Hitchc., and Festuca scabrella Torr. were incubated at 28 C for 47 wk. Carbon dioxide production and percent loss of carbohydrate were inversely related to [(C:N) (% lignin)] (% carbohydrate−½). Percent loss of lignin, however, was directly proportional to this factor. This relationship was also found to fit data in the earlier literature. Decomposition rate appeared to be slower in the laboratory in the absence of soil than has been reported for decomposition rates in field soils. The data are discussed with reference to the dynamics of plant residues and organic matter in soil systems. It is postulated that the effect of soil in controlling decomposition may be as great as the effect of the substrate.

167 citations


Journal ArticleDOI
TL;DR: In this paper, a source of CO2 in the unsaturated zone is proposed to account for this discrepancy, supported by direct measurements of CO 2 in fractures in cave walls and analyses of drip waters.

159 citations


Journal ArticleDOI
TL;DR: The rate of aerobic evolution of 14CO2 from 14C-glyphosate labelled in the methylphosphonyl carbon, varied 100-fold within a group of five Hawaiian sugarcane soils as discussed by the authors.
Abstract: Summary: The rate of aerobic evolution of 14CO2 from 14C-glyphosate labelled in the methylphosphonyl carbon, varied 100-fold within a group of five Hawaiian sugarcane soils. The rate depended inversely on the degree of soil binding, probably associated with the phosphonic acid moiety, and to a less certain extent on soil pH and soil organic matter. After an initial rapid degradation, the rate of 14CO2 evolution in three soils reached a constant at 16–21 days which continued to the 60-day termination. The other two soils showed a continually decreasing rate throughout. Two soils released over 50% of the labelled carbon in 60 days, a third released 35%, while the remaining soils released 1.2 and 0.8% respectively. Labelled carbon in the soils after 60 days consisted of glyphosate and one metabolite, aminomethyl-phosphonic acid, with glyphosate predominating in high fixing soils. The 14C could be extracted almost completely with NaOH solution, and remained mainly in solution after acidification.

128 citations


Journal ArticleDOI
01 Mar 1977-Ecology
TL;DR: A dynamic simulation model of nitrogen flow in a grassland ecosystem has been developed that includes a simple producer-decomposer submodel, but the nitrogen sections have also been incorporated into the ELM model.
Abstract: A dynamic simulation model of nitrogen flow in a grassland ecosystem has been developed. State variables in the model include the nitrogen in the following major components: soil ammonium, soil nitrate, live roots, dead roots, soil organic matter, live tops, and litter. Belowground components are subdivided into four depth layers. The model includes a simple producer-decomposer submodel, but the nitrogen sections have also been incorporated into the ELM model.

90 citations


Journal ArticleDOI
TL;DR: In this paper, the root growth and nodulation of soybeans were investigated and it was shown that ozone does not appreciably penetrate the plant growth substrates nor did it oxidize soil organic matter to form compounds inhibitory to Rhizobium.

Journal ArticleDOI
01 Dec 1977-Nature
TL;DR: In this paper, it has been found, using organic extractants, that solutions of soil humic substances, capable of NMR spectroscopic investigation, may be prepared, and the spectra obtained suggest that polymers of a similar structure to oxidised polyethylene are important components of soils.
Abstract: THE nature of soil humic acids and similar substances derivable from oxidised brown coal is of considerable fundamental and practical interest. It has now been found, using organic extractants, that solutions of soil humic substances, capable of NMR spectroscopic investigation, may be prepared. The spectra obtained suggest that polymers of a similar structure to oxidised polyethylene are important components of soils. Numerous other types of chemical structures are also evident from the NMR absorptions of soil organic matter solutions; the amounts and types present vary widely from soil to soil. It is suggested here that chemical fractionation of soil organic matter can be most easily followed by observation of the NMR spectra.


Journal ArticleDOI
TL;DR: The effectiveness of hydrogen peroxide in oxidizing soil organic matter was markedly increased by the presence of 0.1M sodium pyrophosphate at pH 7, with residual C after treatment being reduced up to 20 times lower compared to conventional soil peroxidation.
Abstract: The effectiveness of hydrogen peroxide in oxidizing soil organic matter was markedly increased by the presence of 0.1M sodium pyrophosphate at pH 7, with residual C after treatment being reduced up to 20 times lower compared to conventional soil peroxidation. “Electropositive” (Orange II) and external (N₂) surface areas increased, whereas “electronegative” (cetyl pyridinium bromide) surface area values generally decreased after H₂O₂ treatment, supporting the assumption that metals released from organic matter may precipitate as hydroxide coatings that hinder further oxidation. Some soil sorption sites appear to be occluded by organic matter, so that changes in soil properties after peroxidation cannot be solely attributed to organic matter.

Journal ArticleDOI
TL;DR: In this article, two experimental fields were studied in terms of their soil microbial and biochemical characteristics in relation to soil management practice and crop yields, and it was shown that the yields of winter wheat were related positively to phosphatase activity while the sugarbeet yields were related negatively to soil urease activity.
Abstract: From 1969 to 1974, two experimental fields were studied in terms of their soil microbial and biochemical characteristics in relation to soil management practice and crop yields. Of the various microbial and biochemical properties measured soil phosphatase, saccharase, β-glucosidase and urease activities, N mineralization and soil respiration were found valuable to characterize the soils. These characteristics increased with increasing soil organic matter, clay and CaCO 3 content. They also revealed a strong effect of organic fertilization. Multiple regression analyses indicated that the alkalinity and the humus content of the soil largely determined the magnitude of these characteristics. The regression analyses also showed that the yields of winter wheat were related positively to phosphatase activity while the sugarbeet yields were related negatively to soil urease activity.

Journal ArticleDOI
TL;DR: In this article, an element balance for a beech forest is given, where the acidification of the soil chemical conditions is changed in a way that plants rooting close to the soil surface are affected.
Abstract: Acidity of throughfall precipitation is increased by the filtering of S and N from the atmosphere by trees. An element balance for a beech forest is given. As a consequence of acidification the soil chemical conditions are changed in a way that plants rooting close to the soil surface are affected. Losses of nutrients may pose a problem in forest plant nutrition in the near future in Central European forests on light or medium textured acid soils.

Journal ArticleDOI
TL;DR: In this article, simazine, linuron and propyzamide were incubated in 18 different soils at 25°C and field capacity soil moisture content, and the degradation of each herbicide followed first-order kinetics.
Abstract: Summary: Simazine, linuron and propyzamide were incubated in 18 different soils at 25°C and field capacity soil moisture content. The degradation of each herbicide followed first-order kinetics. The half-life of simazine varied from 20 to 44 days, that of linuron from 22 to 86 days and that of propyzamide from 10 to 32 days. The rate of linuron degradation was highly significantly correlated with soil organic matter content, clay content, soil respiration and the extent of herbicide adsorption by the soil. The rate of simazine degradation was significantly and negatively correlated with soil pH, but the rate of propyzamide degradation was not related with any of the soil factors examined.


Journal ArticleDOI
TL;DR: The role of naturally-occurring soil organic matter (SOM) in the translocation of metal ions from parent materials to biological systems is discussed in this article, where a hypothesis or model is proposed wherein their translocation includes a sequence of reactions.
Abstract: The role of naturally-occurring soil organic matter (SOM) in the translocation of metal ions from parent materials to biological systems is discussed. To explain the movement of essential elements, a hypothesis or model is proposed wherein their translocation includes a sequence of reactions



Book ChapterDOI
01 Jan 1977
TL;DR: Fungi usually comprise the dominant microbial biomass in terrestrial decomposer communities, and contribute substantially to cycling of both macronutrients and trace elements.
Abstract: Biodegradation of litter components and soil organic matter is a complex process in which both microorganisms and soil animals take part. Fungi usually comprise the dominant microbial biomass in terrestrial decomposer communities, and contribute substantially to cycling of both macronutrients and trace elements (Harley, 1971; Stark, 1972; Ausmus and Witkamp, 1973). Fungi are also important as energy and nutrient sources for many vertebrates and invertebrates (Miller and Halls, 1969; Fogel and Peck, 1974; Mitchell and Parkinson, 1976). Invertebrates adapted to coprophagy can obtain increased quantities of essential elements from feces colonized by microbes (Wieser, 1966; McBrayer, 1973).

Book ChapterDOI
01 Jan 1977
TL;DR: In this article, a model of soil carbon dynamics is described which takes account of decomposition of soil organic matter, losses through erosion, and input from crop residues and manure, and results are presented on the equilibrium soil carbon content for various management practices, yield levels, and soil characteristics.
Abstract: A model of soil carbon dynamics is described which takes account of decomposition of soil organic matter, losses through erosion, and input from crop residues and manure. Results are presented on the equilibrium soil carbon content for various management practices, yield levels, and soil characteristics. Estimates are given for the increase in grain yield and nitrogen fertilizer use efficiency for different levels of soil organic matter.

Journal ArticleDOI
TL;DR: In this article, field experiments dealing with responses of subterranean and white clover pastures to applied phosphate at a range of soil phosphorus levels, were carried out and a preliminary estimate is made of the way yield/soil test functions vary with changes in soil phosphate buffering capacity.
Abstract: Fifty-one field experiments dealing with responses of subterranean and white clover pastures to applied phosphate at a range of soil phosphorus levels, were carried out. The level of sodium bicarbonate extractable phosphorus above which little or no response to applied phosphate occurs (critical level), increased from 22 to 48 pg phosphorus/g soil with increases in soil phosphate buffering capacity (at solution [P] of 0.3 pg phosphorus/ml) from 1 to 20 ml/g x 10-1. On the few highly buffered soils occurring outside this range critical levels up to 60 µg phosphorus/g soil were indicated. A preliminary estimate is made of the way yield/soil test functions vary with changes in soil phosphate buffering capacity.

Journal ArticleDOI
TL;DR: In this paper, the occurrence and amount of fallout 137Cs were determined in 12 watersheds in the arid southwestern United States using stepwise regression techniques, and the factors believed to influence the distribution of 137Cs in the watershed soils and in the reservoir sediments were investigated by using step-wise regression technique.
Abstract: The occurrence and amount of fallout 137Cs were determined in 12 watersheds in the arid southwestern United States. The factors believed to influence the distribution of 137Cs in the watershed soils and in the reservoir sediments were investigated by using stepwise regression techniques. Seventeen parameters, in the case of soils, and 21 parameters, in the case of sediments, were used in the study. Ninety percent of the variation in the 137Cs content of soils, per unit weight, could be predicted in terms of the percentage of soil nitrogen, the R factor (rainfall intensity) of the universal soil loss equation, the percentage of sand in the soils, and the soil cation exchange capacity. Also, 90% of the variation in the content of 137Cs in the watershed soils, per unit area, could be predicted in terms of the fallout intensity, the percentages of silt and clay, and the cation exchange capacity. For reservoir sediments the equivalent predictors of 137Cs accumulation in the sediment profile, per unit weight, were the soil cation exchange capacity, the January–March average precipitation, and the soil contents of total P and N. The distribution Of 137Cs in sediments per unit area was similarly predicted by watershed area, percentage of total soil C, reservoir surface area, areal concentration of 137Cs in the watershed soils, and soil organic matter.

Journal ArticleDOI
TL;DR: Organic matter characteristics at both locations were closely associated with seasonal fluctuations and grazing-induced pressures; therefore, the time of sampling and the type of management before sampling soils should be defined in range studies.
Abstract: Highlight: At Manyberries and Stavely, Alberta, Mixed prairie and Fescue Grassland ranges were grazed at various intensities for 19 and 22 years, respectively. In 1973,13 chemical characteristics were determined on the organic matter developed in the soils of the ungrazed and heavy grazed treatments at the two locations. Samples were taken in spring, summer, autumn, and winter. Organic matter characteristics at both locations were closely associated with seasonal fluctuations and grazing-induced pressures; therefore, the time of sampling and the type of management before sampling soils should be defined in range studies. The results further emphasize the fragility of the equilibrium under which the organic matter of the soil of heavily grazed Mixed prairie at Manyberries forms and exists.

Journal ArticleDOI
TL;DR: In this paper, the Δ15N values for fertilizer nitrogen ranged from -4•1 to 1 • 9 and for nitrate nitrogen in water from 4•4 to 6 • 1.
Abstract: The15N abundance in components from a 100 ha catchment was determined. Δ15N values for fertilizer nitrogen ranged from -4•1 to 1 • 9 and for nitrate nitrogen in water from 4•4 to 6 • 1. Δ15N values for total nitrogen from three sites ranged from 2•9 to 6•7 and for nitrate released during laboratory incubations from -0•2 to 4•2. The variability in Δ15N of nitrate released by mineralization between replicates and within each sampling site was small. The Δ15N for nitrate released under bare fallow was 5•5. The use of these variations in15N abundance is discussed. The Δ15N values for nitrate from soil intervals to 6m increased with depth. This result is discussed in terms of fractionation in a nitrate adsorbing soil.


Journal ArticleDOI
Mike Kirkby1
01 Apr 1977
TL;DR: In this article, the interaction of slope profile models with soil profile models is discussed in general terms to show the external constraints on each individual soil profile which set it within its catena context.
Abstract: The interaction of slope profile models with soil profile models is discussed in general terms to show the external constraints on each individual soil profile which set it within its catena context. The soil profile models discussed are primarily chemical, and treat the soil hydrology as externally imposed. Soil inorganic minerals are treated as mixtures of elementary oxides, using modified values for Gibb's free energies which are approximately valid for silicates. Soil organic matter is considered to consist of carbohydrates, amino acids and lignins, in order to simulate soil organic matter distributions with and without vertical mixing. The soil CO2 distribution is simulated via gaseous diffusion of the CO2 produced by organic matter decomposition. Soil pH is calculated with reference to the CO2 distribution, and allows the solubility equations to be solved through the resulting inorganic soil profile. A worked example is given for a soil profile in equilibrium with given external rates of mechanical and chemical denudation.

Journal ArticleDOI
TL;DR: In this article, the mineralization of several kinds of microbial cells added to soil were accelerated considerably by the drying effect, and they were roughly divided by mechanical procedure into two parts, i.e., cytoplasmic and cell wall substances, and separately added to the soil with or without drying previously.
Abstract: 1) The mineralization of several kinds of microbial cells added to soil were accelerated considerably by the drying effect. 2) When microbial cells were roughly divided by mechanical procedure into two parts, i.e., cytoplasmic and cell wall substances, and separately added to soil with or without drying previously, the former was mineralized very quickly both with and without drying previously and its mineralization was not accelerated by the drying effect. The latter without drying previously was mineralized rather slowly, and the latter with drying previously was mineralized very quickly and remarkably. Furthermore, the former with and without drying previously left hardly any residual matter in soil, but the latter without drying previously left considerable residual matter because of making a complex resistant to microbial decomposition with colloid materials such as clay minerals and humus, and mineralization of the residual matter was remarkably accelerated by the drying effect. 3) From the...