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Showing papers on "Soil organic matter published in 1969"


Journal ArticleDOI
TL;DR: It has now been demonstrated conclusively that application of certain compounds to leaves affects the quantity and types of exudates.
Abstract: Although the quantities of organic compounds exuding from roots is not large, seldom exceeding 0.4% of the carbon photosynthesized, they do exert a very strong influence on the soil microorganisms and may be significant in affecting plant nutrient availability. There is evidence that exudates from the roots of some plants are toxic to roots of neighboring plants and to the germination of some seeds.

829 citations


Book
01 Jan 1969
TL;DR: In this article, a modern synthesis of plant and soil water relationships is presented, based on modern synthesis techniques, using modern synthesis synthesis techniques for plant-to-soil water relationships.
Abstract: Plant & soil water relationships: a modern synthesis , Plant & soil water relationships: a modern synthesis , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

446 citations



Journal ArticleDOI
TL;DR: Comparisons of paired virgin and pasture samples of Coolup sand showed that nitrogen had accumulated in the top 12.5 cm under pasture at an average of 24 p.p.m. per year, and there was a strong annual cycle of nitrogen and sulphur availability.
Abstract: Comparisons of paired virgin and pasture samples of Coolup sand showed that nitrogen had accumulated in the top 12.5 cm under pasture at an average of 24 p.p.m. per year. Carbon, sulphur, and organic phosphorus also accumulated to give C : N : S : P ratios of 118 : 10 : 1.2 : 0.47. The accumulation of sulphur accounted for about a quarter of the sulphur added in fertilizer and the accumulation of organic phosphorus accounted for about a tenth of the phosphorus added. Inorganic phosphorus had also accumulated but the amount varied between soils. The cation exchange capacity, as measured by summation of exchangeable cations and exchange acidity, increased by an average of 44 m-equiv. per g increase in nitrogen or 3.7 m-equiv. per g increase in carbon. Most of the increase was due to increases in exchange acidity. However, the buffering capacity of the soil for potassium was only slightly affected by the increase in organic matter. The water held by the soil between 0.1 bar and 15 bar suction increased by an average of 3.3 per cent per 0.1 per cent increase in soil nitrogen. When the soils were incubated the ratio of nitrogen mineralized to sulphur mineralized was large, especially when the incubation period was short. In the field there was a strong annual cycle of nitrogen and sulphur availability. Values were high in autumn, low in winter, and rose again at the end of spring.

74 citations



Journal ArticleDOI
TL;DR: In this paper, the authors describe a continuous and concurrent decomposition and release of nitrogen in soil, whereby the nitrogen of the decomposing system is transformed steadily from inorganic to organic state by immobilization and back from organic to inorganic state by decay and mineralization.
Abstract: Usually, immobilization and release of nitrogen in soil are going on continuously and concurrently, whereby the nitrogen of the decomposing system is transformed steadily from inorganic to organic state by immobilization and back from organic to inorganic state by decay and mineralization. The driving agents of this turnover are soil microorganisms, C/N ratio, temperature, moisture, pH etc., and the energy needed to keep this cycle running derives from decomposable organic compounds added to soil in the forms of plant residues and excretions of roots and stored in the form of soil organic matter.

66 citations


Journal ArticleDOI
TL;DR: In this article, a comparison of N : S ratios and percentages of reducible sulphur in soils and extracts suggested that none of the reagents studied extracted a sample of organic matter that was fully representative of the organic matter in soil.
Abstract: Organic sulphur in soil appeared to be stable in mildly alkaline solutions at 20°, and thus reagents such as bicarbonate or the sodium form of a chelating resin may be used for the partial extraction of organic sulphur in a chemically unmodified form More complete extraction of organic sulphur from soil could be achieved by the use of sodium hydroxide solutions at pH 126, but degradation of humic acid sulphur to fulvic acid sulphur and conversion of organic sulphur to inorganic sulphur occurred in both hot and cold hydroxide solutions at this pH A comparison of N : S ratios and percentages of reducible sulphur in soils and extracts suggested that none of the reagents studied extracted a sample of organic matter that was fully representative of the organic matter in soil The results confirm that most of the sulphur in these surface soils is organic and that there is very little inorganic sulphate present Sulphur that could be reduced by hydriodic acid occurred in compounds of both high and low molecular weight but data obtained from extraction with bicarbonate and the chelating resin suggested that much of the reducible sulphur occurred in the high molecular weight fraction of soil organic matter

63 citations


Journal ArticleDOI
TL;DR: The effect of applied cobalt on the cobalt content of pasture plants has been studied in pot, field, and laboratory experiments as mentioned in this paper, and the generally poor agreement between pot and field experiments may be partly due to the noted variation of cobalt status of pasture with season and the influence of waterlogging.
Abstract: The effect of applied cobalt on the cobalt content of pasture plants has been studied in pot, field, and laboratory experiments. The generally poor agreement between pot and field experiments may be partly due to the noted variation of cobalt status of pasture with season and the influence of waterlogging. Cobalt treatments were effective for at least 2 yr on the humus podzol soils, but there was only a residual effect for 1 yr on other soils. Alteration of the soil pH did not prove a satisfactory means of increasing cobalt status of pasture on soils where it was most required. The efficiency of cobalt fertilizers as a means of alleviating problems of cobalt deficiency depends on the manganese content of the soil. Plants grown on soils containing > 1000 p.p.m. of total manganese are unlikely to benefit from application of cobalt fertilizer to the soil, necessitating foliar application by sprays or the use of cobalt oxide pellets for stock.

62 citations


Journal ArticleDOI
20 Sep 1969-Nature
TL;DR: The authors found that only a small fraction of the surface of the soil is responsible for the sorption of certain herbicides, whereas others found no relationship between water solubility and sorption on soil.
Abstract: PARTITION between soil and water of organic compounds that do not ionize in the pH range 4–8 is closely correlated with the soil's content of organic matter. Lambert1 and Furmidge amd Osgerby2 have expressed sorption in terms of partition coefficients between soil organic matter and water, neglecting mineral constituents. Some investigators have also reported inverse correlations between water solubility and sorption on soil whereas others have found no relationship2,3. Little is known about the mechanisms of sorption on soil, but apparently only a small fraction of the surface is responsible for the sorption of certain herbicides3. I have attempted to learn more about sorption mechanisms by studying how changes in the chemical structure of related compounds affect sorption.

51 citations


Journal ArticleDOI
01 May 1969-Ecology
TL;DR: The chemical and physical soil characteristics of the Eucalyptus associations in Benandra State Forest are described in this article, where changes in species associations occur over a gradient of increasing moisture and nutrient status of soils from ridge to gully sites.
Abstract: The chemical and physical soil characteristics of the Eucalyptus associations in Benandra State Forest are described. Changes in species associations occur over a gradient of increasing moisture and nutrient status of soils from ridge to gully sites. Concentrations of major nutrients in leaves and bark of dominant trees on these sites generally follow the soil gradients. In particular, leaf phosphorus and bark calcium are correlated with the corresponding soil nutrients. Soil calcium and magnesium are also correlated with leaf phosphorus, indicating a possible interaction between these soil nutrients and phosphorus uptake by the trees. Soil magnesium is similarly correlated with bark calcium. Aluminum is the major exchangeable cation in soils of the poorer ridge sites which are the most acid. It is hypothesized that soil aluminum competes with other nutrient cations such as calcium and magnesium for sites of absorption on plant roots. In addition to the effect of soil pH on phosphate solubility, competiti...

45 citations


Journal ArticleDOI
TL;DR: Animal activity contributed little to the rate of decay and disappearance of herbage on the soil surface and did not accelerate decay of herbish in the soil.
Abstract: A study was made of the role of soil animals in the decay and disappearance of herbage confined in nylon bags of different mesh sizes in the soil and on the soil surface. The size of the animals admitted was controlled by mesh size. Animal activity contributed little to the rate of decay and disappearance of herbage on the soil surface and did not accelerate decay of herbage in the soil.


Journal ArticleDOI
TL;DR: In this article, the authors found that the rate of moisture uptake from the vapour phase by superphosphate increased directly with an increase in relative humidity above 89% and was also influenced by temperature and surface area of the particle.
Abstract: Capillary uptake of soil water appeared to be more important than hygroscopic uptake of moisture by monocalcium phosphate in the wetting of surface-applied superphosphate particles. For hygroscopic uptake of water a relative humidity greater than 89% was found necessary, but particles on the soil surface are exposed to atmospheric humidity which is frequently well below 89%. This may prevent uptake of moisture from soils of low moisture content. The rate of moisture uptake from the vapour phase by superphosphate increased directly with increase in relative humidity above 89%. The rate of uptake was also influenced by temperature and surface area of the particle. Capillary uptake of soil water was influenced by soil moisture content, density of the particles, and the degree of contact between soil and particle. Movement of phosphate from the moist particle into the soil was rapid but the rate was affected by soil moisture, temperature, contact with the soil, and certain physical properties of the particle. In contrast to phosphate, movement of sulphate into the soil was slow because of the low solubility of calcium sulphate, and was greatly influenced by particle size. Leaching by rainfall may be an important factor in the movement of sulphate from coarse particles.

Journal ArticleDOI
30 May 1969-Science
TL;DR: Soils from the dry-valley region of Antarctica can be sterile by the usual microbiological criteria and yet contain significant amounts of organic carbon, which has significant implications for the biological exploration of Mars.
Abstract: Soils from the dry-valley region of Antarctica can be sterile by the usual microbiological criteria and yet contain significant amounts of organic carbon Examination of one such soil shows that the organic material is finely divided anthracite coal These findings have significant implications for the biological exploration of Mars

Journal ArticleDOI
TL;DR: In this article, five soil profiles on alluvial terraces in the Macleay River Valley, N.S. have been studied to determine changes in soil development with increasing age.
Abstract: Five soil profiles on alluvial terraces in the Macleay River Valley, N.S.W., have been studied to determine changes in soil development with increasing age. The criteria used were mainly macromorphology, micromorphology (basic fabric, evidence of weathering of lithorelicts and biotite, and depth functions of illuviated clay), depth functions of grain-size distributions, and clay mineralogy. The evidence suggests that the four youngest soil profiles represent successive stages of profile development by weathering for the most part and, to a lesser extent, formation of an horizon of illuviated clay; data for the oldest soil indicate a different history of profile development.

Journal ArticleDOI
TL;DR: The union of mineral and organic matter to form the organo-mineral complex is a synthesis as vital to the continuance of life as, and less understood than, photosynthesis as mentioned in this paper.
Abstract: “The union of mineral and organic matter to form the organo-mineral complex is a synthesis as vital to the continuance of life as, and less understood than, photosynthesis.”(JACKS) (1).

Journal ArticleDOI
TL;DR: In this paper, the respiration of the soil in situ was studied during a period of 15 months in four Eucabbus stands of diverse physiognomy and productivity, and it was found that respiration rates were low in winter, and during periods of drought in summer; they were high in spring, and were stimulated by precipitation during the summer.
Abstract: The respiration of the soil in situ was studied during a period of 15 months in four Eucabpbus stands of diverse physiognomy and productivity. Respiration rates were low in winter, and during periods of drought in summer; they were high in spring, and were stimulated by precipitation during the summer. Although soil respiration rates were not directly related to the organic matter content of the soil, to the amount of litter fall, or, in general, to the productivity of the stands as measured in terms of tree growth, the magnitude of the spring flush of respiration and the levels of respiration that were maintained during periods of summer drought were found to be related to stand productivity. The pattern of variation of the carbon dioxide content of the soil air differed markedly between stands, and there was a positive relationship between the productivity of the stands and the depth in the soil to which biological activity occurred.

Journal ArticleDOI
TL;DR: The results of pot trials with soil taken from the experiment showed that the different levels of superphosphate had induced large differences in the phosphorus status of the soil but had had much smaller effects on the sulphur status.
Abstract: The total nitrogen content of the soil was significantly increased at each of four levels of superphosphate applied to a densely sown subterranean clover pasture on a coarse-textured sand at Kojonup, W.A. During the first 4 years of the experiment nitrogen build-up was similar for all four treatments, but over the 11 year term the build-up was significantly slower at the lowest level of superphosphate. The relationship between the age of the pasture and soil nitrogen was linear at the lowest level of fertilizer but curvilinear at all other levels. The relationship between total superphosphate applied and soil nitrogen was curvilinear. There were no differential effects of the fertilizer treatments on either the bulk density or the pH of the soil. At the two lower levels of superphosphate a high percentage of both phosphorus and sulphur was retained in the major plant root zone (0–10 cm) of the soil. At the two higher levels most of the phosphorus was retained but there were heavy losses of sulphur. The results of pot trials with soil taken from the experiment at the end of the 11 year period showed that the different levels of superphosphate had induced large differences in the phosphorus status of the soil but had had much smaller effects on the sulphur status. The possible effect of this loss of sulphur on the accumulation of soil organic matter is discussed.





Journal ArticleDOI
TL;DR: In this paper, the authors discuss the application of the analysis developed in Part I to hydrology and soil mechanics, with the aid of calculated examples, and apply it to two-and three-dimensional systems.
Abstract: The paper discusses, with the aid of calculated examples, applications in hydrology and soil mechanics of the analysis developed in Part I Various classical concepts of groundwater hydrology fail completely for swelling soils The distributions of saturation and of hydraulic conductivity relative to the water table differ entirely from the conventional picture Variations in surface topography affect moisture distribution in swelling soils The theory of this effect is developed for topographies that are not too steep and is illustrated by examples The equilibrium distributions found would be classically interpreted as disequilibrium states persisting because of small hydraulic conductivity; but, in fact, the moisture differentials are maintained, not by a lack of conductivity, but by a lack of difference in total potential The variation of specific yield with water table elevation and stratum thickness in swelling soils is basically different from that in non-swelling soils The analysis of Part I is used to discuss the following topics in soil mechanics: the variation of equilibrium soil levels with water-table depth, and with water depth over the soil; the effect of surface loading on equilibrium moisture profiles and on soil levels Extension of the analysis to two- and three-dimensional systems is treated briefly

Journal ArticleDOI
TL;DR: The authors discusses basic soil factors related to agriculture and agricultural productivity; results of soil organic matter research, including compost utilization; and avenues (present and proposed) for compost discharge to the land.
Abstract: Composting is the biological stabilization of refuse and similar solid wastes; the end product of composting is a material of supposed benefit to the soil. However, farmers have not generally been eager to use compost because increased crop yields are obtained more economically with chemical fertilizers. Yet composting has significant potential as a method of solid wastes processing, if and when a reasonable system for disposing of the compost can be devised. This paper, in three parts, discusses basic soil factors related to agriculture and agricultural productivity; results of soil organic matter research, including compost utilization; and avenues (present and proposed) for compost discharge to the land. The point is made that the land should be considered a sink or receiver of wastes, rather thinking that wastes, in the form of compost, will benefit the land.

Journal ArticleDOI
TL;DR: In this article, it has been proved that volcanic soil is characterized by smaller number of bacteria and larger number of actinomycetes than non-volcanogenous soil, and the difference in microflora of both soil groups is considered to reflect the difference between the properties inherent in each soil.
Abstract: The microbiological characterization of Japanese soils has been one of main themes in the authors' laboratory, and it has been proved that volcanogenous soil is characterized by smaller number of bacteria and larger number of actinomycetes than non-volcanogenous soil (1) Such difference in microflora of both soil groups is considered to reflect the difference between the properties inherent in each soil As the next step, it seems quite reasonable to consider whether there exists qualitative difference in each group of microorganisms

Journal ArticleDOI
TL;DR: Quite marked changes occurred in the populations of the main invertebrate groups and of themain species of Acari and Collembola present during the course of decomposition, the changes occurring in buried material being quite different to those occurring in surface material.
Abstract: The fauna associated with the decomposition of grassland herbage decaying in the soil and on the soil surface was studied. Herbage was confined in nylon bags of different mesh sizes, the size of animals admitted being controlled by mesh size. Quite marked changes occurred in the populations of the main invertebrate groups and of the main species of Acari and Collembola present during the course of decomposition, the changes occurring in buried material being quite different to those occurring in surface material.


Journal ArticleDOI
TL;DR: In this article, it was shown that after 3 weeks, wheat from irradiated inoculated soil had three times the asparagine content found in wheat from unsterilized soil.
Abstract: The recolonization by Nitrosomonas and Nitrobacter of a soil sterilized by gamma radiation was extremely slow compared with the rates of recolonization by heterotrophic bacteria and fungi. As a consequence, ammonium N formed during and following irradiation was not nitrified for at least 11 weeks and plants growing on irradiated inoculated soil were ammonia fed. Under these conditions plant growth was better in irradiated-inoculated soil than in unsterilized soil. After 3 weeks, wheat from irradiated inoculated soil had three times the asparagine content found in wheat from unsterilized soil. Soil that has been irradiated then inoculated could be a useful tool for studying both nitrogen turnover in soil and the availability of nitrate and ammonium to plants growing in soil under nearly natural conditions.

Journal ArticleDOI
TL;DR: In this paper, the uptake of five herbicides by the dead roots of six plant species was investigated and it was concluded that the process involved was probably adsorption The adsorptive capacity of the dry matter of roots was lower than soil organic matter but was of a similar order of magnitude.
Abstract: The uptake of five herbicides by the dead roots of six plant species was investigated and it is concluded that the process involved was probably adsorption The adsorptive capacity of the dry matter of roots was lower than soil organic matter but was of a similar order of magnitude It is suggested that in some cases adsorption might provide a significant pathway by which herbicides are taken up by the living plant It seems unlikely that adsorption by roots will normally exert much influence on the herbicide concentration in the soil solution

Journal ArticleDOI
TL;DR: It is well known that tillage of soil produces greater aeration and incorporates crop residues and fertilizers into inner soil layers, thus stimulating the microbial activities and increasing the rate of decomposition of soil organic matter as mentioned in this paper.
Abstract: It is well known that tillage of soil produces greater aeration and incorporates crop residues and fertilizers into inner soil layers, thus stimulating the microbial activities and increasing the rate of decomposition of soil organic matter. Tillage operation has been, therefore, one of the important practices to increase soil productivity.