Incorporation Of Organic Matter Research Articles

Shear Strength Prediction of Compacted Soils with Varying Added Organic Matter Contents

ABSTRACT THE shear strength of compacted soils is affected by many factors including soil density, overburden pressure, moisture content, energy applied for compaction and soil type. Measurements were made of the shear strength of three soil textures, varying in organic matter contents and subjected to three levels of compaction energy. Soil compaction increased the shear strength of the soils irrespective of moisture content, while organic matter incorporation decreased their shear strength. Based on the liquid limit, the pressure applied for compaction and the water content, a method for predicting the shear strength of soils was developed. The estimated shear strength using the model was in good agreement with the measured values.

The Effects of Soil Compaction and Organic Matter on the Growth of Bush Beans

ABSTRACT BUSH BEANS (Phaseolus vulgaris) were planted in three soil textures having varying organic matter contents that were subjected to three levels of compaction energy. Measurements were made of some plant and yield parameters in a controlled environment. Soil compaction decreased the fresh yields of the crop, the plant height, the root dry matter and increased the plant diameter. On the other hand, organic matter incorporation which tends to reduce compaction increased the fresh and dry yields of the crop, the plant height, the leaf area index and the root dry matter. The results indicate that there is a great potential for using organic matter to alleviate the problems of soil compaction in crop production.

Effect of chemical treatments and incorporation of organic matter on the pathogenicity and survival of <em>Pseudomonas solanacearum</em> (Smith) in soil

The Journal of the National Science Foundation of Sri Lanka publishes the results of research in all aspects of Science and Technology. The journal also has a website at http://www.nsf.gov.lk/. 2020 Impact Factor: 0.515The JNSF provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.

The Firestone Sill ganister, Namurian, northern England—the A 2 horizon of a podzol or podzolic palaeosol

The Firestone Sill is a sandstone of early Namurian age which outcrops in the northern Pennines. Occasionally the top of this sandstone contains a conspicuous white quartz arenite upto 1.5 m thick. This was formerly worked for refractory purposes and became known as the Firestone Sill ganister. The presence of roots, rootlets, soil horizons and pedogenically produced structures, e.g. cutans associated with the quartz arenite suggest that it represents the A 2 (eluvial) horizon of a podzol or podzolic palaeosol. The main processes operating during pedogenesis were the accumulation and incorporation of organic matter into the surface (A 1) horizon, destruction of sedimentary structures by bioturbation (principally rootlets), and the downward translocation of carbonaceous material, clays and other mineral breakdown products. The latter led to a relative quartz enrichment of a few percent in the A 2 (ganister) horizon and resulted in the development of a B-horizon of accumulation. The presence of occasional feldspars in the A 2-horizon and the rather small amount of quartz enrichment which took place in this zone suggest that pedogenesis was of fairly brief duration.

Sedimentary Facies of an Arid Zone Delta: Gascoyne Delta, Western Australia

The Gascoyne delta is forming on a semi-arid, wave-dominated coast at the northern end of Shark Bay, Western Australia. The Gascoyne River flows intermittently. The delta has a flattened lobate form with a peripheral strandplain of elongate lagoons and tidal flats separated by beach spits and low beach ridges. Three major stratigraphic components form the Gascoyne delta: basal sheet, deltaic sequence, and plain sequence. The basal sheet is a thin transgressive unit deposited during the Holocene sea-level rise. Offshore it is shelly quartz sand with a relict, shallow-water sandflat fauna. Inshore it contains sediment admixed from contemporary seagrass communities or overlying units. The deltaic sequence is a regressive terrigenous wedge overlying the basal sheet. It consists of the bar unit, the delta bay unit, and the strandplain sheet. The bar unit is an upward-coarsening sand body being deposited on the distributary mouth bars and the shoreface; it grades laterally into the delta bay unit, a muddy sand body accumulating in the protected embayment to the south of the delta. The strandplain sheet overlies both units and is composed of sand and muddy sand with minor mud. It is being deposited in beach, beach ridge, tidal flat, and supratidal flat environments. The plain sequence consists of three units: the channel and levee units and the plain sheet. The channel unit is coarse sand and gravel; the levee unit is fine sand, silt, and mud. The channel and levee units form a narrow belt of bedded fluvial deposits normal to the strandline. The plain sheet is homogeneous, red-brown mud and sandy mud deposited by sheetwashing. The marine deltaic sequence is a laterally extensive, upward-coarsening sand body typical of other wave-dominated deltas (e.g., Sao Francisco and Rhone). However, the subaerial sequence, a narrow, axial belt of channel sands and levee silts flanked by extensive red-brown muds, forms a different cap. In contrast both the Sao Francisco and Rhone deltas have sandy deltaic plain sequences. Other arid zone deltas (Colorado and New River) differ markedly in their process style. Neither are wave-dominated. Arid climate in the Gascoyne does not markedly influence the marine sequence but is reflected in subaerial units by extensive red-brown, desiccated muds and confinement of marsh deposits to the narrow coastal, tidal zone. The Gascoyne is a potential redbed delta, particularly the subaerial sequences. Reddening of marine sequences is theorized as being dependent on the incorporation of organic matter, and possibly on inshore productivity.

Characterization of soil structure and stability using modulus of rupture - exchangeable sodium percentage relationships

Measurements of the modulus of rupture (MOR) and in particular of the way in which it changes for a given soil with change in exchangeable sodium percentage (ESP) from zero to 20, have been used to characterize the structural stability of a range of soils from the Western Australian wheat-belt. For convenience soils were categorized as hard-setting or non-hard-setting by an arbitrary choice of an MOR value of the natural soil of 60 kPa as the lower limit of the hard-setting behaviour. The most striking differences between the two soil categories are the higher soil strength at zero ESP (baseline MOR) and rapid increase in MOR with increasing ESP (sodium sensitivity) generally characteristic of the hard-setting soils compared with the non-hard-setting soils. The MOR values quantitatively evaluate the tendency of the soils to slake on wetting, and the sensitivity of the MOR to increasing ESP (as a result of increasing double layer swelling forces) illustrates the extent and permanency of the stabilizing bonds in the soil matrix. The presence of exchangeable magnesium on the exchange sites has been shown to increase the MOR values compared with those for exchangeable calcium at all ESP values in line with previous evidence of the deleterious effects of this cation on soil structure. Although more detailed studies are required, the value of this approach is illustrated by its apparent ability to differentiate clearly between the effects of different management techniques (e.g. continuous cultivation as against continuous cropping), and even between short term effects arising within 1/1 rotations. The results from the 'paired' sites where soils, similar in most respects and having undergone identical management, exhibit significant differences in sodium sensitivity of their MOR, suggest that the strength and longevity of structural bonds may be related to the nature of the exchangeable cations present (in particular, whether sodium or calcium dominate) at the time of incorporation of organic matter in the soil.

Influence of Topographic Heterogeneity on Deciduous Litter Decomposition

Woodlot floor topography, consisting of rises (high sites), hollows (low sites) and more extensive level areas (level sites) about 1 m in diameter with a 0.5 m vertical maximum, affected structural and functional components of the litter system. Topographic effects were measured on litter accumulation, substrate temperature and moisture, bacterial populations, litter decomposition, and organic matter incorporation in soil. Average litter accumulation (April to October) was 416.2 g m-2, 1209.9 g m-2 and 2438.3 g m-2 on high, level and low sites, respectively. Greater litter weight and depth in low sites reduced moisture loss from underlying litter and soil by up to 63%. At low sites, temperature variability of the litter-soil interface was reduced 13% of the mean by surface litter and by the heat capacity of a greater moisture content. Average bacterial populations were approximately 3.5 times larger in low sites. Litter decomposition in mesh bags averaged an exponential weight loss of -0.015 over 16 months. Interaction of low topographic site and litter composition enhanced decay. Finally, the soil of low sites was characterized by greater incorporation of organic fragments and humus formation.

Soil as the source of trace elements.

The nature of the parent rock determines the trace element content of soils. Ultrabasic and basic rocks, which solidified first from the molten magma, incorporated bioessential trace elements such as Co, Ni, Zn and Cr by isomorphous replacement of Fe and Mg in ferromagnesian minerals, while acidic rocks, the last to solidify, tended to be richer in other elements such as Ba and Pb. Cu, Mn and, to a lesser extent, B, Mo and Se are more evenly distributed. The weathering of rocks by pedological and biological processes such as glacial and hydrodynamic comminution, secretion of acids and liganding species by microbes and plants leads to the formation of sands, silts and clays, and finally the incorporation of organic matter causes humification and the formation of soils as we know them. Part of the soil's store of bioessential elements is held in forms that are available to plants. Availability is controlled by the forms of occurrence and the nature of binding of the trace elements in the soil, which in turn is affected by soil acidity, redox balance (drainage) and organic matter content. These and other factors are discussed along with measures for alleviation of deficiency problems. Future progress in this area will depend to a large extent on interdisciplinary research by biologists, chemists, physicists and statisticians.

Effect of organic matter incorporation into soils on 137cesium uptake by wheat plants

The effect of four straw and two 137cesium levels, with and without fertilization, on 137cesium uptake by wheat plants was studied using soils from the Blaine Lake and Waiteville soil associations of Saskatchewan (Canada). Uptake of 137cesium using either soil type, when fertilized and treated with any of the four straw and two 137cesium levels, significantly decreased with plant age. Such a trend was generally not observed in an unfertilized Blaine Lake soil. Increasing straw application, with and without fertilization, increased the dry matter yields in both the soils although the heavier (particularly the 3 tons/acre) straw addition produced slightly depressed yields for the fertilized soils. Increasing straw application to both fertilized soil types did not significantly enhance the 137cesium uptake in plants grown at either 137cesium level. However, increasing the straw levels, without fertilization, in the Blaine Lake soil contaminated with either 137cesium level, did not appreciably and consistently affect the 137cesium uptake by the plants. Plants absorbed highly significantly greater 137cesium from the 100 compared to the 50 μCi 137cesium level in both the soils applied with any straw-fertilizer combination. This trend did not occur with unfertilized Blaine Lake soil.

Impact of Earthworm Introduction on Litter Burial and Nutrient Distribution in Ohio Strip‐Mine Spoil Banks

AbstractEarthworms (Lumbricus terrestris L.) actively buried leaf litter and humus, and deposited castings on the surface of an acid (pH 3.5–4.0) shale spoil bank revegetated with black locust (Robinia pseudoacacia L.). Earthworms persisted for 5 years in the coal spoils and buried or consumed the equivalent of 5 metric tons of leaf litter/ha. In a greenhouse study, earth‐worms in cores of spoil from the mined area buried or consumed a 60‐mm thick layer of litter and humus in 174 days. The equivalent of 9.5 metric tons of litter and 52.5 metric tons of humus was buried or consumed/ha, while the equivalent of 16.7 metric tons of castings was deposited on the surface. Exchangeable cations and available P in the mineral spoils increased as follows: K from 0.17 to 0.19, Ca from 1.7 to 2.7, and Mg from 1.8 to 2.5 meq/100 g of spoil; and available P increased from 1.7 to 4.2 ppm. Earthworm activity did not influence growth of northern red oak (Quercus rubra L.) seedlings planted in the cores.In another study, 10 Lumbricus terrestris were introduced on a calcareous strip‐mine spoil revegetated with European alder (Alnus glutinosa L.). In 5 years, the earthworm population increased to a density of 60 middens/m2 over an area of 700 m2.Clearly, earthworms can be established on revegetated coal spoil banks, where they promote incorporation of organic matter into the mineral spoil.

Soil improvement trials using scarification and fertilization in stagnant white spruce plantations, Quebec, Canada

Scarification of a cleared Cladonia-Polytrichum site type on a deteriorated sandy area resulted, after 3 years, in a marked increase in height of white spruce (Picea glauca (Moench) Voss) transplants. This increase was presumably due to the incorporation of ground-vegetation organic matter in the surface soil. Additions of buckwheat residue, N, P, and K fertilizers, and bacterial compost, did not significantly increase height over that observed for seedlings in the scarified areas. In unscarified surface and root-zone soils, nutrients, pH, and organic-matter levels showed no appreciable difference over a period of 5 years. In scarified or in scarified-fertilized surface soils, nutrients and organic matter levels decreased during the 5 years after treatment, while soil acidity increased. In the root zone of the treated soils, potassium content increased with time, while phosphorus and pH levels remained almost constant, and nitrogen and organic matter contents declined. Nutrient-element levels in the needles of white spruce planted in treated soils exhibited changes somewhat similar to those found in the root zone of treated soils, while concentrations of N, P, and K in control transplants did not vary significantly over 5 years.

COMPOSITION AND NUTRITIVE VALUE OF FECAL PELLETS OF A MARINE CRUSTACEAN1

The role of feces in energy flow and nutrient cycles in the marine ecosystem was examined using fecal pellets of the shrimp Palaemonetes pugio, fed on the diatom Nitzschia closterium. The pellets were rich in organic matter, particularly protein. The feces were readily eaten by P. pugio when diatoms were not available and assimilation efficiency was high, indicating that the pellets contained considerable assimilable organic matter. Solution and bacterial respiration reduced the organic content of the feces while light and dissolved organic matter stimulated the growth of autotrophic and heterotrophic microorganisms.It is estimated that the rate of incorporation of organic matter into fecal pellets in the sea exceeds the rate of incorporation of organic matter into herbivore tissue and that fecal pellets therefore constitute a major potential food source for marine animals.

STUDIES ON THE ROLE OF SULFUR DIOXIDE IN VISIBILITY REDUCTION.

Highly sensitive radiotracer techniques were used to see if the H2SO4 mist from SOt oxidation allows the incorporation of organic matter. Tagged organic compounds were irradiated with and without SO2. When the aerosol was filtered off, no radioactivity was found on the filter paper showing the absence of organic matter and the lack of SO2 synergism.

Study of a Grassland Mosaic at Austin, Texas

ble of assisting relatively rapid incorporation of organic matter into the soil humus, is directly antagonistic to plant growth. In nature blackbutt root development may be largely dependent on the dominance or suppression of antagonistic microorganisms, and this could well depend on a considerable degree of fluctuation in the soil environment. The nature of the community-site interaction has been suggested as an important environmental force in the determination of vegetational relationships.

Isolation of Cellulose-decomposing Fungi from the Soil

ATTENTION has been directed to the paramount importance of studying the substrate relationships of soil-inhabiting fungi1. The incorporation of organic matter into the soil provides a series of habitats which become colonized by the microfauna and microflora present in the soil. On plant remains, a succession of fungi can be traced from the early colonizers, the ‘sugar fungi’, to those species able to grow on the residual debris2. This residual debris contains a large percentage of cellulose3, together with lignin, hemicelluloses and other polysaccharides. The techniques most commonly used for isolating soil fungi frequently miss the species responsible for breaking down these important residual constituents, which are more slowly utilized than simple sugars, and in which, therefore, the active fungal colonizers may be growing for a comparatively long time. The ‘sugar fungi’ grow veiy rapidly on new material and then fade away when their very accessible fraction of the substrate has been utilized. Such fast-growing, heavily sporing species normally dominate the scene in routine investigations of soil fungi, unless methods selective for particular groups of fungi are used.

Soil Aeration as Affected by Organic Matter Application

AbstractThe effect of the method of incorporation of organic matter under various conditions of soil moisture and soil compaction on the composition of soil air was the object of this research. Application of fresh chopped alfalfa resulted in a pronounced depression of the oxygen content of the soil air. The order of decreasing oxygen content for the different methods of application was: check > surface mixed > layer at 2‐inch depth > surface application. High moisture content and compaction of the soil increased the time during which the oxygen content remained below 15% at 8‐inch depth. Both the oxygen and the carbon dioxide contents were determined at the 1‐, 3‐, and 8‐inch levels, as well as the amount of carbon dioxide given off at the soil surface.

PROFILE DEVELOPMENT IN THE SAND DUNES OF CULBIN FOREST, MORAYSHIRE

SummaryChanges in some physical properties of the sand dunes of Culbin Forest, Morayshire, brought about by fixation and afforestation of the sand, have been studied on sites ranging from bare sand to mature plantations. Trees appear to be having no measurable effect on the mechanical composition of the sand apart from the deposition of litter, but studies of soil moisture and temperature, using gypsum moisture blocks and thermistors, have shown that, while the moisture content of the unplanted dunes remains comparatively high throughout the growing season due to their coarse texture, the growth of trees dries out the sand considerably, although the total moisture‐holding capacity of the upper soil layers in the older stands is greatly increased by the incorporation of organic matter. The artificial fixation of the dunes by means of brushwood (“thatching”) has been found to be an efficient method of conserving soil moisture.

Virgin Hemlock Forest Segregates in the Joyce Kilmer Memorial Forest of Western North Carolina

1. Two segregates can be readily distinguished in the virgin hemlock forest which occupies the flats and lower slopes in the Joyce Kilmer Memorial, a part of the Nantahala National Forest in western North Carolina. The first of these types, restricted to the flats and lowermost parts of the slopes along the streams, is characterized by a dense undergrowth of Rhododendron and a sparse herb layer. The other type, occurring higher up on the slopes, has a very open shrub stratum but a fairly dense and diversified herb layer. 2. Tsuga canadensis is the dominant tree species in both types, with Fagus grandifolia, Tilia americana, Betula lenta, Fraxinus pennsylvanica, and Halesia carolina as almost constant associates. Liriodendron tulipifera and Acer saccharum are more abundant in the Herb type, while Betula lutea is restricted to the Rhododendron type. The total tree density is lower, but the BA is greater in the latter type (60% more). Hemlock reproduction is about equivalent at the seedling stage, but saplings are considerably less numerous in the Rhododendron type. Age-diameter relationships in hemlock indicate that the species is able to stand suppression relatively well but not so long as some other climax conifers. 3. Herbs which are constants for both types include Mitchella repens and Viola rotundifolia, observed in every stand, and Tiarella cordifolia, Laportea canadensis, Trillium sessile, Dryopteris spinulosa var. intermedia, and Oxalis montana, with lower presence values. In spite of their general distribution, these are the important herbs of the Rhododendron type. The characteristic herbs of the Herb type are therefore those numerous additional species which appear. Among these, Carex plantaginea, Medeola virginiana, Adiantum pedatum, and Polygonatum pubescens are exclusive and constant. 4. The soils are very similar under both types. They are sandy loams with an A-C profile, good incorporation of organic matter, and good structure. The better growth of dominant components in the Rhododendron type is attributed to better soil-water relations, owing to topography and possibly to microclimatic differences. 5. A comparison is made with the two types (Rhododendron and Polycodium) of virgin hemlock forest found in Ravenel's Woods. Differences in species composition and in growth of hemlock lead to the conclusion that there are at least four types of hemlock cove forest, which are believed to be relic association-segregates of Braun's Tertiary Mesophytic Climax. The considerably greater BA of hemlock in Ravenel's Woods and the differences in associated species are attributed to differences in general climate (higher precipitation and lower temperature). 6. The sampling method used in this study is discussed. It consists of a strip random sampling in which each strip is in turn systematically subsampled at a 50% intensity.

Forest Floor in the Piedmont Region of South Carolina

AbstractThe annual litter fall, weight of forest floor, and organic matter incorporation in the surface foot of mineral soil are reported for three pine, three pine‐hardwood, and three hardwood stands in the South Carolina Piedmont.The litter fall for the stands averaged 4,400 pounds per acre, of which 3,500 pounds was leaf material. The weight of the forest floor was greatest in the pine stands and least in the hardwoods. The forest floor weight, expressed on a volatile matter basis, ranged from 6,160 pounds per acre in an old hardwood stand to 16,430 pounds in a 40‐year‐old shortleaf pine stand. The organic matter content in the surface foot of mineral soil ranged from 83,550 pounds per acre in the old hardwood stand to 25,780 pounds in a young loblolly pine plantation. The weight of the forest floor and organic matter in the mineral soil show that decomposition is more rapid beneath hardwood stands.The forest floors are classified as to humus type and the discussion presented shows some practical application of the information to forest management work.

The Palatability of Freshly Fallen Forest Tree Leaves to Millipeds

M\Iillipeds are quite widely distributed throughout the forests and cultivated lands of the Northeast, and they are of some importance in the decomposition of the forest floor and in the incorporation of organic matter into the upper soil layers. Romell ('35) has noted the importance of a large species, Fontaria trimaculata (Wood), in the formation of one type of mull and Heiberg and Chandler ('41) have indicated that millipeds are rather common in fine mull. The fact that mulls permit rapid infiltration of water thereby minimizing soil erosion is well known and the action of millipeds is, therefore, of importance not only from the standpoint of favorable forest growth but also from the standpoint of the conservation of the soil. This present study was conducted by the use of the common brown milliped, Dipioiulus londonensis caeruleocinctus (Wood),2 an European form, long established in the Eastern United States and Canada, and the aim of the study was to discover: (a) The time of year when millipeds are most active. (b) Which tree leaves are most desirable as food to millipeds. (c) How palatability of the leaves varies with soil type. (d) How palatability of the leaves varies with the amount of ash and calcium present. The importance of millipeds in the decomposition of the forest floor should not be over estimated. Millipeds, in general, probably do not devour more than one to five per cent of the forest floor except in isolated areas, and, no doubt, they are of less importance in this respect than are earthworms and minute insects. Nevertheless, the results of this study may be of value because it suggests a rather rapid laboratory method for studying the relative palatabilities of tree leaves to one species of forest floor inhabitant and shows how the palatability of several tree species of economic importance varies with the soil type. These data have practical application providing the hypothesis is made that the leaves which are most palatable to millipeds are also most palatable to the more numerous forest floor invertebrates. The close connection between the presence of mulls and certain forest trees, (Chandler, '39, '41), the prevalence of fauna in certain types of forest floor, and the likes and dislikes of earthworms, (Gast, '37), (Johnston, '36), would seem to furnish grounds for believing that this hypothesis is tenable.