Soil Use Research Articles

Influence of mineral fertilizers and different soil types on nutrient leaching: Results of lysimeter studies in East Germany

AbstractA lysimeter experiment on mineral fertilizer use and soil type was begun in 1985 to study the interrelationships between the level of mineral fertilization and the leaching of nutrients. Increased application of mineral fertilizers brought about not only a significant reduction in effluence build‐up, but also a significant increase in yield. The lowest levels of nitrogen leaching were found in clay‐sand soil in use as grassland, and the highest in sandy soil used as arable land. Unexpectedly, the study was unable to prove statistically that a reduction in N, P and K leaching follows automatically from a reduction in mineral fertilization. Hence, suboptimal fertilization cannot be the only corrective measure if a noticeable or marked reduction in the adverse impact on water quality due to nutrient leaching is to be achieved. Interim plantings should be integrated in crop rotations. Agricultural crops must be siteadapted and suited to the fertilization regime.

The use of isotopic composition in field studies of lead in upland Scottish soils (U.K.)

Experimental plots were set up originally at two research stations in upland areas of Scotland with the intention of characterising environmental samples using lead isotopic composition. The further use of isotopic composition to trace the movement of lead in the soil and along the food chain from soil to plants to animals requires well-characterised sources. The distribution of lead within soil, both in terms of concentration and isotopic composition, was however, found to be heterogeneous with accumulations at the surface characterised by lower 206Pb/ 207Ph ratios than at greater depth. A procedure was therefore developed to homogenise soils used in field studies and, at the same time, give the opportunity to introduce enriched stable isotopes not only of lead but also other metals of interest. Soil was removed from the plots, mixed by rolling, and spiked with enriched 207Pb. This increased the 207Pb/ 204Pb ratios from ∼15.5 to within the range 16.6–17.5 and decreased the 206Pb/ 207Pb ratio to below 1.087, both of which are well outside the range normally found in soils. The mixed soils were homogeneous in terms of isotopic composition and presented a much more precisely characterised soil for use in tracer studies. Up to 50% of the lead in unwashed grass grown on the spiked soils had its origin within the soil and at least 10% of this remained after washing. Furthermore, ∼ 10% of the lead in grass grown on undisturbed soil adjacent to, but separated from, the spiked soil was shown to have its origin in the spiked soil. The technique provides a means of introducing enriched spikes of most metals and, in combination with precise analysis by thermal ionisation mass spectrometry, offers high sensitivity in studies of metals within the soil and plant environment.

Strength and compressibility of Abqaiq marl, Saudi Arabia

The increasing number of construction projects and the lack of good quality soil for use in these projects in eastern Saudi Arabia necessitate the use of available marginal soils. Most, if not all, engineering projects use the fine-grained calcareous sediments, known locally as marl, either as a foundation material or as a fill material. The lack of published information on their engineering characteristics and behavior under ambient conditions has resulted in many construction and post-construction problems. This investigation is one of a series to evaluate the geotechnical properties of selected marl soils obtained from different areas in eastern Saudi Arabia. Marl samples, obtained from Abqaiq, were prepared in the laboratory under controlled conditions and subjected to different tests including CBR (soaked and unsoaked), triaxial compression, unconfined compression and one-dimensional compression tests. Samples were prepared at different moisture contents on both the wet and dry sides of optimum. X-ray diffraction analysis indicates that this marl contains high percentages of dolomite and calcite, in addition to other materials. The molding water content significantly affects the engineering properties of this material. Compaction on the dry side of optimum resulted in samples that have some swelling potential and highly compressible characteristics when subjected to a load after inundation.

Evaluation of Bacillus thuringiensis H-14 isolates from Nigerian soils for use in mosquito control

Eleven mosquitocidal Bacillus thuringiensis isolates from Nigerian soils were screened for the degree of toxicity against Aedes aegypti larvae. The six most larvicidal isolates, code-named OBGI, OBG8, BUS4, BAR3, GSC3 and GNA13, were identified as subsp. israelensis (B.t.i). pores of the six isolates of a B. t. i. from a commercial powder (R-153-78, Roger Bellon Laboratory, Belgium) and of IPS 82 (Institut Pasteur (Standards)) were subjected to ultraviolet irradiation (280-350 nm) for up to 75 min. After irradiation, the toxicity of OBG8, OBGI, BUS4, and BAR3 was higher than that of R-153-78 but lower than that of IPS 82.

Rating soil and water information for aquaculture

A system is provided to aid in site selection and design for aquaculture ponds. This technique is based on similar systems used in evaluating soils for use in agriculture, road construction, waste disposal, residential development, etc. Information necessary for decision making has been system-atized in tabular form giving limitation ratings (slight, moderate or severe) and restrictive features for each important soil or water property.

A simple mini-method to extract DNA directly from soil for use with polymerase chain reaction amplification

A rapid, simple method is used that yields amplifiable fungal and bacterial DNAs directly from soil. DNA is separated from soil contaminants by electrophoresis in low-melting-temperature agarose and used directly in polymerase chain reaction amplification. Fifty 20-mg samples can be processed in one day. Fragments of 16S and 18S ribosomal RNAs are amplified by polymerase chain reaction with DNA extracted from the soil. Universal primers are used that are capable of amplifying ribosomal DNA from a wide variety of bacteria and fungi. Eubacterial and fungal primers are used that are capable of distinguishing between eubacterial and fungal DNAs. Restriction enzyme digests are performed on amplified DNA fragments from five soil samples.

A methodology for comparing soils for use in knowledge-based systems

Knowledge-based systems (KBSs) can be particularly useful in assisting with the interpretation of ground conditions from site investigation information, a major part of geotechnical design. This requires interpolating or extrapolating from observations at discrete points, such as boreholes, and involves considerable engineering (and geological) judgement. Such a system must be able to compare soils observed at two or more locations, in order to identify whether the soils observed belong to the same horizon. A scheme is put forward for calculating the similarity of two soils based on engineering soil descriptions. The descriptive terms are converted to quantitative representations. Similarity numbers can then be calculated from the quantitative parameters for a number of different factors such as soil type, structure, consistency and colour. These similarity numbers can then be combined using appropriate weighting factors to give an overall similarity number which represents a comparison based on all these factors. The approach used is procedural, but can be used as part of a KBS for interpreting ground conditions.

Factors Influencing Thermal Resistivity of Sands

Although many engineering projects require assessment of the thermal properties of soils for use in heat transfer calculations, geotechnical engineers are often unfamiliar with procedures for measuring these properties. A simple test for measuring the thermal properties of soils, called the “thermal needle” test is described. The apparatus and procedure have been refined to allow measurement of the thermal resistivity of sands for conditions of elevated temperature, water content reduction by stage, drying, and long‐term saturation. Laboratory thermal needle tests were conducted using surge sand, silica sand, and Monterey 60 Sand; it was found that the thermal resistivity decreased with increasing temperature and increasing compaction water content. Also, the thermal resistivity of silica sand decreased with time of saturation. The test results are not only useful for study of thermal geotechnical problems, but could be used to interpret other structural and mechanical property characteristics of sands.

Field investigations in landslide areas and shearing strength of soil for use in stability analysis : Ikeda, T; Ogawa, S; Konagai, K; Kamei, T Natural Disaster SciV8, N1, 1986, P29–44

Field investigations in landslide areas and shearing strength of soil for use in stability analysis : Ikeda, T; Ogawa, S; Konagai, K; Kamei, T Natural Disaster SciV8, N1, 1986, P29–44

The behaviour of normally consolidated clay as observed in undrained direct shear tests

The direct shear test as conventionally used for measuring the strength parameters of soil for use in classical stability analyses has the major disadvantage that the stress conditions in the specimen during the test are not known. The shear stress and normal stress acting on the central (horizontal) plane of the specimen are deduced from the observations made on the boundary; the values measured at failure are assumed to lie on the Mohr-Coulomb failure envelope from which the strength parameters are derived. Two special types of apparatus that apply simple shear allow measurements to be made from which the complete stress system (assumed to be uniform) within the specimen can be deduced. The effective stress paths obtained in shear tests on two normally consolidated clays reveal complex patterns of behaviour. In particular, they show that the conventional interpretation of the direct shear test is wrong; the stress point associated with the horizontal plane at failure does not lie on the failure envelope and the maximum shear stress is not the same as the undrained shear strength. L'essai de cisaillement direct employé traditionnellement pour mesurer les paramètres de résistance du sol pour les analyses classiques de stabilité a un grave défaut: les conditions de contrainte dans l'échantillon au cours de l'essai ne sont pas connues. La contrainte de cisaillement et la contrainte normale agissant sur le plan central (horizontal) de l'échantillon sont déduites des observations effectuées à la limite et on admet que les valeurs mesurées lors de la rupture sont situées sur l'enveloppe de rupture Mohr-Coulomb, à partir de laquelle les paramètres de résistance sont calculés. Deux appareils spéciaux, qui appliquent le cisaillement simple, permettent des mesures à partir desquelles on peut déduire le système entier supposé uniforme des contraintes dans l'échantillon. Les chemins de contraintes effectives obtenus dans deux essais de cisaillement sur deux argiles normalement consolidées montrent un comportement complexe et plus particulièrement ils indiquent que l'interprétation traditionnelle de l'essai de cisaillement direct est erronée: le point de contrainte associé avec le plan horizontal lors de la rupture n'est pas situé sur l'enveloppe de rupture et la contrainte de cisaillement maximale n'est pas identique à la résistance à la rupture au cisaillement dans l'état non-drainé.

Effects of cement-lime mixes on lateritic soils for use in highway construction

This study describes the effects of cement-lime mixes on the geotechnical properties of lateritic soils and recommends the optimum mix proportions of cement and lime for use in highway construction. The following geotechnical properties of the stabilized lateritic soils were measured: Atterberg limits, compaction characteristics, unconfined compressive strength and CBR characteristics. The test results show that cement-lime mixes can be utilized for base materials in highway construction.

地すべり発生に及ぼす間隙水圧の影響

In order to investigate the influence of pore water pressure on landslide occurrence, we conducted model test in laboratory and two kinds of ring shear test on cohesive soil.In addition, we made slope stability analyses by using the results of ring shear test.Our main conclusions from the laboratory investigations are as follows; i) Landslide may be occurred by increment of pore water pressure at the slip surface. Therefore, when making slope stability analyses, pore water pressures should be measured directly all along the slip surface with piezoelectric meters. ii) The shearing strength parameters of soil for use in slope stability analyses was shown. The shearing strength parameters using a ring shear apparatus are useful in making stability analyses.

The Use of Small Scale Trial Compactions for Earthwork Design

Abstract The paper describes an on-site method of assessing the suitability of soil for use in earthworks. The method consists of a miniature compaction trial on material excavated and recompacted into a trial pit using a narrow trench roller. The application and utility of the method is discussed and a comparison is made with laboratory based suitability assessments.

A method for separating fungal hyphae from soil

When fungal hyphae were separated from two mineral soils by wet sieving and density gradient centrifugation, a preparation consisting of 50% of the total soil fungal hyphae and 3% of the soil dry weight was obtained. Residual soil particles were removed by an additional sieving step which resulted in a final recovery of 20% of the fungal hyphae from soil. Scanning electron microscopy revealed that some soil particles still contaminated the hyphae but the exact amount of soil could not be determined by dry weight measurements. These data indicated that reasonable separation of fungal hyphae from soil for use in biomass (i.e., nutrient analysis) studies is feasible.

A Tractor-Powered Method for Installing Earth Anchors during Fence Construction

Fencing is an important tool for managing rangelands. However, the cost of conventional fencing is often prohibitive for anything other than boundary or important cross fences (Moore et al. 1968). Suspension fences cost about half as much as conventional fences, and, under many conditions, will turn cattle equally well, last as long, and require less upkeep (McNamee and Kinne 1965). A suspension fence requires strong comer assemblies. A typical comer is double braced with the first brace post guyed to a ‘deadman” (a large object such as a rock or section of post) buried 60 cm deep midway between the corner and first brace post. Installing a deadman is hard, time-consuming work. Under most soil conditions it takes one man approximately 45 minutes per deadman if a power auger is used to dig the hole. This paper describes the adaptation of a tractor-powered post hole digger to screw earth anchors into the soil for use as a deadman, thus reducing the installation time per deadman from 45 to 10 minutes. It also reports on the suitability of earth anchors for holding fence-corner assemblies. The use of a tractor to install screw-in earth anchors requires an adapter to transmit the turning force of the auger power head to the earth anchor. The adapter (Fig. 1) fits on the power head in place of the auger and holds the eye of the earth anchor so that the power head can screw the anchor into the soil. The materials needed to construct the adapter are readily available ih most communities from some of the larger hardware stores (Fig. 1). The earth anchor used with the adapter shown in Figure 1 had an 1 1 / 16-inch (18 mm) rod, a 6-inch (15 cm) helix, and an overall length of 48 inches (122 cm). If an anchor with a different sized eye or rod were used, the dimensions of the adapter would need to be adjusted accordingly. Also, if the shaft of the power-head were different in size than the one used, a different sized adapter sleeve would be needed (Fig. 1). Earth anchors should be lined up and installed before the posts are set; this allows room to operate the tractor. The anchor is started perpendicularly to the ground and turned until the helix is covered by the soil surface. The anchor shaft is then angled towards

Repetitive Load Deformation of Cohesionless Soil

Presented is a simplified procedure for obtaining material characterization of free draining cohesionless soils for use in calculating permanent deformations of transportation support systems. Experimental data is presented in support of the described simplified procedure, which shows that plastic strains are largely governed by the deviator stress level and, thus, the factor of safety against shear failure. Plotting logarithm of plastic strain versus logarithm of number of load repetitions resulted in a slope essentially independent of confining pressure or deviator stress level for stress levels less than 60%. Plotting logarithm of plastic strain at a given number of load cycles versus deviator stress level resulted in a slope which was essentially constant. These two findings allowed the development of the presented procedure resulting in a method of obtaining material characterization which gives a significant savings in laboratory testing time over present methods. Such material characterization is an essential requirement for predicting the rate of accumulation of permanent deformation (rutting) using the well-known layered elastic or non-elastic technique.

Determination of Evaporation from a Soil Surface by Measuring the Gradient of Soil Moisture

Usually water losses by evaporation from a soil surface are replenished from below by 3 ways:(1) inflow of gravity water in a saturated state in soil; (2) upward movement of water by the action of capillary force; (3) diffusion of water vapor in soil crevices. The sampling ground of soil for use to measure the soil moisture is flat and bare so that the water supply by (1) may be disregarded except when raining. In (2) and (3), water moves in soil obeying the same law as heat. So the moisture distribution in soil partakes of the same function as the temperature in conductor.(1+k)∂c/∂t=(D+kD')∂2c/∂x2where D, D' are diffusion-coefficients of water in soil and of vapor through crevices and c is the water content per unit volume of soil (soil moisture) at the depth x and at the time t, k being the ratio of the vapor content g/cc in the crevice to the water content of soil g/cc of the boundary of the crevice. The above equation needs one more correction-term to get it complete if the vapor in the creviee is not of saturated state. It is proved not only by showing k being very small with physical experiments but also by taking into consideration of a well-known preventive method of water losses by sand-strewing over the soil that (3) plays no important part in evaporation from the soil. Therefore the evaporation from the soil surface is computed bywhere (D+kD')(1+k)∂c/∂k≈(D+kD')Δc/Δt/Δ2c/Δx2·Δc/Δx Δ2c/Δx2=(c1+c3-2c2)/(Δx)2Δc/Δt=(c2(t+Δt)-c2(t))/Δtand c1, c2, c4 are the soil moisture at the depth 0.5cm, 1.5cm and 2.5cm respectiviely and Δt is 15 minute-interval. The result of measurements by this method is presented in Table 3 which shows the amount of evaporation measured is of the reasonable order of magnitude.

Some Factors Influencing the Utilization of Phosphorus from Crop Residues

AbstractA large proportion of phosphorus of crop residues was found to be readily available to succeeding crops. Some of the factors that influence the rate of release of phosporus from plant residues added to soils for use by succeeding plants were studied. They were: (a) maturity of the crop residue, (b) phosphorus content of the residue, (c) rate of application of the residues, (d) time of contact of the crop residue with the soil, (e) kind of crop residue, and (f) plant part involved. The study was conducted under greenhouse conditions in large glazed pots that held 1 kg. or more of soil.The influence of the above factors on the utilization of phosphorus by several test crops is less pronounced in soils well supplied with available phosphorus than in soils low in available phosphorus. The rate of availability of the phosphorus of the crop residues to the test crops, ryegrass and tomato, was inversely related to the stage of growth of the residues. For example, green manures cut prior to blooming supplied plants with about as much phosphorus as did liquid H3PO4 fertilizer. The phosphorus of straw, on the other hand, was absorbed by plants to a lesser extent than that of the liquid H3PO4. The phosphorus of residues high in total phosphorus was more readily available to plants than was that of residues low in phosphorus. The threshold phosphorus content of the crop residue above which the phosphorus of the residue was not wholly immobilized by microorganisms for use in decomposition was found to be about 0.2%. Phosphorus from root residues was less readily available than that from top residues only if the residues came from fully mature plants.

Studies on the control of wind erosion

The expeiment with the wind erosion was carried out on clean-tilled wheat field and the kittatemaki field (that is, wheat field sown on fallowed soil in use of stubbles of the previous crop).1. Wind velocityBy the investigations of the horizontal distributions of wind velocity, it was made clear that the clean-tilled field and kittaternaki field were below the similar condition of wind.On the ridges in the kittatemaki field, the wind velocity decreased vertically about up to the height of 45cm. As for the influence of particular ridges on vertical distribution of wind velocity, the velocitybecomes constant at about the fifth ridge from the windward. The nature of the surfaces of both fields is as tabulated hereunder, according the formula of the curve of vertical distribution of wind velocity-:U(z)=5.75U*logz/KIt is remarkable that the value of U* is very large, and this is thas the value is the total friction velocity of the surface and the ridge.U*……Total friction velocity of surface and ridge, U′*……Friction velocity of ridge.U*-U′*=U″*The above formula is the friction velocity of the surface soil. The following is the deduced value.U″*=17.4m/secAccording to the formula of the coefficient of resistance (CX), ρU*21=1/2ρUm2C×hd+ρV″21∴C×=0.28This means that the ridge makes the wind velocity required to the initial movement increase almost by 1.70 times of the soil.2. Soil moistureThe quantity of water contained near the surface is less from 4 to 6% in the clean-tilled field than in the kittatemaki field. The causes are considered to be (1) the cutting-off the capillary tubes owing to tillage, (2) the exposure of the surface soil to the wind, and (3) the limitation of sunshine by the ridge, and so forth.3. Flying soil.The quantity of flying soil in the clean-tilled wheat field amounts to more than 4 to 5 times of that in the kittatemaki field. As regards the height distribution of flying soil, in the case of the former the majority of the particles near the surface are of great diameters, but according as the height increases, particles of small diameter are found to increase. On the other hand, in the case of the latter the diameters do not vary according to the height from the ground.This shows that in the clean-tilled the flying soil is mostly from its own surface, while in the other it consists mainly of the soil carried from the fields to its windward.

Study on the control of wind-erosion

The expeiment with the wind erosion was carried out on clean-tilled wheat field and the kittatemaki field (that is, wheat field sown on fallowed soil in use of stubbles of the previous crop).1. Wind velocityBy the investigations of the horizontal distributions of wind velocity, it was made clear that the clean-tilled field and kittaternaki field were below the similar condition of wind.On the ridges in the kittatemaki field, the wind velocity decreased vertically about up to the height of 45cm. As for the influence of particular ridges on vertical distribution of wind velocity, the velocitybecomes constant at about the fifth ridge from the windward. The nature of the surfaces of both fields is as tabulated hereunder, according the formula of the curve of vertical distribution of wind velocity-:U(z)=5.75U*logz/KIt is remarkable that the value of U* is very large, and this is thas the value is the total friction velocity of the surface and the ridge.U*……Total friction velocity of surface and ridge, U′*……Friction velocity of ridge.U*-U′*=U″*The above formula is the friction velocity of the surface soil. The following is the deduced value.U″*=17.4m/secAccording to the formula of the coefficient of resistance (CX), ρU*21=1/2ρUm2C×hd+ρV″21∴C×=0.28This means that the ridge makes the wind velocity required to the initial movement increase almost by 1.70 times of the soil.2. Soil moistureThe quantity of water contained near the surface is less from 4 to 6% in the clean-tilled field than in the kittatemaki field. The causes are considered to be (1) the cutting-off the capillary tubes owing to tillage, (2) the exposure of the surface soil to the wind, and (3) the limitation of sunshine by the ridge, and so forth.3. Flying soil.The quantity of flying soil in the clean-tilled wheat field amounts to more than 4 to 5 times of that in the kittatemaki field. As regards the height distribution of flying soil, in the case of the former the majority of the particles near the surface are of great diameters, but according as the height increases, particles of small diameter are found to increase. On the other hand, in the case of the latter the diameters do not vary according to the height from the ground.This shows that in the clean-tilled the flying soil is mostly from its own surface, while in the other it consists mainly of the soil carried from the fields to its windward.