Showing papers on "Soil compaction published in 1978"
TL;DR: In this paper, an interdisciplinary field study was made to study the effect of soil compaction on potato growth in a young alluvial loamy sand soil in the very dry growing season of 1976.
Abstract: An interdisciplinary field study, including consideration of soil tillage, soil physics, pedology and crop science was made to study the effect of soil compaction on potato growth in a young alluvial loamy sand soil in the very dry growing season of 1976. The treatments consisted of different degrees of compaction in or just below the arable layer and also consider the effect of irrigation. Compaction decreased soil pore vol. whereas the volumetric water content at any given pressure potential was increased or decreased depending on the degree of compaction. A high mechanical resistance encountered by the roots proved to be the primary factor affecting root elongation. Roots penetrated the compacted layers in all treatments but at very different rates. As a result the pressure potential at the rooting front was relatively low as long as roots were growing in the compacted layers. Moisture flow to the roots by capillary rise from the water table occurred during the entire growing season but varied significantly among treatments as a function of the distance above the water table and hydraulic conductivity of the various layers. Moderate compaction increased, but severe compaction decreased, the potential for capillary rise in the topsoil. The plough pan in the subsoil increased the potential for capillary rise. Critical groundwater levels at a given rooting depth were calculated for different steady upward fluxes for some of the treatments. (Abstract retrieved from CAB Abstracts by CABI’s permission)
46 citations
TL;DR: A 100-plot experiment was performed during the growing season of 1976 in a Ste.
Abstract: A 100-plot experiment was performed during the growing season of 1976 in a Ste. Rosalie clay soil, using a randomized complete-block design with 25 treatments of machinery traffic within each of four blocks. Three vehicle contact pressures, four numbers of tractor passes, before or after seeding groups and a control of zero traffic were used to relate the growth and yield variables to wheel traffic and resulting soil compaction. Plant emergence and tasselling were delayed with increasing machinery traffic. The plant growth rate monitored at 29, 44, 60, 74 and 88 days from the seeding time was dramatically different from plot to plot. Growth models at different times of the season were derived in terms of the product of contact pressure and number of passes of the vehicle. Plant and ear moisture contents were higher in plots with heavier traffic treatment. Yield, ear yield and grain yield all decreased with increases in machine contact pressure and passes. The reduction in yield was over 50% in some cases,...
37 citations
TL;DR: In this article, soil compaction of the subsoil (formation of a plough pan) initially resulted in relatively rapid foliage growth, which was partly due to a high capillary flux from the water table.
Abstract: Potato plant reactions to soil compaction were studied in the field in the dry yr 1976 Irrigation was applied in some of the treatments Strong compaction of topsoil resulted in shallow rooting, low water availability and relatively slow foliage and root growth in the first 60 days after emergence, compared with the non-compacted treatment Compaction of the subsoil (formation of a plough pan) initially resulted in relatively rapid foliage growth, which was partly due to a high capillary flux from the water table; however the rate slowed down as vertical root elongation became inhibited by the plough pan Topsoil compaction resulted in depressed tuber yields and severe induction of second growth compared to the non-compacted or irrigated treatments At maturity, differences in total yields among treatments were small except for the treatment with a plough pan where the yield was low; soil compaction decreased marketable tuber yield The quantity of available water for the crop, defined as the measured water uptake from the rooted zone and a calculated capillary flux to the rooting front was compared with potential evapotranspiration and significant differences thus obtained among treatments were well reflected by observed differences in vegetative growth (Abstract retrieved from CAB Abstracts by CABI’s permission)
32 citations
TL;DR: Root growth in a field study was enhanced by delaying the harvest for newly established seedings, and soil-compaction root-growth relations were substantiated by a glasshouse study that char.
Abstract: Reduced growth and fewer plants are common in wheel paths of post harvest equipment in alfalfa (Medicago sativa L.) fields of the San Joaquin Valley. Up to 70% of the soil surface may be covered by equipment wheels in a single harvest. Field and glasshouse studies were conducted to quantify plant and soil responses to wheel traffic in confined paths scheduled to simulate harvest operations. Three field compaction treatments simulated harvest, postharvest, and harvest plus postharvest wheel traffic. A no-traffic area served as a control treatment. Compaction of a sandy loam soil (Typic Xerorthents) in traffic zones reduced root-length density (cm of root per cm³ of soil) as much as 60% in a 15-to-30-cm depth zone. Postharvest traffic reduced plant population and yield by damaging crowns and regrowth shoots. Field observations on soil-compaction root-growth relations were substantiated by a glasshouse study that char. acterized alfalfa root-length density (Rd, cm³ of root per cm³ of soil) as a function of soil bulk density (Dₛ, g cm⁻³) and time (T, days) as Rd = −23.51 +27.88Dₛ +0.2210T −9.135D,ₛ ² −0.0003548T² −0.08360DₛT, R² = 0.84. Root growth in a field study was enhanced by delaying the harvest for newly established seedings.
24 citations
1 Jan 1978
TL;DR: In this article, a wide range of topics including soil moisture in engineering works, current practices in the treatment of soft foundations, admixture stabilization, massive compaction of granular soil, tension and compression elements of reinforcement, collapsible soils and their stabilization, and soil placement and improvement are discussed.
Abstract: This report is intended to help engineers meet the need for practical, efficient, economical, and environmentally acceptable means for improving unsuitable soils and sites, for expanded utilization of soil as a construction material, and for management and use of waste materials. It covers a wide range of topics including soil moisture in engineering works, current practices in the treatment of soft foundations, admixture stabilization, massive compaction of granular soil, tension and compression elements of reinforcement, collapsible soils and their stabilization, and soil placement and improvement.
22 citations
TL;DR: An experimental technique which avoids wheel marking and permits accurate control of the working depth of normal farm machines is described and the results given of an experiment to measure the effects of extreme soil compaction and method of fertilizer application on the growth of spring barley.
22 citations
TL;DR: In this article, the influence of seed-bed condition on the emergence and development of pepper seedlings (Capsicum frutescens L) was studied and it was found that the severity of soil compaction on seedling root and shoot development was dependent on the soil moisture and organic matter content.
13 citations
TL;DR: In this article, a survey of trampling pressure and soil compaction, and their effects on both the soil environment and the plant community structure, is presented, where the response of the vegetation to trampling levels is assessed by linear regression analysis.
Abstract: Increase in recreational demand on the countryside makes the monitoring of resulting change in vegetation of value, especially in areas of recognized ecological importance. Methods are described for an initial survey of trampling pressure and soil compaction, and their effects on both the soil environment and the plant community structure. With reference to a dune slack habitat the response of the vegetation to trampling levels is assessed by linear regression analysis. Variation in diversity is noted together with changes in the ratio between monocotyledons and dicotyledons. Occurrence indices may be used to identify the species resistant to trampling; these, in general, are found to adopt a hemicryptophytic or therophytic growth form. Such studies can make a useful contribution to field investigations for older secondary school and undergraduate students, and provide starting points for further detailed investigations.
11 citations
1 Oct 1978
TL;DR: In this article, a simple impact soil test device based on the laboratory dynamic soil compaction test is described, which is a modified AASHO compaction hammer to which an accelerometer is attached and outputs to a specially designed peak hold meter.
Abstract: The paper describes a simple impact soil test device based on the laboratory dynamic soil compaction test. The usual form is a modified AASHO compaction hammer to which an accelerometer is attached and outputs to a specially designed peak hold meter. It is shown that the peak deceleration is a useful soil strength parameter and that correlation with CBR is evident and this can be substantiated by theoretical analysis. Its application to subgrade and base course strength for design and acceptance is discussed. It is concluded that this test procedure is rapid, inexpensive and provides a basic strength test for low volume, low cost, road construction where testing also needs to be low cost, and to require the minimum of technical expertise (a).
10 citations
1 Jun 1978
8 citations
Journal Article•
TL;DR: In this paper, statistical regression relationships were established for dry density, strength, and their respective variabilities, and these relationships were then plotted as one combined nomograph, and the plot will yield a predicted mean compressive strength as well as the variability in the strength.
Abstract: Laboratory compaction data and associated strength test results have been generated for a study to improve predictability of compacted behavior. Statistical regression relationships were established for dry density, strength, and their respective variabilities. These relationships were then plotted as one combined nomograph. When mean water content, mean dry density, and variation in dry density are entered on the nomograph, the plot will yield a predicted mean compressive strength as well as the variability in the strength. Such a nomographic model based on field compaction relationships could be used to establish moisture and density ranges and thus the desired mean strength and tolerable variation in strength, i.e., the specification region. Field data are now being generated for various combinations of soils and rollers to allow this design tool to be tested for real embankments. /Authors/
1 Jan 1978
TL;DR: In this paper, the effects of mulches on alleviating sugarbeet stand loss from soil crusting, the effect of seedbed firmness on sugar beet stand establishment, and the impact of soil compaction on potato production were investigated.
Abstract: Soil Structural Studies have been conducted to determine the effects of mulches on alleviating sugarbeet stand loss from soil crusting, the effect of seedbed firmness on sugarbeet stand establishment, and the effect of soil compaction on potato production. Results indicate marginal potential for anti-crust mulching in a dry year, point to enhanced sugarbeet stand establishment in firm seedbeds in a dry spring, and indicate an overall negative response of potatoes to Compaction.