Ft Of Soil Research Articles

Zinc Subsea Production System: An Overview

Exxon Co. U.S.A.'s Zinc development, in 1,460 ft of water in the Gulf of Mexico, uses a subsea production system to produce gas to a host platform 6 miles away. The 10-slot subsea template, designed specifically to accommodate the soft soil conditions at the Zinc site, supports the non-through-flowline (non-TFL) wells, which are controlled by means of an electrohydraulic control system. This paper describes key features of the development.

Colorado Potato Beetle Control with Biorationals, 1993

Abstract Nine products were tested at the Michigan State University Montcalm Research Farm, Entrican, MI. Plots were 20 ft long and 3 rows wide (34 inches between rows, 12 inches between plants in a row), and were separated by 6 ft of soil. The four plots per treatment were arranged in a randomized complete block design. Potatoes were planted on 6 May and sprayed (backpack sprayer; 30 gal/acre, 30 psi, four nozzles) on 23 Jun, 1 and 7 Jul. Asana was applied to all plots on 23 Jul and 4 Aug to control adults. Two randomly selected plants from the middle row of each plot were sampled for Colorado potato beetles on 28 Jun, 6 and 12 Jul; defoliation was rated on the latter two dates. Potatoes were harvested, sized, and weighed on 14 Sep.

Fate of Viruses in Treated Sewage Effluent During Soil Aquifer Treatment Designed for Wastewater Reclamation and Reuse

Land application or soil aquifer treatment of wastewater has been considered as a low-cost method for improving its quality for potential reuse. The objective of this work was to evaluate more quantitatively than in the past the fate and removal of viruses as they pass through the soil. A mini-basin (12 feet × 12 feet) was constructed at a site where secondary treated wastewater will be applied to large basins for underground storage. Suction samplers were placed at various depths in the upper 20 feet of the vadose zone directly beneath the mini-basin, and monitoring wells were placed at various distances (10 to 150 feet) from the mini-basin. Two experiments (August and September, 1990) were conducted where bacteriophage MS-2 and PRD-1 were added to the effluent before its application to the basins. High infiltration rate (up to 50 feet/day) and impeding layers at 15 ft resulted in nearly saturated flow conditions and up to 150 ft of horizontal transport of the viruses. The results also indicated that at least 90% removal of MS-2 and 99% removal of PRD-1 could be expected after movement of the sewage through 15 ft of soil and greater removal was observed at a slower infiltration rate (3 feet/day).

Nonharvested Forage Legumes: Nitrogen and Dry Matter Yields and Effects on a Subsequent Corn Crop

In government cropland diversion programs, forage legumes are grown for one or more years without harvesting, except during emergency feed shortages. Our objectives were to determine herbage and root dry matter (DM) and N yields of nonharvested and conventionally harvested (3 cuts/yr) 1- to 3-yr-old stands of alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), and birdsfoot trefoil (Lotus comiculatus L.), and the grain and stover DM yields and N uptake of subsequent corn (Zea mays L.) crops. Nonharvested legumes were not cut and herbage residue was accumulated in place until plowdown. Soil NO3− was measured in the spring following fall plowing of the 1- to 3-yr-old legume stands. The soil was a Tallula silt loam (coarse-silty, mixed, mesic Typic Hapludoll). Averaged for all species and years, nonharvesting resulted in 285% and 244% more legume DM and N for plowdown than a three-harvest schedule. This was attributed to greater herbage DM and N accumulation in nonharvested legumes. Root-plus-crown DM and N yields were similar for the two harvesting regimes. Nonharvested alfalfa and birdsfoot trefoil accumulated 280% more DM than red clover, but similar amounts of N. Average spring soil NO3− in the top 1 ft of soil was 34% larger after plowdown of 1 yr of nonharvested legumes than after plowdown of legumes which were harvested; however, soil N03− in spring did not correlate with legume N plowed down the previous fall. Whole-plant corn yields were 13% greater following 3 yr of legume nonharvesting than following harvesting, but were not affected by legume species. Whole-corn plant N uptake was 18, 35, and 51% greater, respectively, following 1, 2, and 3 yr of nonharvesting than after conventional harvesting of legumes. Corn plant N uptake in the first year after legume plowdown was most related to the amount of herbage N incorporated, and less to legume species differences. We conclude that the greatest positive effect on yield of a subsequent corn crop from non-harvested legume plowdown is from legume stands older than 2-yr and in the first year after plowdown. Birdsfoot trefoil and alfalfa should be selected to supply N and DM for plowdown in nonharvested legume production systems.

VERIFICATION OF THE ANALYTICAL MODEL FOR OCEAN WAVE-SOIL-CAISSON INTERACTION

An analytical model for wave-soil-caisson interaction is verified by comparison with a finite element model and large scale experimental results. The analytical and finite element model estimates of the stresses and surface displacements of an elastic layer of finite thickness are in good agreement. The physical model experiments were conducted at the O.H. Hinsdale Wave Research Facility at Oregon State University. A 10-ft high, 8-ft long caisson was constructed on a bedding layer overlying 1 to 3 ft of soil. The caisson was exposed to waves with heights of 0.68 to 4.4 ft with periods of 1.77 to 8.80 sec. Experimental and analytical comparisons for porewater pressure were in agreement but the displacements were quite scattered.

Damage to Woody Species by Anaerobic Landfill Gases

Refuse landfills are constructed on areas of land set aside for depositing solid waste. Current practice dictates that the refuse be spread and compacted, before being covered daily with a 6in. layer of soil., for environmental protection, to save space, and to reduce the amount of settlement that will take place in the area after the landfill is completed. Soil cover is placed over the refuse to improve aesthetics; prevent papers from blowing; reduce odors; control insects, rodents and birds; reduce the hazard of fire; and reduce water infiltration into the refuse. The initial soil cover is supposed to be increased from 6 in to a 12-in-thick intermediate cover after a limited period of time, and the final soil cover for the refuse is supposed to be at least 2 ft deep. Many landfills have been completed, however, with less than 2 ft of soil over their top surface. It is in this top layer of soil cover that any vegetative cover will be planted. Although many uses have been proposed for completed landfills, experience has shown that they are generally unsuitable for excavation or for construction purposes. Open-space recreational areas, such as parks, playgrounds, picnic areas, and golf courses, therefore, are deemed to be a suitable use for such sites. In some locations attempts have been made to use the completed landfills for agricultural purposes. Depending on the composition of the fill and the environmental conditions within it, however, there are serious inherent disadvantages, not the least of which are ecological upsets due to pollution of water supplies, the production of toxic and explosive gas mixtures from anaerobic microbial decomposition of the organic matter present and surface settlement. Excessive landfill ground temperatures have also been reported. Prior to 1965 landfills were frequently operated as open-burning dumps. While this caused air pollution and vector control problems at the time of their operation, the result was that most of the material left in the landfill was nonbiodegradable, resulting in much less ultimate settlement of the landfill and much less anaerobic gas development after the landfill was closed. The present-day landfill does not permit open burning; therefore, it provides more nutrients for the microorganisms that generate the gases, mainly carbon dioxide and methane, that present problems for growing vegetation. High concentrations of carbon dioxide in the root zone of plants, have been reported to be directly toxic to vegetation (4,5). Although methane has not been reported to be phytotoxic per se, perhaps, when combined with the carbon dioxide, it can remove oxygen from the root zone of the vegetation by direct displacement, by utilization of the oxygen by methane-consuming bacteria, or by a combination of these. The end

Foundation Practices for Talbingo Dam, Australia

The dam site for Talbingo Dam, a 530-ft high rockfill structure, is located in shyolite lava flows except for the upper right abutment, which is in tuff beds. On the right abutment the rock is generally hard, durable and broadly jointed, but on the left abutment the rock is more weathered and relatively soft at the surface. Most of the dam site was covered with 2 ft to 5 ft of soil. Surface stripping was nominal on the left abutment but special treatment was required on the right abutment because of the presence of the weathered tuff. To assume an impervious cutoff, a cutoff trench was used and in some areas the rock was excavated to depths of 50 ft. Extensive foundation preparations, utilizing air and water jets, thick grout, mortar and concrete was also used in the core contact zone; in addition, a 2-ft layer of the more plastic soil compacted wet of optimum was placed against the abutments to further reduce the possibility of seepage along the core contact. Blanket and curtain grouting were also performed as an integral part of the foundation treatment.

Uptake and distribution of macro‐nutrients in trees of Coffea arabica L. in Kenya as affected by seasonal climatic differences and the presence of fruits

SUMMARYYoung to mature, conventionally managed, single‐stem, deblossomed and fruiting Arabica coffee trees growing in a fertile lateritic clay loam at Ruiru, were uprooted at 2‐ to 3‐monthly intervals between February 1967 and June 1968. Each was divided into ten parts which were dried, weighed, completely ground, and analysed for organic‐N, and total P, K, Ca and Mg.Mature trees took up about 100 g N, 6 g P, 100 g K, 35 g Ca and 10 g Mg each per annum, of which 8‐29 % (depending on the element) would be removed in an average crop of fruits, and 50‐81 % returned to the soil in prunings and fallen leaves. About half the P and K in senescing leaves was returned to the tree.N, K, Ca and Mg uptake by deblossomed trees was relatively rapid when they produced a large post‐drought ‘flush’ of shoot growth in February‐April 1967. Thereafter uptake kept pace with changes in dry weight, and the concentration of N, K, Ca and Mg in the tree parts changed relatively little. By contrast, P‐uptake was relatively rapid over the cool, dry season 1967 (June‐September), when the roots < 1 mm diameter grew rapidly, and during the subsequent Short Rains, but was slow during the hot, dry season 1968 (December‐March) when the surface 2‐3 ft of soil dried out. The concentration of P in the trees changed accordingly, especially in the branches. The flower buds took 39 % of the small total P‐uptake during the hot, dry season 1968.Trees bearing a light or moderate crop of fruits absorbed all the minerals determined more rapidly than deblossomed trees. The fruits on heavily fruiting trees took 89,95,98 and 99 % of the net current increment in Mg, K, organic‐N and P, respectively, but only 39 % of the Ca. All leaves on the fruiting trees became rich in Ca, and most of their woody parts were depleted of P.Mineral uptake in a coffee plantation is compared with that in plantations of other woody perennial crops, and some practical implications are noted in relation to soil and plant factors affecting the mineral nutrition of coffee in Kenya, with special reference to phosphates.

Bridge Foundation Behavior In Alaska Earthquake

Extensive damage was sustained by highway bridges with a wide variety of foundation types located within 80 miles of the zone of energy release of the 1964 Alaska earthquake. Data on foundation conditions, bridge and channel configurations, and foundation displacements have been collected and analyzed to asses the effects of foundation-support conditions on bridge performance during the earthquake. Bridges founded wholly on bedrock sustained little or no foundation displacement. The greatest concentrations of severe damage occurred in thick deposits of saturated cohesionless soils; ample evidence of soil liquefaction was found in these materials. Bridge foundations in saturated sands and silts sustained severe displacement even where the average standard penetration resistance of the upper 30 ft of soil was as high as 25 blows per foot. Broad recommendations are offered for precluding bridge damage of this type during major earthquakes.

Ecological Importance of Snowbrush Ceanothus Velutinus in the Oregon Cascades

Twelve stands of snowbrush were selected for a biomass study to estimate nitrogen fixation under field conditions west of the summit of the Oregon Cascades. Total nitrogen in the upper 2 ft of soil was higher under snowbrush than in the open, but the difference may have been caused by loss of nitrogen from open areas rather than by nitrogen fixation. Total nitrogen in the upper 15 cm of soil under snowbrush did not differ from that found under nonfixing shrub species. Various shrub species may increase the total soil nitrogen under their canopies, however, if only by accumulation from sites that lack vegetation. More nitrogen may be tied up in the biomass of mature snowbrush stands than in stands of other shrubs. The difference could be explained by nitrogen fixation, which may range from zero to about 20 kg/ha per year under conditions of this study. Nodulated snowbrush seedlings produced 2.5 times the dry weight that non—nodulated seedlings produced in a nitrogen deficient soil. Sixty—one per cent of the nitrogen in nodulated greenhouse seedlings was fixed. Such fixation rates may be reached on infertile soils in the field, but they seem unlikely on soils of medium or better fertility. This point seems to be substantiated by delay in nodulation of snowbrush in soils with increased levels of organic matter. Bioassay tests using Douglas fir seeds and hemlock seedlings showed that snowbrush did not add to the soil any significant amount of nitrogen by nitrogen fixation. The species contributes to the formation of a new organic layer, however, through large amounts of nitrogen—rich litter.

Responses of Sugarcane to Supplementary Irrigation on Two Soils in Natal

SummarySupplementary irrigation experiments were conducted on a Clansthal sand and a Windermere clay. Irrigation treatments were based on the application of 1 inch of water when the soil moisture deficit reached 2·5, 3·5, 4·5 and 5·5 in. in 7 ft of soil on the sand, and 1·00, 1·75, 2·50 and 3·25 in. in 2 ft of soil on the clay. Each experiment included a dryland control and soil moisture was estimated weekly in each plot with a neutron probe. The results showed that there were significant linear increases in yield with increasing quantities of water applied. The crops exploited soil moisture to a depth of 6 ft in the sand and 3 ft in the clay, even with the maximum water treatments. Under dryland conditions, on the sand the crop exploited soil moisture to the wilting point only in the surface foot of soil, but on the clay the crop extracted moisture held at tensions greater than 15 bars in the top 3 ft of soil. The conclusions are that, where available water for supplementary irrigation is limited, heavy soils should be irrigated in preference to sandy soils, and that the most efficient use of both rainfall and irrigation water is achieved when 1 cusec is used to irrigate about 200 acres.

Aspen Root Studies on Three Sites in Northern Utah

Aspen (Populus tremuloides Michx.) root distribution was studied on the, Davis County Experimental Watershed (DCEW) near Farmington, Utah, and at the head of Cowley Canyon, a secondary valley that drains into Logan Canyon near Logan, Utah. At the DCEW two groups consisting of 9 and 15 trees, respectively, in sandy loam soil and one of five trees in clay were identified by the use of eosin bluish dye as a tracer, and were then excavated to determine rooting habits. A single tree was excavated in Cowley Canyon. Nine of the 29 trees sampled had no vertical adventitious roots and 12 had no lateral root development. Seven trees had no root development whatsoever other than the parent root from which they originated; six others had only a single adventitious lateral or vertical root. Root development was similar in all soils except that small roots were nearly absent in the clay. Root depth at the DCEW exceeded 114 inches in sandy loam and 50 inches in the clay. At Cowley Canyon rooting depth in loam with a dense clay B horizon exceeded 60 inches for a tree of agfe 52 years. The, majority of roots in all soils were concentrated in the top 4 ft of soil. The total length of the parent root between terminal ramets was 113.2 and 56.8 ft, respectively, in the two clones in sandy loam and 20.5 ft in the clone growing in clay on the DCEW. Parent root depth varied from 0.2 to 3.3 ft. Lateral roots (one in Cowley Canyon and four from the two clones in sandy loam on DCEW) extended 26, 26.5, 10, 8 and 6 ft, respectively. All ramets appeared to originate at depths ranging from 2 to 12 inches. INTRODUCTION Quaking aspen (Populus tremuloides Michx.) in the Intermountain Region characteristically develop dense stands, from which transpiration losses are believed large enough to, be of economic significance in respect to water yields. For this reason, research concerning comparative water uses of aspen and other vegetation is needed. Knowledge of the rapidity of regeneration, depth of penetration, and the volume of soil occupied by the root system is requisite to an accurate and adequate determination of the water economy of aspen. Aspens have unique root systems. The lateral system of roots is widespread (Baker, 1925; Brown, 1935; Day, 1944; Smirnov, 1959). Although most roots are confined to the upper 2 or 3 ft of soil, sinkers or vertical roots descending from laterals may reach a considerable depth (Berndt and Gibbons, 1958; Brown and Thompson, 1965; Cook and Harris, 1950; Love, 1958; Stoeckeler, 1956). Depending on the site, lateral spread may exceed 100 ft and depth of penetration may exceed 8 ft. The rate of elongation of selected roots can be as much as 58 inches per year (Buell and Buell, 1959). ' Present address: College of Agriculture., Division of Plant, Soil and Water Science, University of Nevada, Reno 89507.

Fertility investigations on the black earth wheatlands of the Darling Downs, Queensland. III. Mineral nitrogen in the soil and its relation to the wheat crop

The level of mineral nitrogen in the soil under fallow and crop was measured for the years 1951 to 1953. Relationships of mineral nitrogen at planting to yield and nitrogen content of wheat grain and straw were examined. Values for nitrate nitrogen at the end of the fallow period ranged most commonly from 10 to 20 µg/g in the surface 2 ft and from 0 to 10 µg/g at 2-4 ft. Approximately one-third of the sites showed an increase from the third to the fourth foot. One site showed extremely high values throughout the profile, particularly at 3-4 ft where a value of 127 µg/g was recorded. Values for ammonia nitrogen were most commonly in the range of 0-3 µg/g . Under the growing crop, mineral nitrogen declined for most depths in the period from planting up to September or October, after which there was little further change to harvest. Uptake of mineral nitrogen was normally greatest from the surface 2 ft of soil. Below 3 ft there were two groups of sites. One group showed moderate to high uptake and the second group low uptake. The low uptake in the latter group provides a reason for mineral nitrogen accumulation below 3 ft at some sites. Mineral nitrogen to 4 ft at planting averaged 126 lb/ac, excluding the one site with exceptionally high values. This was double the mean value of 63 lb/ac for nitrogen recovered in grain and straw, for crops planted in May-June. These figures, combined with trends in the soil under crop, suggest that most of the nitrogen used by the crop was derived from that in the soil at planting. Correlations between mineral nitrogen at planting and grain yield were mostly non-significant, suggesting that in general nitrogen was not an important factor limiting yield. Low grain yield and protein percentage were recorded at a number of sites which had been cultivated more than 50 years.