Physical Sciences and Mathematics Commons^™

Shotgun Metagenomic Sequencing Data Of Sunflower Rhizosphere Microbial Community In South Africa, Olubukola Oluranti Babalola, Temitayo Tosin Alawiye, Carlos M. Rodriguez Lopez, Ayansina Segun Ayangbenro

Horticulture Faculty Publications

This dataset presents shotgun metagenomic sequencing of sunflower rhizosphere microbiome in Bloemhof, South Africa. Data were collected to decipher the structure and function in the sunflower microbial community. Illumina HiSeq platform using next generation sequencing of the DNA was carried out. The metagenome comprised 8,991,566 sequences totaling 1,607,022,279 bp size and 66% GC content. The metagenome was deposited into the NCBI database and can be accessed with the SRA accession number SRR10418054. An online metagenome server (MG RAST) using the subsystem database revealed bacteria had the highest taxonomical representation with 98.47%, eukaryote at 1.23%, and archaea at 0.20%. The most …

Soil Net Nitrogen Mineralisation Across Global Grasslands, A. C. Risch, S. Zimmerman, R. Ochoa-Hueso, M. Schütz, B. Frey, J. L. Firn, P. A. Fay, F. Hagedorn, E. T. Borer, E. W. Seabloom, W. S. Harpole, J. M. H. Knops, Rebecca L. Mcculley, A. A. D. Broadbent, C. J. Stevens, M. L. Silveria, P. B. Adler, S. Báez, L. A. Biederman, J. M. Blair

Plant and Soil Sciences Faculty Publications

Soil nitrogen mineralisation (N_min), the conversion of organic into inorganic N, is important for productivity and nutrient cycling. The balance between mineralisation and immobilisation (net N_min) varies with soil properties and climate. However, because most global-scale assessments of net N_min are laboratory-based, its regulation under field-conditions and implications for real-world soil functioning remain uncertain. Here, we explore the drivers of realised (field) and potential (laboratory) soil net N_min across 30 grasslands worldwide. We find that realised N_min is largely explained by temperature of the wettest quarter, microbial biomass, clay content and bulk density. …

Three-Dimensional Vapor Intrusion Modeling Approach That Combines Wind And Stack Effects On Indoor, Atmospheric, And Subsurface Domains, Elham Shirazi, Kelly G. Pennell

Civil Engineering Faculty Publications

Vapor intrusion (IV) exposure risks are difficult to characterize due to the role of atmospheric, building and subsurface processes. This study presents a three-dimensional VI model that extends the common subsurface fate and transport equations to incorporate wind and stack effects on indoor air pressure, building air exchange rate (AER) and indoor contaminant concentration to improve VI exposure risk estimates. The model incorporates three modeling programs: (1) COMSOL Multiphysics to model subsurface fate and transport processes, (2) CFD0 to model atmospheric air flow around the building, and (3) CONTAM to model indoor air quality. The combined VI model predicts AER …

Managing Nitrous Oxide Emissions In Agricultural Fields, Mark S. Coyne, Wei Ren

Plant and Soil Sciences Research Report

Agriculture is a major contributor to atmospheric nitrous oxide (N₂O) (Smith et al., 2014; Tian et al., 2015). Unfortunately, nitrous oxide destroys stratospheric ozone (O₃) which protects us from ultraviolet radiation (Cicerone, 1989) and it increases ground level O_3, whichis an air pollutant threatening human health and food production. Nitrous oxide is also 298 times more potent than an equivalent amount of carbon dioxide (CO₂) in terms of trapping and absorbing reflected solar radiation (Forster et al., 2007). Basic chemistry and physics assure us that increased levels of N₂O in the …

Generalized Geologic Map For Land-Use Planning: Jessamine County, Kentucky, Daniel I. Carey, Martin C. Noger, Paul Howell

Map and Chart--KGS

This map is not intended to be used for selecting individual sites. Its purpose is to inform land-use planners, government officials, and the public in a general way about geologic bedrock conditions that affect the selection of sites for various purposes. The properties of thick soils may supercede those of the underlying bedrock and should be considered on a site to site basis. At any site, it is important to understand both the soils, and the underlying rock.

How Do Bacteria Move Through Soil?, Mark S. Coyne, J. M. Howell, R. E. Phillips

Soil Science News and Views

The contamination of water supplies by fecal bacteria is an important water quality issue in Kentucky. Contamination may come from point sources, such as straight pipes depositing raw sewage into streams, or nonpoint sources, such as manure runoff from cropland. A direct cost of contaminating water supplies is the expense that homesteads or water companies incur to chlorinate, filter, and otherwise treat water to make it potable. Indirect costs are the time lost to illness from drinking inadequately treated water, slower weight gain in livestock drinking contaminated water, and the degradation of aquatic habitats.

Profitability Of Variable Rate Fertilization On A Kentucky Soil (A Theoretical Analysis), Lloyd W. Murdock, Paula L. Howe

Soil Science News and Views

Grid soil sampling and variable rate fertilizer applications are a part of the precision agriculture movement that has captured the interest of many farmers. Variable rate fertilization requires extra expense and effort plus the use of often unfamiliar technology. Global Positioning Systems (GPS) equipment and computer software are used to outline and grid the field into small manageable units or “cells” (usually 2.5 acres). Each grid cell is soil sampled and tested for pH and available nutrients. Fertilizer recommendations are made on each grid cell and the fertilizer is spread by each grid cell using a truck equipped with GPS …

Tillage Slows Fecal Bacteria Infiltration Through Soil, Mark S. Coyne, S. W. Mcmurry, E. Perfect

Soil Science News and Views

Bacterial pathogens can degrade ground water quality by infiltrating and eroding from land treated with poultry wastes. The potential for ground water contamination (as well as associated health risks and cost of water treatment) greatly depends on the depth of soil to the water table or bedrock and soil structure. Pathogens must move through the soil profile to contaminate ground water (although sinkholes can provide a direct channel from the soil surface to the water table in karst areas). Deep soils have less potential for contamination than shallow soils. Structureless soils retain fecal bacteria better than well structured soils. Research …

Infiltration Of Fecal Bacteria Through Soils: Timing And Tillage Effects, Mark S. Coyne, C. S. Stoddard, John H. Grove, William O. Thom

Soil Science News and Views

Land-applying animal wastes potentially exposes humans and animals to fecal pathogens, either by direct contact with soil and produce, or via ground water contamination. Some of these organisms are Salmonella, certain pathogenic Escherichia coli strains, protozoa such as Cryptosporidium and Giardia, and enteric viruses. Whether soil adequately filters these pathogens before they reach ground water depends on the interaction of porosity, texture, depth, water content, rainfall intensity and duration, and soil management.

Quality Of Runoff From Four Northwest Arkansas Pasture Fields Treated With Organic And Inorganic Fertilizer, Dwayne R. Edwards, Tommy C. Daniel, John F. Murdoch, Philip A. Moore Jr.

Biosystems and Agricultural Engineering Faculty Publications

Long-term land application of animal manures, even at agronomic rates, can promote accumulation of soil phosphorus (P) which can, in turn, contribute to increased P loadings to downstream waters. The objective of this study was to assess the soil and runoff effects of replacing animal manure as a soil amendment with inorganic fertilizer (ammonium nitrate, NH₄NO₃) on fields that had been treated previously with animal manures. Runoff from two pairs of small fields (0.57 to 1.46 ha) was sampled from September 1991 to April 1994. All fields had been treated previously with animal manures; after runoff …

The Effect Of Organic Matter On Maximum Compactability Of Soil, Grant W. Thomas, Gerald R. Haszler, Robert L. Blevins

Soil Science News and Views

Bulk density is the weight of a given volume of soil expressed by soil scientists as grams per cubic centimeter (g/cm3). The higher the bulk density, the lower the volume of soil occupied by pore space, that volume of soil in which air and water reside. Because of this, there is much interest on the degree to which soil can be compacted.

The Proctor test is a means of determining the maximum bulk density that can be attained in a soil sample. This "maximum compactibility" is widely used on highways and building foundations but has had little use in agricultural …

Factors Affecting Crop Response To Liming, Kenneth L. Wells, J. L. Sims

Soil Science News and Views

Soil acidity levels directly affect the rate, kinds, and degree of chemical reactions which take place in soil. Crops respond to varying degrees to these chemical reactions. For the most part, these reactions affect the solubility of mineral elements in soil and the activity of the soil's biological processes. As a result, the availability of many plant nutrient elements is regulated by soil acidity. The level of availability of plant required nutrients can be adequate, deficient, or toxic to the plant, depending on the nutrient, soil acidity, and the crop. That is why measurement of soil acidity is regarded by …

Developing Efficient Crop Production Systems, Kenneth L. Wells

Soil Science News and Views

Land is initially the most limiting resource to consider in setting up a farm system aimed at maximizing returns. This is because soil, its topographical features, and its physical and chemical properties are largely fixed. There is little which can be done about them except to manage soil fertility and control erosion. Over the long run, crop production from any land tract will be directly influenced by the nature and character of the soils in that land tract. For this reason, the most basic step in initiating or redesigning a farming operation is to get an evaluation of the soil …

Evaluation Of Gamma Ray Attenuation For Measuring Soil Bulk Density Part I. Laboratory Investigation, Xiwen Luo, Larry G. Wells

Biosystems and Agricultural Engineering Faculty Publications

Gamma ray attenuation was evaluated as a means of determining soil bulk density. Experiments were conducted using clay, silt, and sandy loam soils wherein samples were compacted to uniform densities at various moisture contents. We determined the attenuation characteristics of dry soil to be independent of soil texture while being significantly different from that of water. Comparison of gamma density measurements with known soil sample densities indicated that the gamma gauge provided reliable measurement of soil bulk density, provided that the effect of soil moisture on attenuation was accounted for and the manufacturer-prescribed calibration procedure was followed daily. Further, we …

Evaluation Of Gamma Ray Attenuation For Measuring Soil Bulk Density Part Ii. Field Investigation, Larry G. Wells, Xiwen Luo

Biosystems and Agricultural Engineering Faculty Publications

A field investigation was conducted at sites near Lexington and Central City, Kentucky, to evaluate the use of gamma ray attenuation for measuring soil bulk density. Experiments were conducted whereby the gamma gauge was calibrated by various means and compared with volumetric cores collected from the field soils. Calibration by the manufacturer’s recommended procedure was determined to be as accurate as more rigorous laboratory calibration or calibration via regression of soil bulk density data, provided that the effect of soil water on gamma attenuation is correctly considered. We also developed a linear regression equation to correct for the occurrence of …

Managing Soil Content Of Nitrate Nitrogen, Kenneth L. Wells

Soil Science News and Views

The concerns about leaching of fertilizer nitrogen (N} into groundwater which were raised in the late 1960's were largely silenced during the 1970's as our agricultural economy was massively expanded. But since the early 80's they have been raised again to the point that national legislation (the Clean Water Act) was put into place to bring purity of the nation's water supplies into compliance with EPA-established standards. Beyond the apprehension largely about nitrate (NO₃) levels in groundwater, the groundwater issue today also includes concerns about pesticides. At the current time, the public is apprehensive about drinking water and …

Effectiveness Of Surface Application Of Phosphorus And Potassium On Yield Of No-Till Corn Grown On Soils Testing Low Or Medium Below A Depth Of 3 Inches, Grant W. Thomas

Soil Science News and Views

When crops are grown continuously under no-tillage or very minimum tillage, there is a tendency for phosphorus (P) and potassium (K) to become concentrated at or near the soil surface. This occurs when P and K fertilizers are broadcast on the surface and not mixed with the soil as would occur with plowing. The result is a stratification of P and K such that the surface few inches become very high in those nutrients, but soil test levels remain largely unaffected below that. The question is whether high yields of no-till crops can be obtained under these conditions.

Tests With A Product Having Alleged Value For Increasing Plant Available Water In Soil, Gale Dunn

Soil Science News and Views

Currently, there are a number of products being marketed for agricultural and horticultural use that have tremendous water absorbing properties. Some of these products are polyacrylamides which are synthetic compounds with chemical and physical properties which allow them to absorb large amounts of water relative to their dry weights. The implied advantage for use of such materials is that they can absorb more water than the soil itself, and acting like a sponge, hold more plant available water in the root zone.

Managing Soils For Optimum Crop Production, Kenneth L. Wells

Soil Science News and Views

The major resources which must be manipulated to develop a farm operation are LAND, LABOR, CAPITAL, and MANAGEMENT. Of these four broad categories of resources, LAND is the one which imposes constraints which ultimately determine the productive capacity of the individual farming system developed. This is because land is a fixed resource from the standpoint of the nature and amount of it available for developing a specific farming system. In this regard, the allocation of LABOR, CAPITAL, and MANAGEMENT should be directly linked to LAND productive capability in order to economically optimize the farming system developed. In other words, the …

Potassium Mineralogy Of Kentucky Soils, Anastasios D. Karathanasis

Soil Science News and Views

Feldspars and mica minerals are the two primary natural sources of potassium for most agricultural soils in Kentucky. Potassium feldspars are common mineral constituents of loess deposits in western Kentucky. Mica minerals, although dominant in shales, are also found in variable quantities in siltstone, sandstone and limestone parent materials of soils in the other regions of Kentucky. Because most of the soils in the western Coalfields and western Pennyroyal, and to a lesser extent in eastern Pennyroyal and Bluegrass, are covered by a loess cap of variable thickness, their surface mineralogy has been influenced by the feldspar-rich mineralogy of the …

Using Residual Soil Fertility Effectively, Grant W. Thomas

Soil Science News and Views

During the past 30 years, the use of commercial fertilizer in Kentucky has resulted in increases in the levels of phosphorus and potassium in soils. As might be expected, the soil test levels are higher with tobacco than with any other crop. but all soils for all crops show increases in fertility levels. Comparisons between 1975 and 1985 (the latest year available) show the proportion of samples sent to the University of Kentucky that are medium or high in soil test phosphorus has increased considerably. Even more striking is the decrease in very low values of phosphorus.

Soil Microbes And Biotechnology, M. Scott Smith

Soil Science News and Views

There is nothing new about attempts to develop and market microbial products for crop or soil improvement. Several types of microbes have been sold for a variety of agronomic purposes for many years. With the important exception of rhizobial inoculants. these have been generally unsuccessful. Recently however. the scientific revolution in genetics and molecular biology, the need for low cost agronomic inputs. and widespread concern for environmental safety have tremendously stimulated research and commercial activity on microbial products. Claims that cheap, effective microbial inoculants can be developed for pest control, detoxifying pollutants, providing plant nutrients and improving soils have been …

Cutting Production Costs In 1986, Kenneth L. Wells, John H. Grove

Soil Science News and Views

With the stressful economic situation that continues to face Kentucky farmers in 1986, the College of Agriculture is continually asked, "What are some of the things which can be done to ease the cost-price squeeze?" In response to this question, the following suggestions for improved, more cost efficient soil and crop production management are offered: These management techniques to get the highest possible yields without added costs are sometimes overlooked although they can offer increased yield potential at no added cost.

Effect Of Soil Additives On Water Infiltration On Kentucky Soils, Lloyd W. Murdock

Soil Science News and Views

Many products are advertised and sold in Kentucky as soil additives to aid the movement of water into and through the soil. Most of these additives contain compounds that reduce the surface tension of water. That means that they change the way water is absorbed onto surfaces that have a tendency to repel water. However, their effectiveness in this regard has been questioned due to the huge volume of soil to be effected and the fact that our Kentucky soils are not hydrophobic. In order to determine the effectiveness of these types of products, an experiment was designed to test …

Mineralogy Of Kentucky Soils, Anastasios D. Karathanasis

Soil Science News and Views

Very few mineralogical data have been published for soils in Kentucky. As an initial attempt to classify mineralogy of the subsoil, a general mineralogy map of the state was constructed based on currently available information (Fig. 1). The map suggests that quartz, mica, and feldspars are the dominant minerals of the sqnd and silt size fractions and that illite, smectite, kaolinite and hydroxyinterlayered vermiculite or smectite dominate the clay size soil fraction. Soils of the Western Coalfields, Eastern Coalfields, and Eastern Pennyrile regions generally contain more quartz in the sand and silt fraction than soils of the Purchase, Western Pennyrile, …

Soil Testing: Improving Reliability, John H. Grove

Soil Science News and Views

Late summer is a good time to check forage and row crop fields for possible nutritional problems and to make plans for fall soil sampling. "Problem" areas can be identified for selective sampling and the test results can be used to plan fertilizer and lime expenses for the next crop production season. Fields scheduled for tobacco, small grain and/or double cropping need to be sampled first in order to determine lime, phosphorus (P) and potassium (K) needs before fall application.

Does Use Of Gypsum Improve Soil Structure In Kentucky?, V. P. Evangelou, Kenneth L. Wells

Soil Science News and Views

Gypsum is sometimes recommended as a soil amendment in order to improve structure. Although this practice is often used for reclamation of sodic soils (Na⁺ saturated) in the western USA, it's value in improving soil structure in Kentucky is questionable. The following discussion explains way.

Causes Of Soil Compaction And Ways To Minimize Them, Lloyd W. Murdock

Soil Science News and Views

In order for a soil to become compacted, two conditions must be present, pressure and a soil that will compact . Different soils have different compaction characteristics. Sandy loam soils compact most readily; however, most soils with a high percentage of sand compact easily. Silt loam soils are more resistant to compaction, but they too are easily compacted when wet. When silt loam soils are not wet, it requires high pressure to compact them. When the soil is wet, each particle is lubricated and less pressure is required to compact the soil. Clayey soils can be compacted; but, as they …

Effect Of Lime Quality On Soil Ph Changes, Monroe Rasnake

Soil Science News and Views

Quality of a liming material depends primarily on two factors - purity and size of the individual particles. Purity is an indication of how much active material is present. Particle size determines how fa st the lime can dissolve and react with soil acidity.

Current Research On Band Application Of Fertilizer To Burley Tobacco, J. L. Sims

Soil Science News and Views

Present Status: Generally, past research conducted in the United States has shown that only one-half to two-thirds as much fertilizer is required to produce maximum crop yields when the fertilizer is properly banded as when it is broadcast. However, the magnitude of plant response to banding compared to broadcast applications varies widely with soil nutrient levels, soil temperature, soil pH, and the mobility of the nutrient being applied. Greatest benefits from banding result from (a) applications to soils having low or very-low soil test levels of the nutrient in question, (b) applications to crops grown in cool climates, (3) applications …