Masters Theses

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Anion reactions in soils
Swoboda, Allen R. (Virginia Polytechnic Institute, 1963)
The associative effect of legumes on non-legumes
Digges, Dudley Dice (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1915)
Characterization, classification, and genesis of Cullen soils from the Virginia Piedmont
Wysocki, Douglas A. (Virginia Polytechnic Institute and State University, 1979)
The Cullen soil series concept in the Virginia Piedmont has been the subject of much debate. This series was originally named Lloyd and was mapped throughout the southeastern Piedmont. In 1969 the Lloyd series was deactivated because of conflicting concepts. The Cullen series was established in 1970 to cover the Lloyd concept in Virginia. This soil is developed from a mixed felsic and mafic parent material and has been mapped over various rock types. A dark red (10R or 2.5YR 3/6) B subhorizon is the major morphologic feature of this soil series. Field and laboratory evaluations were undertaken to: (1) examine the relationship of Cullen and associated soil series and provide a method for their separation, (2) determine if geomorphic or weathering differences exist in Cullen and associated soil series, and (3) determine the classification of the Cullen series in Soil Taxonomy. The majority of Cullen pedons sampled classified as Typic Hapludults, clayey, mixed, thermic, but bordered on the kaolinitic and oxidic mineralogy classes. Chemical and physical properties were consistent in the pedons sampled and did not relate well to parent rock type or B horizon color. Weathering for an extensive time period has brought soils derived from various parent materials to a similar mineralogical state. We recommend that the Cullen series concept be broadened to include red (10R or 2.5YR) soils that have a mixed mineralogy. This concept covers a range between the Davidson and Tatum series and includes what has been mapped as Georgeville in Virginia.
Characterization, classification, and productivity studies of typic hapludult mapping units in the southern Piedmont of Virginia
Thomas, Pamela J. (Virginia Polytechnic Institute and State University, 1987)
Two studies were initiated in the Virginia southern Piedmont to assess characterization, classification, and productivity of soils mapped as Cecil-Pacolet (clayey, kaolinitic, thermic Typic Hapludults). Effects of erosion on Ap and Bt soil properties and soybean grain yields were studied in Pittsylvania and Lunenburg counties. Relationships between soil properties, soybean yields, and erosion classes were not observed until the soils became severely eroded. Water contents at -10kPa and -1500kPa increased as clay content increased but plant available water remained at 0.09 m³ m⁻³ across erosion classes. Available phosphorus (P) decreased with severity of erosion and was significantly correlated with soybean yield. The highest grain yields were on slightly and moderately eroded soils and were attributed to available P levels above 18 mg P kg⁻¹ critical level for optimum crop production. Low yields on the severely eroded sites corresponded to available P below 18 mg kg⁻¹. A second study on composition and variability of the Cecil-Pacolet map unit in Appomattox County showed large variation in soil properties and taxonomic classes. Variability is attributed to intrusions of mafic materials in the map unit. Variability was extreme within delineated soil bodies and was reflected in taxonomic classification in which up to six taxa can occur within the same delineation. Cecil and Pacolet soils comprise 62 percent of the map unit. Similar soils comprise 70 percent of the map unit and dissimilar soils make up the remaining 30 percent. The map unit is named Pacolet-Cecil and dissimilar soils are included in the mapping unit description.
A comparative analysis of the reproductive efficiency of 14 Virginia market type peanut cultivars (Arachis hypogaea L.)
Seaton, Maurice L. (Virginia Polytechnic Institute and State University, 1986)
There is inadequate basic information available on the reproductive efficiency of peanut (Arachis hypogaea L.) cultivars and a need to determine the sources of yield improvement made in peanut over the past four decades. Therefore, a study of the reproductive efficiency (RE) of 14 virginia market-type peanut cultivars was conducted using field experiments at the Tidewater Research Center, Suffolk, Virginia, in 1983 and 1984. The 14 cultivars vary in maturity from early to late, in release dates from 1944-1981, in breeding method of development from selection within an existing cultivar to hybridization followed by selection, and in growth habit from erect to spreading. The traits studied included flower total (FT), mature pod total (MPT), seed total (ST), pod total (PDT), peg total (PGT), immature pod total (IMPDT), mature pod dry weight (MPDW), plant dry weight (PLDW), vine weight (VW) and seed weight (SW). The five methods used to measure RE were (1) MPDW/PLDW (Harvest Index), (2) MPT/FT, (3) PDT/FT, (4) PGT + PDT/FT and (5) ST/(2*FT). The results indicate that the five most recently released cultivars produced more plowers, 10% more mature pods, 9.7% more mature seeds, and 11% more plant dry weight than the nine previously released cultivars. Using Harvest Index (HI) there was a 4% increase in RE for more recent vs. older cultivars, and about an 8% higher RE for early maturing vs. later maturing cultivars. Also, there was a 3% increase in RE for erect vs. similar advantage for hybrids spreading cultivars and a vs. pure lines. A slight decrease in RE for cultivars released since 1970 vs. those released earlier was observed using Methods 2, 3, 4 and 5. In addition, there was a 4-10% advantage in RE for the two earlier maturing classes over the medium or late classes using the same methods and also a 6% increase in RE for erect vs. spreading cultivars. The growth habit of the 14 cultivars was a very important determining factor for all trait differences. HI appears to be the single best measure of RE in peanuts; however, at least one other method should also be used for obtaining the truest estimate of the RE of a cultivar. It appears that the total peanut cultivar is early maturing and erect with a high RE. This study shows that plant breeders have increased yield in peanuts by (a) increasing apparently the total number of flowers, (b) increasing the HI and (c) increasing reproductive efficiency by increasing the proportion of flowers that form mature pods. Any further increase in yield must combine these three methods of increasing yield as well as overcoming any limiting factors, such as photosynthetic capacity, in order to surpass the present yield plateau.
Comparative methods in liming for soil needs
Noblin, E. Y. (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1921)
Comparative value of scarified and of unhulled seeds of biennial white sweet clover for hay production
Earley, Ernest Benton (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1929)
Unhulled white sweet clover seeds return larger yields of bay and greater profits than do similar scarified seeds. Seedlings resulting from unhulled seeds are more resistant to low temperatures than seedlings coming from scarified seeds. Sweet clover seedlings are most resistant to cold when in very early stages of development. They become more susceptible with advance in age. High soil moisture exerts a protective influence on seedlings which are in a susceptible stage of growth at the time of exposure to low temperatures. There is some evidence, although not conclusive, that seedlings coming from scarified seeds are more active physiologically than those coming from unhulled seeds.
Corn responses to high levels of copper application as copper rich pig manure
Bajracharya, Keshari (Virginia Polytechnic Institute and State University, 1987)
The use of copper (Cu) in pig production to stimulate growth and improve feed efficiency is presently being questioned due to the potential environmental hazards associated with the repeated disposal of the resulting Cu rich manure in agricultural land. Results of field experiments conducted on three diverse Virginia soils indicated that the long-term application of Cu as either copper sulfate or Cu rich pig manure, even at high application rates (average application rate for 9 years was 108 metric tons of manure ha⁻¹ year⁻¹ or 32 kg Cu ha⁻¹ year⁻¹), had no adverse effects on corn yields. Copper levels in corn grain and leaf tissue were not increased by the nine annual applications of Cu rich manure or CuSO₄ , except for a slight increase in Cu concentration in corn grain from CuSO₄ application on only one soil. Copper concentrations in all plant tissues were well within normal ranges for all treatments at all sites. Corn grain yields were not decreased by Cu application on any of the three soils.
Correction and diagnosis of boron deficiency in corn
Wijesundara, Sunetra M. (Virginia Polytechnic Institute and State University, 1986)
Field experiments were conducted during the 1985 growing season on six soils in the Atlantic Coastal Plain region and one from the Piedmont region to determine the response of irrigated corn (Zea mays L.) to boron application. Two treatments applied to each of the soils consisted of 1) a control and 2) both band and foliar boron applied at rates of 2.0 and 0.5 kg ha⁻¹, respectively, as Solubor when corn plants were in the V5 to V6 growth stage. Corn grain yields averaged 13,485 kg ha⁻¹ across treatments on the seven soils. Based on published calibration data for the hot water soluble boron procedure, a corn grain yield response to boron application was not expected on any of the seven soils. Nevertheless, boron application increased corn grain yield from 13,485 kg ha⁻¹ on the control treatment to 14,300 kg ha⁻¹ on the plus boron treatment for one of the seven soils, an Altivista loamy sand. This soil had a hot water soluble boron concentration of 0.56 mg kg⁻¹ and a Mehlich 3 extractable boron concentration of 0.78 mg kg⁻¹. The six soils for which boron application did not increase yields had hot water soluble boron concentrations from 0.55 to 0.92 mg kg⁻¹ and Mehlich 3 extractable boron concentrations from 1.02 to 1.33 mg kg⁻¹. The boron concentration in whole corn plants sampled at the V5 to V6 growth stage was 6.7 mg kg⁻¹ on the Altivista soil where boron application increased corn grain yields and ranged from 9.6 to 103.1 mg kg⁻¹ on the six soils where boron application did not increase yields. The boron concentrations in ear leaves sampled at the early silk growth stage ranged from 8.5 to 18.6 mg kg⁻¹ and in corn grain from 0.66 to 3.31 mg kg⁻¹ on the control treatments of the seven soils. Ear leaf and grain boron concentrations were 10.7 and 0.74 mg kg⁻¹ for plants grown on the control treatment on the Altivista loamy sand, respectively. It can be concluded that, of the plant tissue and soil test procedures evaluated, boron concentration in whole young plants and Mehlich 3 extractable B were the most promising for diagnosis of boron deficiency in corn plants. Nevertheless, research is required on more soils before boron concentrations in young plants and Mehlich 3 extractable B can be used as a routine procedure for detection of boron deficiency in corn plants.
The cultivation of corn
Trimble, Joseph Marshall (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1915)
The determination of the accumulation and penetration of exchangeable potassium found in Dunmore silt loam under long-time rotational practices
Smith, George Kinnear (Virginia Polytechnic Institute, 1947)
An investigation of the amount of exchangeable potassium found in the surface and subsoils of a 33-year rotation experiment at Blacksburg, Virginia, was made. The rotation is located on Dunmore silt loam, Which is rated as a relatively fertile soil in Virginia. There are indications that sheet erosion has removed considerable amounts of the surface soil from the steeper slopes of the first nine treatments, and it is evident that an accumulation of this material has occurred on the four lower plots. It is believed by the writer, and others familiar with these plots, that.this erosion occurred prior to the beginning of the rotation in 1909. Composite soil samples were taken from each of the 8 treatments in each of the 4 series of this rotation and resulted in a total of thirty-two fertilized subplot samples, and a corresponding thirty-two unfertilized subplot samples were collected and analyzed for exchangeable potassium. Similar analyses were ma.de on the thirty-two subsoils of both the fertilized and the unfertilized treatments. The resulting data from the surface and subsoils were then statistically analyzed and the following conclusion drawn: 1. The applications of both muriate of potash and manure significantly increased the amount of exchangeable potassium found in both the surface and subsoils. 2. The surface soils are significantly higher in exchangeable potassium than the subsoils. 3. Exchangeable potassium may be leached from the surface horizon to the subsoil when applied in a complete fertilizer in excess of plant needs. 4. Manure applications which contained considerably less potassium than the potassium added to the soils in the muriate applications, resulted in larger amounts of exchangeable potassium in the surface soils, a 30 per cent increase in crop yields, and significantly less exchangeable potassium leached to the subsoils. 5. The difference in exchangeable potassium between the fertilized subplots receiving muriate of potash. and the unfertilized subplots. resulted in an increase in the amount of potassium found in the surface soils which was equivalent to 996 pounds of 50 per cent potash fertilizer, and this figure would represent an amount equivalent to 15 per cent of the total muriate added to the surface soils. 6. The difference in exchangeable potassium found in the subsoil between the fertilized and unfertilized plots represents an equivalent of approximately 9 per cent of the total potash added. 7. Significantly larger amounts of exchangeable potassium were leached to the subsoil from plots, receiving muriate of potash than soils which received manurial treatments. Greater utilization of the applied potassium is indicated by the manurial applications. 8. A chemical analysis should be made of the manure which is applied to this experiment in order to obtain a more comprehensive understanding of the yields, and physical and chemical properties of these soils.
Development and preliminary evaluation of the simulation model C- maize VT1.0
Molten, K. W. (Virginia Polytechnic Institute and State University, 1987)
C-Maize VT1.0 is a simulation model of corn (Zea mays) growth in a soil plant atmosphere continuum. The purpose of developing the C-Maize VT1.0 simulation model was to provide an additional tool to researcher’s investigating the affects of water and nitrogen stress on corn growth and the movement of water and nitrates in the soil. The user may select either a 1-dimensional or a 2-dimensional approach to the simulation of the soil system. After an initial series of runs and a preliminary assessment of the model’s credibility it was concluded that the 2-dimensional approach provided a ‘sufficiently credible’ solution to modeling all aspects of the soil-plant-atmosphere system. The 1-dimensional approach as currently programmed provides a ‘non-credible solution’. The 1-dimensional approach failed to adequately simulate the soil subsystem and failed to simulate the plant’s response to water and nitrogen stresses.
A diallel study of stalk rot resistance in elite maize and its interaction with yield
Donahue, Patrick J. (Virginia Polytechnic Institute and State University, 1986)
Stalk rot reaction of maize (Zea mays L.) and its effect on yield was studied using 12 elite inbred parents (A619, A632, B73, H60, H93, H96, Mo17, Oh7B, Pa91, Va17, SS419, Va85) and all possible single crosses among them. The diallel study was conducted at Warsaw, Virginia in 1985. The experimental design was a split-plot with two stalk rot pathogens (Diplodia maydis and Fusarium moniliforme) and a control being the three whole plots and the inbreds described above and their single cross hybrids being the sub-plots. Plots were inoculated with the pathogens approximately three weeks following silking. Stalk rot scores and yield was taken four weeks following inoculation. Analyses of variance and combining ability analyses were performed on stalk rot scores and grain yield. There were no significant differences between the two pathogens for mean stalk rot score, but both were significantly higher in score than the control. Differences among the whole plots for mean yield were not significant. Hybrid/line by pathogen interactions were not significant for yield or stalk rot scores, indicating that the inbreds and their hybrids performed consistently across the pathogens and control. The estimates of GCA and SCA effects for stalk rot score both were significant with the GCA effects being the greater. This should indicate that stalk rot reaction would respond readily to selection in a breeding population. Per plant yields were not affected by the stalk rot treatments. Two Virginia lines, Val7 and Va85, were found to have both high yield and high levels of resistance to stalk rot, and should be good candidates for a breeding program stressing stalk rot resistance.
The diffusion of no-till corn information and adoption in selected counties in Virginia
Spann, Mary-Louise (Virginia Polytechnic Institute and State University, 1974)
The information sources used prior to the adoption of no-till corn production, the time pattern of the adoption, and the changes caused by the adoption of the no-till corn method were investigated. A mail questionnaire was utilized for data collection. Farm journals were found to be the major source of initial knowledge about no-till corn production, and the county agent was the major source utilized for additional information on the subject. Those who adopted during different time periods had different lag times between awareness and adoption. Earlier adopters had shorter lag times. The majority of respondents experienced reduced labor requirements after converting to no-till corn production. The most common problem associated with no-tillage production was weed control. The majority of respondents had contacted the county agent for information in the five year period prior to the study. Most farmers contacted the county agent at least once a year. Use of the state soil testing laboratory was high, as was use of branch experiment stations as information sources.
Distribution and physical parameters of solid waste disposal sites in Southwestern Virginia and the nature of leachate emissions
Black, Elwood David (Virginia Tech, 1975-03-04)
A total of 62 solid waste disposal sites were documented and evaluated in the 18 county study area of southwestern Virginia. The solid waste disposal operations encompassed a combined area in excess of 458.7 ha. An estimated 32 workers and 40 pieces of heavy equipment were utilized for the disposal of the waste at the various dumps, landfills, and sanitary landfills. The largest number of disposal sites were operated as dumps (62%), while only 14% of the sites qualified as sanitary landfills. The dump type of operation was characterized by: erosion, odor, leachate, minimum compaction, burning, lack of final or daily cover, and limited soil, financing, cover material, personnel, equipment, and planning. Generally, the waste was deposited at a remote or obscure site and left unattended. The landfill form of waste disposal, which occurred in 17% of the sites, required the construction of a trench for the disposal of the waste material which was later covered. The landfill form of waste disposal was characterized by shallow soils, limited cover material, steep slopes, and/or underground springs. The sanitary landfills were located in areas of deep soils, with moderate slopes, and showed an absence of interacting water. These sites demonstrated proper management of the resources and limited alteration of the surrounding area.
Dry matter estimation and potassium fertilization of intensively managed soft red winter wheat
Morrison, L. Teri (Virginia Tech, 1988)
Dry matter production must be predicted to utilize nitrogen recommendation models for winter wheat at growth stage 30. Four methods of dry matter estimation were evaluated for their ability to predict dry matter production. The pasture probe, height, and rising plate methods did not have adequate prediction ability. The drop plate method predicted dry matter with an r² of prediction of 0.82 for all sites combined. The predictive ability for an individual site was lower. The combined model on an individual site caused a wide range of errors. Consequently, the four methods are not recommended for estimating dry matter. The changes in percent nitrogen and dry matter near growth stage 30 were measured. Dry matter increased significantly, but percent nitrogen did not vary significantly. The number of clipped samples necessary to estimate the dry matter for the five ha field studied was four samples. The number of samples needed for larger fields will depend on the variability of the dry matter in the field and on the variation inherent to the sampling technique. Adequate potassium nutrition is required for high yields of winter wheat. Current soil test levels were evaluated and found to adequately describe the crop’s need for potassium. The influence of preplant and growth stage 25 applied potassium on yield and lodging was evaluated. On the medium to high potassium test soils used, the timing of the application did not affect yields or lodging. Ethephon reduced lodging better than potassium.
Effect of applied B, Cu, Mn and Zn on soybean yield and micronutrient concentration
Gunaratne, Lionel (Virginia Polytechnic Institute and State University, 1984)
The effect of applied B, Cu, Mn and Zn on soybean seed yield and tissue micronutrient concentration was studied under different field conditions. Manganese application increased soybean seed yield on the Dragston, Myatt and Slagle fine sandy loams, but not on Rains fine sandy loam. Seed yield was not affected by applied B, Cu or Zn. Broadcast and foliar Mn applications were similarly effective in correction of Mn deficiency and, among foliar Mn applications, split application resulted a higher seed yield than single applications. Micronutrient concentration of the leaf blades, petioles and seeds was increased with the application of B, Cu, Mn and Zn. The increase in tissue B concentration was much greater than that of the other micronutrients. Broadcast Mn application resulted in a higher tissue Mn concentration than foliar Mn applications. The critical Mn concentration in leaf blades at the R1 growth stage was above the level of 13 µg/g, which is reported in the literature. It was concluded that the present calibration of the dilute HC1-H₂SO₄ extractable Mn soil test overpredicts the incidence of Mn deficiency in soybeans.
The effect of different fertilizer treatments on the nitrogen and organic matter content of a soil when cropped to a definite rotation for a period of twenty-four years
Salomon, Milton (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1938)
In a large part of the soil fertility studies that have been attempted in the past, a great number of the results obtained were based almost entirely on crop yields. These yields were used as the final criterion upon which to draw conclusions as to whether a given system of soil management was a profitable one. At the Virginia Agricultural Experiment Station, Blacksburg, Virginia, a series of rotation and continuous cropping experiments have been undergoing a specified treatment for a period of 24 years. Conclusions as to the expediency of the practices followed have been approached from a purely crop yield basis. This method is serving its purpose in showing exactly how much the land is producing at the present time under a given soil management practice. It is believed, however, that a soil management program goes further than this. A practice based on crop production alone may prove, over a long period of time, to be a poor one. Perhaps just as important are the conditions arising within the soil relating to these practices. Whether or not the system evolved is one of soil building rather than one of soil depletion, is a question which necessarily must be considered before any recommendation as to the soil management practices to be followed, may be attempted.
The effect of fertilizers on the calcium and phosphorus content of clippings of pasture grasses
Webb, T. W. (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1930)
The effect of fertilizers on the protein, calcium and phosphorus content of some crops grown on the different soil types of Virginia
Grizzard, Alton Lee (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1929)

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