Browsing by Author "Frame, William Hunter"
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- 2021 Home Grounds and Animals PMG - IndexBalota, Maria; Besancon, Thierry E.; Cahoon, Charles W.; Chandran, Rakesh; Currin, John F.; Day, Eric R.; Flessner, Michael; Frame, William Hunter; Frank, Daniel; Hines, Tommy; Herbert, Ames Jr.; Johnson, Charles S.; Johnson, Quintin; Jordan, David; Koehler, Alyssa; Langston, David B.; Laub, Curt; Lingenfelter, Dwight; McCoy, Tim; Singh, Vijay; Taylor, Sally V.; VanGessel, Mark; Vollmer, Kurt; Wallace, John M.; Wilson, James (Virginia Cooperative Extension, 2021-02-12)This is a chapter of the 2021 Field Crops PMG. The Virginia Pest Management Guide (PMG) series lists options for management of major pests: diseases, insects, nematodes, and weeds. These guides are produced by Virginia Cooperative Extension and each guide is revised annually. PMG recommendations are based on research conducted by the Research and Extension Division of Virginia Tech, in cooperation with other land-grant universities, the USDA, and the pest management industry. Commercial products are named in this publication for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products that also may be suitable.
- Advancing Water Security and Environmental Sustainability Through Evaluation of Water Use From the Field to State-Wide ScaleSangha, Laljeet Singh (Virginia Tech, 2023-01-17)The United States (US) has experienced a surge in water shortages and droughts in recent times. Water shortages can result from population growth, climate change, inadequate water management policies, and the improper use of available technologies. The existing data and research on water use associated with water management policy structures are limited. Many states in the US follow strict regulations on water discharge into streams to enforce water quality standards; however, water withdrawal restrictions from streams are limited and inadequate in terms of water management at times of low flow. In states such as Virginia (VA), the Virginia Department of Environmental Quality (VDEQ) requires a Virginia Water Protection (VWP) permit for all water withdrawals from VA's surface waters. However, under certain provisions of VWP regulations, users are exempted from having a permit. Such permit exemptions exist in many states and present a severe challenge to water supply management. Chapter 2 compares the impact of permit exemptions on surface water availability and drought flows and compares these impacts to the relatively well-studied risks presented by dry climate change and demand growth in Virginia (VA). It was observed that in some regions, the impacts under the exempt user scenario were higher than those under the dry climate change scenario. In addition, water supply managers and government agencies use user-reported water withdrawal data to develop water management programs. Irrigated agriculture is the largest source of water consumption in the US. However, water-reporting regulations exempt users from withdrawing water for irrigation under a certain threshold. Moreover, as water is not metered, users often do not report their irrigation water use, resulting in considerable uncertainty about the impacts of irrigation withdrawals, which could potentially impact other water users, lead to water shortages or conflicts, and negatively impact stream ecology. Chapter 3 focuses on developing a novel methodology for quantifying unreported irrigation water withdrawals using publicly available USDA-Census and USDA-IWMS datasets. This method was used to evaluate the unreported water withdrawals in the VA. Finally, water use practices at the field level intersect with other environmental issues at a larger scale. For example, irrigation practices can influence nutrient uptake and transport at the field level. Insufficient water for irrigation, especially during critical growth stages, results in yield and economic losses and reduces agricultural productivity. However, excessive irrigation can lead to wasted water and energy as well as runoff and leaching of nutrients and agricultural chemicals. Therefore, the adoption of technological advancements at the field scale can reduce the amount of water needed to fulfill the needs while mitigating any nutrient impacts on the soil due to the excessive use of water. This is highly important when fertilizer prices are always high. Chapter 4 focuses on quantifying the impact of the use of short-term weather forecast data in irrigation scheduling on nutrient and water use efficiency in humid climates: experimental results for corn and cotton. It was found that irrigation scheduling using short-term weather forecast data is helpful for improving the nutrient and water use efficiency of corn. For cotton, nutrient and water use efficiency are highly influenced by irrigation and precipitation with respect to the growth stage.
- Ammonia Volatilization, Urea Hydrolysis, and Urease Inhibition with the Application of Granular Urea in AgroecosystemsFrame, William Hunter (Virginia Tech, 2012-03-22)Synthetic nitrogen (N) fertilizers play a key role in human nutrition and crop production. The most widely used N source globally is urea; however, N loss via ammonia volatilization can be great in agricultural systems where urea is surface-applied. The objectives of the experiments reported in this dissertation were: 1) evaluate the performance of a new laboratory ammonia volatilization measurement system for measuring ammonia volatilization from coated granular urea; 2) determine if urease can be extracted from corn and soybean residues; 3) determine if differences in urease activity are present in corn and soybean residues; and 4) evaluate N content and yield of corn treated with surface-applied coated urea fertilizers. The laboratory ammonia volatilization system had a system recovery efficiency (SRE) of 97% of the applied N and the lowest variation in mg N captured in the acid traps when the air flow rate was 1.00 L min⁻¹, at 26°C, and an acid trap volume of 100 ml 0.02M phosphoric acid. Ammonia volatilization was greatest from 12-24 h after N application with a total of 17% of the applied N being lost during that period. The urease inhibitor N-(n-butyl) thiophosphoic triamide (NBPT) was the most effective ammonia volatilization control treatment and reduced ammonia losses 30-40% compared to urea in the laboratory trials. Urease was extracted from soybean residue and retained activity during extraction; however, urease from corn residue could not be identified in extracts. The agronomic field trials indicated that NBPT increased N concentration in corn ear leaves; however the effect on corn grain yield was masked by environmental conditions. The data from this study suggests that ammonia volatilization from granular urea can be effectively controlled using NBPT, and corn tissue N content in the field indicates that NBPT allows for more N to be utilized by the plant. The urease extraction showed that there may be differences in urease activity in different crop residues. Further research is needed to determine if varying levels of volatilization control are needed for urea applied to different crop residues in no-till systems.
- Consider Your Whole System: Nitrogen and Sulfur Leaching Potential in VirginiaReiter, Mark S.; Frame, William Hunter; Thomason, Wade E. (Virginia Cooperative Extension, 2018-06-25)Provides information about the leaching of nitrogen and sulfur from crop soils, and whether or not to fertilize these soils.
- Cotton yield response to soil applied potassium across the U. S. Cotton BeltLewis, Katie; Morgan, Gaylon; Frame, William Hunter; Fromme, Daniel; Dodds, Darrin M.; Edmisten, Keith L.; Robertson, Bill; Boman, Randy; Cutts, Trey; Delaney, Dennis P.; Burke, Joseph Alan; Nichols, Robert L. (2021-05-11)Across the U.S. Cotton Belt, potassium (K) deficiency symptoms in cotton (Gossypium hirsutum L.) have become more common over the past decade. In 2015-2017, an experiment was conducted in Alabama, Arkansas, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, two regions in Texas, and Virginia for a total of 23 site-years. The objectives were (a) to quantify soil K levels at-depth in representative soils where cotton is commonly grown in major cotton production regions with observed K deficiencies; and (b) to evaluate the effects of application method and K rates on cotton lint yield, loan value, and return on fertilizer investment. Granular and liquid potassium chloride were broadcast or injected, respectively, 2-4 wk prior to planting at 0, 45, 90, 135, and 180 kg K2O ha(-1). Locations other than Texas and Oklahoma generally had soil K levels 1,653 kg lint ha(-1)). Inconsistent yield responses among locations indicate that K dynamics in the soil-cotton plant system are not well understood and deserve continued investigation.
- Evaluation of Cover Crops, Conservation Tillage, and Nitrogen Management in Cotton Production in Southeastern VirginiaMcClanahan, Sarah Jane (Virginia Tech, 2019-06-10)The response of upland cotton (Gossypium hirsutum L.) to legume and small grain cover crop establishment, in-season nitrogen (N) rate, and fertilizer N placement was investigated in two experiments located in coastal plain Virginia and North Carolina. The first experiment examined 1) soil compaction and cotton yield response to strip-tillage compared to no-tillage with a precision planted tillage radish and 2) the influence of legume mix, rye, and legume mix/rye combination cover crops with four in-season nitrogen (N) rates applied to cotton on cover crop biomass, cover crop nutrient uptake, soil compaction, soil N cycling, petiole nitrate-N (NO3-N) during the first week of bloom, cotton lint yield, and fiber quality parameters over two years. Legume mix cover crops resulted in greater N uptake, soil NO3-N during the growing season, and lint yields compared to LMR, rye, and fallow treatments over both study years. Soil compaction and lint yields were not significantly different between strip-tilled and no-till with tillage radish treatments in either year. Relative lint yields after LM were maximized at 93% relative yield with 110 kg N ha-1 applied in-season while relative lint yields for cotton following LM with 0 kg N ha-1 applied reached 75%, measuring at least 9% higher than cotton following other cover crop treatments. The second experiment investigated the effect of five N rates (0, 45, 90, 135, and 180 kg N ha-1) and three placement methods (broadcast, surface banded, and injected) on lint yield, petiole nitrate-N (NO3-N), lint percent turnout, and fiber quality parameters. Nitrogen rate and placement had a significant effect on lint yield but only N rate affected petiole NO3-N concentration. It was estimated that injecting fertilizer N requires an N rate of 133 kg N ha-1 to achieve 95% relative yield while surface banded fertilizer N required a rate of 128 kg N ha-1 to produce 90% relative yield. A critical petiole NO3-N concentration threshold of 5,600 mg NO3-N kg-1 was calculated to reach 92% relative yield. Other agronomic management practices such as cover crop termination timing, cover crop species blends, and number of fertilizer N applications are of interest in order to develop better recommendations and promote conservation agricultural practices in coastal plain Virginia and North Carolina.
- Field Crops: 2022 Pest Management GuideBesancon, Thierry E.; Cahoon, Charlie; Chandran, Rakesh; Currin, John F.; Day, Eric R.; Flessner, Michael; Frame, William Hunter; Frank, Daniel; Hines, Tommy; Johnson, Quintin; Jordan, David; Koehler, Alyssa; Langston, David B.; Lingenfelter, Dwight; Reed, T. David; Singh, Vijay; Taylor, Sally V.; VanGessel, Mark; Vollmer, Kurt; Wallace, John M.; Wilson, James M. (2022-02-03)
- Full-Season and Double-Crop Soybean Response to Potassium FertilizerStewart, Anna Elizabeth (Virginia Tech, 2015-08-11)Demand for potassium (K) increases with increasing soybean yield. Little research has been conducted on soybean response to K on coastal plain and piedmont soils of Virginia, especially in double-crop systems. Nineteen full-season and 14 double-crop soybean experiments were conducted in 2013 and 2014 in Virginia and northeastern North Carolina to determine full-season and double-crop soybean (with wheat straw remaining or removed) response to soil test K and K fertilizer application rates. Field moist, air dried, and oven dry soil test K extraction techniques were also compared to predict responsiveness of sites to K applications. Potassium fertilizer increased yield in five of 19 full-season experiments and one of 14 double-crop experiments. Full-season soybean yield plateaued at 88% relative yield and soil test K value of 38.8 mg K kg-1. Full-season plant K critical concentrations were 18.2 g K kg-1 for V5 and 24.6 g K kg-1 for R2. Although critical concentrations could not be determined for double-crop soybean, V5 and R2 concentrations ranged from 17.6 to 35.6 g K kg-1 or 13.2 to 28.1 K kg-1, respectively, most of which were within or above accepted sufficiency levels. Eight of 13 sites resulted in greater soil K concentrations when alternative soil drying methods were compared to air-dry methods. However, differences were not consistent and no single method was superior for these soils. More data is needed for double-crop soybean systems due to lack of response and lack of low soil test K sites in these experiments.
- An Integrated Approach for Nitrogen Management in Upland Cotton ProductionOfori, Bright Kwabena (Virginia Tech, 2023-01-23)Nitrogen (N) fertilizer application constitutes a major portion of farmers' cost of production since N is the most applied nutrient in U.S. cotton production. Despite this, N uptake and use efficiency (NUE) in cotton remains below 50%, which presents challenges of environmental quality. Studies were conducted across 4 states in the US Cotton Belt with the overall objective of evaluating strategies to reduce loss of N to the environment, increase N uptake and NUE. The first study had two objectives: 1) compare NH3 volatilization from surface versus subsurface application/placement of granular (urea) and fluid N source (urea ammonium nitrate; UAN32); and 2) compare NH3 volatilization from urea and UAN treated with enhanced-efficiency fertilizer products. For this study, four A horizon soils of different types were collected from four sites in Virginia (VA), Georgia (GA), Tennessee (TN), and Texas (TX). The EEF products were N-(n-butyl) thiophosphoric triamide (NBPT), nitrapyrin, and ESN. In the first set of experiments (N placement experiments), it was found that across soil types, subsurface placement of granular N source reduced NH3 volatilization by 58 – 81% and subsurface placement of UAN reduced NH3 volatilization by 56 – 98%. In the second set of experiments (EEF experiments), it was found that NBPT reduced NH3 volatilization by 5 – 77% across soil types, and the highest reduction in losses by NBPT was observed on sandier and low CEC soils. Treating urea with both nitrapyrin and NBPT was more effective at reducing NH3 volatilization compared to treating urea with nitrapyrin alone. Based on our findings, subsurface application of granular and fluid N sources is recommended as strategy to reduce NH3 volatilization. Where subsurface placement is not possible, EEF products should be considered. The objectives of the second study were: 1) determine the effects of small grain and legume cover crops on N cycling; 2) evaluate the effects of cover crops and N fertilization on N uptake; and 3) evaluate the effects of cover crops on lint yield. Cover crops were winter fallow (winter weeds), small grain [cereal rye (Secale cereale)], legume mix [(50% crimson clover (Trifolium incarnatum): 50% hairy vetch (Vicia villosa)], and legume mix + rye [(67% legume mix:33% hairy vetch)]. Fertilizer N application rates were 0, 45, 90, and 135 kg ha-1. Soil inorganic N in the top 30 cm depths of the legume mix and legume mix + rye plots was consistently higher than in the rye lone or fallow plots. Cotton lint yield following legume mix with 45 kg ha-1 fertilizer N application was comparable to following fallow plots with 135 kg N ha-1. Thus, fertilizer N rate could considerably be reduced when cotton follows legume cover crops. The objectives of the third study were: 1) evaluate urea and UAN placement (broadcast, dribbling, and injection) on lint yield and fiber quality of three cotton maturity groups (early-, mid-, and full-maturity); (2) assess N use and agronomic efficiencies as influenced by N source, rate, and placement; (3) evaluate the impact of N source and placement on fiber quality. A study including 9 site-years studies was conducted in VA, GA, and TX. It was found that placement had no effect on yield in VA, had effect in all 3 years in TX, and had effect in 1 year in GA. Yield responded to N application in 8 out of 9 site-years in this study. Nitrogen use efficiency was highest among the early- and mid-season varieties. Overall, N rate and variety, rather than application/placement strategy, had the most pronounced effects on lint yield.
- Investigating Nutrient Management Innovations in Upland Cotton Production to Increase Agronomic EfficiencyBrown, Austin B. (Virginia Tech, 2015-04-20)This research was focused on increasing the efficiency of upland cotton production in the northern cotton belt through the use of new fertilizer formulations, placement, and timings. The objectives of the experiments reported in this thesis were to: 1) evaluate the effects of side-dress potassium (K), sulfur (S), and boron (B) formulation and application timing on tissue nutrient levels during the bloom period; 2) evaluate lint yield response of cotton to different formulations of nitrogen (N), K, S and B applied at side-dress; and 3) compare 5x5 banding (5 cm beside and 5cm below the seed) and deep placement of complete N-P-K-S blends to current nutrient management strategies on early season plant growth, nodes above white flower, total nodes, petiole nutrient concentrations during bloom, and lint yield. Tissue S and B concentrations were increased more often than K concentrations when the nutrients were applied with side-dress N. When evaluating P and K placement, petiole P levels were found to be significantly higher in unfertilized plots when no side-dress N was applied. Phosphorus and K placement and/or rate had no effect on lint yield when N was applied at side-dress during the study. Environmental conditions potentially influenced the response to P and K placement as 5x5 placement produced yields significantly higher during 2013 growing season at location 1, while deep placement produced significantly higher yields in 2014 at location 3. As a result, Virginia nutrient management recommendations for cotton have been updated to incorporate management strategies to maximize lint yields.
- Nitrogen and Sulfur Management in Soybean and Edamame Production in the Mid-Atlantic Coastal PlainBrooks, Keren Ruth (Virginia Tech, 2023-01-23)The United States is a world leader of soybean [Glycine max (L.) Merr.] production, but to maintain quality production at this level, soybean management needs to be continually monitored and improved. Sulfur (S) deficiencies in soybean have become more frequent in the U.S. due to fertilizer purity, emissions regulations, and higher yields. We completed a study for soybean grown in sandy loam soils in the mid-Atlantic coastal plain system to determine proper S fertilizer rate and application timing. Yields ranged from 1,236-4,051 kg ha-1. Neither S rate nor application timing influenced yield. S treatments increased methionine concentration (methionine = -0.0001 S rate2 + 0.002 S rate + 5.60). Sulfur fertilization can improve soybean quality and may impact marketability. Another study was conducted to determine optimal source and rate of S application for soybeans in the Mid-Atlantic coastal plain system. Yields ranged from 1,316-4,914 kg ha-1. While sulfur rate did not influence yield and fertilizer source responses were site-specific. Sulfur leaf tissue concentrations were directly related to S rate (S concentration = 0.004S rate + 2.103). Nutrient uptake responses to S fertility indicate the potential for S yield responses in the future when soils become S depleted and contain less available S. Soybean producers and retailers in the United States are interested in capitalizing on new edamame markets to provide a domestic product. To aid the shift from oilseed production to vegetable production, a study was conducted to determine the optimal N rate and N application timing for edamame yield and quality in the Mid-Atlantic coastal plain system. Nitrogen rate significantly increased yield one out of three years (Yield = 29.9N Rate + 3387) when all N was applied at planting but was not significant with split applications. Fertilizer rate and timing did not impact edamame maturity or final pod/bean quality. N fertilizer applied at-planting may aid edamame yield and profit for sandy loam soils in the mid-Atlantic, USA. Currently, mid-Atlantic coastal plain soils, coupled with S deposition, are able to supply enough S for soybean growth and development, but without fertilization soybean soils are being mined of S and will eventually become depleted. Sulfur must be monitored if future deficiencies are to be avoided. Nitrogen fertilizers may improve yield in vegetable soybean production. Both oilseed and vegetable soybean farmers should continue to monitor soil nutrient levels to ensure proper nutrition for soybean growth and development.
- Nutrient Availability from Poultry Litter Co-ProductsMiddleton, Amanda Jo (Virginia Tech, 2015-08-03)Phosphorus (P) is a nutrient of concern in the Chesapeake Bay watershed due to nutrient imbalances in areas with confined animal feeding operations. By converting poultry litter to an ash via thermal conversion, nutrients are concentrated and are economical to ship out of nutrient surplus watersheds to nutrient deficient regions, such as the corn-belt. We initiated incubation and field studies on sandy loam soils to test P and potassium (K) availability from poultry litter ash (PLA). Four PLA products, derived from different sources using different combustion techniques, and 2 biochar products were characterized. Poultry litter (PL) co-products were compared to a no-fertilizer control and inorganic P (triple super phosphate; TSP) and inorganic K (muriate of potash; KCl) fertilizer at similar rates. In the incubation study, standard fertilizers (TSP and PL) had the greatest initial availability for P (55.50% TSP; 9.13% PL) and K (97.99% PL), respectively. The PL co-products varied in availabilities based on thermo-conversion system from 1.60- 8.63% for P to 8.14- 88.10% for K. One ash co-product (ASH4) produced similar availabilities to the industry standard fertilizers after 56 days. In conclusion, co-products from combustion thermo-conversion systems were found be superior to gasification and pyrolysis systems when the desire was to produce the most plant available P and K dense PL co-products. In the field studies, yield, Mehlich-I extractable soil nutrients, plant tissue and grain samples, and organic matter content was used to compare treatments. Poultry litter ash co-products were highly variable due to the thermo-conversion system and feedstock of formation. If all ideal combustion criteria are met, then PL co-products are feasible to use as fertilizer sources, but will need to be individually analyzed for nutrient content before making application recommendations. A greater amount of the co-products will have to be applied to meet the same nutrient availability of the standards due to their lower availability. Fresh PL tends to be the better fertilizer due to its added N content, which is lost in thermo-conversion systems and would have to be supplemented with the ash co-products. Biochars tend to be less available than their ash counter parts. More research using the water soluble availabilities instead of the total concentration nutrients of the co-products are needed to be able to identify stronger relationships with standard fertilizers.
- Reducing Ammonia Volatilization and Escherichia coli from Broiler Litter Using Multiple Applications of Sodium BisulfateHunolt, Alicia Erin (Virginia Tech, 2015-04-17)Ammonia (NH₃) emissions from animal manure, such as poultry litter, can cause air quality problems. These emissions also result in excessive nitrogen (N) loading into aquatic environments which can lead to water quality problems where N is the limiting nutrient for eutrophication, such as the Chesapeake Bay. Poultry litter treatment (PLT, sodium bisulfate) is an acidic amendment that is applied to litter in poultry houses to decrease NH3 emissions, but currently it can only be applied before birds are placed in the houses. This project analyzed the effect of multiple PLT applications on litter properties and NH₃ release in a controlled and field environment. Volatility chambers with acid traps were used to compare multiple, single, and no applications of PLT to poultry litter. Both single and reapplied PLT caused a greater moisture content and lower pH in litter. Additionally, the E.coli in litter was decreased significantly with both single and reapplied PLT. After 15 days, NH₃ released from litter treated with reapplied PLT was significantly less than litter with both single and no applications. Furthermore, NH₄⁺-N content of litter was greatest in litter treated with reapplied PLT increasing its fertilizer value. The efficacy of a new farm scale system capable of applying several additions of PLT to poultry litter throughout the growth of a flock was also evaluated. Though litter pH, E.coli, and NH₃ volatilization were temporarily decreased with PLT application, the overhead reapplication auger system is not recommended at this time due to moisture and corrosion problems.
- Studies of Low-Nicotine Flue-Cured Tobacco ProductionHinkle, Caleb Daniel (Virginia Tech, 2021-06-03)Flue-cured tobacco (Nicotiana tabacum) has been managed to optimize the yield of high-quality cured leaf while maintaining nicotine levels within a relatively narrow range based on the Regional Minimum Standards Program. Among the 3,000 plus alkaloids found in tobacco, nicotine accounts for greater than 90% of the total alkaloids produced in commercial tobacco varieties. Precious research has demonstrated an association with nicotine levels and cured leaf yield and quality. On March 16, 2018, the Food and Drug Administration issued a notice for proposed rulemaking to limit nicotine in combustible cigarettes to 0.3-0.5 mg nicotine per gram of tobacco (an approx. 98% reduction from current levels). Studies on achieving decreased levels of nicotine in flue-cured tobacco have been conducted since the mid-1900's and some success has been found through breeding and genetics. The FDA proposal suggested changes to standard agronomic production practices as a means of achieving their proposed nicotine levels. The primary objectives of this work are: (1) evaluate the impact of standard agronomic production practices on nicotine levels and the resulting yield and cured leaf quality and (2) quantify differences in nitrogen-use efficiency between conventional and low-nicotine flue-cured tobacco varieties. Results showed that the changes to production practices did not sufficiently lower nicotine levels to the range proposed by the FDA. The only publicly available low-nicotine variety, LA FC53, did not achieve the targeted nicotine level and the yield and cured leaf quality was severely reduced. The study of nitrogen-use efficiency quantified differences between conventional and low-nicotine flue-cured tobacco varieties. Proprietary, low-nicotine varieties developed from K 326 tended to have lower nicotine levels than LA FC53 with improved yield and cured leaf quality. Both yield and quality are associated with nitrogen-use efficiency and the nitrogen-use efficiency of the new low-nicotine lines was comparable to K 326 and better than the previously developed, low-nicotine standard variety. No evaluation of smoking characteristics of the cured tobacco from these studies was conducted and would be necessary for commercial utilization of low-nicotine flue-cured tobacco.
- Tillage System Effects On Upland Cotton Yield and Development In VirginiaLongest, Robert Joseph (Virginia Tech, 2017-04-18)Identifying the proper tillage system which provides the best agronomic benefits for cotton production in the coastal plain soils of Virginia was the basis for this research. Strip-tillage was evaluated from 2015-2016 on-farm to determine the effects of annual and biennial treatments on plant growth and lint yield, as well as measuring the impacts on soil compaction. Also, small plot tillage experiments were conducted from 2013-2016 assessing no-till, conventional tillage, minimum tillage, and strip-tillage as well as the subsequent effects of these systems on four cotton varieties. Biennial strip-tillage produced similar lint yields to annual strip-tillage at 3 of 4 locations, with only one location showing a significant difference in lint yield of 135 kg ha-1. Persistence of subsoil tillage within the row from the previous year was observed at some locations and plant heights were not different at all locations, although annual strip-tillage provided deeper potential rooting depths both early season and at harvest. In short term tillage systems, minimal penalties in plant growth and lint yield were observed in no-till verses the other systems, primarily associated with greater soil compaction, shorter plant heights, and lower yields. An overall 8% reduction in yield was found with no-till systems, with no significant differences in yield among tillage systems observed in any year. Varietal effects on plant growth and yield were observed annually, with FM 1944 GLB2 being the shortest plants, and DP 1321 B2RF having the tallest plants. No tillage by variety interaction was observed, supporting the idea that varieties respond similarly across tillage systems.
- To Mix or Not to Mix: Performance and Management of Diverse Cover Crop MixturesWolters, Bethany Rose (Virginia Tech, 2020-01-27)Cover crops (CC) are planted in between cash crops to improve soil quality and to supply nitrogen (N) to cash crops through biological N fixation or soil N scavenging. Most producers use single species CC, in part because potential benefits of using mixtures of three or more CC species are poorly understood. A three-year study was initiated at Painter, Virginia to observe effects of CC mixtures on a no-till (NT) corn (Zea mays), wheat (Triticum aestivum L.), and soybean (Glycine max) rotation to measure CC performance, N cycling, cash crop yield, and soil quality in a sandy, low organic matter soil. Twelve treatments were created with conventional tillage (CT), NT, no CC control, and monoculture or CC mixtures of 3 to 9 species. Corn was grown in year 3 in all 12 treatments and four N rates were applied (0, 56, 112 and 156 kg N ha-1). Cover crop biomass, N accumulation, CC C:N ratio, and corn and soybean yield were measured annually. Soil bulk density, compaction, infiltration rate, pH, electrical conductivity, soil respiration, earthworm counts, soil microbial respiration, and soil microbial biomass carbon (C) after three years of CC. Cover crop biomass production varied significantly each year (5633 kg ha-1 in year 1, 755 kg ha-1 in year 2, 5370 kg ha-1 in year 3) due to climate and agronomic parameters, but a CC mixture always produced the highest biomass at termination. Nitrogen accumulation was strongly correlated with biomass production (R2= 0.94) and followed the same trend due to all CC having C:N < 30:1. Corn and soybean yields in years 1 and 2 were not significantly different, but corn yield was significantly affected by treatment and N fertilizer rate in year 3. After 3 years, soil respiration, earthworm populations and soil microbial biomass C increased in CC compared to CT without CC. However, infiltration rate, bulk density, microbial respiration, pH did not improve or declined compared to CT. In conclusion, adding CC mixtures to crop rotations shows promise for producing high CC biomass, accumulating N, and increasing crop yields, while improving some soil quality parameters on sandy low organic matter soils.
- Yellow Corn in Virginia - Spring 2016Reiter, Mark S.; Frame, William Hunter; Thomason, Wade E.; Reiter, Scott; Spencer, Janet (Virginia Cooperative Extension, 2016-10-10)Discusses the status of corn plants in spring 2016 in Virginia. Many of the plants were noted as stunted and yellowed. Reasons for this include colder than average spring temperatures, wet soils, lack of sunshine, nutrient deficiencies, soil pH, and perhaps types of hybrids planted.