Browsing by Author "Alley, Marcus M."
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- Agronomic and Nitrate Leaching Impacts of Pelletized versus Granular UreaShah, Sanjay Bikram (Virginia Tech, 2000-08-02)Agronomic and water quality impacts of urea particle size were evaluated through field and laboratory experiments and mathematical modeling. In a two-year field study, corn silage yield, corn nitrogen (N) removal, and nitrate-N (NO₃⁻-N) leaching from urea pellets (1.5 g each) and granules (0.01-0.02 g each) applied at 184 kg-N/ha were compared. A control treatment (no N) and two other N application rates (110 and 258 kg-N/ha) were also included. Urea particle size impact on dissolution rate, dissolved urea movement, mineralization, and N0³-N leaching were evaluated in the laboratory. A two-dimensional (2-D) mathematical model was developed to simulate the fate of subsurface-banded urea and its transformation products, ammonium (NH₄⁺)and NO₃⁻. With 184 kg-N/ha, corn silage yield was 15% higher (p = 0.02) and corn N removal was 19% higher (p = 0.07) with pellets than granules in the second year of the field study. In the absence of yield response at 110 kg-N/ha, reason for higher yield at 184 kg-N/ha with pellets was unclear. Greater N removal reduced NO₃⁻-N leaching potential from pellets compared to granules during the over-winter period. No urea form response to yield or corn N removal was observed in the first year. In 23 of 27 sampling events, granules had higher NO₃⁻-N concentration in the root zone than pellets, with average nitrate-N concentrations of 2.6 and 2.2 mg-N/L, respectively. However, statistically, NO₃⁻-N leaching from the root zone was unaffected by urea form, probably due to high variability within treatments masking the treatment effects. In October 1997, pellets retained 16% more (p = 0.04) inorganic-N in the top half of the root zone than granules, due to slower nitrification in pellets as was determined in the mineralization study. Slower NO₃⁻-N leaching allowed for greater N extraction by plants. Pellets had lower dissolution, urea hydrolysis, and nitrification rates than granules; however, nitrification inhibition was the dominant mechanism controlling N fate. The model took into account high substrate concentration effects on N transformations, important for simulating the fate of band-applied N. The model exhibited good mass conservative properties, robustness, and expected moisture and N distribution profiles. Differences in measured field data and model outputs were likely due to uncertainties and errors in measured data and input parameters. Model calibration results indicated that moisture-related parameters greatly affected N fate simulation. Sensitivity analyses indicated the importance of nitrification-related parameters in N simulation, particularly, their possible multiplicative effects. Need for extensive model testing and validation was recognized. The validated 2-D N model could be incorporated into a management model for better management of subsurface-banded granular N. However, the 2-D model is not appropriate for simulating the three dimensional N movement from pellets.
- Agronomy HandbookBrann, Daniel Edward; Abaye, Azenegashe Ozzie; Peterson, Paul R.; Chalmers, David R.; Whitt, David L.; Chappell, Glenn F.; Herbert, D. Ames Jr.; McNeill, Sam; Baker, James C.; Donohue, Stephen J.; Alley, Marcus M.; Evanylo, Gregory K.; Mullins, Gregory L.; Hagood, Edward Scott; Stallings, Charles C.; Umberger, Steven H.; Swann, Charles W.; Reed, David T.; Holshouser, David L. (Virginia Cooperative Extension, 2009-05-01)Provides readers with a source of agronomic information such as field crops, turfgrasses, variety selection, seed science, soil management, nutrient management and soil suitability for urban purposes that does not change frequently - pesticide and varietal information changes frequently and is therefor not included.
- 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.
- Assessing the Effect of Nitrogen Sources, Rates and Time of applications on Yield and Quality of Stockpiled Fescue and Tall Fescue PasturesYarber, Elizabeth Lee (Virginia Tech, 2008-08-01)In Virginia, tall fescue [(Schedonorus phoenix (Scop.) Holub,) formally known as Festuca arundinacea L.] can be found on more than 4 million ac of hay and pastureland. Two separate experiments were conducted at three different geographical locations over two growing seasons. The objective of Experiment 1 was to evaluate the influence of N sources and rates on yield and nutritive value of stockpiled tall fescue. Experiment 2 examined the effect of split spring and fall N applications at various rates on yield and nutritive value of tall fescue pastures. The first experiment was conducted at three locations (Blacksburg, Blackstone, and Steeles Tavern, VA) while the second experiment was conducted only at the Blacksburg and Steeles Tavern locations. In Experiment 1, the N sources included ammonium nitrate, ammonium sulfate, urea, urea + Agrotain®, Environmentally Smart N® (ESN), Nutrisphere (NSN), Nitamin® (Blackstone only), pelleted biosolids (Blackstone only), and broiler litter (Steeles Tavern only) applied at 0, 28, 56, 84, and 112 kg plant available N (PAN) ha-1. Plots were harvested in mid-December (Blacksburg and Steeles Tavern) and late January (Blackstone). The yield of the stockpiled tall fescue in 2006 ranged from 1,300 to 2,900, 1,700 to 3,000, and 2,600 to 3,300 kg DM ha-1 for the Blacksburg, Steeles Tavern and Blackstone locations, respectively. In 2007, however, the yield response to N rate and sources was significantly less than that of 2006 due to low rainfall. At the Blacksburg location, ammonium sulfate and ESN resulted in higher CP concentrations, ranging from 11-14% and 12-20% for 2006 and 2007 growing seasons, respectively. Similar variation (12-20%) was observed for the Steeles Tavern location in 2006. In general, the ADF and NDF content decreased as N rate increased from 0-112 kg ha1. Although the source and rate that resulted in high yield and nutritive value varied across location and years, N rates and sources improved the quality and yield of stockpiled fescue. Experiment 2 utilized urea which was applied in the fall at the rates of 0, 45, 90 or 135 kg N ha-1. followed by spring application of 0, 45, 90 or 135 kg N ha-1. A total of 16 treatment combinations per replication were used. Yields ranged from 1,900 to 3,600 kg DM ha-1 and 700 to 2,500 kg DM ha-1 in 2007 and 2008, respectively. At the Steeles Tavern location, yields ranged from 3,100 to 5,700 kg DM ha-1 and 2,500 to 5,100 kg DM ha-1, in 2007 and 2008, respectively. In both years CP increased with increasing N fertilization. On a dry matter basis, CP values ranged from 14 to 23% for both years. Treatments did not affect on NDF and ADF values. Split fall/spring N applications did not maximize yield of cool-season grass pastures in these experiments.
- Assessment and Reaction of Triticum aestivum Genotypes to Fusarium graminearum and effects on Traits Related to Grain Yield and Seed QualityChappell, Matthew (Virginia Tech, 2001-12-14)Fusarium graminearum (Schwabe), causal organism of fusarium head blight (FHB), has become a major pathogen of wheat (Triticum aestivum L.) throughout North America. Since its discovery in the United States, the disease has spread south and east until at present it is an annual threat for growers of winter wheat in the Mid-Atlantic region. Yield losses for soft red winter (SRW) wheat averaged 908 kg ha-1 in the FHB outbreak of 1998 (Griffey et al., 1999). The economic loss from this single FHB epidemic was an estimated 8.5 million dollars. Environmental conditions favorable for FHB development, including above average rainfall and temperatures during anthesis, have become more common in the Upper-Midwestern wheat-growing region over the past decade, leading to substantial losses in wheat and barley crops. This, coupled with low prices being paid for wheat, has prompted research toward solving the problem of FHB across the nation. The majority of labor and financial resources devoted to FHB research are dedicated to incorporating FHB resistance into adapted wheat lines. While this is a prudent method of combating this disease, this process will take many years to complete. We have examined all FHB assessment parameters, which include FHB incidence, FHB severity, FHB index, percentage fusarium damaged kernels (percentage FDK), and 15-acetyl deoxynivalenol toxin (DON toxin) accumulation, to ascertain which assessment parameters best quantify FHB resistance levels in addition to grain yield and grain volume weight (GVW) losses. FHB index provides the most reliable in-field assessment of a genotype's resistance level, whereas percentage FDK provides a reliable measure of a genotype's resistance level post-harvest. FHB index and percentage FDK are also the most predictive assessment parameters with regard to grain yield and GVW loss. A wide range in both level and type of resistance was observed among genotypes examined in this study. The cultivars Agripro Patton, Ernie, INW9824, Roane, and the experimental line NY87048W-7388 consistently had lower scores for FHB assessment parameters and lower losses of grain yield and GVW.
- Assessment of Spectral Reflectance as Part of a Variable-Rate Nitrogen Management Strategy for CornLewis, Emily Kathryn (Virginia Tech, 2004-08-02)Spectral reflectance-based, remote sensing technology has been used to adjust in-season nitrogen (N) fertilizer rates for wheat to account for spatial variability in grain yield potential at a sub-meter resolution. The objective of this study was to examine the relationships among spectral reflectance indices, corn tissue N content, chlorophyll measurements, plant size and spacing measurements, and grain yield to develop a similar strategy for variable-rate N management in corn. Irrigated and non-irrigated studies were conducted during the 2002 and 2003 growing seasons in eastern Virginia. Plots were treated with various rates of preplant, starter, and sidedress N fertilizer to establish a wide range of grain yield potential. Spectral measurements, tissue N, chlorophyll measurements, and plant physical measurements were collected at growth stages V6, V8, and V10. At maturity, grain yield was determined and correlated with in-season data and optimum N rate to calibrate in-season, variable-rate N fertilization strategies. Results from these studies indicate that spectral reflectance is well correlated with plant N uptake and chlorophyll meter readings and can also be correlated with final grain yield. These relationships may be used to develop a model to predict in-season, variable N application rates for corn production at a sub-meter resolution.
- Availability and Surface Runoff of Phosphorus from Compost Amended Mid-Atlantic SoilsSpargo, John Thomas (Virginia Tech, 2004-12-14)The accumulation of P in soil from land-applied biosolids and manure increases the risk for P enrichment of agricultural runoff. Transport of these residuals to areas where P may be efficiently utilized is necessary to reduce the threat to water quality. Composting can improve biosolids and manure handling characteristics to make their transportation more feasible; however, little is known about P dynamics in compost-amended soil. We investigated the factors controlling P solubility and plant availability in two soils, a Kempsville fine sandy loam (Typic Hapludult) and a Fauquier silty clay loam (Ultic Hapludalf), amended with one of 4 composts (2 biosolids composts and 2 poultry litter - yard waste composts), poultry litter, or inorganic P (as KH2PO4) in incubation and greenhouse pot studies. We also compared the effects of compost, poultry litter and commercial fertilizer on surface P runoff from a Fauquier silty clay loam that had received compost, poultry litter, or commercial fertilizer for 5 years. Organic amendments with higher concentrations of Fe, Al, and Ca had lower relative P solubility/availability. Phosphorus solubility in the Kempsville fine sandy loam, having far lower native P binding capacity, was more affected by Fe, Al, and Ca applied with the organic amendments. The concentration of P in runoff from the compost treatments was higher; however, infiltration was increased and runoff decreased so the mass loss of P and sediment was lower. Improved soil physical properties associated with compost applications aid to limit P runoff.
- Chemical, Physical, and Biological Factors Influencing Nutrient Availability and Plant Growth in a Pine Tree SubstrateJackson, Brian Eugene (Virginia Tech, 2008-10-24)Pine tree substrate (PTS) produced from freshly harvested loblolly pine (Pinus taeda L.) trees has potential for replacing or reducing the use of aged pine bark (PB) and peat moss as container substrates for horticulture crop production. The objective of this work was to determine the factors influencing nutrient availability in PTS compared to PB or peat substrates. Chapter two reports data on the response of japanese holly and azalea to fertilizer rate when grown in PTS and PB. This study demonstrated that an additional 2.4 kg·m-3 of Osmocote Plus (15N-3.9P-10K) controlled release fertilizer is required for both species when grown in PTS compared to PB. Data are reported in chapter three on the effects of fertilizer rate, substrate particle size, and peat amendment on growth and floral quality, and on post-production time-to-wilting of poinsettias. Data from this work show that PTS requires an additional 100 mg·L-1 N to grow poinsettias comparable to plants grown in peat unless the particle size of PTS was decreased or 25% peat was added, in which case no additional fertilizer was needed. Results also indicated that PTS shrinkage was similar to that of peat, and that post-production time-to-wilting in PTS plants was similar as plants grown in peat. Data in chapter four compares nitrogen (N) immobilization rates, substrate carbon dioxide (CO₂) efflux levels, and nutrient leaching in peat, PB, and PTS over time. Data from these studies indicated that more N immobilization occurs in PTS than in PB or peat and that the substrate CO₂ efflux levels (estimate of microbial activity) corresponds to N immobilization in all substrates. Nutrient availability, changes in physical and chemical properties, substrate shrinkage, and microbial activity in PTS compared to PB during long-term nursery production are reported in chapter five. Results showed that substrate nutrient levels remain lower in PTS and that pH levels of PTS decrease considerably over two growing seasons compared to PB. Results also indicate that PTS does decompose over time in containers, but substrate shrinkage of PTS is similar to that of PL and PB during crop production.
- Combining ability, protein, heterosis, and prediction of F₁ performance with RFLPs in a diallel of maizeBall, Dale Warren (Virginia Tech, 1994-07-06)Improving protein quality and identifying superior inbreds and hybrids are significant challenges in commercial maize breeding programs. These two problems were addressed in separate studies on inbreds and hybrids from a complete diallel cross of 12 elite proprietary inbred lines of maize evaluated in field trials in two locations for two years. One of the inbreds (WI) was a novel source of high quality protein obtained from Wilson Seeds, Inc. in Harlan, Iowa. In the first study, diallel analyses were used to study combining ability and types of gene action important in the inheritance of protein content, grain yield, grain moisture at harvest, time to silk, kernel hardness, and density. General combining ability (GCA) and specific combining ability (SCA) effects were highly significant for all traits indicating presence of both additive and non-additive effects, respectively. Reciprocal effects (REe), often assumed to be absent in maize diallel studies, were significant for grain yield and protein concentration, suggesting that choice of female parent may be important for these traits. Ratios expressing the relative importance of GCA and SCA indicated that protein concentration is controlled primarily by additive gene action. In the second study, restriction fragment length polymorphism (RFLP) data were obtained for the 12 inbreds using 42 genomic clones each with four restriction enzymes. Modified Roger's distances were calculated and used in cluster analyses for heterotic grouping of the inbreds. Two measures of level of heterozygosity and hybrid value were evaluated as means of predicting Fl performance of hybrids in the complete diallel set of hybrids and in groups of hybrids representing crosses between and within heterotic groups. Results from this study confirm those of previous investigations with respect to prediction of hybrid performance when comparable groupings of crosses between related and unrelated lines were evaluated. This study further indicates that RFLPs may also be useful for prediction of hybrid performance in situations typical of early generations of many maize breeding programs where recombinant inbreds are testcrossed to a common tester inbred.
- Continuous No-till Management: Implications for Soil Quality, Carbon Sequestration, and Nitrogen ConservationSpargo, John T. (Virginia Tech, 2008-02-01)No-till management for agronomic crop production is recognized as an effective practice to regain a portion of soil organic matter lost following decades of cultivation. Increasing soil organic matter sequesters C, conserves organic N and concomitantly improves soil quality. Objectives of this research were to: i) quantify C sequestration rate and N conservation with duration of continuous no-till; ii) measure C stratification with continuous no-till as an indicator of soil quality; and iii) evaluate the Illinois soil N test (ISNT) for its value to predict fertilizer N needs of corn in Virginia. Objectives i and ii were achieved by collecting soil samples from 63 production fields in the Virginia Coastal Plain that were managed using continuous no-till from 0 to 14 yrs. No-till management resulted in sequestration of 0.308 ± 0.280 Mg C ha⁻¹ y⁻¹ and conservation of 22.2 ± 21.2 kg N ha⁻¹ yr⁻¹ (0-15 cm). The C stratification ratio (0-2.5 cm: 7.5-15 cm) increased with increasing duration of continuous no-till (0.133 ± 0.056 yr⁻¹) due to the accumulation of organic matter at the soil surface indicating improved soil quality with continuous no-till management. Objective iii was addressed by conducting 29 on-farm fertilizer N response trials in major corn producing areas of Virginia with the duration of continuous no-till management ranging from 0 to 25 yrs. The ISNT values were significantly related to yield without fertilizer N (r² = 0.57; p<0.001) and relative yield (r² = 0.64; p<0.0001). We also found that the ISNT extracted a relatively consistent percentage of total soil N (16.3 ± 0.73 %) suggesting it is a poor indicator of labile N. Total soil N values did almost as well as the ISNT in predicting yield without fertilizer N (r² = 0.53; p = 0.0002), and equally well predicting relative yield (r² = 0.64; p<0.0001). Results do not suggest the ISNT is useful for measuring mineralizalbe N or improving fertilizer N recommendations in Virginia cropping systems.
- Corn Fertility Update--Spring 2010Reiter, Mark S.; Alley, Marcus M.; Thomason, Wade E.; Reiter, Scott (Virginia Cooperative Extension, 2010)This document offers advice on testing soil, and corn plant tissue to diagnose nutrient deficiencies.
- Corn Planting Dates in the Piedmont and Valley Regions of Virginia: How early is early?Alley, Marcus M.; Roygard, Jon; Brann, Daniel Edward, 1945-; Thomason, Wade E. (Virginia Cooperative Extension, 2019-03-29)Discusses best times to plant corn at various locations in the piedmont, and ridge and valley regions of Virginia.
- Corn Planting Dates in the Piedmont and Valley Regions of Virginia: How early is early?Alley, Marcus M.; Roygard, Jon; Brann, Daniel Edward, 1945- (Virginia Cooperative Extension, 2019-01-24)Discusses best times to plant corn at various locations in the piedmont, and ridge and valley regions of Virginia.
- Corn Planting Dates in the Piedmont and Valley Regions of Virginia: How Early Is Early?Alley, Marcus M.; Roygard, Jon; Brann, Daniel Edward, 1945- (Virginia Cooperative Extension, 2009)Discusses best times to plant corn at various locations in piedmont, and ridge and valley regions of Virginia.
- Corn Planting Dates in the Virginia Coastal Plain: How early is early?Alley, Marcus M.; Roygard, Jon; Brann, Daniel Edward, 1945- (Virginia Cooperative Extension, 2019-01-24)Discusses best times to plant corn at various locations in the coastal plain of Virginia.
- Corn Planting Dates in the Virginia Coastal Plain: How Early Is Early?Alley, Marcus M.; Roygard, Jon; Brann, Daniel Edward, 1945- (Virginia Cooperative Extension, 2009)Discusses best times to plant corn at various locations in the coastal plain of Virginia.
- Corn Planting Dates in the Virginia Coastal Plain: How early is early?Alley, Marcus M.; Roygard, Jon; Brann, Daniel Edward, 1945- (Virginia Cooperative Extension, 2019-02-13)Discusses best times to plant corn at various locations in the coastal plain of Virginia
- Cotton Yield as Related to Selected Physical and Chemical Properties of Soils of the Coastal Plain of Virginia and North CarolinaAdcock, Clyde Wesley (Virginia Tech, 1998-08-28)Cotton (Gossipium hiristum, L) is a warm season perennial with indeterminant growth habit. In 1995, 42,500 and 300,000 hectares were grown in Virginia and North Carolina, respectively. Soil physical and chemical properties may limit cotton yields. The objective of this study was to; 1) determine influences of soil physical and chemical properties on yield, 2) validate existing preharvest yield estimators, and 3) determine the effect of subsoiling and/or subsurface liming on cotton development and root growth. Two hundred sites were sampled across the Coastal Plain of Virginia and North Carolina to a depth of 92 cm representing 5 major soil series. Soil samples were analyzed for selected physical and chemical properties from each horizon. Boll and plant counts were obtained while harvesting a 3-meter length of row at each site to determine yield for the 1996 and 1997 growing season. Cotton was grown in the greenhouse on 30 cm diameter cores of a soil with low subsoil pH and a hard pan to determine the effects of subsoiling and/or subsurface liming. Ninety days after planting, the cotton plants were harvested and the above ground biomass and rootmass were analyzed. Physical and chemical properties explained 52% of yield variability in 1996 and 27% in 1997. Physical and chemical properties that were significant to yield were surface bulk density, available water holding capacity, depth of the water table and Bt horizon, Mg, K, Ca, and Al content. Soil analysis for nutrient status at depths up to 45 cm were better indicators of cotton yield. Subsoiling with or without subsurface liming increased rooting depth over the untreated check. The subsurface liming reached first flower 11 days prior to the other treatments. The additional period for flowering and boll set in Virginia and North Carolina could increase potential yield.
- Deep Tillage Prior to No-Till Corn: Research and RecommendationsThomason, Wade E.; Grisso, Robert D.; Balderson, T. Keith; Davis, Paul H.; Johnson, Sam; Lawrence, Chris; Lewis, Matthew A.; Moore, David M.; Alley, Marcus M. (Virginia Cooperative Extension, 2019-03-29)Compares cultivation of corn by no-till and deep tillage and notes ways to reduce soil compaction, using deep tillage if soil compaction has effected crop growth and yield.
- Deep Tillage Prior to No-Till Corn: Research and RecommendationsThomason, Wade E.; Grisso, Robert D.; Balderson, T. Keith; Davis, Paul H.; Johnson, Sam; Lawrence, Chris; Lewis, Matthew A.; Moore, David M.; Alley, Marcus M. (Virginia Cooperative Extension, 2009)Compares cultivation of corn by no-till and deep tillage and notes ways to reduce soil compaction, using deep tillage if soil compaction has effected crop growth and yield.