Browsing by Author "Maguire, Rory O."
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- Biochar in Agricultural SystemsMaguire, Rory O.; Agblevor, Foster A. (Virginia Cooperative Extension, 2010-08-20)There has been a great deal of interest in biochar recently for many reasons, including bioenergy production, carbon sequestration, use as a soil amendment to improve productivity, and as an end use for animal manure. This publication serves as a brief introduction to biochar and many of the issues surrounding its generation and use.
- Biochar in Land Reclamation, Biosolids Applications and Prescribed FiresFields-Johnson, Christopher Warren (Virginia Tech, 2016-12-01)Biochar is a form of stable organic carbon whose application to soils has the potential to sequester large amounts of atmospheric CO2 while improving the physical, chemical and biological properties of soil. However, the optimal rates and methods of biochar application are unknown for many situations. Three experiments were performed to test methods of biochar application to soils as a stand-alone amendment, in combination with biosolids as a complementary amendment and in-situ through controlled landscape burning. The first was a greenhouse pot study, which involved combining biochar with spoil from an Appalachian surface coal mine to grow trees. Biochar combined with mine soil produced a much higher growth rate for trees, and pure biochar helped tree root growth, suggesting that it might be useful as a broadcasted amendment, as a nursery growing medium or as a backfill in tree planting holes. The second experiment explored methods to combine biochar and biosolids materials to form a granular product. Combining biochar and biosolids before applications reduced windborne losses of biochar as well as the nutrient leachate produced by the biosolids. Drum rolling was found to work best for producing aggregate granules. Wetting pure biochar to 100% gravimetric water content before applications reduced windborne losses from over 50% to under 5% as compared to when it was applied as a dry product. A series of controlled burns were conducted in the third experiment to determine the ideal range of meteorological conditions to produce the highest possible biochar yields in-situ. Relative humidity, forest litter moisture and ambient temperature were found to be the governing factors over the tonnage of biochar produced. Up to 3.0 Mg Ha-1 of biochar were produced under ideal conditions by controlled burning. Repeated high-yielding burns have the potential accumulate large amounts of biochar in the soil to improve soil properties.
- Building Healthy Soil with Best Management PracticesPoukrel, Sapana; Maguire, Rory O.; Thomason, Wade E.; Stewart, Ryan D. (2022-10-12)
- Compost Application Practices for Revegetating Disturbed SoilsDunifon, Shea Nicole (Virginia Tech, 2009-12-04)Urban development alters the physical and chemical properties of soil which presents challenges for vegetation establishment. Compost, when applied as a soil amendment, can help to ameliorate these challenges. In field trials, we evaluated the effect of surface-applied composts and standard hydroseeding applications on changes in soil properties and turfgrass stand on a highway roadside. The short-term effects of (1) no compost application; (2) 2.5 cm compost surface mulch; (3) 2.5 cm compost application, incorporated; (4) 5.0 cm compost application, incorporated; (5) 0.6 cm compost blanket; and (6) straw mat on turfgrass establishment, quality and changes in soil properties were measured on an urban soil devoid of topsoil. In greenhouse studies, we compared the effect of depth of planting of two variously-sized turfgrass seeds in compost. The soils of the disturbed roadside and the urban soil had increased Mehlich I-extractable soil K, Mg, and P following compost application. Analysis of botanical composition on the highway roadside demonstrated that the percentage of fescue decreased with time, while weed species increased inversely in both treatments. Compost amendments on the urban soil increased turfgrass color over time, whereas turfgrass density was not affected by time. Turfgrass density was greatest in applications of a 5 cm depth compost incorporated 7-10 cm into the soil. No differences were observed in biomass harvested among treatments. Tall fescue seeds had greater germination and establishment than smaller sized bermudagrass seeds when sown below the surface of compost, regardless of depth. Composts help to regenerate topsoil-like functionality in disturbed soils by promoting vegetation establishment, including weeds, on highway roadsides and improving turf quality on urban soils.
- Culturable antibiotic-resistant fecal coliform bacteria in soil and surface runoff after liquid dairy manure surface application and subsurface injectionHilaire, Sheldon Shervon; Chen, Chaoqi; Radolinski, Jesse; Leventhal, Talia; Preisendanz, Heather; Kleinman, Peter J. A.; Maguire, Rory O.; Stewart, Ryan D.; Saporito, Lou S.; Xia, Kang (Wiley, 2022-02-05)Land application of manure, while beneficial to soil health and plant growth, can lead to an overabundance of nutrients and introduction of emerging contaminants into agricultural fields. Compared with surface application of manure, subsurface injection has been shown to reduce nutrients and antibiotics in surface runoff. However, less is known about the influence of subsurface injection on the transport and persistence of antibiotic-resistant microorganisms. We simulated rainfall to field plots at two sites (one in Virginia and one in Pennsylvania) 1 or 7 d after liquid dairy manure surface and subsurface application (56 Mg ha–1) and monitored the abundance of culturable antibiotic-resistant fecal coliform bacteria (ARFCB) in surface runoff and soils for 45 d. We performed these tests at both sites in spring 2018 and repeated the test at the Virginia site in fall 2019. Manure subsurface injection, compared with surface application, resulted in less ARFCB in surface runoff, and this reduction was greater at Day 1 after application compared with Day 7. The reductions of ARFCB in surface runoff because of manure subsurface injection were 2.5–593 times at the Virginia site in spring 2018 and fall 2019 and 4–5 times at the Pennsylvania site in spring 2018. The ARFCB were only detectable in the 0-to-5-cm soil depth within 14 d of manure surface application but remained detectable in the injection slits of manure subsurface-injected plots even at Day 45. This study demonstrated that subsurface injection can significantly reduce surface runoff of ARFCB from manure-applied fields.
- The effect of fast pyrolysis biochar made from poultry litter on soil properties and plant growthRevell, Kenneth Todd (Virginia Tech, 2011-12-20)Little is known about the effect of biochar created from poultry litter on soil properties and plant growth. Five studies were conducted using biochar made by the fast pyrolysis of poultry litter. Two were greenhouse studies and three were field studies. The greenhouse studies were conducted with a sandy loam soil and a silt loam soil. First, lettuce (Lactuca sativa L) seeds were germinated in the greenhouse across biochar incorporation rates from 0 to 100%, and secondly a trial was conducted in which green peppers (capsicum annum L) were grown in soils with up to 5% biochar by weight. Elemental analysis was completed on the biochar and the soils were analyzed for bulk density (BD), water holding capacity (WHC), pH, cation exchange capacity (CEC), soluble salts (SS) and extractable nutrients. The field studies all used the rates of 0, 4.5, and 9 Mg ha-1 biochar and the rates were applied in the early spring of 2009 and 2010. Biochar was surface applied on a tall fescue pasture [Lolium arundinaceum (Schreb.) Darbysh. (=Festuca arundinacea Schreb. subsp. arundinacea)] and tilled in on two green pepper field sites. The soils were analyzed for carbon (C) content, pH, CEC, Mehlich 1 P, and SS. No significant difference was found in yields at any of the three sites, but differences in forage quality were found. Biochar made from poultry litter showed several benefits as a soil amendment in all the studies, but application rates would be limited by soil test P and pH.
- Effect of Synthetic Chelating Agent Application to Soils on Phosphorus AvailabilityEdwards, Cristie LeAnne (Virginia Tech, 2013-08-06)Fertilizer phosphorus (P) can become unavailable to crops due to immobilization of P in acidic soils through forming chemical bonds with iron (Fe) and aluminum (Al) amorphous oxides. Organic chelating agents form strong bonds with metals in soil and may reduce P binding with Fe and Al. Ethylenediamine tetraacetic acid (EDTA), hydroxyethyl ethylenediamine triacetic acid (HEEDTA), gluconic acid (GA), and citric acid (CA) were tested to determine their influence on water-soluble P (WSP), Mehlich-1 P and Mehlich-3 P in Loam and Sand soils fertilized with P and incubated for 49 days. Soil P sorption capacity (PSC) was estimated from an oxalate extraction of Fe and Al, and chelates were applied at rates of 90 percent of the PSC. The EDTA, HEEDTA, and CA significantly (P<0.05) reduced P sorption in the Loam and Sand when measured by WSP. In soils without P fertilizer added, EDTA and HEEDTA significantly increased WSP, Mehlich-1, and Mehlich-3 P concentrations. EDTA and HEEDTA were also applied at 0, 30, 60, 90, 120, and 150 percent PSC to produce a rate response curve for WSP in a second soil incubation. With increasing chelating rate, there was a linear increase in WSP for both soils, thus indicating higher rates of chelating agents were most efficient at decreasing P sorption. EDTA and HEEDTA were also tested in a 4-week greenhouse study for efficiency at increasing plant available P to corn (Zea mays L.) in two soils. Phosphorus was added with and without the addition of chelating agents to the center of the pot, simulating a starter band of P. After 4weeks, soils were analyzed for WSP, Mehlich-1, and Mehlich-3 P and corn above- and below-ground biomass was quantified and analyzed for total P concentration. Without the presence of chelating agents, concentrations of WSP, Mehlich-1 P, Mehlich-3 P, above- and below-ground biomass, and TKP increased linearly as P fertilizer rates increased at 0, 9.6, 19.3, 28.9, and 38.5 kg P ha-1. Decreased P sorption using chelating agents was not observed in this experiment. However, with the results from the soil incubation, chelating agents do show potential for increasing plant available P, but the application and incorporation method needs to be further studied.
- Effects of Biofertilizers and Organic Amendments on Nutrient Availability in Soil and Plant GrowthMott, Joshua Darell (Virginia Tech, 2022-04-28)Applications of fertilizers derived from non-renewable resources, along with improved land management practices have contributed greatly increased crop yields in the past 70 years. Biofertilizers and organic amendments, provide alternative sources of nutrients for increased plant yields and resistance against abiotic stress. The objective of this work was to evaluate the effectiveness of various biofertilizers and an organic amendment on improve plant health and/or crop yield. The first study focused on the organic amendment, glucoheptonate and found that applications of 800-1600 kg/ha can increase available water capacity in fine textured soils by up to 3%. The second study evaluated the effectiveness of dual-inoculating biofertilizers Mung beans (Vigna radiata (L.) Wilczek) with two, bradyrhizobium spp. and arbuscular mycorrhizal fungi. Dual inoculation significantly increased grain yield (+33%) compared to a synthetic N fertilizer application but did not significantly increase grain yield compared to the control (+22%). Dual inoculation may increase grain yields of mung beans compared to synthetic fertilizer regime but does not show evidence of improving N fixation. The final study was a greenhouse experiment focused on evaluating some mung bean cultivars to determine their susceptibility to salt stress while also evaluating the effect of inoculation in combating saline soils. Germination was significantly decreased at 6 dS/m in all cultivars by about 36% when compared to the control treatment (0 dS/m). Seed yields, pods per plant and seeds per plant, increased as salt concentration increased. No factors recorded where affected by inoculation. Overall, our research suggests that the use of biofertilizers and organic amendments can improve crop health, but other management and environmental considerations need to be accounted for when reporting effectiveness of such alternative soil amendments
- Effects of Manure Injection on Transport and Transformation of Nutrient and AntibioticsKulesza, Stephanie Brooke (Virginia Tech, 2015-10-13)Overapplication of manure in sensitive watersheds is an issue of increasing environmental concern due to increased nutrient loading and antibiotic release into aquatic environments. Manure is typically surface applied, leaving nutrients and antibiotics vulnerable to loss at the soil surface. Elevated nutrient and antibiotic loading into water bodies can increase the rate of eutrophication and occurrence of antibiotic resistance genes in areas of high animal agriculture production, such as the Chesapeake Bay watershed. Manure injection is a new technology that incorporates manure into the soil with minimal disturbance, and management strategies that reduce manure loss from agricultural fields could prevent the transport of nutrients and antibiotics to sensitive waterways. However, little is known about the efficacy of dry litter injection to decrease nitrogen (N) loss when compared to surface application. Also, there are no studies that determine the effects of injection on antibiotic transport and transformation after manure application. Therefore, this project focused on changes in N cycling, orchardgrass hay yield and quality, and transport and transformation of pirlimycin and cephapirin, two common antibiotics in dairy production, when manure is injected. Subsurface injection eliminated ammonia volatilization and N loss in runoff and increased soil inorganic N when compared to surface application after volatilization, incubation, and rainfall simulation studies. Although these benefits did not translate to higher yields in orchardgrass hay, protein increased when poultry litter was injected, indicating greater N uptake. Injection of dairy manure decreased losses of pirlimycin to levels of the control when compared to surface application. Although, pirlimycin had a slower degradation rate within the injection slit compared to surface application, potentially increasing the amount of time soil microbes are exposed to antibiotics. In an incubation study, pirlimycin concentrations decreased after 7 days, but concentrations increased sharply after 14 days. This indicates that conjugates formed in the liver or digestive tract of dairy cows may revert back to the parent compound after manure application. With increased retention of nutrients and antibiotics, injection could be a best management practice used to reduce the loss of these compounds to the environment while increasing the quality of crops produced.
- Effects of Phosphorus Supplementation on Grazing Beef CattleNeil, Scott Joseph (Virginia Tech, 2015-11-04)Phosphorus (P) losses due to overfeeding of the mineral to livestock can contribute to surface water degradation. The objective of this study was to examine the impact to supplementing various levels of mineral P to grazing beef cattle. A producer survey and a research trial were conducted to examine the effects of supplementing mineral phosphorus (P) to grazing cattle. In the first study, mineral tags, producer surveys, and fecal, forage, and soil samples were collected from beef cattle operations in Virginia's Chesapeake Bay watershed. Samples (n=166) were collected from 120 producers in 11 counties. Soil test P results were based on Virginia Cooperative Extension soil test guidelines characterized as low (12 %), medium (37 %), high (35 %), and very high (16 %). Pasture grab samples contained 0.34 ± 0.12% P and forage P concentration increased (P < 0.01) across soil P categories going from low to very high. Fecal total phosphorus (TP) was lowly correlated (R2 = 0.18, P < 0.01) to forage P concentration. Mineral supplements were categorized as nil (<1.0% P), low (1.0-<3.0% P), medium (3.0-<6.0% P), and high (>6.0% P). Fecal TP and inorganic phosphorus (Pi) concentration increased (P < 0.01) with mineral P levels. Fecal TP and Pi were lower (P < 0.01) when nil and low P mineral were supplemented as compared to medium and high P mineral. Soluble P (defined as fecal Pi/fecal TP*100) also increased (P < 0.01) with increasing mineral P content going from nil to high. All farms surveyed required little or no P supplementation in regard to beef cattle P requirements. The majority (82%) of producers were receptive to modifying mineral P supplementation practices based on forage P levels. A 56-d study was also conducted with eight yearling Hereford steers (261±30 kg) grazing cool-season grass fall re-growth to determine the effects of varying levels of P supplementation on fecal P excretion. Treatments consisted of dicalcium phosphate supplemented at 0 (D1), 10.0 (D2), 20.0 (D3), or 30.0 (D4) g/d in a randomized 4x4 replicated Latin square design. These treatments provided an additional 0, 1.9, 3.7, and 5.6 g/d of P respectively. Two esophageally cannulated steers were used to collect forage samples for nutrient analysis. Forage P content was analyzed from hand collected samples. Forage P concentrations averaged 0.49% of dry matter (DM) across all periods. Chromic oxide (Cr2O3) was administered twice daily via gelatin capsule at 0630 and 1830 to serve as an external marker for determination of fecal dry matter excretion (DME). Indigestible NDF (iNDF) was used as an internal marker to determine dry matter intake (DMI). Due to the high forage P content, average P intake was in excess of National Research Council (NRC) requirements for all diets (D1 = 281%; D2 = 297%; D3 = 323%; D4 =348%). Orthogonal contrasts were performed to assess the relationship between treatment and P excretion. A linear response (P < 0.01) in daily inorganic P (Pi) excretion (0.054, 0.052, 0.062 and 0.063 g/kg of BW ± 0.003 for D1, D2, D3 and D4, respectively) was observed across treatments. Daily total P (TP) excretion increased linearly (P < 0.01) across treatments (0.080, 0.079, 0.092 and 0.093 g/kg of BW ± 0.003 for D1, D2, D3 and D4, respectively. When forage P content is sufficient to meet the requirement of grazing cattle, increasing P supplementation results in greater P excretion without additional benefits to growth or nutrient digestibility.
- The Effects of Rootstock Selection and Carbon-based Fertility Amendments on Apple Orchard Productivity and Soil Community EcologyThompson, Ashley A. (Virginia Tech, 2016-12-08)In apple (Malus domestica Borkh.) orchards, rootstock genotype, and soil fertility management practices impact soil fertility, plant associated soil microbial communities, and orchard productivity. Apple growers select rootstocks to confer beneficial traits, including size control, precocity, and pest and disease resistance. Rootstock genotype may also influence microbial communities, resulting in changes that affect tree health and productivity. Many apple growers apply synthetic nitrogen fertilizers to improve fruit yield and quality. In excess of tree requirements, nitrogen fertilizers may reduce crop yield and quality, as well as contribute to water pollution. The addition of carbon-based amendments, such as yardwaste, chicken litter composts, and biochar, may potentially reduce nitrogen and water loss, while improving soil structure and mineral nutrient availability. Orchard and pot-in-pot experiments were designed to study the following objectives: 1) determine the effects of integrated carbon-based fertilizer amendments on tree growth, productivity, and orchard soil fertility, 2) assess the effects of biochar on tree growth, leaf mineral nutrition, soil physiochemistry, and microbial community structure and activity, and 3) understand how rootstocks and fertilizers alter soil microbial communities. Applications of composts, integrated compost-calcium nitrate fertilizers, and biochar increased soil carbon, organic matter, cation exchange capacity and microbial respiration. In the orchard study, nitrogen fertilizer application did not increase tree growth, fruit quality, or leaf nitrogen concentration. Biochar applied at high rates with nitrogen fertigation increased tree growth and leaf nitrogen concentration similar to nitrogen fertigation. In the pot-in-pot compost study, chicken litter compost increased tree growth, and integrated compost-calcium nitrate fertilizer applications increased leaf N concentration. Analysis of the microbial community structure of bulk soil samples from the biochar and compost pot-in-pot experiments determined that the community structure was similar for all treatments during the three-year study. Metagenomic sequencing of the rhizosphere bacterial community indicated that compost applications altered community diversity and evenness, and that compost treatments were more similar to each other than to the calcium nitrate treatment. Data from my dissertation research suggests that compost can be used to increase orchard soil fertility, tree growth, and leaf nutrition, and that compost applications increase soil microbial community diversity and activity.
- Environmental Fate of Animal Manure-associated Antibiotics and Seed-coated Pesticide in SoilsCushman, Julia Ananieff (Virginia Tech, 2017-02-20)There is growing concern over the environmental and human health impacts of chemical contaminants in agricultural systems. The environmental persistence of veterinary antibiotics applied to agricultural fields during manure fertilization could lead to increased antibiotic resistance. New generation, neonicotinoid pesticides pose a threat to aquatic ecosystem health due high water mobility and increased potential for non-target exposure. The objectives of this research were to develop a sensitive, analytical method for quantification of pirlimycin (PLY) in soils to be used in field research and determine the ability of second-generation neonicotinoids to move through soil when applied as a seed coating using a greenhouse study. Liquid-solid extraction of PLY from soil using (1:6, v/v) ammonium hydroxide/methylene chloride produced good PLY recovery (67-140%). Liquid-chromatography coupled with tandem mass-spectrometry for instrumental analysis provided good sensitivity with minimal matrix interferences. The mass balance distribution of neonicotinoid treatment coated onto corn seeds was determined in plant and soil samples for a single pot after 3 weeks of growth. A large percent (83-87%) of initial pesticide coating applied to seed was un-detected in plant in soil. Of the detected portion of neonicotinoid treatment, between 96-98% was observed to move out into the soil. This suggests the potential for long-range transport of seed-coated neonicotinoids.
- Evaluating Effects of Bradyrhizobium and Arbuscular Mycorrhizal Fungi Inoculation on Yield Components of Mung Bean (Vigna radiata (L.) Wilczek) and Nitrogen FixationMott, Joshua; Abaye, Azenegashe Ozzie; Reiter, Mark S.; Maguire, Rory O. (MDPI, 2022-09-30)Mung beans (Vigna radiata (L.) Wilczek) are only inoculated in some production systems, but there is a current lack of knowledge on the best inoculants to use for effective nitrogen fixation (nodulation) and plant yields. The objectives of the present study were to determine if the dual inoculation of Arbuscular Mycorrhizal Fungi (F) and Bradyrhizobium (R) provides greater (a) mung bean yield and quality (b) nitrogen fixation for mung bean and residual soil nitrogen for the following crop, and (c) determine if these effects are consistent across various environments. Field trials were conducted in Blacksburg, VA (sandy clay loam), and Eastern Shore, VA (sandy loam), over the summers of 2020 and 2021. There were 5 treatments replicated 5 times for each variety at each site; R, F, R + F, high nitrogen (N) (100 kg ha−1), and a control, for a total of 25 plots per site. Mung beans grown in Blacksburg in 2020 and 2021 averaged 53.8% more seeds per pod than mung beans grown at the Eastern Shore. Overall yield components (seeds per pod, pods per plant) are heavily influenced by soil type. Dual inoculation significantly increased grain yield (+33%) compared to a synthetic N fertilizer application, but did not significantly increase grain yield compared to the control (+22%). Dual inoculation may increase the grain yields of mung beans compared to synthetic fertilizer regime, but does not show evidence of improving N fixation.
- Evaluation of alternative forage species to reduce risk for cow-calf production systems in the Appalachian regionNewman, Christina Louise (Virginia Tech, 2010-11-30)Optimizing forage productivity is essential to reduce pasture seasonality and ensure available forage to meet the nutritional needs of livestock. This study explores the risk-buffering ability of warm-season forages to fill the summer slump gap in production of cool-season grasses. Small plot experiments were initiated in summer of 2008 in Kentland Farm, Northern Piedmont AREC and Shenandoah AREC, Virginia. Treatments included endophyte-infected tall fescue (KY31 E+), endophyte free tall fescue (KY31 E-), novel endophyte tall fescue (MaxQ), Crabgrass in combination with endophyte-infected tall fescue, Teff, Bermudagrass (BG), and Caucasian bluestem (CB). Plots were harvested May through October of 2009 and 2010 at the late boot stage at a cutting height of 10cm. Subsamples were analyzed for dry matter and nutritive value. To assess risk, bootstrap distributions of biomass and quality data were generated by Monte Carlo simulation and compared against an objective function defined as 59 kg ha-1 d-1 forage yield; 10% CP; 60% TDN. Regardless of variability, warm-season grasses produced biomass yields and nutritional values adequate to fill the summer slump from cool-season forages and demonstrated a higher probability of meeting the minimum requirements in July, August and September. Teff was most consistent in meeting the minimum requirements in mid-summer. However, with good conditions for establishment, both BG and CB can help to fill the gap in summer months when compared to cool-season tall fescue. Bootstrap distributions provide producers with a tool that links their production goals with a measurable value of production risk.
- Explanation of Soil TestsMaguire, Rory O.; Heckendorn, Steven E. (Virginia Cooperative Extension, 2018-12-07)Explains soil tests, and helps with assessing fertilizer and lime requirements for plants.
- Fertilizer Types and Calculating Application RatesMaguire, Rory O.; Alley, Marcus M.; Flowers, Webb (Virginia Cooperative Extension, 2009)Offers advice on inorganic fertilizers, types to use, when to apply, and methods of application in relation to soil types of crop fields.
- Fertilizer Types and Calculating Application RatesMaguire, Rory O.; Alley, Marcus M.; Flowers, Webb (Virginia Cooperative Extension, 2019-08-30)Offers advice on inorganic fertilizers, types to use, when to apply, and methods of application in relation to the soil types of crop fields.
- Fertilizing Cool-Season Forages with Poultry Litter versus Commercial FertilizerMaguire, Rory O.; Tracy, Benjamin F.; McGrath, Steven Russell; Clark, Bobby (Virginia Cooperative Extension, 2009)The choice between using poultry litter and commercial fertilizer should be based on price of nutrients, their availability, and any machinery limitations as litter and fertilizer use different spreaders.
- Fertilizing Cool-Season Forages with Poultry Litter versus Commercial FertilizerMaguire, Rory O.; Tracy, Benjamin F.; McGrath, Steven Russell; Clark, Bobby (Virginia Cooperative Extension, 2019-08-30)Compares using poultry litter and commercial fertilizers, with choices based on price of nutrients, their availability, and spreader limitations.
- Impact of Changing From Nitrogen- to Phosphorus- Based Manure Nutrient Management PlansMaguire, Rory O. (Virginia Cooperative Extension, 2009)Animal manures are a good source of nitrogen (N) and phosphorus (P) for agricultural crops, but they have an imbalance in their N to P ratio.