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Wheat (Triticum aestivum, L.) producers have the choice to retain or remove residue from the cropping system following grain harvest. In the U.S. Pacific Northwest and other regions, wheat residue is often sold to increase operational profitability, especially from higher-yielding systems. But there are several benefits to retaining residue, including recycling of mineral nutrients contained therein, though this is understudied. Therefore, the primary objectives of this research were to collect and analyze a large and diverse dataset on wheat residue nutrient uptake (N, P, K, Ca, Mg, S, Fe, Zn, Mn, Cu), develop tools to estimate nutrient amounts in residue, and make economic estimates of the fertilizer replacement value of those nutrients. This was accomplished by conducting replicated variety trials on five classes of wheat across many Pacific Northwest sites over two years, then collecting and analyzing data on wheat residue biomass, residue nutrient concentrations, and grain yield. The results showed that wheat residue contained a significant amount of nutrients, but was particularly concentrated in K. Production environment had the most substantial effect on residue mineral uptake amounts, due to site differences in yield and soil nutrient availability. To enable simple estimation of residue nutrient uptake across a broad range of wheat production levels, two estimation tools are presented herein. Economic analysis showed the substantial monetary value of residual nutrients. For example, in a high-yielding wheat crop (9 Mg ha−1), the average fertilizer replacement value of just residue N, P, K, and S was similar to the entire fertilizer budget to grow the crop (~$211 vs. $205 ha−1), not considering micronutrients in the residue or any nutrients removed through grain harvest. In making residue management decisions, wheat producers should consider the tradeoff between the immediate economic gains of residue sale and the multifaceted benefits of residue retention, including savings on future nutrient costs. [ABSTRACT FROM AUTHOR]

Determination of barley (Hordeum vulgare L.) nutrient uptake in residue biomass is important for agronomic, economic, and environmental decisions. Improved understanding of grain yield, residue biomass, nutrient uptake, and their relationships are needed. Research determined these factors in 2018 and 2019 from trials of four barley classes (spring animal feed, human food, and malt, as well as winter malt), using three common cultivars of each, at five locations in southern Idaho. Production environment created the largest difference in residue biomass and nutrient uptake. Barley harvest index ranged from 0.46 to 0.52 Mg Mg−1 across feed, food, and malt classes. Compared to previous estimates, nutrient concentrations from the combined dataset were greater than for N, less than for P, and greater than for K. Correlation of grain yields to nutrient uptake (excluding Cu and Fe) had r2 ranging from 0.68 to 0.89. At current prices, economic analysis indicated that fertilizer replacement costs for total residue biomass nutrients were greater than previous estimates and could greatly exceed current sale value. These relationships and value estimates can be used to improve prediction of barley residue biomass production and nutrient uptake to guide best management practices. The decision of how to utilize these metrics (on‐farm, regional, etc.) should be considered based on known variation in measured nutrient and residue data and considered in relation to the proposed task. Core Ideas: Limited research has focused on nutrient uptake and economic value of barley residue biomass (straw + chaff).Production environment created the largest differences in residue biomass and nutrient uptake across barley classes.Average harvest indices (HI) were 0.51, 0.47, 0.52, and 0.46 Mg Mg−1 for feed, food, spring malt, and winter malt barley.N uptake combined across classes was greater than previous estimates, P was less, and K was greater.Fertilizer replacement cost of nutrients removed in residue may far exceed the sale value. [ABSTRACT FROM AUTHOR]

Alfalfa (Medicago sativa L.) intercropping with maize (Zea mays L.) silage is being developed in the northern United States to improve the profitability and environmental sustainability of forage production. This study, conducted under rainfed conditions in Wisconsin and semiarid irrigated conditions in Idaho, compared the establishment of alfalfa and dry matter yield of four intercropping systems to three conventional systems. The former systems included alfalfa interseeded at planting or the vegetative emergence (VE) stage of maize and grown with or without prohexadione growth retardant. The latter systems included alfalfa seeded in spring, summer‐seeded after barley (Hordeum vulgare L.), or late summer‐seeded after maize silage. Spring seeded and interseeded alfalfa in Wisconsin also received foliar fungicide and insecticide during establishment. During alfalfa establishment, yield of intercropped maize silage was 1.8‐ to 4.4‐fold greater than spring‐seeded alfalfa. Compared to spring‐seeded alfalfa, interseeded alfalfa had similar or somewhat lower stand density but similar first cut yield the following year, provided that intercropped maize was harvested near September 1 to allow ample alfalfa fall regrowth. Shifting interseeding from maize planting to the VE stage decreased early‐season alfalfa growth, but improved maize silage yield, with minor effects on alfalfa fall growth, stand density, and first cut yield. Prohexadione application had little impact on establishment or yield of interseeded alfalfa. While having high plant density, alfalfa seeded after barley or especially maize had less fall growth and low first cut yield. Overall, alfalfa establishment and yield of intercropping systems compared favorably with conventional systems. Core Ideas: Delaying alfalfa interseeding until the vegetative emergence stage improved maize silage companion crop yield.During alfalfa establishment, intercropped maize silage had up to 4.4‐fold greater yield than solo‐seeded alfalfa.Early harvest of maize silage improved fall growth and first cut yield of interseeded alfalfa after establishment.Interseeded and spring solo‐seeded alfalfa had comparable stand density and first cut yield after establishment.Summer solo‐seeded alfalfa had relatively poor fall growth and first cut yield after establishment. [ABSTRACT FROM AUTHOR]

Approximately 37% of US milk production occurs in semiarid regions, providing an opportunity to recycle manure nutrients through a variety of cropping systems. Accurate prediction of nitrogen (N) mineralization is critical to determine manure application suitability in intensive irrigated agriculture as many crops in the region have quality parameters that are sensitive to N. Research was conducted in southcentral Idaho to evaluate N mineralization via a buried bag methodology to develop a predictive N‐mineralization model. The study was arranged in a randomized complete block design with manure application rates of 18, 36, and 52 Mg·ha−1 (dry weight basis) both annually and biennially with synthetic fertilizer and untreated check treatments. The crop rotation included small‐grain and broadleaf crops. In the final year of the study, preplant soil organic carbon, total nitrogen, and NO3–N concentrations were positively linearly correlated with manure application rate. Nearly five times as much N was mineralized annually in the 0‐ to 30‐cm depth as compared to the 30‐ to 60‐cm depth. Increased rates of N mineralization for each kilogram of added N occurred in years when residue from broadleaf crops (slope = 0.17) was applied as compared to years with manure only application (slope = 0.07). Stepwise modeling determined that the most predictive model for seasonal N mineralization (R2 = 0.79) included manure N, residue N, soil organic matter, and electrical conductivity. These results allow preplant N mineralization estimation and will prove critical for managing manure in semiarid regions for agronomic, economic, and environmentally sound crop production. Core Ideas: Tools are needed to estimate nitrogen (N) mineralization from applications of dairy manure in semiarid irrigated soils.N mineralization was affected by manure application rate, timing, and broadleaf residue N.Average manure N mineralization was 27% and 18% of N applied in the first and second years, respectively, following application.The incorporation of broadleaf residue with manure increased N mineralized to 41% of N applied.The best predictors of N mineralization were soil organic matter, soil electrical conductivity, manure N, and broadleaf N residue. [ABSTRACT FROM AUTHOR]

Semiarid regions are reliant on irrigation to produce large‐yielding and high‐quality malt barley (Hordeum vulgare L.). Drought in the western United States is of concern as surface and ground water reductions are occurring that affect irrigation water availability. Implementing a seasonal water deficit compared to evapotranspiration (ET) is a potential strategy to reduce water usage if yield and quality can be maintained. Research was conducted in Aberdeen, ID, on the effects of deficit irrigation on yield, grain quality, and malt characteristics. Five genotypes were selected to represent those used for large‐scale adjunct brewing and those targeted at the all‐malt craft industry. Irrigation was managed at three rates (100%, 75%, and 50%) of estimated crop evapotranspiration (ETc) using sprinkler irrigation. Total aboveground dry matter was not affected by irrigation until soft dough (Feekes 11.2). Yield was similar within a genotype with irrigation reduction from 100% ETc to 75% ETc. Averaged across genotypes, yields were 6936 kg ha−1 at 100% ETc and 6297 kg ha−1 at 75% ETc. At 75% ETc, protein remained just below the adjunct target (130 g kg−1) for four of five genotypes while all five exceeded the all‐malt target (120 g kg−1). Reduced irrigation decreased malt extract and increased diastatic power, where β‐glucan either did not differ or increased. Deficit irrigation is promising, particularly for adjunct brewing; however, expected changes to malting quality must be understood and genotype selection, altered fertilizer management, and/or changes to malting criteria may be needed for implementation. Core Ideas: Grain yields were similar within a genotype with a reduction in irrigation from 100% to 75% crop evapotranspiration (ETc).Total aboveground dry matter yields at the F10 (boot) stage, when forage is commonly harvested, were unaffected by irrigation rate.Adjunct (130 g kg‐1) but not all‐malt (120 g kg‐1) protein was met with irrigation reduction to 75% ETc.With decreased irrigation, malt extract and soluble protein to total protein ratio decreased, diastatic power increased, and β‐glucan did not differ or increase.Irrigation reductions to 75% ETc are promising for adjunct targets; caution is needed for all‐malt targets. [ABSTRACT FROM AUTHOR]

A non-mycoparasitic restriction enzyme-mediated DNA integration (REMI) mutant of Coniothyrium minitans (R2427) contains two tandem plasmid copies integrated towards the 3' end of an ORF. The predicted polypeptide (845 aa) exhibits high similarity with DNA-helicase proteins from other filamentous fungi and yeasts that play a role in mitochondrial DNA maintenance and repair. Disruption of the C. minitans PIF1 DNA helicase gene results in altered morphology, reduced growth rates and a concomitant loss in ability to mycoparasitize sclerotia of Sclerotinia sclerotiorum. In infection bioassays, R2427 exhibited sparse mycelial growth on the surface of live sclerotia, but no mycelia were detected inside the sclerotia. Conversely, R2427 readily colonized autoclaved sclerotia. Complementation of the mutant with wild-type PIF1 restored normal mycelial growth and mycoparasitic capability, confirming a functional role in the host-pathogen interaction. The C. minitans PIF1 DNA helicase may maintain mitochondrial stability in response to reactive oxygen species, either produced endogenously within the mycoparasite, or exogenously from the sclerotial host.

Idaho is a major malt barley (Hordeum vulgare L.) producer in the United States. Production is concentrated in the semi‐arid Snake River Plain region of southern Idaho. Irrigation and fertilizer N applications are two of the most important managed factors. Research was conducted at the University of Idaho Kimberly Research & Extension Center near Kimberly, ID, to determine yield, grain quality, and malt characteristics as affected by N application rate (0, 56, 112, and 168 kg N ha−1) and final irrigation timing at Feekes 10.0 (boot; F10.0), Feekes 11.2 (soft dough; F11.2), and +7 d after Feekes 11.2 (+7F11.2). Irrigation termination at F10.0 resulted in decreased yields and unacceptable malt characteristics across N rates. Irrigation termination at F11.2 and +7F11.2 yielded 6,439 kg ha−1 at a fertilizer N application of 56 kg N ha−1, similar to higher N applications. Greater predicted yields up to 6,886 kg ha−1 were calculated by regression analysis with applications up to 147 kg N ha−1. Grain yield, protein, plumps, and test weights did not differ at any N rate for F11.2 or +7F11.2. Malt extract, free amino N, and diastatic power were similar for the F11.2 and +7F11.2 irrigations. Malt β‐glucan content did not differ up to 56 kg N ha−1 for any treatment, but reductions of up to 30 mg kg−1 were measured at higher N rates for the +7F11.2 irrigation. Results warrant further investigations into increased N applications and provide evidence of the effects of irrigation cutoff timing and N for malt barley. Core Ideas: Irrigation termination at the F10.0 stage caused severe yield and quality issues.F11.2 and +7F11.2 yields did not differ and increased with N from 4,769 to 6,845 kg ha‐1.Grain protein was less than 130 g kg‐1at all N rates for F11.2 and +7F11.2.Irrigation past F11.2 did not generally improve or detract from quality.Malt β‐glucan decreased up to 30 mg kg‐1at higher N rates for +7F11.2. [ABSTRACT FROM AUTHOR]

Optimizing crop N uptake while minimizing NH3 volatilization from N fertilizer sources is a critical part of agricultural best management practices. Urea is the most widely used N fertilizer but is also one of the most susceptible to losses as NH3. Fertilizer sources and additives can be used to reduce NH3 volatilization. Specifically, urease inhibitors [e.g., N‐(n‐butyl) thiophosphoric triamide (NBPT)] can reduce NH3 volatilization from urea. A novel fused ammonium sulfate nitrate (ASN) product has recently been developed as another potential alternative N fertilizer source but has not been studied widely. A field study was performed to quantify NH3 volatilization from the newly available ASN fertilizer as compared with various N fertilizers (ammonium sulfate [AS] and urea) including urea treated with the urease inhibitor NBPT in an alkaline calcareous loam soil in Idaho. Further, we assessed NH3 volatilization from surface applied and incorporated N fertilizers from these various N sources. Untreated surface‐applied urea volatilized the highest amount of NH3, whereas incorporation of N fertilizers was effective in reducing volatilization as compared with untreated surface‐applied urea. Our study indicated that the N fertilizer sources (AS, ASN, and urea+NBPT) were equally effective in reducing NH3 volatilization when compared with surface‐applied urea. Our study will help refine N fertilizer management under multiple field situations and traditional management practices of crop producers in the western United States. Further, site‐years and study locations would be needed to provide evidence of the effectiveness of ASN in reducing NH3 volatilization under a wider range of soil and environmental conditions. Core Ideas: Source and method of N fertilizer were assessed for NH3 volatilization.Greatest NH3 volatilization was from untreated surface applied urea.Incorporation of N fertilizer was effective for reducing NH3 volatilization.AS, ASN, and urea‐NBPT were comparable in reducing NH3 volatilization compared with urea. [ABSTRACT FROM AUTHOR]

Well-defined nitrogen (N) management in irrigated two-row malting barley (Hordeum vulgare L.) is critical for yield and quality and to minimize environmental impacts. Data on fertilizer N recovery efficiency (FNRE) and the fate of fertilizer-N in the soil are lacking. The study objective was to determine uptake and partitioning of 15N-labeled urea in the plant and soil. Urea was either surface applied or incorporated at a total N rate (inorganic-N + applied N) of 214 kg N ha-1 at planting. Three malt cultivars were grown, and samples were collected four times during the growing season (Feekes growth stages 4/5, 10.0, 11.2, and 11.4). Barley plants at Feekes 11.2 and 11.4 were separated into vegetative tissue and spikes. Plant N accumulation was lowest at Feekes 4/5 and reached a maximum at Feekes 11.2, whereas FNRE was greatest at Feekes 10.0. Nitrogen was redistributed from vegetative tissue to the spike from Feekes 11.2 to 11.4. Plant FNRE averaged 43% at Feekes 11.4. Total plant--soil FNRE for the surface application was 66%, which was less than the incorporated FNRE of 77%. Results provide evidence of the increased plant--soil system FNRE of incorporated applications in high-input barley production systems compared with surface applications despite no yield difference. Similar FNRE as compared to previous work with lower yields was measured, and modern cultivars out-yielded an older cultivar with no reduction in FNRE. Results of the study indicate that a relatively high plant--soil system FNRE of irrigated malting barley was achieved under high-input, irrigated conditions common in southern Idaho. [ABSTRACT FROM AUTHOR]

Determination of soil organic carbon (SOC) is highly desirable for assessing fertility and carbon sequestration; however, numerous methods of determination warrant study of method agreement. Recently, a novel method was developed following dichromate oxidation using a microplate spectrophotometer. This novel method was compared with (a) total C by dry combustion − soil inorganic carbon (DCw/o pretreatment–pressure calcimater [Pcal]); (b) traditional Walkley–Black titration (WBTIT) and (c) loss on ignition (LOI360°C) in calcareous soils of south‐central Idaho (n = 75) in conjunction with North American Proficiency Testing program soils (n = 10). A two‐way ANOVA was fit with soils as a blocking factor to identify any difference between methods; means were separated using Tukey's honestly significant difference test (α =.05). Additional comparisons were made for all soils (n = 85) and for soils in the lower 75th percentile of SOC determined by WBTIT (n = 56) using regression analysis. Only the WBTIT and LOI360°C methods were statistically equivalent nevertheless there was high agreement (Lin's concordance coefficients >.90) between all methods (n = 85). Under low SOC soils (n = 56) the agreement between all methods decreased, but the Walkley–Black spectrophotometric method (WBSPEC) method fit other methods comparatively well r2 =.71,.74, and.78 for LOI360°C, DCw/o pretreatment–Pcal, and WBTIT respectively. The WBSPEC method provided estimates of SOC between the methods currently used in the region while reducing hazardous waste generation over traditional WBTIT and sample handling over LOI360°C and DCw/o pretreatment–Pcal methods, positioning it as a sensible option for SOC determination in low SOC calcareous soils of south‐central Idaho. [ABSTRACT FROM AUTHOR]

Optimizing barley (hordeum vulgare L.) production in Idaho and other parts of the Pacific Northwest (PNW) should focus on farm resource management. The effect of post-harvest residue management on barley residue decomposition has not been adequately studied. Thus, the objective of this study was to determine the effect of residue placement (surface vs. incorporated), residue size (chopped vs. ground-sieved) and soil type (sand and sandy loam) on barley residue decomposition. A 50-day(d) laboratory incubation experiment was conducted at a temperature of 25°C at the Aberdeen Research and Extension Center, Aberdeen, Idaho, USA. Following the study, a Markov-Chain Monte Carlo (MCMC) modeling approach was applied to investigate the first-order decay kinetics of barley residue. An accelerated initial flush of residue carbon(C)-mineralization was measured for the sieved (Day 1) compared to chopped (Day 3 to 5) residues for both surface incorporated applications. The highest evolution of carbon dioxide (CO2)-C of 8.3 g kg-1 dry residue was observed on Day 1 from the incorporated-sieved application for both soils. The highest and lowest amount of cumulative CO2-C released and percentage residue decomposed over 50-d was observed for surface-chopped (107 g kg-1 dry residue and 27%, respectively) and incorporated-sieved (69 g kg-1 dry residue and 18%, respectively) residues, respectively. There were no significant differences in C-mineralization from barley residue based on soil type or its interactions with residue placement and size (p >0.05). The largest decay constant k of 0.0083 d-1 was calculated for surface-chopped residue where the predicted half-life was 80 d, which did not differ from surface sieved or incorporated chopped. In contrast, incorporated-sieved treatments only resulted in a k of 0.0054 d-1 and would need an additional 48 d to decompose 50% of the residue. Future residue decomposition studies under field conditions are warranted to verify the residue C-mineralization and its impact on residue management. [ABSTRACT FROM AUTHOR]

Advanced soil tests can improve the estimation of plant available nutrients to better match fertilizer additions with plant needs and, in some cases, provide a measure of soil health. In the present study, 334 samples from four separate studieswere evaluated using the Soil Health Tool (SHT) vs. the standard regional (University of Idaho [UI] Guidelines) method for determining fertilizer application, assuming a crop of spring irrigated wheat. Recommended N applications using the SHT were ~138 kg ha-1 greater than the UI recommendations. Nitrogen mineralization predicted using the SHT (47 kg ha-1) was similar to the N mineralization value used in the regional methodology (50 kg ha-1). The P fertilizer recommendations were similar between the two methodologies with the SHT recommending, on average 4.7 kg ha-1 less P than the regional method. The lower P recommendation are likely due to a lack of accounting for the effects of high calcium carbonate levels on the P availability from fertilizers in this region. The soil health score (SHS) was correlated with measures of soil C but was not positively correlated to crop yield. In some instances, increasing SHS were correlated with decreases in crop quality as the addition of manure increased soil C but also created issues such as high salt contents and release of late season N. With modification to more accurately represent irrigation conditions and including sampling to greater soil depths, the SHT may be tailored to better estimate soil nutrient status and provide better fertilizer recommendations for the region. [ABSTRACT FROM AUTHOR]

Total dry matter (TDM) and nutrient accumulation, nutrient partitioning, and cumulative growing degree days at the time of maximum nutrient accumulation for two‐row spring barley (Hordeum vulgare L.) are not well quantified under high‐yielding irrigated conditions common in the semi‐arid western United States. Thus, five cultivars of barley were grown under irrigated conditions on a loam soil in the 2015 and 2016 growth seasons to determine these factors. Total nutrient accumulation was greatest at either the soft dough or maturity stage where specific nutrients were greater at one stage as compared to the other. Mean N accumulation was greatest at the soft dough stage (256 kg ha−1) where the regression model accounted for 80% of the variation in the data. Additionally, spike N increased from 91 to 105 kg ha−1 from soft dough to maturity. Specific nutrients (e.g., K) had significantly greater plant (i.e., culms plus leaves) accumulation between soft dough and maturity, 253 and 172 kg ha−1, respectively, where the spike at the same growth stages had an accumulation of 37 and 42 kg ha−1, respectively. In contrast, other nutrients (e.g., P) were remobilized to the spike as noted by the increase from 14 kg ha−1 at soft dough to 26 kg ha−1 at maturity. In addition to nutrient partitioning, linear regressions resulted in well‐correlated models between TDM and total nutrient accumulation (R2 = 0.35–0.88) for measured nutrients. Results from the current study provide critical data on nutrient accumulation as well as regression models for two‐row barley under high‐yielding conditions. This information can be used to improve harvest decisions as well as more accurately predict nutrient cycling in barley cropping systems. [ABSTRACT FROM AUTHOR]

Information on the effects of phosphorus (P) and sulfur (S) applications on crop response and soil-P status of two-row malt barley (Hordeum vulgare L.) under high-input conditions are limited in alkaline soils despite widespread fertilizer-P and -S use. A field study was conducted during the 2015 and 2016 growing seasons where the barley cultivars (ABI-Voyager and Moravian 69) were grown at five rates of P (0, 37, 73, 110, and 147 kg P ha−1) and three rates of S (0, 112, 224 kg S ha−1). ABI-Voyager had significantly greater biological yield (17,023 kg ha−1) and grain yield (7433 kg ha−1) but a lower (44%) harvest index (HI) than Moravian 69 (15,037 kg ha−1, 7168 kg ha−1 and 49%, respectively). Grain yield increased with rate of P-application until 37 kg P ha−1 where the maximum calculated yield was obtained at 98 kg P ha−1 by a quadratic model. Sulfur application had no significant effect on any of the measured crop or soil parameters. Olsen P increased linearly with greater fertilizer-P applications, indicating grain-P removal was not sufficient to reduce or retain STP concentrations at initial levels when P was applied. Crop-P uptake and soil-P response to fertilizer P applications are important, as remaining soil P is available for subsequent crop usage and may have potential negative environmental impacts. Thus, cultivar selection and appropriate fertilizer-P and S management will ensure optimal agronomic and economic returns while minimizing potentially negative environmental impacts for two-row malt barley produced in the western United States. [ABSTRACT FROM AUTHOR]

Soil P testing is critical to ensure the accuracy of fertilizer recommendations and to optimize crop yield while minimizing negative environmental consequences. Olsen-P is the most commonly used soil P test for alkaline calcareous soils found in Idaho and the western United States. The Bray-1 test is commonly used in the Pacific Northwest on neutral to acidic soils but underestimates P in alkaline calcareous soils. Mehlich-3 has been evaluated throughout various regions in the United States. Few data evaluating Mehlich-3 exist for soils in the western United States. Additionally, the comparatively newly developed Haney–Haney–Hossner–Arnold (H3A) test, a component of the soil health tool, has not been widely evaluated on alkaline calcareous soils. Soil samples from the 0- to 30-cm depth were collected from agricultural fields throughout Idaho and analyzed with Bray-1, H3A, Mehlich-3, and Olsen-P extractants. The results indicate that Olsen-P was correlated with Mehlich-3, whereas Bray-1 and H3A were not correlated with Olsen-P. Both Bray-1 and H3A resulted in lower values of extractable P than the Olsen-P test, whereas Mehlich-3 resulted in greater values. A threshold point in CaCO3 (i.e., inorganic C) of 6.7 and 5.1 mg kg-1 for the Bray-1 and H3A was obtained, respectively, which indicated that inorganic C concentrations at or above these levels resulted in a reduction in extractable soil P. Thus Mehlich-3 could be evaluated for use in alkaline calcareous soils, whereas Bray-1 and H3A have notable issues that would limit their applicability. [ABSTRACT FROM AUTHOR]

Barley yellow dwarf (BYD) is one of the most common diseases of cereal crops, caused by the phloem‐limited, cereal aphid‐borne Barley yellow dwarf virus (BYDV) (Luteoviridae). Delayed planting and controlling aphid vector numbers with insecticides have been the primary approaches to manage BYD. There is limited research on nitrogen (N) application effects on plant growth, N status, and water use in the BYDV pathosystem in the absence of aphid control. Such information will be essential in developing a post‐infection management plan for BYDV‐infected cereals. Through a greenhouse study, we assessed whether manipulation of N supply to BYDV‐infected winter wheat, Triticum aestivum L. (Poaceae), in the presence or absence of the aphid vector Rhopalosiphum padi L. (Hemiptera: Aphididae), could improve N and/or water uptake, and subsequently promote plant growth. Similar responses of shoot biomass and of water and N use efficiencies to various N application rates were observed in both BYDV‐infected and non‐infected plants, suggesting that winter wheat plants with only BYDV infection may be capable of outgrowing infection by the virus. Plants, which simultaneously hosted aphids and BYDV, suffered more severe symptoms and possessed higher virus loads than those infected with BYDV only. Moreover, in plants hosting both BYDV and aphids, aphid pressure was positively associated with N concentration within plant tissue, suggesting that N application and N concentration within foliar tissue may alter BYDV replication indirectly through their influence on aphid reproduction. Even though shoot biomass, tissue N concentration, and water use efficiency increased in response to increased N application, decision‐making on N fertilization to plants hosting both BYDV and aphids should take into consideration the potential of aphid outbreak and/or the possibility of reduced plant resilience to environmental stresses due to decreased root growth. This work evaluates the effects of nitrogen supply on Barley yellow dwarf virus (BYDV) titer and disease progress in winter wheat. Nitrogen supply did not affect BYDV titer but could promote multiplication of the vector aphid Rhopalosiphum padi (Hemiptera: Aphididae). As nitrogen may also reduce early‐stage root development, it is suggested that ideally nitrogen application in high‐risk BYDV areas is conducted when aphids are absent, or following aphid control. However, this needs to be confirmed in field experiments. [ABSTRACT FROM AUTHOR]

Barley (Hordeum vulgareL.) is a cereal grown for animal feed, human consumption, and malting. Nutrient concentrations are important as they provide information regarding the dietary values of barley consumed by animals or human beings. In addition, grain nutrient removal may be useful for refining fertilizer recommendations. A study was conducted in 2015 and 2016 investigating the cultivar effects on grain yield, quality, and grain nutrient concentrations and removal under irrigated conditions for two-row barley cultivars. Adjunct and feed cultivars produced the highest yields compared with the all-malt and food cultivars. Specific quality and nutrient values were greater than or equal to in the food cultivar compared to the malt or feed cultivars. Variations in nutrient concentrations were measured among the adjunct and all-malt cultivars, which could potentially affect the malting and brewing qualities. Grain yield, quality, nutrient concentrations and nutrient removal varied among cultivars grown under identical environmental conditions, which may influence end-use. [ABSTRACT FROM AUTHOR]

Ammoniacal fertilizers are susceptible to ammonia (NH3) volatilization, and multiple methods have been introduced to quantify loss. Methods to quantify differences in NH3loss are important for evaluating the effectiveness of treatments. Recent research hypothesized that opening chamber enclosures resulted in nitrogen (N) loss (16–30%). Thus, the recovery efficiency of static diffusion chambers used in laboratory experiments was investigated. Chambers with a sand–calcium carbonate (CaCO3) mixture received ammonium-N (NH4-N) solutions. Three time intervals were used to determine if variation in enclosure opening influenced recovery. Acid trap percent recovery and a mass balance approach were used. No differences in cumulative NH3volatilization were measured from either acid traps or using a mass balance approach. No differences were measured in percent recovery based on N application rate, sample interval, or their interaction, and mean percent N recovery was 99.0%. Thus, diffusion chambers can be reliably used to measure differences in NH3volatilization. [ABSTRACT FROM PUBLISHER]

Due to anaerobic conditions that develop in soils under flooded-rice (Oryza sativa L.) production, along with the global extent of rice production, it is estimated that rice cultivation is responsible for 11% of global anthropogenic methane (CH4) emissions. In order to adequately estimate CH4 emissions, it is important to include data representing the range of environmental, climatic, and cultural factors occurring in rice production, particularly from Arkansas, the leading rice-producing state in the US, and from clay soils. The objective of this study was to determine the effects of previous crop (i.e., rice or soybean (Glycine max L.)) and cultivar (i.e., Cheniere (pure-line, semidwarf), CLXL745 (hybrid), and Taggart (pure-line, standard-stature)) on CH4 fluxes and emissions from rice grown on a Sharkey clay (very-fine, smectitic, thermic Chromic Epiaquerts) in eastern Arkansas. Rice following rice as a previous crop generally had greater (p<0.01) fluxes than rice following soybean, resulting in growing season emissions (p<0.01) of 19.6 and 7.0 kg CH4-C ha−1, respectively. The resulting emissions from CLXL745 (10.2 kg CH4-C ha−1) were less (p=0.03) than those from Cheniere or Taggart (15.5 and 14.2 kg CH4-C ha−1, resp.), which did not differ. Results of this study indicate that common Arkansas practices, such as growing rice in rotation with soybean and planting hybrid cultivars, may result in reduced CH4 emissions relative to continuous rice rotations and pure-line cultivars, respectively. [ABSTRACT FROM AUTHOR]

Improvements in rice (Oryza sativa L.) production in the mid-south United States have been made through advances in N management, harvest strategies, and cultivar selection. Efficient fertilizer-N management is important for producing large yields. Harvest moisture content (HMC) affects grain quality [i.e., milled rice yield (MRY) and head rice yield (HRY)], as harvesting above or below optimum HMC results in decreased milling yields. Research was conducted from 2011 to 2013 investigating rough rice and milling yields as affected by fertilizer-N application (0, 45, 90, 135, and 180 kg N ha-1), HMC (high, medium, and low), and cultivar ('Cheniere', 'CLXL745', and 'Wells'). Maximum rough rice yields of 8916, 10,263, and 9353 kg ha-1 were calculated at N rates of 135, 149, and 146 kg N ha-1 for Cheniere, CLXL745, and Wells, respectively. At N rates to achieve maximum rough rice yield, MRY and HRY were 98 to 99.9% of the maximum milling yield within a cultivar-HMC combination, excluding Wells harvested at low HMC. Within a cultivar-HMC combination, HRYs were <1 to 25% points greater at the maximum HRY- producing N rate than the minimum. Nitrogen rates needed to maximize rough rice yield and harvesting at high and medium HMC lead to near-maximum HRYs; however, harvest at low N rates and HMC reduced HRY, particularly for CLXL745 and Wells. Further research focused on other hybrid and pure-line rice cultivars will ensure that the current data are consistent for a wide range of cultivars. [ABSTRACT FROM AUTHOR]

Previous research has demonstrated that rice (Oryza sativa L.) production poses two large, global environmental concerns: rice uses 25% of the global freshwater supply and generates considerable greenhouse gas (GHG) emissions. The shorter vegetative stage of hybrids compared with conventional (inbred) cultivars may provide two environmental improvements: reduced water consumption and decreased CH4 emissions. This study evaluated the effect of cultivar type on water-use efficiency and net GHG emissions. Water usage and GHG emissions on a per-hectare and per-kilogram-of-grain basis were estimated for hybrid and conventional rice cultivars with a new methodology using seven consecutive years of cultivar-trial data. Because GHG emissions have not been observed directly in cultivar trial experiments, a method of synthesizing GHG emission levels was designed. This method utilizes results from in-field chamber experiments from flooding to after harvest plus emergence and 50% heading dates. Hybrid rice cultivars were estimated to be 23.22% more efficient than conventional cultivars in reducing GHG emissions and 33.47% more efficient in reducing water required per unit grain yield produced. Unlike other approaches to lowering GHG emissions and water usage, substituting hybrids for conventional cultivars appears to be a viable option with low producer transaction costs as opposed to such alternatives as alternate wet-dry flooding, building on-farm reservoirs, etc.. The methodology used produced results that are consistent with the present knowledge of the physiological and cultural practice differences between conventional and hybrid rice production. The GHG synthesizing methodology could be directly applied to other states' historic cultivar trial data. [ABSTRACT FROM AUTHOR]

The effects of abrupt dietary transition on the faecal microbiota of forage-fed horses over a 3-week period were investigated. Yearling Thoroughbred fillies reared as a cohort were exclusively fed on either an ensiled conserved forage-grain diet (“Group A”; n = 6) or pasture (“Group B”; n = 6) for three weeks prior to the study. After the Day 0 faecal samples were collected, horses of Group A were abruptly transitioned to pasture. Both groups continued to graze similar pasture for three weeks, with faecal samples collected at 4-day intervals. DNA was isolated from the faeces and microbial 16S and 18S rRNA gene amplicons were generated and analysed by pyrosequencing. The faecal bacterial communities of both groups of horses were highly diverse (Simpson’s index of diversity >0.8), with differences between the two groups on Day 0 (P<0.017 adjusted for multiple comparisons). There were differences between Groups A and B in the relative abundances of four genera, BF311 (family Bacteroidaceae; P = 0.003), CF231 (family Paraprevotellaceae; P = 0.004), and currently unclassified members within the order Clostridiales (P = 0.003) and within the family Lachnospiraceae (P = 0.006). The bacterial community of Group A horses became similar to Group B within four days of feeding on pasture, whereas the structure of the archaeal community remained constant pre- and post-dietary change. The community structure of the faecal microbiota (bacteria, archaea and ciliate protozoa) of pasture-fed horses was also identified. The initial differences observed appeared to be linked to recent dietary history, with the bacterial community of the forage-fed horses responding rapidly to abrupt dietary change. [ABSTRACT FROM AUTHOR]

Sugar beet crown and root rot caused by Rhizoctonia solani is a major yield constraint. Root rot is highly increased when R. solani and Leuconostoc mesenteroides co-infect roots. We hypothesized that the absence of plant cell-wall-degrading enzymes in L. mesenteroides and their supply by R. solani during close contact, causes increased damage. In planta root inoculation with or without cell-wall-degrading enzymes showed greater rot when L. mesenteroides was combined with cellulase (22 mm rot), polygalacturonase (47 mm), and pectin lyase (57 mm) versus these enzymes (0–26 mm), R. solani (20 mm), and L. mesenteroides (13 mm) individually. Carbohydrate analysis revealed increased simpler carbohydrates (namely glucose + galactose, and fructose) in the infected roots versus mock control, possibly due to the degradation of complex cell wall carbohydrates. Expression of R. solani cellulase, polygalacturonase, and pectin lyase genes during root infection corroborated well with the enzyme data. Global mRNAseq analysis identified candidate genes and highly co-expressed gene modules in all three organisms that might be critical in host plant defense and pathogenesis. Targeting R. solani cell-wall-degrading enzymes in the future could be an effective strategy to mitigate root damage during its interaction with L. mesenteroides. [ABSTRACT FROM AUTHOR]

Rice [Oryza sativa L.) production is unique among staple food crops because the majority of the growing season typically occurs under flooded-soil conditions. Flooding the soil leads to anaerobic conditions, which are a precursor to methane (CH4) production. However, no known research has investigated CH4 emissions from the drill-seeded, delayed-flood rice production system common in Arkansas, the leading rice-producing state in the United States. Therefore, research was conducted in 2011 to determine the effects of vegetation (rice and bare soil), chamber location (in- and between-rice rows), and nitrogen (N) fertilization (optimal and no N) on CH4 emissions from a silt-loam soil. Methane fluxes measured weekly from flooding until flood release were affected by vegetation, chamber location, and sample date (P < 0.05). In-row CH4, fluxes were <0.7 mg CH4,-C m-2 h-1 until 20 d after flooding (DAF) and <1.0 mg CH4-C m-2 h-1 from between-row and bare soil until 41 DAF and were unaffected by fertilization over time. The largest weekly measured CH4 flux (31.9 mg CH4-C m-2 h-1) was observed from in-row rice at 41 DAF. Post-flood-release CH4 fluxes were affected by vegetation, fertilization, chamber placement, and sample date (P < 0.05) and accounted for approximately 3 to 7% of the season-long CH4 emissions. Methane emissions averaged 195 kg CH4-C ha-1 per growing season and were unaffected by fertilization. Direct measurement of CH4 emissions from drill- seeded, delayed-flood rice grown on a silt-loam soil will improve the accuracy of assessments of the carbon footprint and long-term sustainability of rice. [ABSTRACT FROM AUTHOR]

Objective--To investigate the effect of exercise during yearling sales preparation on the risk of interruptions during training in Thoroughbred racehorses. Animals--114 Thoroughbred racehorses. Procedures--Information regarding the daily exercise of yearlings during sales preparation was obtained prospectively from a convenience sample of stud farms. Yearlings were followed to entry into race training, and subsequently, daily training information was recorded until the end of the racing season. Competing-risks survival analysis was used to model time from entry into race training to voluntary training interruption (no known condition or disease identified) and time from entry into race training to involuntary training interruption (due to presence of a condition or disease) occurring before the first trial (practice race for education). Total hand walking time and mechanical walker time accumulated during sales preparation were the main exposures of interest. Results--82 of 114 (71.9%) horses had an interruption before the first trial; 65 (79%) interruptions were voluntary, and 17 (21%) interruptions were involuntary. Increased total hand walking time was significantly associated with decreased risk of voluntary interruptions, whereas longer cumulative distances at a canter were significantly associated with decreased risk of involuntary interruptions. Conclusions and Clinical Relevance--Results identified an association between early exercise during sales preparation and decreased risk of voluntary interruption and increased risk of involuntary interruption during training of 2-year-old Thoroughbred racehorses. Further investigation into the effects of early exercise on racing performance is needed, but results have indicated that there may be an opportunity to modify early exercise programs. [ABSTRACT FROM AUTHOR]

Abstract: Restriction enzyme mediated integration (REMI) and Agrobacterium-mediated transformation (ATMT) were used to transform protoplasts or germinated conidia of the mycoparasite Coniothyrium minitans to hygromycin resistance. Using REMI, up to 32 transformants μg DNA−1 were obtained, while 37.8 transformants 5×105 germlings−1 were obtained using ATMT. Single-copy integrations occurred in 8% and 40% of REMI and ATMT transformants, respectively. A novel microtitre plate-based test was developed to expedite screening of 4000 REMI and ATMT C. minitans transformants. Nine pathogenicity mutants that displayed reduced or no pathogenicity on sclerotia of Sclerotinia sclerotiorum were identified. [Copyright &y& Elsevier]