Core Ideas Crop yield contests provide a unique research opportunity. Planting date is highly related to yield across yield contest sites. An early soybean production system is advantageous for high yields. Increasing soybean [Glycine max (L.) Merr.] yields requires a multi‐pronged approach. Annual state soybean yield contest fields can provide information about yield potentials and plant response differences between high and average‐yield producing areas. The objectives of this study were to i) assess plant physiological property and elemental seed concentration differences between high‐ (HY) and average‐yield (AY) areas and across soybean growth stages and ii) evaluate relationships among plant properties and yield across the seven regions of the “Grow for the Green” soybean yield contest in Arkansas. Seed yields in AY and HY areas averaged 74.4 and 88.3 bu/ac, respectively, in 2015. Harvest index, average seed weight, and seed K concentration differed (p < 0.05) by at least 10% across growth stages and between yield areas. Averaged across growth stage, aboveground dry matter and seed B and C concentrations differed (p < 0.05) by at least 0.7% between yield areas across regions. Averaged across yield area, seed N, P, Ca, Fe, Mn, Zn, Cu, and B concentrations differed (p < 0.05) by at least 2.5% across growth stages. Planting date was most strongly correlated with yield (p < 0.001; r = –0.62), confirming previous research. Encompassing a wide variety of landscapes and management systems, results of this study validate the importance of planting date to soybean yield. Additional factors need to be evaluated to discover stronger relationships with yield to continue closing the soybean yield gap.

Drought stress is a global constraint for crop production, and improving crop tolerance to drought is of critical importance. Because transpiration cools a crop canopy, a cool canopy under drought indicates a genotype still has access to soil moisture. Because measurements of canopy temperature may be increased in scale in field environments, it is particularly attractive for large-scale, phenotypic evaluations. Our objectives were to identify genomic regions associated with canopy temperature (CT) and to identify extreme genotypes for CT. A diverse panel consisting of 345 maturity group IV soybean accessions was evaluated in three environments for CT. Within each environment CT was normalized (nCT) on a scale from 0 to 1. A set of 31,260 polymorphic single nucleotide polymorphisms (SNPs) with a minor allele frequency ≥ 5% was used for association mapping of nCT. Association mapping identified 52 SNPs significantly associated with nCT, and these SNPs likely tagged 34 different genomic regions. Averaged across all environments, eight genomic regions showed significant associations with nCT. Several genes in the identified genomic regions had reported functions related to transpiration or water acquisition including root development, response to abscisic acid, water deprivation, stomatal complex morphogenesis, and signal transduction. Fifteen of the SNPs associated with nCT were coincident with SNPs for canopy wilting. Favorable alleles from significant SNPs may be an important resource for pyramiding genes, and several genotypes were identified as sources of drought-tolerant alleles that could be used in breeding programs for improving drought tolerance.

Soya bean [ Glycine max (L.) Merr] yields >6719 kg/ha (100 bu/ac) have only recently and infrequently been achieved. Quantifying soil property differences between high‐ and average‐yielding areas can help to further identify non‐plant‐related properties contributing to soya bean yield potential. The objective of this study was to evaluate the effects of region and soil depth on soil property differences between high‐ and average‐yielding areas. In each of the seven regions of the ‘Grow for the Green’ yield contest in Arkansas, prior to or just after harvest in 2014 and 2015, soil samples were collected from the top 20 cm of one contest high‐yield ( HY ) area that was in close proximity to an average‐yield ( AY ) area. Across all regions and both years, soya bean yields differed ( P < 0.05) between yield areas, averaging 4701 and 5498 kg/ha in AY and HY areas, respectively. Averaged across soil depth and years, numerous soil properties differed ( P < 0.05) between HY and AY areas within at least one of seven regions. Total soil C content was at least 20.2% greater in the HY than in the AY area in three of seven regions. Extractable soil P content was, on average, 19.4 kg/ha greater in HY than in AY areas in three of the seven regions. Results from this study have the potential to help producers better understand soil properties that contribute to or hinder achieving ultra‐high (>6719 kg/ha) soya bean yields.

采用2个大豆品种Hutcheson和Archer,通过温室一系列试验研究了水淹和终极腐霉（Pythium ultimum）对大豆的影响。一个试验是,大豆种子播种到经过灭菌土壤中,一部分土壤里接种沙子-玉米面的终极腐霉接菌体使之侵染,另一部分未接种病原菌;水淹处理是分别在出苗期水淹2 d、4叶节期（V4）水淹5 d,在每个试验中Hutcheson

Repeated annual land application of organic soil amendments, such as broiler litter (BL), to managed grasslands for increased forage yields has increased concerns about potential surface water contamination from runoff. Furthermore, water quality concerns are exacerbated in areas of underlying karst, such as the Ozark Highlands, where runoff can rapidly enter the groundwater system. Therefore, the objective of this study was to determine 8‐yr (May 2003–April 2011) linear trends in annual runoff water quality from a silt loam soil in the Ozark Highlands region of northwest Arkansas under natural precipitation and typical forage management amended annually with BL at three application rates (0 [control], 5.6 [low], and 11.2 [high] Mg BL ha−1) with a history of BL amendments and high soil‐test P. Average annual runoff, flow‐weighted mean (FWM) runoff concentrations of Ca, Cd, Cu, Na, and Se, and all nutrient and metal losses increased with time (P < 0.05) but were unaffected (P > 0.05) by BL application rate. Average annual FWM concentrations of As decreased with time (P < 0.05) and were unaffected by BL (P > 0.05). Eight‐year cumulative runoff losses of Se exceeded 200% of that applied in BL. Results indicated that pasturelands with a history of BL application and high soil‐test P may continue to release BL‐derived As and Se at concentrations potentially harmful to human and environmental health regardless of current management practice long after litter application has ceased.

Application of broiler (Gallus gallus) litter (BL) to pasturelands in karst regions like the Ozark Highlands can potentially reduce water quality due to leaching of BL‐derived nutrients and trace metals. The objective of this study was to determine long‐term linear trends in drainage and soil leachate water quality under natural precipitation from a silt‐loam soil amended annually with BL at three application rates (0 [control], 5.6 [low], and 11.2 [high] Mg BL ha−1]. Automated equilibrium tension lysimeters were used to continuously monitor and collect leachate from an undisturbed soil profile with a history of litter applications under forage management at a depth of 0.9 m for the 8‐yr period from May 2003 through April 2011. Average annual flow‐weighted mean (FWM) concentrations and loads of NH4–N, As, Mn, and Ni decreased linearly (P < 0.05), while Cu and Se increased (P < 0.05) linearly during the 8 yr. Nearly all water quality parameters measured were unaffected (P > 0.05) by BL rate alone. Continued annual additions of BL linearly increased (P < 0.05) the average annual FWM leachate Na concentrations relative to the unamended control. Results indicated that pasturelands with a history of BL application may continue to release BL‐derived metals, such as As and Se, at concentrations harmful to health regardless of current management practice long after litter application has ceased. Land application of nutrient‐ and trace‐metal‐containing animal wastes in regions with underlying karst features needs to be carefully managed to minimize subsoil leaching losses.

On-site wastewater treatment systems (OWTSs) are commonly used by households in areas of low population density to treat household wastewater and recycle it back to the environment. However, new absorption field products of differing architecture types have recently become available. A 3-yr field study was conducted in Bethel Heights, northwest Arkansas to assess several newer architecture types (i.e., chambers, polystyrene-aggregate, and gravel-less pipe) relative to the traditional pipe-and-gravel design under wet- and dry-soil conditions. Thirteen products of four different architecture types were installed in 46-cm-deep trenches in a Captina silt loam (fine-silty, siliceous, active, mesic Typic Fragiudult). Products were evaluated based on in-trench solution storage measured with an electronic water-level sensor approximately weekly from January 2009 through January 2012. Between May 2010 and January 2012, the thickness of any biomat formation was measured approximately weekly by insertion of a wooden dowel through in-trench monitoring ports. Architecture type alone did not affect ( > 0.05) in-trench solution storage. However, solution storage among individual products differed under wet- and dry-soil conditions ( < 0.05). When present, biomat thickness differed significantly ( < 0.05) among all four architecture types, ranging from 1.4 to 6.2 cm thick on average in the pipe-and-aggregate and polystyrene-aggregate types, respectively. Regression analyses showed that biomat thickness increased in three products, did not change in nine products, and decreased in one product over time. Results showed that several currently approved alternative products had similar in-trench solution storage but that several alternative products also had greater solution storage than that of the traditional pipe-and-gravel system. With no observed effluent surfacing, the soil morphology approach appears to be adequate and appropriately environmentally conservative for assigning typical single-family loading rates to alternative OWTS products and to the traditional pipe-and-gravel system.

The importance of fungicide seed treatments on cotton was examined using a series of standardized fungicide trials from 1993 to 2004. Fungicide seed treatments increased stands over those from seed not treated with fungicides in 119 of 211 trials. Metalaxyl increased stands compared to nontreated seed in 40 of 119 trials having significant fungicide responses, demonstrating the importance of Pythium spp. on stand establishment. Similarly, PCNB seed treatment increased stands compared to nontreated seed for 44 of 119 trials with a significant response, indicating the importance of Rhizoctonia solani in stand losses. Benefits from the use of newer seed treatment chemistries, azoxystrobin and triazoles, were demonstrated by comparison with a historic standard seed treatment, carboxin + PCNB + metalaxyl. Little to no stand improvement was found when minimal soil temperatures averaged 25°C the first 3 days after planting. Stand losses due to seedling pathogens increased dramatically as minimal soil temperatures decreased to 12°C and rainfall increased. The importance of Pythium increased dramatically as minimal soil temperature decreased and rainfall increased, while the importance of R. solani was not affected greatly by planting environment. These multi-year data support the widespread use of seed treatment fungicides for the control of the seedling disease complex on cotton.

Pesticides used in rice production have the potential to harm nontarget species. The objective of this study was to measure concentrations of selected rice pesticides in four rivers in eastern Arkansas from spring through mid-August for 2002 through 2008 to determine if changes over time might be leading to environmental water quality problems above a threshold of 2 μg L−1 (2 ppb). Most of the pesticide detections were in May, June, and early July. The probability of detecting a given compound in any sample ranged from 0.0042 on the St. Francis River to 0.0387 on the Cache River. After 2002, clomazone and quinclorac accounted for 55% to 96% of detections each year. Of the samples collected, 60% to 86% that contained a pesticide contained only one pesticide, and 12% to 34% of all samples collected contained two pesticides. Large concentrations were more common in samples collected upstream than those taken downstream. Clomazone and quinclorac were often detected on consecutive sampling dates, indicating the possibility that concentrations greater than 2 μg L−1 may be present over an extended period of time. Compared to ecotoxicity data, observed levels of these pesticides do not appear to be causing an environmental problem unless there is strong synergism between clomazone and quinclorac over a period of several weeks.

Urea is the primary N source used for the large preflood N application in delayed‐flood rice (Oryza sativa L.) production in the southern United States. Urea is prone to substantial NH3 volatilization losses, however, if fields are not flooded quickly. Most delayed‐flood rice fields require 5 to 10 d to flood. Consequently, a study was conducted to evaluate the use of less NH3–volatile N sources for the preflood N application. The objectives were to evaluate the NH3 volatilization loss and impact on N uptake and rice yield when urea, urea plus the urease inhibitor N‐(n‐butyl)thiophosphoric triamide (NBPT), (NH4)2SO4, or a urea‐(NH4)2SO4 (UAS) blend were applied preflood and a flood established 1, 5, or 10 d after N application. When flooding was delayed for 5 or 10 d after N application, NH3 volatilization was the least for urea + NBPT (2–10%) and (NH4)2SO4 (4–5%) and they produced the highest rice N uptake and yield. The UAS blend that had NH3 volatilization losses (11–15%) at 5 and 10 d after application that were intermediate between urea (17–24%) and (NH4)2SO4 or urea + NBPT also had N uptake and grain yield intermediate between these N sources. Urea should only be used if ∼2 d are required to flood a field. If 3 to 5 d are required to flood a field, then UAS has some merits but it is not as consistent as (NH4)2SO4 or urea + NBPT. When >5 d are required to flood, (NH4)2SO4 or urea + NBPT should be used.

The Arkansas poultry industry produced more than 1.2 billion broiler chickens (Gallus gallus domesticus) and generated approximately 1.3 million Mg of broiler litter in 2002. High transportation costs of relocating broiler litter have led to annual land applications near poultry houses, increasing concern for potential surface water contamination from runoff. The objective of this study was to evaluate the effect of broiler litter application rate on runoff water quality in response to natural precipitation. Six plots (1.5 by 6.0 m), located on a Captina silt loam (finesilty, siliceous, active, mesic Typic Fragiudult), were amended with fresh broiler litter at 0, 5.6, and 11.2 Mg ha(-1) (control, low, and high litter treatments, respectively) once annually for 4 yr (May 2003 through April 2007). Runoff collected after each runoff-producing event was analyzed for soluble nutrients and metals. Cumulative runoff did not differ among litter treatments over the 4-yr study. At times, flow-weighted mean (FWM) concentrations of As from all litter treatments exceeded the maximum contaminant level for drinking water (0.01 mg As L(-1)). Four-year FWM Fe concentrations and runoff losses were greater (P < 0.05) from the high than from the low litter treatment and unamended control, and the 4-yr FWM P concentration from the low litter treatment (3.0 mg L(-1)) was greater than that from the unamended control (1.8 mg L(-1)). Since precipitation is temporally variable, evaluating runoff water quality in response to natural precipitation over several years is key to ascertaining the long-term impacts of surface-applied soil amendments like broiler litter.

Due to the popularity of double-crop production systems in the southern United States, particularly soybean [Glycine max (L.) Merrill] following wheat (Triticum aestivum L.), wheat-residue management practices are critical to the successful establishment of double-cropped soybean. The objective of this study was to ascertain the effects of N application to wheat on no-tillage soybean growth and production in a double-crop system. This study was conducted over two cropping seasons at two locations on silt-loam Alfisols in eastern Arkansas. Wheat grain yield and subsequent residue mass generally increased as total applied N increased. Soybean plant population, height, and growth-stage rating approximately 30 days after planting were generally unaffected by total applied N to wheat or wheat-residue level. These results indicate that there is no negative impact to soybean planted without prior tillage into a wide range of wheat-residue levels and demonstrates that technological advancements with field implements have been able to overcome the concern of planting into high-residue situations.

Consumer interest in free-range and organic poultry is growing. An experiment was conducted to assess the impact of alternative genotype and production systems on the sensory attributes of chicken meat. Specifically, a slow-growing genotype and a fast-growing genotype were raised for 91 and 63 d. The slow-growing birds were placed before the fast-growing birds to achieve a similar final BW at processing. Each genotype was assigned to 4 pens of 20 birds each and raised in indoor floor pens in a conventional research facility; each genotype was also assigned to 4 floor pens in a small facility with outdoor access. The diet was formulated to be low in energy and protein for slow growth. Birds were commercially processed and deboned at 4 h postmortem. A descriptive analysis of breast and thigh meat was conducted on all treatments by a trained descriptive panel. A consumer analysis was also conducted on the breast and thigh meat from only 2 treatments: slow-growing birds raised with outdoor access and fast-growing birds raised indoors. A descriptive analysis indicated that the breast meat from birds with outdoor access was more cohesive than the meat from indoor birds (P < 0.05). There were no significant differences for most basic tastes; however, both the breast meat and thigh meat of the fast-growing birds tasted saltier than that of the slow-growing birds (P < 0.05). Meat of the slow-growing birds had more dark meat fat flavor than that of the fast-growing birds (P < 0.05). Results from the consumer panel showed no significant differences in overall liking, appearance, texture, or flavor of the breast meat or thigh meat. Just-About-Right distributions of consumer responses did not vary between slow-growing birds with outdoor access and fast-growing birds raised indoors for most attributes; however, more panelists found the breast meat of slow-growing birds with outdoor access too dry (P < 0.05). Although a descriptive panel detected some differences in texture and flavor among treatments, the consumer panel did not indicate differences in liking between conventional and specialty products.

Approximately 25% of the soybean [Glycine max (L.) Merr.] grown in the mid-South is produced in a wheat (Triticum aestivum L.)-soybean double-crop system. Pre-soybean field preparations often consist of removing wheat residue by burning followed by conventional tillage (CT). However, crop residue burning has serious negative environmental consequences and will likely be outlawed in the future. Therefore, the objective of this study was to evaluate the short-term effects of alternative wheat-residue management practices, tillage [no-tillage (NT) and CT], burning (burn and no burn), and wheat-residue level (low and high), on soil surface properties after two full cropping cycles in a wheat-soybean double-crop production system on two silt-loam Alfisols in east-central Arkansas. Soil bulk density increased over time, but the increase was unaffected by imposed treatments. Changes in soil pH and electrical conductivity (EC) were generally unaffected by tillage or burning, whereas soil EC increased by 7% under the high and decreased by 8% under the low wheat-residue level treatment at one location, but not the other. Mehlich-3-extractable Mg and Zn increased more and Na decreased less under NT than CT at one location or the other. Soil organic matter and total N and C also increased more under NT than CT at one location, but not the other. The results of this study indicate that, in a wheat-soybean double-crop production system in a relatively warm and wet environment, numerous soil properties can be improved more under NT than CT and more when crop residues are left unburned than when they are removed by burning. Extended use of alternative wheat-residue management practices that improve soil tilth will result in more sustainable agriculture and likely increase production.

Producers control crop fertilization practices. If the amount of grain yield per unit of aboveground biomass produced can be optimized with proper fertilization, nongrain aboveground biomass will be minimized. Achieving this goal would be especially beneficial in a wheat (Triticum aestivum L.) and soybean (Glycine mar L.) double-crop production system where proper fertilization could promote a residue-management shift from burning and conventional tillage to a conservation or no-tillage system. The objectives of this study were to i) determine the effect of nitrogen (N) rate on wheat yield, aboveground biomass, and partial harvest index (PHI), and ii) identify an appropriate predictive response model for wheat yield and PHI as a function of total N applied under low phosphorus (P) and potassium (K) fertility. This study was conducted over two cropping seasons at two locations on similar silt-loam Fragiudalfs in eastern Arkansas where wheat was fertilized at 10 N rates ranging from 0 to 10 1 kg N ha(-1) applied once at the early-jointing stage and from 151 to 269 kg N ha-1 applied in a split application at the early-jointing stage and at the late-jointing stage as depicted in the Feekes staging method. The effects of N fertilization on wheat growth and production varied somewhat between locations and from one year to the next. However, the current N recommendation for wheat in Arkansas (i.e., a single application of 101 kg N ha(-1)) appears to be too low to produce maximum yields under low P and K. fertility. Differing yield responses between locations were likely due to the combination of inherent P and K fertility differences and carryover N from the previous crop during the first year of the study. Capitalizing on the relationship among N rate, grain yield, and PHI will allow wheat producers to minimize N applications and production of excessive aboveground biomass, while still being able to produce an economically viable yield.