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The use of alternative fuels, particularly bio-based fuels, has been an important strategy to achieve greenhouse gas (GHG) emission reductions compared to petroleum-based fuels. However, discrepancies between results obtained by using different attributional life-cycle assessment (LCA) tools have challenged the credibility of the individual assessments, and as result, the progress towards or compliance with GHG mitigation targets. The objective of this study was to identify the main differences and commonalities in methodological structures, calculation procedures, and assumptions for the major commercial biofuel, ethanol, across three public LCA tools, BioGrace (EU), GHGenius (Canada), and GREET (U.S.), and a research-oriented fourth, the Virtual Sugarcane Biorefinery (VSB), a Brazilian platform for sugarcane ethanol assessments. The calculated emissions across models ranged from 16 to 45 for sugarcane, 43–62 for corn, and 45–68 g CO 2 eq MJ−1 for wheat ethanol. Harmonizing the three public models with VSB assumptions for sugarcane ethanol produced in Brazil, the range was reduced to 16–17 g CO 2 eq MJ−1 for sugarcane ethanol. Agricultural production (e.g., N 2 O emissions from fertilizers; energy and fuel use; straw field-burning; and limestone application) and ethanol shipping were found to be the major causes for variations for differences calculated for sugarcane ethanol. Similarly, harmonizing BioGrace and GHGenius calculations using GREET assumptions for U.S. corn ethanol generated nearly identical results (models varied within a 3% range). The coproduct treatment method was found to be the most influential parameter in the variations calculated for both corn and wheat ethanol. The application of the tools as part of GHG emissions accounting requirements is often defined via regulations and differences and/or conflicting assumptions set-forth in these models lead to most differences observed. Our study provides recommendations for promoting transparency in LCA calculations and assumptions across the tools used in research and development or for regulatory tools regarding biofuels. • Emissions ranged from 16 to 45 for sugarcane and 43–62 g CO 2 eq MJ−1 for corn ethanol. • LCA tools produce similar results when harmonized to the maximum possible extent. • Models are sensitive to methodology, which is a risk factor in policy arena. • We recommend strengthened efforts to strive for transparency in LCA. [ABSTRACT FROM AUTHOR]

Abstract Selection of the best wheat variety for cellulosic ethanol production is very important. With dozens of varieties available, information on the sugar yield of different straws is needed to help farmers choose the most profitable wheat variety, for both grain yield and straw yield. Thirty winter wheat lines from the Pacific Northwest of the US were chosen for analysis based on historical and current production. Two pretreatment methods, dilute acid and hot water, were compared to determine the optimum pretreatment condition for wheat straw. Using the optimum dilute acid pretreatment condition, sugar yields from the straw of the 30 wheat varieties were compared. The differences in variety performance were then evaluated based on relationships among several measured parameters, including straw yield, grain yield, and chemical composition of biomass. The ranges of chemical composition for the 30 wheat straw varieties were 33.7–36.3% glucan (proxy for cellulose), 16.8–19.5% xylan (proxy for hemicellulose), and 18.4–20.6% lignin. Results also showed significant differences in total sugar recovery, which varied between 0.239 and 0.401 g g−1 dry matter of raw biomass across wheat straw varieties. Among the 30 tested varieties, Weatherford was selected as the best for dual-purpose wheat because it ranked highest in straw yield and potential sugar production per area and 6th-highest in grain yield. Highlights • Straw from 30 winter wheat varieties were compared for bioethanol production. • Significant differences were found in sugar yield across wheat straw varieties. • The variety, Weatherford, showed the highest potential sugar production per area. [ABSTRACT FROM AUTHOR]

Wheat ( Triticum aestivum L.) breeding strategies can benefit from periodic evaluation of genetic gains for physiological and morphological traits, and their contribution to yield progress over time in a particular environment. The objective of this research was to expand the recent work at Virginia Tech on genetic yield improvement in soft red winter (SRW) wheat and determine the magnitude of progress for several physiological traits in 50 SRW wheat cultivars released from 1919 to 2009. Physiological traits evaluated here were extensively reported in the literature to be relevant for future wheat breeding as they directly contributed to yield increase under optimum and suboptimal environmental conditions; these traits include canopy temperature depression (CTD), flag leaf width (W), flag leaf area (LA), flag leaf dry weight (DW), flag leaf specific area (SLA), SPAD (soil plant analysis development) chlorophyll reading, and grain 13 C isotope discrimination (Δ). Replicated experiments were performed at Warsaw and Holland, VA, in 2009–2010 and 2010–2011 growing seasons. Results showed that three traits consistently changed in magnitude over time and, at the same time, were significantly (p < 0.01) related to yield; they were LA, smaller leaf area-higher yields; DW, lighter leaves-higher yields; and Δ, higher Δ-higher yields. CTD decreased in magnitude and SLA, W, and SPAD chlorophyll reading did not significantly change over time. Our data suggest that further yield increase in the SRW wheat grown in eastern Unites States can be achieved through selection of cultivars with smaller leaves, and with high Δ. [ABSTRACT FROM AUTHOR]

The Southern Great Plains are characterized by a fine-scale mixture of different land-cover types, predominantly winter-wheat and grazed pasture, with relatively small areas of other crops, native prairie, and switchgrass. Recent droughts and predictions of increased drought in the Southern Great Plains, especially during the summer months, raise concern for these ecosystems. We measured ecosystem carbon and water fluxes with eddy-covariance systems over cultivated cropland for 10 years, and over lightly grazed prairie and new switchgrass fields for 2 years each. Growing-season precipitation showed the strongest control over net carbon uptake for all ecosystems, but with a variable effect: grasses (prairie and switchgrass) needed at least 350 mm of precipitation during the growing season to become net carbon sinks, while crops needed only 100 mm. In summer, high temperatures enhanced evaporation and led to higher likelihood of dry soil conditions. Therefore, summer-growing native prairie species and switchgrass experienced more seasonal droughts than spring-growing crops. For wheat, the net reduction in carbon uptake resulted mostly from a decrease in gross primary production rather than an increase in respiration . Flux measurements suggested that management practices for crops were effective in suppressing evapotranspiration and decomposition (by harvesting and removing secondary growth), and in increasing carbon uptake (by fertilizing and conserving summer soil water). In light of future projections for wetter springs and drier and warmer summers in the Southern Great Plains, our study indicates an increased vulnerability in native ecosystems and summer crops over time. [ABSTRACT FROM AUTHOR]

Agriculture, by its intentional design, manipulates the ecological functions of soils. It does so by altering carbon and nutrient inputs; by controlling the plant community; and in the case of tillage, by physically disrupting and redistributing the soil within the soil profile. While there are many studies that contrast soil microbiomes across farming systems, few studies have examined the effect of farming system on the vertical organization of taxa in the soil profile. We hypothesized that large effects of farming systems on edaphic factors would lead to large impacts on the microbial community that would reflect the underlying life history strategy of the microbes. For example, that tillage would increase the proportion of unicellular fungi. Our study compared farming systems that had been in place for 13 years in the mid-Atlantic region of the United States. Each system is a 3-year rotation of corn (Zea mays), soybean (Glycine max), and wheat (Triticum aestivum), managed with either conventional no-till, conventional chisel-till, or using organic methods. We determined the relative effect of long-term farming system management on edaphic factors and the soil microbial community with depth structured sampling (0–5, 5–10, 10-Ap, Ap-30 cm). We found relatively small effects of farming system but substantial effects of depth on edaphic factors and microbial communities. For example, differences in management resulted in subtle differences in %C above the Ap horizon. Fungal gene abundance increased in the organic system relative to the no-till system, although neither fungal nor bacterial richness differed across farming systems. Farming system effects on microbial community composition were greatest in the top 10 cm but did not affect the abundance of unicellular fungi. Several groups including Pseudomonas and Mortierellomycota appear to be sensitive to redistribution by tillage in the organic system, but it is not clear to what extent this effect is due to legacy DNA from tillage. Thirteen-year management of organic and conventional grain farming systems results in modest differences to microbial communities along soil depth profiles 1) Organic treatment results in a increase in soil %C and differences in %C depth distribution 2) No difference in richness and evenness among farming systems 3) A 30 cm depth profile represents a much greater environmental gradient for microbial abundance and diversity than differences among long-term row-crop farming systems that differ in tillage, fertility and pest management [Display omitted] • Depth had larger effect than farming system on microbial community. • Farming system effects were concentrated in top 10 cm. • Farming systems altered the distribution of some taxa across depth increments. • No effect of farming system on abundance of unicellular fungi. [ABSTRACT FROM AUTHOR]

Hard red winter wheat crops on the U.S. Southern Great Plains often experience moderate to severe drought stress, especially during the grain filling stage, resulting in significant yield losses. Cultivars TAM 111 and TAM 112 are widely cultivated in the region, share parentage and showed superior but distinct adaption mechanisms under water-deficit (WD) conditions. Nevertheless, the physiological and molecular basis of their adaptation remains unknown. A greenhouse study was conducted to understand the differences in the physiological and transcriptomic responses of TAM 111 and TAM 112 to WD stress. Whole-plant data indicated that TAM 112 used more water, produced more biomass and grain yield under WD compared to TAM 111. Leaf-level data at the grain filling stage indicated that TAM 112 had elevated abscisic acid (ABA) content and reduced stomatal conductance and photosynthesis as compared to TAM 111. Sustained WD during the grain filling stage also resulted in greater flag leaf transcriptome changes in TAM 112 than TAM 111. Transcripts associated with photosynthesis, carbohydrate metabolism, phytohormone metabolism, and other dehydration responses were uniquely regulated between cultivars. These results suggested a differential role for ABA in regulating physiological and transcriptomic changes associated with WD stress and potential involvement in the superior adaptation and yield of TAM 112. [ABSTRACT FROM AUTHOR]

The opportunity cost of producing efficient energy from renewable energy sources especially from agricultural products amid increasing threat of food insecurity has remained policymakers' nightmare. On this note, this study employed the regime inference (the Markov switching model) to examine the response of renewable energy equity relative to prices of corn, soybean and wheat for the United States over the period 20/01/2012 -2/08/2018. Additionally, the SADF (Supremum Augmented Dickey Fuller) test is further employed to investigate the evidence of speculative bubbles in the prices of the concern commodities. With a significant evidence of regime switching, the study reveals positive impacts of soybean and wheat on the renewable energy equity in both regimes while the impact is negative in the regimes for corn prices. The positive impact of soybean is an indication that the share of renewable energy and share of its export is highest while corn is being recently preferred and consumed as stable food rather than a source of renewable energy. Furthermore, a sparing evidence of explosive process and collapse bubbles is observed in all the examined commodities except for soybeans. Moreover, with the frequency domain Granger causality approach, the results show overwhelming evidence of bidirectional Granger causality especially between renewable energy equity and the agricultural commodities at varying frequencies. Thus, the study offers effective policy frameworks through the lens of renewable energy development and agriculture for the United States and for other similar economies. • The dynamics in renewable energy equity and agricultural commodities are examined. • There is significant evidence of regime switching, speculative bubbles, and frequency domain causality. • Soybean and wheat positively affect the renewable energy equity in both regimes. • There is an explosive process and collapse bubbles in corn and wheat commodities. [ABSTRACT FROM AUTHOR]

Abstract: A total of 144 breakfast cereal and snack samples collected from six areas in the United States (U.S.) were surveyed for the presence of ochratoxin A (OTA). All samples are the processed products including mainly corn, oat, wheat, and rice. The analytical methods in this study were immunoaffinity columns (IAC) and high performance liquid chromatography (HPLC) with fluorescence detection (FLD). The method provided recoveries of OTA from all sample matrices in the range of 95–100%. The limits of detection and limits of quantification for OTA were 0.032 and 0.10 ng/g for corn, wheat, and rice based samples; 0.038 and 0.12 ng/g for oat based samples, respectively. Analytical results showed that 75 samples (52%) were contaminated with OTA in the range of 0.10 and 7.43 ng/g. Among the OTA contaminated samples, 40% were labeled as organic and 60% were conventional with mean concentrations of 1.21 and 1.07 ng/g, respectively. There were ten contaminated samples, all from oat based products, exceeding the maximum limits for OTA by European Commission Regulation (3 ng/g) in cereal based products. [Copyright &y& Elsevier]

Highlights: [•] Corn and pea ahead of wheat did not increase wheat WUE in the central Great Plains, USA. [•] Corn ahead of proso millet did not increase proso millet WUE. [•] Dryland wheat yield was not increased with corn included in a rotation. [•] Growing pea ahead of wheat decreased wheat yield. [•] Growing corn ahead of proso millet decreased millet yield. [ABSTRACT FROM AUTHOR]

Highlights: [•] High speed imaging of freefalling wheat kernels for inspection of damage. [•] Multiple simultaneous views of kernel covering >82% of surface. [•] Process logic for selecting view that gives min, max, mean of each kernel property. [•] Tested on wheat damaged by mold, black point, and pre-harvest sprouting. [Copyright &y& Elsevier]

Abstract: Triticum mosaic virus (TriMV), an economically important virus infecting wheat in the Great Plains region of the USA, is the type species of the Poacevirus genus in the family Potyviridae. Sensitive and high-throughput serology-based detection methods are crucial for the management of TriMV and germplasm screening in wheat breeding programs. In this study, TriMV coat protein (CP) was expressed in Escherichia coli, and polyclonal antibodies were generated against purified soluble native form recombinant CP (rCP) in rabbits. Specificity and sensitivity of resulting antibodies were tested in Western immuno-blot and enzyme-linked immunosorbent assays (ELISA). In direct antigen coating (DAC)-ELISA, antibodies reacted specifically, beyond 1:20,000 dilution with TriMV in crude sap, but not with healthy extracts, and antiserum at a 1:10,000 dilution detected TriMV in crude sap up to 1:4860 dilution. Notably, rabbit anti-TriMV IgG and anti-TriMV IgG-alkaline phosphatase conjugate reacted positively with native virions in crude sap in a double antibody sandwich-ELISA, suggesting that these antibodies can be used as coating antibodies which is crucial for any ‘sandwich’ type of assays. Finally, the recombinant antibodies reacted positively in ELISA with representative TriMV isolates collected from fields, suggesting that antibodies generated against rCP can be used for sensitive, large-scale, and broad-spectrum detection of TriMV. [Copyright &y& Elsevier]

Abstract: Aegilops cylindrica Host (jointed goatgrass) is an exotic invasive weed in the western United States that causes economic loss due to competition with winter wheat (Triticum aestivum L.) and contamination of wheat grain. Further, because Ae. cylindrica is a wild relative of wheat, interspecific hybridization is a possible mechanism for the introgression of advantageous genes from wheat to the weedy species. The risk of introgression of traits conferring environmental stress tolerance, such as drought tolerance, from transgenic wheat has not been studied and is of high concern because it could increase the weed''s competitiveness with wheat, as well as its ability to invade novel habitats. Genetic diversity has been reported among western U.S. Ae. cylindrica accessions, however, studies to determine whether genetic diversity relates to phenotypic diversity have been limited. Here, 30 accessions of Ae. cylindrica from the western U.S. were evaluated over two years at two Colorado locations: Haxtun in 2008–2009 and Fort Collins in 2009–2010. Days to flowering, plant height, number of tillers produced per plant, number of spikelets per spike, and number of spikelets per plant were evaluated under rain-fed and irrigated conditions. Results indicate significant (P <0.01) variation among accessions for each of the traits for both years. Additionally, in 2009–2010 there was a significant (P <0.01) effect of irrigation on all traits, except days to flowering. Similarly, all traits except days to flowering showed a significant effect of the interaction of accession with treatment (P <0.05) in 2009–2010. The study shows that variation exists in traits related to competitive ability and fitness. Our data also suggest differences among accessions in sensitivity to water availability. This observation needs to be confirmed in additional environments. Implications of our results for evaluation of transgene introgression are discussed. [Copyright &y& Elsevier]

Abstract: Understanding N dynamics in biosolids-amended agroecosystems can help avoid over-application and the potential for environmental degradation. We investigated 15-years of biosolids application to dryland-wheat (Triticum aestivum L.) grown on Weld loam soils (fine, montmorillonitic, mesic Aridic Paleustolls) located about 25km east of Brighton, CO, USA, questioning what is the relationship between cumulative grain yield and N uptake (N removal) and biosolids or N fertilizer rates and how many times biosolids or N fertilizer are applied? How are wheat-grain production and N uptake intertwined with residual soil NO3–N? We found that biosolids or N fertilizer rates plus the number of applications of each material produced planar-regression (3D) models with 15-years of grain yield and N uptake data (all R 2 >0.93). To evaluate how yield or N uptake impacted residual soil NO3–N, we completed linear regressions on yield, N uptake, and soil NO3–N. We then correlated the slopes where P <0.10 for the yield and soil NO3–N and the N uptake and soil NO3–N. A significant negative relationship was found for biosolids application for each of these comparisons while the N fertilizer results were inconsistent. For the biosolids treatments, as yield or N uptake increased, residual soil NO3–N decreased. Our findings show that planar-regression models could aid biosolids beneficial-use management programs when considering agroecosystem N dynamics. [ABSTRACT FROM AUTHOR]

Virtual water is the volume of water used to produce a commodity or service. Hitherto, most virtual water ‘trade’ studies have focused on its potential contribution to saving water, especially in water short regions. Very little, however, has been said about the opportunity cost of the associated water. The present research critically evaluates the strategic importance of green water (soil water originating from rainfall) in relation to international commodity trade. Besides having a lower opportunity cost, the use of green water for the production of crops has generally less negative environmental externalities than the use of blue water (irrigation with water abstracted from ground or surface water systems). Although it is widely known that major grain exporters – the USA, Canada, France, Australia and Argentina – produce grain in highly productive rain-fed conditions, green water volumes in exports have rarely been estimated. The present study corroborates that green water is by far the largest share of virtual water in maize, soybean and wheat exports from its main exporting countries (USA, Canada, Australia and Argentina) during the period 2000–2004. Insofar virtual water is ‘traded’ towards water-scarce nations that heavily depend on their blue water resources, green virtual-water ‘trade’ related to these commodities plays a role in ensuring water and water-dependent food security and avoiding further potential damage to the water environments in both importing and exporting countries. This potential of international green virtual-water ‘trade’, however, is constrained by factors such as technology, the potential for further increases in the productivity of soil and irrigation water, the level of socio-economic development, national food policies and international trade agreements. [Copyright &y& Elsevier]

Abstract: The central and eastern United States is an important food and timber production region and could potentially be a large-scale carbon sink. These characteristics are functions of the human management of the landscape and favorable soil and climate conditions. Large-scale assessments of carbon uptake and trends in net primary productivity (NPP) have been previously reported for this region using satellite observations, but they cannot quantify the contributions from changes in management and technology independently from climate effects. To address this shortcoming, we used the Agro-IBIS dynamic ecosystem model to examine the relationship of temperature and precipitation trends to NPP changes from 1950 to 2002 and 1982 to 2002 over both natural and managed ecosystems. In order to isolate the vegetation growth response to climate trends, we minimized the representation of management for agroecosystems and forested ecosystems by removing nitrogen stress and irrigation from the model. Simulated NPP trends were larger during 1982–2002 than during 1950–2002 and were positive across most of the domain. For the 1982–2002 period, corn had the largest NPP trend of 6.43gCm−2 year−2 (p =0.22), followed by soybean, spring wheat, deciduous forest, and grassland with 4.06 (p =0.30), 4.05 (p =0.42), 1.98 (p =0.17), and 0.84gCm−2 year−2 (p =0.73), respectively. Winter wheat had a trend of −0.64gCm−2 year−2 (p =0.55) and evergreen needleleaf forest had a negligible NPP trend. Trends in NPP in grasslands, deciduous forest, spring wheat, and winter wheat were associated with trends in precipitation, while trends in corn and soybean were attributed to a combination of longer growing periods, decreased summer average temperatures, and increased precipitation. We found that 19% of corn and 11% of soybean NPP trends could be explained by temperature trends while 23% of corn and 44% of soybean trends could be explained by precipitation trends. Our results provide further evidence supporting observational results that suggest 20–25% of recent crop yield trends can be explained by changing climate, and suggest that over the past several decades climate changes have favored increased crop productivity in most agroecosystems of the central United States with the exception of winter wheat. [Copyright &y& Elsevier]

Abstract: Mould growth and mycotoxin production are related to plant stress caused by environmental factors such as: extreme weather; insect damage; inadequate storage conditions and incorrect fertilization; these predispose plants to mycotoxin contamination in the field. Fusarium species infect wheat during the flowering period. In addition to losses of yield, these fungi can also synthesize toxic components (mycotoxins) in suitable environmental conditions, thus threatening animal and human health. Given the severe consequences and the fact that mycotoxins affect production throughout the world, the ability to predict Fusarium head blight (FHB) and deoxynivalenol (DON) and other mycotoxin contamination is important to reduce the year-to-year risk for producers. Owing to these dangerous consequences in Argentina, Belgium, Canada, Italy, the United States and in Europe, computer models, based on weather variables (temperature, rainfall and moisture level), have been developed to predict the occurrence of FHB and DON contamination in wheat. [Copyright &y& Elsevier]

• We determined frequency of environment types (ENVT) for US maize, soybean, and wheat. • Each ENVT corresponded to a combination of drought and heat stress during critical period. • Inter-annual variation in drought and heat stress was higher than spatial variation. • The ENVT scheme explained observed variation in average actual yield for the three crops. • ENVTs can be used to link field-year experiments with target production environments. The impact of agricultural technologies on crop yield is influenced by the environment type (ENVT) as determined by weather and soil. Understanding the correlation between the ENVT of the testing site in relation to the ENVT of the target production region is important for the evaluation and scaling out of agricultural technologies. Here we propose and apply the first explicit method to characterize ENVTs for major rainfed maize, soybean, and wheat producing regions in the United States. We combined a tested spatial framework, Technology Extrapolation Domain (TED), with crop modeling, long-term (30-y) daily weather records, and soil and management databases to calculate the frequency of ENVTs per crop for major harvested areas. Each ENVT was determined based on the intensity of drought and heat stress during key crop stages for yield determination. The ENVT repeatability was calculated based on the frequency of the most dominant ENVT in each TED. We found that inter-annual variation in drought and heat stress was larger than spatial variation. Our ENVTs explained 2x to 7x larger portion of the variance in actual yield compared to the existing TED framework that is based on long-term annual climate means and soil water storage. For maize and soybean, ca. 30% of their harvested area was located in TEDs with highly repeatable ENVTs (>66% of years). In contrast, only 15% of the wheat harvested area was located in TEDs with high ENVT repeatability. In comparison to the TED framework, the ENVTs defined here can help better capture G×E×M interactions and determine the environmental correlation between testing sites and target production environments. [ABSTRACT FROM AUTHOR]

Emission factors (EFs) of pollutants from post-harvest agricultural burning are required for predicting downwind impacts of smoke and inventorying emissions. EFs of polycyclic aromatic hydrocarbons (PAH), methoxyphenols (MP), levoglucosan (LG), elemental carbon (EC) and organic carbon (OC) from wheat and Kentucky bluegrass (KBG) stubble burning were quantified in a US EPA test burn facility. The PAH and MP EFs for combined solid+gas phases are 17±8. 2mgkg−1 and 79±36mgkg−1, respectively, for wheat and 21±15mgkg−1 and 35±24mgkg−1, respectively, for KBG. LG, particulate EC and artifact-corrected OC EFs are 150±130mgkg−1, 0. 35±0. 16gkg−1 and 1. 9±1. 1gkg−1, respectively, for wheat and 350±510mgkg−1, 0. 63±0. 056gkg−1 and 6. 9±0. 85gkg−1, respectively, for KBG. Positive artifacts associated with OC sampling were evaluated and remedied with a two-filter system. EC and OC accounted for almost two-thirds of PM2. 5 mass, while LG accounted for just under 3% of the PM2. 5 mass. Since EFs of these pollutants generally decreased with increasing combustion efficiency (CE), identifying and implementing methods of increasing the CEs of burns would help reduce their emissions from agricultural field burning. PAH, OC and EC EFs are comparable to other similar studies reported in literature. MP EFs appear dependent on the stubble type and are lower than the EFs for hard and softwoods reported in literature, possibly due to the lower lignin content in wheat and KBG. [Copyright &y& Elsevier]

Abstract: A transgenic variety of spring wheat was proposed for deregulation in North America in 2002. (More recently, the developer shelved this plan.) In this paper, a quantitative model is used to analyze the possible economic impact of commercializing a crop for which there may be sizable consumer resistance. At issue is whether, and under what conditions, the economic benefits from biotech wheat could be outweighed by economic costs. The analysis also addresses the distribution of costs and benefits among stakeholders: producers, consumers, and US taxpayers. Specific attention is given to the impacts on consumers in non-biotech and biotech market segments, and those in the United States and foreign countries. Under base-case assumptions, the analysis suggests that commercialization of biotech wheat could lead to a small net loss of total economic welfare. Results depend critically on several model parameters: the rate of biotech adoption; unit cost savings for biotech producers; the share of the non-biotech market segment; and extra costs associated with a ‘dual marketing system’ for wheat. [Copyright &y& Elsevier]

The National Aeronautics and Space Administration (NASA) is developing a zeolite-based synthetic substrate, termed zeoponics. The zeoponic substrate, consisting of NH4+- and K+-exchanged clinoptilolite, and a synthetic apatite, provides all of the plant-essential nutrients through mineral dissolution and ion exchange, with only the addition of water. Initial experiments with wheat resulted in good vegetative growth, however, a subsequent experiment grown to maturity resulted in poor seed yield. Plant-tissue analyses suggested that high P and low Ca concentrations were possible reasons for the low yield. To address the nutrient imbalances, the Ca-bearing minerals dolomite, wollastonite, and calcite were examined as amendments to the zeoponic substrate to provide a common ion effect (i.e., Ca increases in solution from the dissolution of the Ca-bearing minerals will reduce the dissolution of the synthetic apatite, and thus reduce the amount of P available for plant uptake). Plant tissue Ca for all wheat plants grown in amended zeoponic substrates increased with increasing mineral solubilities of the added Ca-bearing minerals, while plant tissue P decreased with increasing mineral solubilities of the added Ca-bearing minerals. Wheat plants grown with the calcite amendment had the highest Ca concentrations (i.e., 0.45 wt.%) and the lowest P concentrations (i.e., 0.76 wt.%). Seed yield and harvest index were also highest of the plants grown in zeoponic substrate when calcite was the amendment (i.e., 1.57 g/plant and 45.7, respectively). This data illustrates that Ca-bearing minerals do provide a common ion effect in zeoponic substrates. [Copyright &y& Elsevier]

Crop management practices are needed that increase crop residue groundcover and reduce soil erosion after winter wheat (Triticum aestivum L. emend. Thell.) planting in the Palouse region of northern Idaho and eastern Washington. This experiment investigates if reduced tillage leaves more residue groundcover from two spring small grain crops following different tillage practices and increases crop performance in subsequent dry pea (Pisum sativum L. subsp. sativum) crops, and into winter wheat crops. In 1996 and 1997, two 3-year trials (spring cereal–dry pea–winter wheat rotation) were seeded to spring wheat and barley (Hordeum vulgare L.) crops as sub-plot treatments. Plow, chisel, and paratill tillage, and no-till main-plot tillage treatments were applied to silt loam soils after the spring small grain crops. Spring small grain residue persisted from fall tillage through pea planting with little change over winter averaging 44% groundcover in 1997 and 74% groundcover in 1998 for the no-till treatment after pea planting. In 1998 pea yield in no-till was highest (1835 kg ha−1), whereas pea yield was lowest in the plow treatment (1605 kg ha−1). Pea residue mass collected after harvest was not different across treatments, but the carryover spring small grain residue mass was highest in no-till at 3010 kg ha−1 for barley and 2160 kg ha−1 for wheat. After winter wheat seeding in 1997, only the no-till treatment had over the minimum 30% groundcover recommended for erosion control. In 1998, all reduced tillage treatments left more than 30% groundcover and the next year no-till had 46% groundcover after winter wheat seeding. Winter wheat yields were not different in 1998, but in 1999 were highest in the chisel and paratill treatment and averaged 5150 kg ha−1. Residue groundcover can be increased by reduced tillage and good yields can be obtained if plant stand is achieved and pest problems are well managed. [Copyright &y& Elsevier]

Stand establishment and subsequent autumn development and growth are important determinants of winter wheat (Triticum aestivum L.) yield. Soil management practices change soil properties and conditions, which alter seedling emergence, crop development and growth. Pre-plant soil management practices were studied for 6 years in a wheat–fallow rotation in eastern Colorado, USA, to isolate the impacts of pre-plant tillage (PT) and residue level on winter wheat seedling emergence and autumn development and growth. A split plot design was used with PT, using a moldboard plow that incorporated surface residue, and with no-tillage (NT). The tillage systems represented the main plots and three residue levels within each tillage treatment as subplots: no residue (0R), normal residue (1R) and twice-normal residue (2R). Residue amount had little effect on emergence or autumn growth and development. PT resulted in soil water loss from the plow zone. NT plots had more favorable soil water levels in the seeding zone which resulted in faster, more uniform and greater seedling emergence in 4 out of the 6 years. This is especially critical for stand establishment in years with low rainfall after planting. Soil or air temperature did not account for differences among treatments. Earlier and greater seedling emergence in NT treatments resulted in greater autumn development and growth. Shoot biomass, tiller density and leaf numbers were greater in NT, and again residue amount had little effect. At spring green-up, NT treatments had greater soil water in the profile. Grain yield was always equal or greater in NT than in PT, and positively correlated with earlier/greater seedling emergence and autumn growth. NT will enhance soil protection and likely increase snow catch, reduce evaporation and benefit yield in semiarid eastern Colorado. [Copyright &y& Elsevier]

Presents information on a study which examined the dynamics of regional, export-wheat, railroad rates linking seven central United States regions to Texas Gulf ports using the time series methods. Method of analysis; Results and discussion of the study.

• Soil moisture has the potential to be used as a measurement of the resiliency. • We examined the applicability of four soil moisture metrics to measure resiliency. • These metrics helped with identifying promising treatments to address resiliency. • No-till and reduced input treatments were the most and least promising. Measuring and improving resiliency is the key goal of climate risk management in rainfed agriculture. Currently, available metrics are generally used to qualitatively measure the resilience of agricultural systems at broader scales. Moreover, these metrics showed non-linear responses to climate variability, thus often fail to capture the temporal dynamics of resilience at field scales. Our objective for this study is to combine a few soil moisture-based metrics to gauge the resiliency of three promising rainfed agricultural treatments, namely the no-till, organic, and reduced input treatments against the conventional treatment. These treatments have been established at the Kellogg Biological Station Long-Term Ecological Research (KBS-LTER) experiment in a randomized complete block design with six blocks per treatment. All four of these treatments consisted of maize (Zea mays)-soybean (Glycine max)-winter wheat (Triticum aestivum) in rotation. Long-term (1993–2018) soil moisture data from this experiment was collected to compute the soil moisture metrics while the total crop biomass, crop yield, and soil organic carbon data were statistically analyzed to evaluate the robustness of the metrics to gauge the resiliency of these systems. Results have shown that, among the soil moisture metrics, the mean relative difference, the Spearman's rank correlation coefficient, and soil water deficit index were suitable, while the index of temporal stability was not suitable to gauge the resiliency of different rainfed agricultural systems. The no-till treatment was identified as the most resilient treatment in terms of soil moisture retention, effectiveness for drought mitigation, and crop yields. Meanwhile, the reduced input treatment was the least resilient in terms of soil water conservation and drought recovery. The results of this study can be extended to other Midwest regions of the United States and similar climatological areas around the world. [ABSTRACT FROM AUTHOR]

Provides information on the testing of flexibility policy rules on the United States wheat sector using stochastic control methods. Specification of the constraint structure; Detailed information on an estimation of the policy criterion function; Conclusion reached.

Argues that price support, conditioned on production constraint, has not increased US wheat production. Evaluation of US agricultural policy reform; Interaction of price support programs and production constraints; US agricultural policy towards the European Community and the Cairns Group.

Focuses on railroads practice of differential pricing in the unregulated wheat transportation market in Kansas. Definition of the pricing method; Effect of the indivisibility of railroad fixed factors; Increase in intra rail competition in the wheat transportation market after 1980; Factors influencing the ability of railroads to differential price.

• We quantitatively map the sensitivity of agriculture to drought stress. • A strong spatial correspondence between drought sensitivity and irrigation exists. • The sensitivity is higher in arid/semi-arid regions and lower in humid regions. • We identify the sub-seasonal pattern of agricultural sensitivity to drought stress. • The non-irrigated crops are more sensitive to drought than the irrigated crops. Drought is a devastating natural hazard posing great threats to agriculture. Identifying the spatial pattern of agricultural sensitivity to drought can provide scientific information for decision-makers to prepare droughts, allocate resources, and mitigate impacts. Here, we use long-term state- and county-level crop data for the 10 major crops: corn grain, soybeans, hay, spring wheat, winter wheat, cotton, corn silage, sorghum, barley, and rice in the United States from 1950 to 2016. First, we perform a correlation analysis between crop yield anomalies and two drought indices (Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Precipitation Index (SPI)) to identify the sub-seasonal pattern of agricultural sensitivity to drought stress. SPEI performs better than SPI. For most crops, the sensitivity to drought increases in the early period, peaks at the critical months, and then declines. July is the most critical month for crop growth for most crops. Among all crops, soybean and corn grain are most sensitive to drought. Second, we develop an Agriculture Drought Sensitivity Index (ADSI) to quantitatively measure the sensitivity of agriculture to drought stress based on the statistical relationship between the ten major crops and SPEI. We demonstrate that there exists a very strong spatial correspondence between higher sensitivity to drought and the lower percentage of acres irrigated, and vice versa. Also, for those regions with limited irrigation, the sensitivity is higher in arid/semi-arid regions and lower in humid regions in summer. Third, given the importance of irrigation, an analysis of covariance (ANCOVA) shows that the irrigated crop yields have much higher long-run mean yields than non-irrigated crop yields. Fourth, to investigate how irrigation affects drought sensitivity, a panel data regression model shows that the responses of crop growth to drought are non-linear for all crops. Non-irrigated crops are more sensitive to droughts than the irrigated crops, particularly in severe drought conditions. This provides quantitative incentive to use irrigation as an important adaptation and coping strategy to mitigate the drought impacts on agriculture in the US. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• Quantified irrigation's role in stabilizing U.S. agricultural yields. • Irrigation-Induced Reduction in Yield Variability (IIRYV) computed for nine crops. • Derived from 220,000 historical records, mean U.S IIRYV was 41 % (range: 0–90 %). • Maize and cotton demonstrated the highest and lowest IIRYV. • IIRYV increased during 1950–2015 for most crops, albeit crop and space variation. Irrigation contributes to enhance and sustain agricultural production in the U.S. across all aridity regimes, via mitigation against interannual environmental variability. Currently, a quantitative understanding of the role of irrigation in stabilizing agricultural yields is lacking, limiting the realization of irrigation-adoption impacts. Here we use >220,000 historical (1950–2015) county-year irrigated and rainfed yield records for the top-nine U.S. crops [maize (Zea mays L.), soybean (Glycine max (L.) Merr.), spring wheat (Triticum aestivum L.), winter wheat (Triticum aestivum L.), alfalfa (Medicago sativa L.), sorghum (Sorghum bicolor (L.) Moench), cotton (Gossypium hirsutum), barley (Hordeum vulgare L.) and oats (Avena sativa)]. To comprehensively quantify the "Irrigation-Induced Reduction in Crop Yield Variability" (IIRYV, defined as the percent reduction in crop yield variability when irrigated with respect to rainfed yield variability). Averaged across all crops, national-level IIRYV was 41 %, which varied from 0 to 90 % across various regions and crops. IIRYV was highly crop-specific, and maize and cotton crops demonstrated the highest and least magnitudes. IIRYV substantially varied spatially within the constituent growing regions for each crop, and thus national scale assessments masked significant spatial differences. IIRYV was subject to interannual (temporal) variability; however, in general, IIRYV increased over time (1950–2015) for most crops. These findings will help in the evaluation of the contribution of historical irrigation development policy and adoption in the U.S in mitigating external shocks (variability) in U.S. agricultural productivity. The demonstration of spatial and temporal dynamics in IIRYV will aid in irrigation-water allocations and adoption by prioritizing irrigation development for vulnerable crops and regions. [ABSTRACT FROM AUTHOR]

• Examined the mechanisms of suppression of RNA silencing (VSR) activity of TriMV P1. • 55 N-terminal and 1 C-terminal amino acids of TriMV P1 are dispensable for VSR activity. • The LXK/RA, zinc-finger, and GW motifs of TriMV P1 are required for VSR activity. • TriMV P1 binds to dsRNAs but not to ssRNAs in size and sequence independent manner. • TriMV P1 protects dsRNA from dicing by the human Dicer enzyme. Triticum mosaic virus (TriMV) is the exemplar strain of the type species of the genus Poacevirus in the family Potyviridae infecting wheat in the Great Plains region of the USA. Previously, we reported that the P1 protein of TriMV is a viral suppressor of RNA silencing. Mutational analyses of P1 showed that deletion of 55 N-terminal amino acids, and a single amino acid at the C-terminus retained its ability to suppress ssGFP-induced RNA silencing. These data suggest that the N-terminal region but not the C-terminal region of P1 is flexible for suppression of RNA silencing activity. Computational analyses revealed that TriMV P1 contains LXK/RA and zinc finger motifs at the N-terminal region and a domain containing the GW motif at the C-terminal region. Mutational analysis of TriMV P1 suggested functional roles for these motifs in suppression of RNA silencing. Electrophoretic mobility shift assays with bacterially expressed P1 protein revealed that P1 binds to 180-nt and 21- and 24-nt ds-siRNAs derived from green fluorescent protein sequence. Additionally, TriMV P1 protected the 655-nt long dsRNA derived from TriMV coat protein from dicing by the human Dicer enzyme into siRNAs. Disruption of the GW motif in TriMV P1 with a W332A mutation abolished silencing suppression, pathogenicity enhancement and viability of TriMV, suggesting a functional role for the GW motif in suppression of RNA silencing. [ABSTRACT FROM AUTHOR]