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Evaluation of residue management practices on barley residue decomposition
Full text linkOptimizing 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 3-mo laboratory incubation experiment was conducted at a temperature of 25 to 30 °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 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 CO2-C of 8.3 g kg-1 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 and 27%, respectively) and incorporated-sieved (69 g kg-1 and 18%, respectively) residues, respectively. There were no significant differences in C-mineralization from barley residue based on soil type or its interactions (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
Moving toward sustainable irrigation in a southern Idaho irrigation project
Full text linkPrivate and public irrigation development projects were a fundamental part of bringing irrigation arid regions of the western U.S. The Twin Falls Canal Company in southern Idaho provides a case study of private and public irrigation development because the project was developed by private investors under the Carey Act and receives a portion of its irrigation water from Bureau of Reclamation reservoirs. The project survived initial financial struggles and waterlogged soil to focus on sustaining the production by reducing chronic furrow irrigation erosion and nutrient losses in irrigation return flow. Average sediment loss from the project was 460 kg/ha in 1970. A cooperative effort by the canal company, state and federal agencies, and farmers improved water quality by installing sediment ponds on fields, applying polyacrylamide with furrow irrigation, converting from furrow to sprinkler irrigation, and constructing water quality ponds on irrigation return flow streams. From 2006-2018, the project retained on average 165 kg/ha of sediment and 0.4 kg/ha of total phosphorus annually, which removed 13,000 Mg of sediment and 33 Mg of total phosphorus from the Snake River each year. Nitrate-N from subsurface drainage, however, was lost at 10 kg/ha each year, which is equivalent to 380 Mg of urea fertilizer from the entire project. While sediment and phosphorus concentrations in irrigation return flow have decreased, they were still greater than the irrigation water concentrations, indicating that more can be done to reduce the project’s influence on water quality in the Snake River
Kentucky bluegrass invaded rangeland: ecosystem implications and adaptive management approaches
Full text linkUSDA-NRCS National Resources Inventory data indicates that between 2011 and 2015 Kentucky bluegrass (Poa pratensis) was present in 14.5% on non-Federal rangelands nationally and 86% in North Dakota, 63% in South Dakota, 40% in Kansas, 38% in Nebraska, and 32% in Montana. Native grasslands provide important services such as nutrient cycling, forage and habitat for wildlife and livestock, pollinator habitat, carbon capture, and regulation of hydrologic cycles, among others. Therefore, grassland degradation due to invasive plant species has far-ranging consequences for both human and ecological systems. We present information from a symposium at the 2019 Society for Range Management Annual Meeting. The symposium covered three topic areas that have been the foci of NGP Kentucky bluegrass research in the last five years: (1) impacts of Kentucky bluegrass on ecosystem services (especially soil water regulation, pollinator services, and forage production); (2) opportunities for using adaptive management approaches that include natural disturbances (such as fire and livestock grazing) for restoring and maintaining diverse grasslands; and (3) how to effectively overcome social barriers to treatment options aimed at restoring these grasslands. We present brief summaries of research progress on these topics. We conclude that despite great advances in knowledge related to Kentucky bluegrass invaded ecosystems there are still knowledge gaps regarding management of this novel ecosystem under changing climatic conditions as well as challenges regarding large scale adoption of management practices needed to manage these systems appropriately
Commercial sugar beet cultivars evaluated for rhizomania resistance and storability in Idaho, 2018
Full text linkRhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet cultivars with resistance to BNYVV and evaluate storability, 30 commercial cultivars were screened by growing them in a sugar beet field infested with BNYVV in Kimberly, ID during the 2018 growing season in a randomized complete block design with 6 replications. At harvest on 26-27 September 2018, roots were dug and evaluated for symptoms of rhizomania and also placed in an indoor commercial sugar beet storage building. After 136 days in storage, samples were evaluated for surface rot, weight loss, and sucrose loss. Surface root rot ranged from 17 to 81%, weight loss ranged from 22 to 32%, sucrose losses ranged from 44 to 87%, and estimated recoverable sucrose ranged from 803 to 7,207 lb/A. Given these response ranges, selecting cultivars for rhizomania resistance and combining this resistance with storability will lead to considerable economic benefit for the sugar beet industry
Beet curly top resistance in USDA-ARS Ft. Collins germplasm, 2019
Full text linkCurly top caused by Beet curly top virus (BCTV) is a widespread disease problem vectored by the beet leafhopper in semiarid sugar beet production areas. Host resistance is the primary defense against this problem, but resistance in commercial cultivars is only low to intermediate. In order to identify novel sources of curly top resistance, 30 sugar beet lines produced by the USDA-ARS Ft. Collins sugar beet program were screened in a disease nursery in 2019. The lines were arranged in a randomized complete block design with six replications. A curly top epiphytotic was created by releasing six viruliferous beet leafhoppers per plant at the four- to six-leaf growth stage on 3 Jul. Foliar symptoms were evaluated on 22 July using a scale of 0-9 (0 = healthy and 9 = dead) in a continuous manner. Curly top symptom development was uniform and no other disease problems were evident in the plot area. The disease pressure in the test was moderately severe with good symptom development in the susceptible checks. Based on the visual rating, entries 9 and 27 were not significantly different from the resistant checks. These germplasm lines will be reevaluated for potential release to the general public so it can be utilized to improve BCTV resistance in commercial sugar beet cultivars
Antibiotic resistance genes, class 1 integrons, and IncP-1/IncQ-1 plasmids in irrigation return flows
Full text linkAntibiotic resistance is encoded by antibiotic resistance genes (ARGs) and surface waters could be a dominant route by which they are disseminated. In the present study we aimed to explore the prevalence and abundance of ARGs [blaCTX-M-1, erm(B), sul1, tet(B), tet(M), and tet(X)], class 1 integron-integrase gene (intI1), and IncP-1 and IncQ-1 plasmids in eight irrigation return flows (IRFs) and a background site (Main Line Canal, MLC) in the Upper Snake Rock watershed in south-central Idaho. Grab samples were collected on a monthly basis for a calendar year, which were processed to extract microbial DNA, followed by droplet digital PCR to quantify the gene copies on an absolute (per 100 mL) and relative (per 16S rRNA gene copies) basis. The antibiotic resistance and intI1 genes and IncP-1/IncQ-1 plasmids were recovered at all IRF sampling sites with detections ranging from 55 to 81 out of 81 water sampling events. The blaCTX-M-1 gene was detected the least frequently (68%), while the other genes were detected more frequently (88 to 100%). All of the genes were also detected at MLC from April to October when water was present in the canal. The genes from lowest to greatest relative abundance in the IRFs were: blaCTX-M-1 < erm(B) < tet(B) < IncQ-1 < tet(M) < sul1 < intI1 = IncP-1 < tet(X). When compared to the average annual relative gene abundances in MLC water samples, they were found to be at statistically greater levels (P = 0.008) except that of the IncP-1 and IncQ-1 plasmids (P = 0.8 and 0.08, respectively). The fact that most IRFs contained higher levels than found in the canal water, indicates that IRFs can be a point source of ARGs that ultimately discharge into surface waters. It was also found that ARG levels were not strongly correlated with the intI1 gene, nor IncP-1 and IncQ-1 plasmids, suggesting that the ARGs were not enriched as a result of horizontal gene transfer among or replication within environmental bacteria
Watershed water balance changes as furrow irrigation is converted to sprinkler irrigation in an arid region
Full text linkIrrigation is the largest water use in the western U.S. The Upper Snake Rock Conservation Effects Assessment Project in southern Idaho began in 2005 to quantify the impacts of conservation practices in this irrigated watershed. The objective of this study was to determine the changes in the watershed water balances as farmers converted furrow irrigated fields to sprinkler irrigation from 2006 to 2016. More than 75% of annual watershed inflow was irrigation water diverted into the watershed from the Snake River and distributed through canals to 82,000 ha of cropland, while annual precipitation was only 10 to 23% of the annual inflow. Approximately 30% of the annual watershed inflow flowed back to the Snake River as irrigation return flow. Water balances indicate that irrigation exceeded evapotranspiration in the spring and fall. Irrigation scheduling based on daily ET or soil moisture measurement would help irrigation application match crop water needs. Annual irrigation project efficiency, defined as evapotranspiration divided by the amount of diverted irrigation water, varied from 61 to 73%, but project efficiency did not increase as the amount of sprinkler irrigation increased from 46% in 2006 to 59% in 2016. The only significant trends indicating that increasing sprinkler irrigation impacted the water balances were increasing irrigation project efficiency in July and increasing irrigation return flow during the irrigation season. Farmers may be applying less Irrigation water with sprinkler irrigation compared to furrow irrigation, which could have caused return flow to increase since irrigation diversion did not change. The irrigation project was designed with a supply-based allocation scheme to uniformly distribute the natural flow water right from the Snake River to farms. Therefore, irrigation diversion depended more on the available water supply than crop irrigation requirements. This study demonstrated that water rights and water policy can have a bigger impact on irrigation project efficiency than practices implemented on farms
Thermal crop water stress index base line temperatures for sugarbeet in arid western U.S.
Full text linkSugarbeet is a deep-rooted crop in unrestricted soil profiles that can readily utilize stored soil water to reduce seasonal irrigation requirements. Utilization of soil water below 0.6 m is not commonly considered for irrigation scheduling due to the labor and expense of soil water monitoring at deeper depths and uncertainty in effective rooting depth and soil water holding capacity. Thermal-based crop water stress index (CWSI) irrigation scheduling for sugarbeet has the potential to overcome soil water monitoring limitations and facilitate utilization of stored soil water. The traditional canopy temperature based CWSI for monitoring plant water status has not been widely used for irrigated crops partly because of the need to know well-watered and non-transpiring canopy temperatures under identical environmental conditions. In this study, canopy temperature of irrigated sugarbeet under full irrigation (FIT) and 25%FIT in 2014, 2015, 2017 and 2018 in southcentral Idaho and FIT and 60%FIT in 2018 in northwestern Wyoming USA was monitored from full cover through harvest along with meteorological conditions and soil water content. Data driven models, multiple linear regression (MLR) and neural network (NN), were used to predict well-watered canopy temperature based on 15-min average values for solar radiation, air temperature, relative humidity, and wind speed collected within 2 hours of solar noon (13:00 – 16:00 MDT). The NN model had significantly less (p 0.6 m) soil water monitoring
Foliar insecticides for the control of curly top in Idaho sugar beet, 2019
Full text linkCurly top caused by Beet curly top virus (BCTV) is a widespread disease problem vectored by the beet leafhopper in semiarid sugar beet production areas. Host resistance is the primary defense against this problem, but resistance in commercial cultivars is only low to intermediate. The neonicotionoid seed treatments currently supplement this resistance to provide early season control. In order to identify other management options eight foliar insecticides were screened in 2019 on a commercial sugar beet cultivar approved for production. The plots were arranged in a randomized complete block design with eight replications. A curly top epiphytotic was created by releasing six viruliferous beet leafhoppers per plant at the eight-leaf growth stage on 24 June. Foliar symptoms were evaluated on 11 August and 16 September using a scale of 0-9 (0 = healthy and 9 = dead) in a continuous manner. Curly top symptom development was uniform and no other disease problems were evident in the plot area. The disease pressure in the test was moderately severe with good symptom development in the non-treated check. Based on visual ratings, root yield, and estimated recoverable sucrose, the foliar insecticides provided little or no influence on the control of curly top. However, the yields for all treatments except the insecticide seed treatment check indicate that the cultivar was severely infected during the study. These data show that sugar beet production in areas with curly top would likely suffer considerably without the neonicotinoid seed treatments
Potato Irrigation Management
Full text linkPotato yield and quality are sensitive to both excess and deficit soil water. This sensitivity, coupled with a relatively shallow root zone and medium- to coarse -textured soils common in many production areas, makes economically efficient irrigated potato production challenging. Potato is grown under all types of irrigation systems worldwide, but irrigation systems capable of light, frequent, uniform water application are best. Optimum potato irrigation management requires a working knowledge of soil water relations and irrigation system characteristics. This chapter introduces both in the context of potato production in arid areas of the Pacific Northwest U.S. General guidelines and irrigation management aids are presented along with examples for implementing quantitative irrigation management of potato in an arid environment