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Removal of vegtative clippings reduces dissolved phosphorus loss in runoff
Get PDFPhosphorus-containing sediment entering surface water may degrade water quality and promote eutrophication. Grass is sometimes planted as a vegetated filter strip buffer along vulnerable receiving water to trap sediment and reduce the severity of phosphorus nutrient loading. However, eutrophication is still a problem in some waterways due to dissolved phosphorus leaching from senesced vegetation in grassed areas, independent of trapped sediment. A rainfall simulator (96 mm/h) was used to study the vegetative conditions under which losses of total dissolved phosphorus and filterable reactive phosphorus leaching are likely. Boxes containing a Portneuf silt loam soil (Xeric Haplocalcid) were planted with annual ryegrass (Lolium perenne) and cut at two different intervals prior to simulated rainfall 14 days apart. Grass clippings were removed from some boxes and retained on others. During the second simulated rainfall, total dissolved phosphorus and filterable reactive phosphorus in runoff were significantly greater for treatments cut the day before irrigation (0.95 and 0.74 mg/L, respectively) with clippings retained as compared to treatments cut the same day as irrigation with clippings retained (0.74 and 0.59 mg/L, respectively). Removing clippings yielded the lowest mean concentration for both total dissolved phosphorus and filterable reactive phosphorus (0.56 and 0.39 mg/L, respectively). Increasing the senesced vegetative surface area for contact with water, and the amount of time for leaching to occur, resulted in the greatest filterable reactive phosphorus loss. Results point to the potential for vegetation management programs to impact runoff water quality from vegetated buffers. Thus, management implications for vegetated filter strips should consider clippings removal, or perhaps no or reduced mowing during the growing season followed by end-of-season removal, to reduce filterable reactive phosphorus leaching losses
Commercial sugar beet cultivars evaluated for rhizomania resistance and storability in Idaho, 2013
Get PDFRhizomania 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, 28 commercial cultivars were screened by growing them in a sugar beet field infested with BNYVV in Kimberly, ID during the 2013 growing season in a randomized complete block design with 4 replications. At harvest on 11 October 2013, roots were dug and evaluated for symptoms of rhizomania and also placed in an indoor commercial sugar beet storage building. After 123 days in storage, samples were evaluated for surface rot, weight loss, and sucrose loss. Surface root rot ranged from 6 to 86%, weight loss ranged from 4.5 to 14.8%, sucrose losses ranged from 30 to 75%, and estimated recoverable sucrose ranged from 917 to 8,686 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
Improving nitrogen management for corn in southern Idaho and southwest Oregon
Get PDFFunding is being sought from multiple sources to update nitrogen fertilizer recommendations for irrigated corn in southern Idaho and southwest Oregon. This paper summarizes the justifications and main objectives of this proposed research. Nitrogen needs to be correctly managed in corn production systems to optimize economic returns and to protect the environment. The fertilizer nitrogen recommendations for irrigated field corn in Idaho and other parts of the Pacific need to be re-evaluated because: (1) University of Idaho (U of I) and PNW region recommendations are based on sparse research data; (2) Recommendation are based on research data that is over 25 years old; (3) Corn production area and yield have increased dramatically in concentrated areas due to the growing dairy industry; (4) There is evidence of variation in optimal nitrogen rates and management between the U of I recommendations and growers, and between U of I and other corn growing regions; (5) In southern Idaho nitrate concentrations have been increasing in groundwater and springs along the Snake River. Agriculture has been implicated by the Idaho Department of Environmental Quality as a major source of the nitrate. This document elaborates on the above justifications
Soil-plant-microbial relations in hydrothermally altered soils of Northern California
Get PDFSoils developed on relict hydrothermally altered soils throughout the Western United States present unique opportunities to study the role of geology on above and belowground biotic activity and composition. Soil and vegetation samples were taken at three unaltered andesite and three hydrothermally altered (acid-sulfate) sites located in and around Lassen Volcanoes National Park in northeastern California. In addition, three different types of disturbed areas (clearcut, thinned, pipeline) were sampled in acid-sulfate altered sites. Soils were sampled (0 to 15 centimeters) in mid-summer 2010 from both under-canopy and between-canopy areas within each of the sites. Soils were analyzed for numerous physical and chemical properties along with soil enzyme assays, carbon and nitrogen mineralization potential, microbial biomass-carbon and carbon-substrate utilization. Field vegetation measurements consisted of canopy cover by life form (tree, shrub, forb, grass), tree and shrub density, and above-ground net primary productivity of the understory. Overall, parameters at the clearcut sites were more similar to the unaltered sites, while parameters at the thinned and pipeline sites were more similar to the altered sites. We employed principal components analysis to develop two soil quality indices to help quantify the differences among the sites: one based on the correlation between soil parameters and canopy cover, and the second based on six sub-indices. Soil quality indices developed in these systems could provide a means for monitoring and identifying key relations between the vegetation, soils and microorganisms
Metals in waste foundry sands and an evaluation of their leaching and transport to groundwater
Get PDFWhile most waste molding foundry sands (WFSs) are not hazardous in nature, regulatory agencies are often reluctant to permit their beneficial use in agricultural and geotechnical applications due to concerns over metal leaching. The objective of this study was to quantify total and Toxicity Characteristic Leaching Procedure (TCLP) metals in 16 waste sands from Brazilian ferrous foundries and assess their potential to leach metals to groundwater using a probabilistic model developed by the U.S. EPA. Total and TCLP metal concentrations in the non-hazardous sands fell within ranges as reported in the literature, although some of the leachate concentrations were found to exceed drinking water and groundwater maximum contaminant levels MCLs. Leachate values above the MCLs were then used in the model to estimate groundwater concentrations at hypothetical wells up to 400 m downgradient from the land application unit. A conservative scenario of one hectare of land applied WFS and high annual rainfall totals (> 1219 mm/year) suggested that groundwater concentrations of Ba, Hg, Mn, Ni, and Pb could potentially exceed health-based MCLs at most wells. Compared to moderate rainfall totals (813–1016 mm/year), the model demonstrated that wet climates can exacerbate the transport of metals from unconsolidated applications of WFS; however, the use of TCLP results as model input values is not considered appropriate for most byproduct beneficial use scenarios since it simulates low pH conditions within a municipal landfill
Manure and fertilizer effects on carbon balance and organic and inorganic carbon losses for an irrigated corn field
Get PDFLittle is known about inorganic fertilizer or manure effects on organic carbon (OC) and inorganic C (IC) losses from a furrow irrigated field, particularly in the context of other system C gains or losses. In 2003 and 2004, we measured dissolved organic and inorganic C (DOC, DIC), particulate OC and IC (POC, PIC) concentrations in irrigation inflow, runoff, and percolation waters (6-7 irrigations/y); C inputs from soil amendments and crop biomass; harvested C; and gaseous C emissions from field plots cropped to silage corn (Zea mays L.) in southern Idaho. Annual treatments included: (M) 13 (y 1) and 34 Mg/ha (y 2) stockpiled dairy manure; (F) 78 (yr 1) and 195 kg N/ha (y 2) inorganic N fertilizer; or (NA) no amendment--control. The mean annual total C input into M plots averaged 16.1 Mg/ha, 1.4-times greater than that for NA (11.5 Mg/ha) or F (11.1 Mg/ha), while total C outputs for the three treatments were similar, averaging 11.8 Mg/ha. Thus, the manure plots ended each growing season with an average net gain of 3.8 Mg C/ha (a positive net C flux), while the control (-0.5 Mg C/ha) and fertilizer (-0.4 Mg C/ha) treatments finished the season with a net C loss. Atmospheric CO2 incorporated into the crop biomass contributed 96% of the mean annual C input to NA and F plots but only 68% to M plots. We conclude that nutrient amendments substantially influence the short-term carbon balance of our furrow-irrigated system. Amendments had both direct and indirect influences on individual C components, such as the losses of DIC and POC in runoff and DOC in percolation water, producing temporally complex outcomes which may depend on environmental conditions external to the field
Aggregate tensile strength and friability characteristics of furrow and sprinkler irrigated fields in Southern Idaho
Get PDFAgricultural crops grown in southern Idaho are furrow or sprinkler irrigated. Therefore, the soil experiences several wetting and drying cycles each growing season that can contribute to changes in aggregate tensile strength and friability. The objective of the research was to evaluate the influence of irrigation on soil structural properties. Four furrow irrigated fields were sampled at the top and bottom of the field, in the furrow and on the bed location of the furrow. Five sprinkler irrigated fields were sampled at 0-5 and 5-15 cm depth and at the top and bottom of the field. Results from this study indicate that differences in tensile strength in furrow irrigated fields were only evident soon after irrigation; otherwise, there were few differences in tensile strength and friability. In sprinkler irrigated fields tensile strength increased with depth in 3 of the 5 fields measured.Friability was less affected by depth
Drought tolerance selection of sugarbeet hybrids
Get PDFIncreased water demands and drought have resulted in a need to indentify crop hybrids that are drought tolerant, requiring less irrigation to sustain yields. This study was conducted to assess differences in drought tolerance among a group of genetically diverse sugarbeet hybrids. The study was conducted over three consecutive growing seasons (2008-2010) at the USDA Northwest Irrigation and Soils Research Laboratory in Kimberly, Idaho on a Portneuf silt loam soil (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid). Drought tolerance was evaluated by measuring sucrose yield production of six breeding hybrids of Klein Wanzlebener Saatzucht (KWS SAAT AG) and one commercial hybrid (Betaseed Inc.) under six water input treatments. Hybrid drought tolerance was evaluated by linear regression analysis (slope and intercept) of yield versus water input, calculation of a drought stress index (DSI), and comparison of yield potential under full irrigation. The water input treatments were based on a percentage of estimated crop evapoatransipration (ETc). Water input treatments were 125% ETc (W1), 100% ETc (W2), 75% ETc (W3), 50% ETc (W4), 25% ETc (W5) and rain-fed (W6). Irrigation was applied three times a week to meet the desgnated rate. There were significant differences in overall yield potential and in the sucrose yield response to water among hybrids. Greater drought tolerance or greater difference in sucrose yield between hybrids was seen at the lowest water input treatment (intercept difference). Greater drought tolerance was observed for the KWS-05 hybrids compared to the commercial hybrid. Based on these results there exist genetic diversity among existing sugarbeet breeding hybrids
Physical Disintegration of Biochar: An Overlooked Process
Get PDFData collected from both artificially and field (naturally) weathered biochar suggest that a potentially significant pathway of biochar disappearance is through physical breakdown of the biochar structure. Through scanning electron microscopy (SEM) we characterized this physical weathering which increased structural fractures and possessed higher numbers of liberated biochar fragments. This was hypothesized to be due to the graphitic sheet expansion accompanying water sorption coupled with comminution. These fragments can be on the micro and nano-scale, but are still carbon-rich particles with no detectable alteration in the oxygen to carbon ratio of the original biochar. However, these particles are now easily dissolved and could be moved by infiltration. There is a need to understand how to produce biochars that are resistant to physical degradation in order to maximize long-term biochar C-sequestration potential within soil systems
Beet curly top resistance in USDA-ARS Kimberly sugar beet germplasm, 2013
Get PDFCurly top caused by Beet curly top virus 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, 14 sugar beet lines were screened in a disease nursery in 2013. 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 27 Jun. Foliar symptoms were evaluated on 16 Jul 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 check. Based on all variables, three of the lines were not significantly different from the resistant control, HM PM90. These germplasm lines will be released to the general public, so they can be utilized to improve resistance in commercial cultivars