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Irrigation: Erosion
Get PDFIrrigation is essential for global food production. However, irrigation erosion can limit the ability of irrigation systems to reliably produce food and fiber in the future. The factors affecting soil erosion from irrigation are the same as rainfall—water detaches and transports sediment. However, there are some unique differences in how the factors occur during irrigation and in our ability to manage the application of water that causes the erosion. All surface irrigation entails water flowing over soil. Soil type, field slope and flow rate all affect surface irrigation erosion, with flow rate being the main factor that can be managed. Ideally sprinkler irrigation will have no runoff, but application rates on moving irrigation systems can exceed the soil infiltration rate, resulting in runoff and erosion. Using tillage practices to increase soil surface storage and selecting sprinklers with lower application rates will reduce sprinkler irrigation runoff. Irrigation can be managed to minimize erosion and maintain productivity
Selection for resistance to the rhizoctonia-bacterial root rot complex in sugar beet
Get PDFThe Rhizoctonia-bacterial root rot complex continues to be a concerning problem in sugar beet production areas. To investigate resistance to this complex in 26 commercial sugar beet cultivars, field studies and greenhouse studies with mature roots from the field were conducted with Rhizoctonia solani AG-2-2 IIIB strains and Leuconostoc mesenteroides. Based on means for the 26 cultivars in the 2010 and 2011 field studies, fungal rot ranged from 0 to 8%, bacterial rot ranged from 0 to 37%, total rot ranged from 0 to 44%, and surface rot ranged from 0 to 52%. All four rot variables resulted in significant (P < 0.0001) cultivar differences. Based on regression analysis, strong positive relationships (r2 from 0.6628 to 0.9320; P < 0.0001) were present among the rot variables. When ranking cultivars, the most consistent rot variable was surface rot, since 12 out of 13 variable-year combinations had significant (P < 0.05) correlations. When cultivar ranking in the greenhouse assays were compared, there was frequently a good positive correlation with storage data but when compared with field results there was no relationship. Thus with this root rot complex, the greenhouse assays related to storage and did not substitute for conducting field screening
Current knowledge on the environmental fate, potential impact, and management of growth-promoting steroids used in the US beef cattle industry
Get PDFGrowth promoting steroids and steroid-like compounds (GPSC) used by the US beef cattle industry are potential contaminants to water resources. Manure generated in concentrated animal feeding operations contains GPSCs that may enter the environment. Several studies have focused on off-site impacts of GPSC in aquatic life and suggest possible adverse impacts such as abnormal blood hormone levels, masculinization of females, feminization of males, altered sex ratios, intersexuality and reduced fertility. Other studies point to potential human health impacts including increased incidence of human cancers, sexual disorders, and decline in male: female ratio in human beings. However, the use of GPSCs in beef production provides benefits to both cattle producers (less time and cost to raise cattle) and consumers (lower meat prices) and to some extent on the environment. This review discusses major scientific findings and issues related to the use of GPSCs by the cattle industry, their environmental impacts, existing knowledge gaps and potential strategies to manage GPSC movement in the environment. We found that although there have been many studies, there is no consensus on the extent of the problem, and the effects in the environment. Current environmental regulations could be adapted to include GPSCs if necessary
Experimental sugar beet cultivars evaluated for rhizomania resistance and storability in Idaho, 2012
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, 26 experimental cultivars were screened by growing them in a sugar beet field infested with BNYVV in Kimberly, ID during the 2012 growing season in a randomized complete block design with 4 replications. At harvest on 3 October 2012, roots were dug and evaluated for symptoms of rhizomania and also placed in an indoor commercial sugar beet storage building. After 134 days in storage, samples were evaluated for surface rot, weight loss, and sucrose loss. Surface root rot ranged from 34 to 90%, weight loss ranged from 8.4 to 15.4%, sucrose losses ranged from 33 to 72%, and estimated recoverable sucrose ranged from 1,997 to 7,601 lb/A. Given these response ranges, selecting cultivars for rhizomania resistance and combining it with storability will lead to considerable economic benefit for the sugar beet industry
The characterization of microorganisms in dairy wastewater storage ponds
Get PDFDairy wastewaters from storage ponds are commonly land applied to irrigate silage crops. Given that diverse microbial populations are associated with cattle feces, the objective of this study was to use a culture-independent approach to characterize Bacteria and Archaea in dairy wastewaters. Using domain-specific primers, a region of the 16S rRNA gene was amplified from pooled DNA extracts from 30 dairy wastewaters and subsequently used to create a clone library. A total of 152 bacterial clones were examined and sequence matches were affiliated with the following groups: Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, and Synergistetes. Firmicutes was identified as the largest phylum representing up to 69% of the clone sequences. Of 167 clones representing Archaea, 7 genera were found to be closely related (91–100% sequence similarity) to isolates obtained from sediments and feces. Most of the putative sequence matches (98%) represented members from the class Methanomicrobia. With respect to the archaeal clones, only one of the putative sequence matches was affiliated with a methanogenic bacterium known to inhabit the rumen. Our results suggest that the dairy wastewater ponds do not support populations of methanogenic bacteria normally found in the cattle rumen
Beet curly top resistance in USDA-ARS Ft. Collins Germplasm, 2012
Get PDFSeventeen sugar beet (Beta vulgaris L.) lines from the USDA-ARS Ft. Collins sugar beet program were screened for resistance to Beet severe curly top virus (BSCTV) and other closely related Curtovirus species in 2012. Commercial sugar beet cultivars Monohikari and HM PM90 were included as susceptible and resistant checks, respectively. The curly top evaluation was conducted at the USDA-ARS North Farm in Kimberly, ID which has Portneuf silt loam soil and had been in alfalfa in 2011. The field was plowed in the fall and in the spring, fertilized (90 lb N and 110 lb P2O5/A) on 16 Apr 12, sprayed with Ethotron (2 pt/A), and roller harrowed. The germplasm was planted (density of 142,560 seeds/A) on 21 May. The plots were two rows 10 ft long with 22-in row spacing and arranged in a randomized complete block design with four replications. The fields were sprinkler irrigated and hand weeded as necessary. Plant populations were thinned to about 47,500 plants/A on 19 Jun. Plants were inoculated at the four to six leaf growth stage on 22 Jun with six viruliferous beet leafhoppers per plant. The beet leafhoppers were moved twice a day (right after sunrise and just before sunset) for one week by dragging a tarp through the field. The plants were sprayed with Lorsban 4E (1.5 pints/A) on 4 Jul to kill the beet leafhoppers. The plots were rated for foliar symptom development on 10 Jul using a scale of 0-9 (0 = healthy and 9 = dead), with the scale treated as a continuous variable (Plant Dis.:90:1539-1544). Leaf samples were also pulled at the time of disease rating and evaluated in an enzyme-linked immunosorbent assay (ELISA) as described previously (Plant Dis. 94:972-976). Data were analyzed using the general linear models procedure (Proc GLM-SAS), and Fisher’s protected least significant difference (a = 0.05) was used for mean comparisons. Disease development was uniform and other disease problems were not evident in the plot area. The disease pressure in the test was severe with good symptom development in the susceptible check. A number of the lines were not significantly different from the resistant check based on both visual symptoms and ELISA, indicating these lines had true resistance to the virus and not just tolerance. The resistant check was not completely resistant since it had symptoms and an ELISA value that was six times higher than the negative background checks. Thus, there is still room for improving resistance to the curly top virus species
Use of a surrogate to evaluate the impact of tillage on the transport of steroid hormones from manure-amended agricultural field
Get PDFBeef feedlot manure distributed to row crop production areas is a potential surface water contaminant source of the steroid hormones commonly used in beef cattle production. This article reports on research conducted at the University of Nebraska Haskell Agricultural Laboratory near Concord, Nebraska, in July 2009. Manure, collected from beef feedlot pens, was stockpiled for ten months prior to application to a row crop field. Previous research identified that the detection frequency of steroid hormones in beef manure varies greatly. Thus, a surrogate (17 alpha-ethynylestradiol, EE2) was applied at a rate of 75 g per ha to ensure detectable concentrations in surface runoff samples. EE2 was applied directly to beef cattle manure and to bare soil. The EE2 and manure were either incorporated using a single disk treatment (T) or left on the soil surface in a no-till practice (NT). A rainfall simulation experiment was conducted 24 h after manure and EE2 incorporation using a factorial design consisting of tillage, manure, and EE2 treatments. Runoff samples were collected at 5 min intervals during a 30 min runoff period for each plot. Results indicated 96 percent less EE2 mass transport from disk tilled plots compared to no-till. The greatest loss of EE2 was 156 and 6 mg per ha from no-till and disked plots, respectively. Results of this study showed that a single-pass disk tillage treatment can limit the overland transport of steroid hormones from crop production areas
Riparian Shrub Metal Concentrations and Growth in Amended Fluvial Mine Tailings
Get PDFFluvial mine tailing deposition has caused extensive riparian damage throughout the western United States. Willows are often used for fluvial mine tailing revegetation, but some species accumulate excessive metal concentrations which could be detrimental to browsers. In a greenhouse experiment, growth and metal accumulation of Geyer willow, Drummond’s willow, diamondleaf willow, Bebb willow, thinleaf alder, water birch, red-osier dogwood, and shrubby cinquefoil were evaluated for potential revegetation use. Bare-root shrubs were grown in tailings collected from three acidic, metal-contaminated (i.e. cadmium, copper, lead, and zinc) fluvial deposits near Leadville, Colorado, USA. Tailings were amended with only lime to raise the soil pH to 7, or with lime and composted biosolids (100 tons/acre). All shrubs survived in the amended tailings; composted biosolids had little effect on plant biomass. Aboveground and belowground biomass increased during the 2 month greenhouse study by 3 – 9 and 1.5 – 5 times initial values, respectively. Most shrubs accumulated lead and copper in roots, and belowground lead concentrations in all shrubs were significantly reduced by the addition of composted biosolids. Compared to other species, alder and cinquefoil accumulated lead in aboveground growth and concentrations exceeded animal toxicity thresholds. Dogwood, alder, and cinquefoil contained low cadmium concentrations in aboveground new growth, whereas Bebb and Geyer willow contained zootoxic concentrations. Dogwood, alder, and cinquefoil are three good candidates for mine tailing revegetation, especially in fluvial deposits with elevated cadmium concentrations
Infiltration model for center pivot irrigation on bare soil
Get PDFThe marked reduction in infiltration rate caused by formation of a soil surface seal due to water droplet impact on bare soil is a well known phenomenon but is rarely considered in infiltration models, especially under center pivot irrigation. The objective of this study was to develop a soil infiltration model for center pivot sprinkler irrigation that incorporates the transient reduction in soil surface seal hydraulic conductivity as affected by soil and sprinkler characteristics. A sealing soil infiltration model was developed using an explicit finite difference solution scheme with a transient soil seal formation model, which is unique from other studies in that it explicitly uses droplet specific power as the driving factor for formation of a soil surface seal. The model was calibrated to four specific soils using published and laboratory runoff data from rainfall simulation studies with varying droplet kinetic energies and application rates. The model was then applied to center pivot irrigation for five common sprinklers to evaluate the effect sprinkler selection has on infiltration. Due to the high susceptibility of the soils to surface sealing from water drop impact, the sprinkler with the largest wetted diameter was predicted to maximize infiltration. If a center pivot sprinkler irrigation system is operated over a bare soil at the application rates used in this study, a surface seal is going to form, and the only way to maximize infiltration depth is to apply the water over the largest time interval possible
Use of an integrated approach to characterize the physicochemical properties of foundry green sands
Get PDFA fresh green sand, spent green sand, and a weathered spent green sand from a landfill were analyzed using diffractometry, electron microscopy, granulometry, spectrometry, and thermogravimetry. Our objective was to understand how the physicochemical properties of the green sands change from their original form after being subjected to the casting process, then after weathering at the landfill. A quantitative phase composition model was also postulated for each material based on thermogravimetric results and it was found to be the most reliable and informative quantitative data for this type of residue. The weathered sample, that remained in a landfill for two years, was found to be composed of almost pure sand. Because of the weathering process, it may be possible to use the wSGS as a virgin sand replacement in the regeneration system or in geotechnical applications where bentonite would affect the properties of the final product