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Transient Soil Surface Sealing and Infiltration Model for Bare Soil Under Droplet Impact.
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. Water application rates under center pivot irrigation commonly exceed infiltration rate, especially near the end of the system lateral. This can lead to off-site runoff and erosion, but more importantly results in field-scale non-uniform water infiltration that can substantially reduce water use efficiency of these irrigation systems. The objective of this study was to develop a sealing soil infiltration model that considers transient soil seal formation on a 30 min or less time scale and can potentially be applied to center pivot sprinkler irrigation systems. 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 form of the transient seal formation model is also unique in that it is expressed as a rational function of specific power rather than an exponential decay function of droplet kinetic energy. The model was applied to published runoff data from two rainfall simulation studies with varying droplet kinetic energies and application rates on three soils. The sealing soil infiltration model represented measured infiltration rates very well for all rainfall simulator tests
Analysis of total metals in waste molding and core sands from ferrous and non-ferrous foundries
Get PDFWaste molding and core sands from the foundry industry have been successfully used around the world as byproducts in geotechnical and agricultural applications. Although waste foundry sands (WFSs) are generally not considered hazardous in nature, relevant data are not available in Argentina. This study aimed to quantify metals in waste molding and core sands from foundries using a variety of metal-binder combinations. Metal concentrations in WFSs were compared to those in virgin silica sands (VSSs), surface soil and soil guidance levels according to hazardous waste law 24.051 from the Argentinean Secretariat of Environment and Sustainable Development. A total analysis for Ag, Al, Ba, Be, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, Te, Tl, V, and Zn was conducted on 96 WFSs and 14 VSSs collected from 17 small and medium-sized foundries. The majority of WFSs analyzed, regardless of metal cast and binder type, contained elemental concentrations similar to those found in virgin sands and native soils. In several cases where alkyd urethane binder was used, Co and Pb concentrations were elevated in the waste sands. Elevated Cr, Mo, Ni, and Tl concentrations associated with the virgin sands should not be an issue since these elements are bound within the silica sand matrix. Because of the naturally low elemental concentrations found in most WFSs examined in this study, they should not be considered hazardous waste, thus making them available for encapsulated and unencapsulated beneficial use applications
Sugar beet germplasm evaluated for rhizomania and storage rot resistance in Idaho, 2011.
Get PDFRhizomania caused by the Beet necrotic yellow vein virus (BNYVV) is a worldwide problem that can lead to loss of tonnage and lower percent sucrose in the field. BNYVV can also reduce the storability of roots. To identify germplasm with resistance to these problems, 14 sugarbeet germplasm lines developed by the USDA-ARS Ft. Collins sugarbeet program were screened in a field experiment arranged in a randomized complete block design with 5 replications. During the growing season plants were evaluated for foliar rhizomania symptoms. At harvest on 29 September, roots were evaluated for rhizomania symptoms and then placed into an indoor commercial sugarbeet storage building in Paul, ID. Foliar symptoms ranged from 0% for one of the resistant checks to 99% for the susceptible check, indicating good separation of germplasm for BNYVV resistance should have been possible in the field study. BNYVV root symptoms ranged from a low of 14 for a resistant check to a high of 25 for one of the susceptible entries at harvest. Fungal growth on the root surface in storage ranged from a low of 21% for an entry with good storability to a high of 100% for the BNYVV susceptible check. Entry 6 ranked among the best entries for all variables indicating it should be investigated further as a potential source of good resistance to these problems. Incorporating better resistance to BNYVV and good storability into commercial sugarbeet cultivars should allow for increased yields in the field and improved recovery of sucrose from roots in storage
Effects of tillage system and nitrogen supply on sugarbeet production
Get PDFThe sugarbeet (Beta vulgaris L.) industry in Idaho is interested in strip tillage (ST) primarily due to the potential savings in tillage costs. This study was conducted to evaluate the use of strip tillage in Idaho compared to conventional tillage practices and to evaluate N requirements of sugarbeet under ST and conventional tillage. The effect of tillage method (strip tillage, moldboard plow system [MP], and chisel plow system [CP]) and N supply (5 levels) on sugarbeet production factors were investigated in Kimberly, ID from 2008 to 2010 on a Portneuf silt loam with barley as the previous crop. Root and estimated recoverable sucrose (ERS) yields were the same under all three tillage practices. However, estimated tillage costs for ST were from 53 percent to 76 percent lower than other tillage systems tested. The CP treatment had significantly lower harvest plant population compared to ST and MP, likely because residue inhibited seed-soil contact. In 2008 and 2010, a significant quadratic relationship was observed between N supply and root and ERS yield. During 2008 and 2010, yields at the economic optimum N supply (EONS) ranged from 73.6 to 79.9 Mg roots per ha and 11,054 to 11,415 kg ERS per ha across N prices ranging from 2.20 per kg N. During 2008 and 2010, nitrogen use efficiency (NUE) at the EONS ranged from 50.1 to 67.9 kg sucrose per kg N supply over all N prices. The N requirements at the EONS ranged from 2.4 to 3.0 kg per Mg in 2008 and 2.5 to 2.8 kg per Mg in 2010 over the range of N prices. Strip tillage can be used to obtain yields comparable to other common tillage practices and decrease tillage costs. Nitrogen requirements could be reduced on heavier textured soils compared to past recommendations in the Pacific Northwest. However, adjusting N requirements based on sugarbeet production and quality history, soil type, and soil residual N should be evaluated
Effects of Planting Configuration and In-Row Plant Spacing on Photosynthetic Active Radiation Interception for Three Irrigated Potato Cultivars
Get PDFResearch studies have evaluated the production of potatoes (Solanum tuberosum L.) grown in conventional and bed planting configurations. However, intercepted photosynthetically active radiation (PAR) from these planting configurations has not been quantified. A study conducted in 2008 and 2009 quantified and compared the intercepted PAR from three planting configurations (four row conventional ridged-row [4RC], five row bed [5RB], and seven row bed [7RB]), and from different plant spacings of cvs Russet Burbank, Russet Norkotah, and Ranger Russet potatoes under sprinkler irrigation. A second study was conducted in 2007 to evaluate the relationship between PAR and leaf area of Russet Norkotah and Russet Burbank for the three planting configurations. These studies were conducted at the USDAARS Northwest Irrigation & Soils Research Lab in Kimberly, ID, on a Portneuf silt loam (coarse–silty mixed mesic Durixerollic Calciorthid). The canopy of Russet Norkotah and Ranger Russet potatoes grown in 5RB and 7RB planting configurations intercepted more PAR during the early vegetative and tuber initiation growth stages compared to the 4RC planting configuration at equal populations in 2008 and 2009 at all measurement dates. The canopy of Russet Burbank intercepted more PAR during the early growth stage in 2008 when planted in the bed planting configurations compared to the 4RC planting configuration, but not on the July 17, 2008 and July 9, 2009 dates. The canopy cover of Russet Burbank potatoes planted in the 4RC planting configuration tended to catch up with the bed planting configurations quicker than the other two cultivars. In general, the quantity of PAR intercepted as affected by planting configuration did not influence total tuber yield and other measured production variables. Cumulative PAR interception 0–72 days after planting (DAP) was increased 35%, 38%, and 32% for the 5RB and 65%, 69%, 23% for the 7RB relative to the 4RC planting configuration for Ranger Russet, Ranger Norkotah, and Russet Burbank, respectively. Cumulative PAR interception for the season was increased 15%, 16%, and 4% for the 5RB and 23%, 23%, 5% for the 7RB relative to the 4RC planting configuration for Ranger Russet, Ranger Norkotah, and Russet Burbank, respectively. The relationship between intercepted PAR and leaf area for Russet Norkotah during the early vegetative and tuber initiation growth stages was significantly different between the three planting configurations, with intercepted PAR at a given leaf area in the order of 7RB>5RB>4RC. For Russet Burbank, the relationship was significantly different for the 5RB and 7RB compared to 4RC
planting configuration only, with intercepted PAR at a given leaf area in the order
of 7RB05RB>4RC
Droplet Kinetic Energy of Moving Spray-Plate Center-Pivot Irrigation Sprinklers
Get PDFThe kinetic energy of discrete water drops impacting a bare soil surface generally leads to a drastic reduction in water infiltration rate due to formation of a seal on the soil surface. Under center-pivot sprinkler irrigation, kinetic energy transferred to the soil prior to crop canopy development can have a substantial effect on seasonal runoff and soil erosion, especially when the soil is not protected by crop residue cover. Droplet kinetic energy of seven commercial off-center action rotating spray-plate sprinklers was characterized over a range of flow rates and pressures. Sprinkler droplet kinetic energy was characterized using two methods; droplet kinetic energy per unit sprinkler discharge and droplet kinetic energy applied per unit water depth under center-pivot irrigation with 3 m sprinkler spacing. The two methods are correlated but kinetic energy per unit sprinkler discharge does not represent droplet kinetic energy applied to the soil under center pivot irrigation as the correlation is not 1:1. Droplet kinetic energy applied for a given flow rate and operating pressure varied by up to 200% among the sprinklers evaluated. Designing sprinklers that minimize kinetic energy transferred to bare soil will require a monotonic decreasing application rate with radial distance as any peak in application rate at large radial distances will result in a peak in specific power. Kinetic energy per unit drop volume will always increase with radial distance as drops sizes get larger with radial distance. The sprinkler with the lowest droplet kinetic energy applied or lowest average composite specific power may not necessarily be the sprinkler that results in the greatest infiltrated depth or least potential runoff. Thus, droplet kinetic energy is not suitable as a single parameter to select between sprinkler choices
Beet curly top resistance in USDA-ARS Ft. Collins Germplasm, 2011
Get PDFTwenty-two 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 2011. Commercial 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 barley in 2010. The field was plowed both in the fall and the spring, fertilized (80 lb N and 120 lb P2O5/A) on 20 Apr 11, sprayed with Ethotron (2 pt/A), and roller harrowed. The germplasm was planted (density of 142,560 seeds/A) on 16 May. The plots consisted of two rows 10 ft long with 22-in row spacing, arranged in a randomized complete block design with three replications. The field was 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 27 Jun with approximately six viruliferous beet leafhoppers per plant. The leafhoppers had been reared in the greenhouse on viruliferous sugar beet plants. The beet leafhoppers were moved twice a day (right after sunrise and just before sunset) for 1 week by dragging a tarp through the field. The plants were sprayed with Lorsban 4E (1.5 pints/A) on 11 Jul to kill the beet leafhoppers. The plots were rated for foliar symptom development on 18 Jul using a scale of 0-9 (0 = healthy and 9 = dead; Mumford 1974), with disease index (DI) treated as a continuous variable. Data were analyzed using the general linear models procedure (Proc GLM-SAS), and Fisher’s protected least significant difference was used for mean comparisons. Yield data were not collected.
Curly Top development was uniform and no other disease problems were evident in the plot area. The test was evaluated while disease pressure was moderate and good symptom development occurred in the more susceptible lines. The experiment was rated only 3 weeks after inoculation, because of the severity of the epidemic; some of the more susceptible entries had died by 4 weeks and thus some of the differences among entries were no longer apparent. Only three experimental germplasms and the susceptible check were significantly different from the resistant controls. However, the three most resistant germplasm tested were not significantly different from the most resistant control (HM PM90, rated 3.1). All three also have increased tolerance of leaf spot caused by Cercospora beticola Sacc. (data not shown). The combination of resistance to both diseases gives this germplasm potential for use in development of hybrid parents in the Great Plains (Colorado, Wyoming, Western Nebraska, and Montana) because both of these diseases can severely limit yield. These lines also may be of use in the Red River Valley of North Dakota and Minnesota, as well as Michigan, two growing areas with severe leaf spot pressure
Empirical evaluation of DArT, SNP, and SSR marker-systems for genotyping, clustering, and assigning sugar beet hybrid varieties into populations
Get PDFDominant and co-dominant molecular markers are routinely used in plant genetic diversity research. In the present study we assessed the success-rate of three marker-systems for estimating genotypic diversity, clustering varieties into populations, and assigning a single variety into the expected population. A set of 54 sugar beet (Beta vulgaris L. ssp. vulgaris) varieties from five seed companies was genotyped with 702 Diversity Array-Technology (DArT), 34 Single Nucleotide Polymorphisms (SNP), and 30 Simple Sequence Repeats (SSR) markers. Analysis of the population structure revealed three well-defined populations and clustering of varieties that generally correlates with their seed company origin. Two populations each contained varieties from two different seed companies indicating genetic similarity of this material. The third population was comprised only of varieties from a single seed company. Analysis of the SSR and SNP datasets indicates that some of the hybrid varieties likely have a common (or very closely related) parent.
Comparison of the three marker-systems revealed substantial differences in the number of loci needed for analyses. Varietal clustering required approximately 1.8 to 2 × more SSR, 3 to 4.5 × more SNP, and 4.8 × more DArT markers than were required for detection of genotypic diversity. When marker-systems were compared across different types of analyses per locus success-rate was the highest for the SSR and the lowest for the DArT markers. Generally, about 1.4 to 3 × more SNPs, and 4.9 to 13.3 × more DArTs then SSRs were needed to achieve the 100% success-rate. However, using only DArT markers with a high level of polymorphism decreased the number of DArT loci needed for analyses by 38% to 61%. Results from the present work provide a premise to selecting the type(s) and number of markers that are needed for genetic diversity analysis of sugar beet hybrid varieties
Infiltration characteristics of bare soil under sequential water application events
Get PDFThe marked reduction in infiltration rate caused by formation of a soil surface seal is a well known phenomenon but often ignored in infiltration models. The effect sequential water application events have on infiltration rate and soil surface seal formation has rarely been investigated. The objective of this study was to investigate the effect sequential water application events have on the infiltration rate of a Portneuf silt loam soil with and without water droplet impact. The Portneuf silt loam soil developed a soil surface seal that reduced infiltration rate both with and without droplet impact on the bare soil surface. When the soil surface was protected during the first rainfall event, drying the soil did not increase infiltration rate for subsequent rainfall events when the soil surface was protected, but drying did increase infiltration when the soil was unprotected in the first rainfall event. Final infiltration rate was inversely related to specific power of the simulated rainfall. Either with or without water droplet impact, final infiltration rate for the Portneuf silt loam soil decreased to less than 20 mm hr-1 within three rainfall events. Given that the Portneuf silt loam soil is extremely vulnerable to surface seal development with little difference in final infiltration rate, irrigation time must be maximized and peak application rate minimized in order to maximize infiltration depth. These requirements combined with the operating characteristics of center pivot irrigation systems means that sprinklers with maximum wetted diameter need to be selected in order to maximize infiltrated depth
Development and application of a soil organic matter based soil quality index in mineralized terrane of the Western US
Get PDFSoil quality indices provide a means of distilling large amounts of data into a single metric that evaluates the soil’s ability to carry out key ecosystem functions. Primarily developed in agroecosytems, then forested ecosystems, we set out to develop and apply an index using the relation between soil organic matter and key soil abiotic and biotic properties in more semi-arid of the Western US arid systems impacted by different geologic mineralization types. We studied these relations in three different mineralization types: serpentine, acid sulfate and Cu/Mo porphyry systems at four different sites in California and Nevada. Soil samples were collected from undisturbed soils in both mineralized and nearby unmineralized terrane as well as waste rock and tailings. We measured eight different microbial parameters (carbon substrate utilization, microbial biomass-C, mineralized-C, mineralized-N and enzyme activities of acid phosphatase, alkaline phosphatase, arylsulfatase, and fluorescein diacetate) along with a number of physicochemical parameters. We developed multiple linear regression models between these parameters and both total organic carbon and total nitrogen, and used the ratio of predicted to measured values as our soil quality index. In most instances, pooling unmineralized and mineralized soil data within a given study site resulted in lower model correlations. Enzyme activity was a consistent explanatory variable in the models across the study sites, while carbon substrate utilization rarely occurred in the models. Though similar indicators were significant in models across different mineralization types, pooling data across sites inhibited model differentiation of undisturbed and disturbed sites. This procedure could be used to monitor recovery of disturbed systems in mineralized terrane and to help link scientific and management disciplines