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Characterizing droplet kinetic energy applied by moving spray-plate center pivot irrigation sprinklers
Get PDFThe kinetic energy of discrete drops impacting a bare soil surface is generally observed to lead to a drastic reduction in water infiltration rate due to soil surface seal formation. 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. In the design of center pivot irrigation systems, selection of sprinklers with minimum applied kinetic energy could potentially minimize seasonal runoff and erosion hazard. Size and velocity of drops from five common center pivot sprinklers with flow rates of approximately 43 L/min were measured using a laser in the laboratory. The data were used to evaluate various approaches to characterize kinetic energy transferred to the soil by each of the five sprinklers on a center pivot irrigation system lateral with 2.5 m spacing between sprinklers. Specific power, which represents the rate kinetic energy per unit area is transferred to the soil as a function of distance from a sprinkler and analogous to a sprinkler radial water application rate distribution, was used to estimate actual kinetic energy transferred to the soil by overlapping specific power profiles of sprinklers equally spaced along a center pivot lateral. Kinetic energy of irrigation sprinklers has traditionally been characterized using area weighted kinetic energy per unit drop volume. This method of characterization heavily weights the largest drops which travel the farthest from the sprinkler and have the largest kinetic energy. This characterization was not correlated to actual kinetic energy transferred to the soil by the sprinklers. Sprinkler kinetic energy per unit volume of sprinkler discharge was also used to characterize sprinkler kinetic energy calculated but was not correlated to actual kinetic energy transferred to the soil by the sprinklers. However, kinetic energy per unit volume of sprinkler discharge was found to be more representative than kinetic energy per unit drop volume. Measured runoff and sediment yield of the sprinklers from a previous study were compared to time averaged specific power. Runoff and erosion appeared to be more dependent upon sprinkler type than time averaged specific power. The sprinklers with the lowest runoff and sediment yield had the lowest time averaged specific power. However, there was a substantial increase in runoff and sediment yield with little associated increase in time averaged specific power applied for some sprinklers. Visually, the functional difference between sprinklers was the manner in which water drops were distributed over the wetted area with respect to time. Sprinklers that visually appeared to distribute water drops more evenly over the wetted area with respect to time had the highest runoff and sediment yield, and sprinklers that had well defined rotating streams of water drops had the lowest runoff and sediment yield, largely independent of time-averaged specific power applied to the soil
The Current State of Predicting Furrow Irrigation Erosion
Get PDFThere continues to be a need to predict furrow irrigation erosion to estimate on- and off-site impacts of irrigation management. The objective of this paper is to review the current state of furrow erosion prediction technology considering four models: SISL, WEPP, WinSRFR and APEX. SISL is an empirical model for predicting annual soil loss from furrow irrigated fields. SISL could potentially be a useful model if a new method was developed to calculate base soil loss for areas other than southern Idaho where it was developed. The WEPP model uses physically-based equations to predict erosion in irrigation furrows, which are assumed to be the same as rills. Primary difficulties with the WEPP model are defining erodibility parameters for furrow irrigation and over-prediction of transport capacity. WinSRFR provides detailed evaluation of furrow hydraulics and sediment detachment, transport and deposition in an individual furrow during a single irrigation event using similar equations as WEPP. Initial evaluations of WinSRFR are promising and development continues to fully simulate the mix of aggregate sizes found in furrow soil and furrow flow. The APEX model uses empirical relationships to predict soil loss from small watersheds. Preliminary evaluation of the APEX model indicated reasonable correlation with measured soil loss in a 170 ha irrigated watershed. All of these methods require further development and/or evaluation before they can be widely applied to furrow irrigated land. In selecting a predictive tool, it should be noted that an empirical equation may be as good as a physically based equation if we cannot quantify the parameters for the physically based equation
Effect of compost-, sand-, or gypsum-amended waste foundry sands on turfgrass yield and nutrient content
Get PDFTo prevent the 7 to 11 million metric tons of waste foundry
sand (WFS) produced annually in the USA from entering
landfi lls, current research is focused on the reuse of WFSs as
soil amendments. Th e eff ects of diff erent WFS-containing
amendments on turfgrass growth and nutrient content were
tested by planting perennial ryegrass (Lolium perenne L.) and
tall fescue (Schedonorus phoenix (Scop.) Holub) in diff erent
blends containing WFS. Blends of WFS were created with
compost or acid-washed sand (AWS) at varying percent by
volume with WFS or by amendment with gypsum (9.6 g
gypsum kg–1 WFS). Measurements of soil strength, shoot and
root dry weight, plant surface coverage, and micronutrients (Al,
Fe, Mn, Cu, Zn, B, Na) and macronutrients (N, P, K, S, Ca,
Mg) were performed for each blend and compared with pure
WFS and with a commercial potting media control. Results
showed that strength was not a factor for any of the parameters
studied, but the K/Na base saturation ratio of WFS:compost
mixes was highly correlated with total shoot dry weight for
perennial ryegrass (r = 0.995) and tall fescue (r = 0.94). Th is was
further substantiated because total shoot dry weight was also
correlated with shoot K/Na concentration of perennial ryegrass
(r = 0.99) and tall fescue (r = 0.95). A compost blend containing
40% WFS was determined to be the optimal amendment for
the reuse of WFS because it incorporated the greatest possible
amount of WFS without major reduction in turfgrass growth
Characterization of physical and chemical properties of spent foundry sands pertinent to beneficial use in manufactured soils
Get PDFAbstract As of 2007, of the 2,000 United States foundries, 93% produce ferrous or aluminum castings, generating 9.4 million tons of non-hazardous spent foundry sand (SFS) annually. Only 28% of the SFS is beneficially used. The U.S. EPA Resource Conservation Challenge identifies SFS as a priority material for beneficial use, with soil blending as a potential reuse option. The objectives of this work were to measure: (1) select chemical and physical properties important to soil quality and function and (2) total and soluble elemental content of 39 SFSs, in order to evaluate SFS suitability as a component in manufactured soils. Total elemental concentration of the SFS was lower than natural background soil levels for most elements analyzed, suggesting limited to no contamination of the virgin sand during metal casting. Pore water elemental concentrations were generally below detection. However, both total and soluble elemental content indicate a potential contribution of plant nutrients. Lettuce (Lactuca sativa) planted in SFS mixtures had a median germination rate of 96.9% relative to the control. Blending SFS at varying ratios with other materials will allow “tailoring” of a manufactured soil’s chemical and physical properties to meet specific growing needs. The SFS organic carbon, clay, and plant nutrient content are benefits of SFS that may make them good candidates as manufactured soil components
Organic Waste Nitrogen and Phosphorus Dynamics Under Dryland Agroecosystems
Get PDFOrganic waste beneficial-use programs effectively recycle plant nutrients when applied at agronomic rates. Plant-nutrient availability, transport, and fate questions have arisen when organic wastes such as biosolids have been applied to dryland agroecosystems. What is the Nfertilizer equivalency of biosolids? What is the N mineralization rate of biosolids over periods of excess moisture or drought, and over long periods of time? Would biosolids, applied at an agronomic N rate for dryland winter wheat (Triticum aestivum L.), oversupply P? If overapplication occurred, what would the repercussions be in terms of excess soil P? Our objectives were to determine: biosolids N fertilizer equivalency; biosolids N mineralization during years of above and below average precipitation, and long-term N mineralization; which soil P phases dominate following years of biosolids application; and the potential increased environment risk of P when applying an agronomic N rate or excessive rate of biosolids. To address questions related to N dynamics, we utilized research results collected between 1993 and 2004 from a site in Eastern Colorado which received 0, 1, 2, 3, 4, and 5 dry tons biosolids A-1. To address questions related to P dynamics, results collected between 1982 and 2003 from a second Eastern Colorado site which received 0, 3, 6, 12, and 18 dry tons biosolids A-1 were used. During years of above-average and below-average precipitation, first-year biosolids N mineralization rates were estimated at 25-32% and 21-27%, respectively; long-term first-year mineralization rate ranged between 27-33%. Based on wheat-grain N uptake, we found that an application rate of 1 dry ton biosolids A-1 supplied about 20 lbs N A-1. Based on the Colorado P index risk assessment, biosolids applied at agronomic N rates would not force producers to alter application strategies. However, based on this risk assessment, biosolids over-application would force land application to be based on crop P requirements. Previous results showed a minimum of 3 cropping cycles were necessary to reduce soil P concentrations to levels considered less apt in causing environmental degradation. A future reduction in water availability may force some Idaho agricultural land to shift from irrigated to dryland conditions. And, coupled with the increased production of dairy waste, land applicators will need to find new means to protect natural resources under dryland conditions. Results from our studies can help improve nutrient use efficiency and minimize environmental risk associated with dryland organic waste land application
Nutrients in Runoff from a Furrow-Irrigated Field After Incorporating Inorganic Fertilizer or Manure.
Get PDFUse of dairy manure to supply crop nutrients is gaining broader acceptance as the cost of fertilizer rises; however, there are concerns regarding manure’s effect on water quality. In 2003 and 2004, we measured sediment, NO3-N, NH4-N, K, dissolved reactive P (DRP), and total P (TP) concentrations in runoff from furrow irrigated field plots (6-7 irrigations/y). Annual treatments included: (M) 13 to 34 Mg/ha stockpiled dairy manure; (F) 78 to 195 kg N/ha inorganic N fertilizer; or (C) control--no amendment. Available N in manure applied each year was similar to amounts applied in fertilizer. Constituent concentrations (mg/L) in runoff ranged widely: sediment, 10 to 50,000; NO3-N, 0 to 4.07; NH4-N, 0 to 2.28; K, 3.6 to 46.4; DRP, 0.02 to 14.3; and TP, 0.03 to 41.5. Fertilizer and manure treatments increased irrigation mean values for NO3-N runoff concentrations (C=0.21, F=0.26, M=0.30 mg/L) and mass losses (C=0.33, F=0.42, M=0.50 kg/ha) relative to controls. Manure treatment also increased mean irrigation runoff DRP (C=0.08, F=0.09, M=0.19 mg/L) and K concentrations (C=0.62, F=0.79, M=1.13 mg/L) compared to controls. Average DRP and K runoff mass losses were 2.0x to 2.4x greater in manure treatments than in controls. Nutrient amendments did not affect season-long cumulative infiltration or seasonal runoff mass losses for sediment or TP. Runoff DRP and inorganic N losses appeared to be influenced more by the timing of the amendment application and environmental conditions, than by the quantity of nutrients applied. Incorporation of nutrients, whether from fertilizer or manure, into furrow irrigated soils can potentially increase nutrient losses in irrigation runoff, depending on the nutrient, amount and timing of application, and whether inorganic fertilizer or manure was applied
Clinoptilolite Zeolite Influence on Inorganic Nitrogen in Silt Loam and Sandy Agricultural Soils
Get PDFDevelopment of best management practices can help improve inorganic nitrogen (N) availability to plants and reduce nitrate-nitrogen (NO3-N) leaching in soils. This study was conducted to determine the influence of the zeolite mineral Clinoptilolite (CL) additions on NO3-N and ammonium-nitrogen (NH4-N) in two common Pacific Northwest soils. The effects of CL application rate (up to 26.9 Mg ha-1) either band applied or mixed with a set rate of nitrogen (N) fertilizer on masses of NO3-N and NH4-N in leachate and soil was investigated in a column study using a Portneuf silt loam (coarse-silty mixed mesic Durixerollic Caliciorthid) and a Wolverine sand (Mixed, frigid Xeric Torripsamment). All treatments for each soil received a uniform application of N from urea fertilizer, with fertilizer banded or mixed with CL. In the Portneuf soil, band application of CL and N contained 109% more total inorganic N (NO3-N + NH4-N) in the soil/leachate system compared to mixing. In both soils, CL application rate influenced the quantity of NO3-N and NH4-N in the leachate and soil. Application of CL at rates of 6.7 to 13.4 Mg ha-1 resulted in the conservation of inorganic N in the soils. Band applying CL and N appears to conserve available inorganic N in the soil compared to mixing CL and N possibly due to decreased rates of microbial immobilization, nitrification and denitrification
Copper Sequestration Using Local Waste Products
Get PDFDairies utilize copper sulfate (CuSO4) foot baths to control hoof infections. Typical
solutions are 5 or 10% CuSO4 (pH ~6), equal to 12,500 or 25,000 ppm Cu, respectively. When
spent, hoof bath solutions are usually disposed of in waste lagoons and subsequently utilized for
irrigation. In the Magic Valley, this practice appears to be causing soil Cu concentrations to
increase. The goal of our research was to use local waste products to sequester Cu from a
simulated hoof bath solution and to use waste products to adsorb excessive Cu from Cu-affected
soils.
We utilized lime waste and fly ash from the Amalgamated Sugar Company, LLC (Twin
Falls, ID) to identify Cu sorption maximum as a function of pH. In triplicate, solutions
containing one gram of material and increasing Cu concentrations (0, 2500, 5000, 12500, 25000
ppm Cu) were shaken for one month buffered at either pH 6, 7, 8, or 9. Materials shaken at pH 6
adsorbed the greatest amount of Cu, but concentrations up to 25000 ppm did not maximize all
adsorption sites. Thus, additional solutions containing waste materials and Cu concentrations of
75000 and 100000 ppm Cu were shaken for one month at pH 6. Results showed that at pH 6
lime waste and fly ash adsorbed a maximum of ~ 45000 and 26000 ppm of Cu. The use of lime
waste to sequester Cu from spent dairy CuSO4 hoof baths appears to be a viable option.
Because lime waste adsorbed a greater quantity of Cu as compared to fly ash, we
investigated the ability of lime waste to sequester Cu from Cu-affected soils. A soil from the
Logan Soil Series (Typic Calciaquoll; pH 8.0; CEC = 14 meq/100g; % lime = 50%) which had
received 0, 250, 500, or 1000 ppm Cu approximately one year earlier was utilized. Using a
completely randomized design with four replicates, lime waste was applied at 0, 0.5, 1, and 2%
by weight (~0, 10, 20, and 40 tons/acre), thoroughly incorporated, and allowed to incubate at
90% of field capacity for 3 months, after which 15 alfalfa (Medicago sativa L.) seeds were
planted in each pot. Plants were allowed to grow for 2.5 months, and then were harvested at ½”
above the soil surface, oven dried at 60oC for 72 hours, ground, weighed, and analyzed for total
Cu content. Soils were air-dried, ground to pass a 1/16” screen, and then
diethylenetriaminepentaacetic acid (DTPA; a measure of plant-availability) extractable Cu was
measured. Soils were also subjected to a sequential metal extraction procedure which identified
Cu associated with a) soluble species, carbonates, and cation exchange sites, b) iron and
manganese oxyhydroxides, c) organic matter and sulfides, and d) residual phases. Increasing soil
Cu application rate decreased alfalfa yield, but increasing lime waste application rate had no
effect on improving alfalfa yield. Increasing soil Cu application also increased plant Cu
concentration, while increasing lime application rate caused a decrease in plant Cu concentration.
Increasing soil Cu application increased DTPA extractable Cu content, while increasing lime
application rate did not affect extractable soil Cu content. Increasing Cu application rate
increased Cu bound in all soil phases. Lime waste significantly affected Cu associated with most
soil metal phases, but the changes were not large enough to help decrease soil Cu concentrations
to below levels that would affect alfalfa growth and Cu accumulation. The use of lime waste to sequester Cu from Cu-affected soils, unlike from solution, does not appear to be a viable treatment process. Results of these studies will be published in a peer reviewed journal later this
year
Commercial Sugar Beet Cultivars Evaluated for Rhizomania Resistance and Storability in Idaho, 2009
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, 22 commercial cultivars were screened by growing them in a commercial sugar beet field naturally infested with BNYVV in Declo, ID during the 2009 growing season in a randomized complete block design with 4 replications. At harvest on 13 October 2009, roots were dug and evaluated for symptoms of rhizomania and also placed in an indoor commercial sugar beet storage building. Storage samples were evaluated for fungal growth known to correlate with sucrose loss. Depending on cultivar, surface fungal growth ranged from 5 to 42% by 18 February 2010. Overall, the commercial cultivars had an average sucrose reduction of 33% after 131 days in storage. Improving cultivar performance for resistance to sucrose loss in storage and rhizomania has the potential to lead to considerable economic benefit to the sugar beet industry
Assessment of Bioaerosols at a Concentrated Dairy Operation.
Get PDFIncreased bioaerosol loadings in downwind plumes from concentrated animal feeding operations (CAFOs) may increase the risk for allergy and infection in humans. In this study we monitored airborne concentrations of culturable bacteria and fungi at upwind (background) and downwind sites at a 10,000 milking cow dairy over the course of a year. The average bacterial concentrations at the upwind site were 8,400 colony forming units (CFU)/cubic meter and increased to 990,000 CFU/cubic meter at the downwind edge of the cattle pens, decreasing to 63,000 CFU/cubic meter 200 m farther downwind. At the same sites, the average fungal concentrations were 515, 945, and 1010 CFU/cubic meter, respectively. Significant correlations between the ambient weather data and airborne fungal concentrations were identified, but not with bacteria. Sequence analysis of PCR-amplified DNA from bacterial clones and fungal isolates revealed genus and species level differences between upwind and downwind sites. Although we could not cultivate gram-negative bacteria, bacterial clones at downwind sites identified as being gram-negative matched with the following genera: Acinetobacter, Bradyrhizobium, Escherichia, Idiomarina, Methylobacterium, Ralstonia, and Novosphingobium. Fungal isolates from downwind matched with the following genera: Acremonium, Alternaria, Ascomycte, Aspergillus, Basidiomycete, Cladosporium, Davidiella, Doratomyces, Emericella, Lewia, Onygenales, Penicillium, Rhizopus, and Ulocladium. None of the bacterial and fungal sequence matches were affiliated with genera and species known to be pathogenic to humans. Overall, the concentrated dairy operation does not appear to increase the risk of exposure to bioaerosols, especially when an individual increases their downwind distance from the facility