Application rate

Volatilization. The susceptibility of a herbicide to loss through volatilization has received much attention, due in part to the realization that herbicides in the vapor phase may be transported large distances from the point of application. Volatilization losses can be as high as 80—90% of the total applied herbicide within several days of application. The processes that control the amount of herbicide volatilized are the evaporation of the herbicide from the solution or soHd phase into the air, and dispersal and dilution of the resulting vapor into the atmosphere (250). These processes are influenced by many factors including herbicide application rate, wind velocity, temperature, soil moisture content, and the compound s sorption to soil organic and mineral surfaces. Properties of the herbicide that influence volatility include vapor pressure, water solubility, and chemical stmcture (251). 

Fig. 7. Historical trends in recommended herbicide application rates, by chemical class (77).

Table 5. Application Rates of Sulfonylurea and Imidazoline Herbicides...

Design and Operation ImpoiTant consideration in the design and operation of landfarming systems include (1) site selection, (2) site preparation, (3) waste charac tei istics, (4) method of waste application, (5) waste-application rate, (6) site management, and (7) monitoring. Important factors related to these design and operation considerations are reported in Table 25-75. 

Method of waste application Waste-application rates... 

Triazole derivatives (diniconazole-M, epoxiconazole, fluhinconazole etc.) are widely used in agricultural practice as fungicides. The low application rates of these formulations require specific conditions for identification of residual quantities in different objects. 

A recent review of research on phosphorus input to surface waters from agriculture highlights the variability of particulate and dissolved phosphorus contributions to catchments. The input varies with rainfall, fertilizer application rates, the history of the application of the fertilizer, land use, soil type, and between surface and sub-surface water. The balance struck between export of nutrients from the catchment and recipient-water productivity is the primary factor which controls its quality. 

Capability to control and extinguish the anticipated fire condition without outside assistance, unless planned for (dependent on requisite spacing of discharge nozzles to cover all areas at risk, application rates, discharge times, quantities of extinguishant available). 

It is probably obvious at this point that the molecular weight distribution of a resole is an extremely important characteristic. It has major influence on such important performance capabilities as cure speed, viscosity, green strength development (or prepress), assembly time tolerance, required application rates. 

Urea is sufficiently important as an additive to PF resins for OSB to warrant some discussion. It has had a large favorable economie impact on the OSB industry. When used, it is generally added after the polymerization is complete. Thus, it is not part of the polymer and does not have any direet effect on polymer resistance to hydrolysis, as might be expected if it was part of the polymer backbone. Under alkaline pH conditions, urea-formaldehyde adducts do not polymerize at a rate that is significant compared to the PF polymerization therefore, the urea does not participate signifieantly in the euring proeess of the PF, despite the faet that it is present during the cure. Since urea is not present in the cured PF polymer per se, it does not detract from the durability of the polymer. Despite this, it is possible to see redueed OSB durability as a result of formulated urea if its use has led to actual PF polymer application rates that are too low. 

Average annual precipitation in Gunnison is 28 cm (I I in.) the typical yearly application rate is 5 dry Mg/ha (2.3 dry ton/ac). Grazing on the biosolids-treated land has increased from once to twice per year. Gunnison is also experimenting with applying grass seed with biosolids to increase production. 

Rollers are available up to 450 mm wide and are at their best on large unbroken surfaces, e.g. storage tanks, pipework etc. when application rates two to three times faster than brush application are achieved. Long-pile (up to 30 mm long) rollers are particularly useful on rough or pitted surfaces. 

General sludging Where dispersants of an inappropriate quality or application rate are employed, the result is the poor dispersion and... 

As with alum, it is necessary to conduct jar tests to identify the most suitable product and optimum application rates, pH level, and so forth. Testing with ferrous sulfate typically requires a starting point application level of around 50 ppm (as 100% active product), while ferric sulfate requires around 25 ppm (as 100% active product). 

Use jar tests to determine the most suitable types of polymers and potential application rates. Tests must be conducted on-site with fresh, representative water samples and fresh reagents. 

Nitrite-based programs require a relatively high application rate to ensure that all anodic areas within the system are fully protected from the risk of pitting corrosion. Undertreatment exposes anodic areas, which are subject to localized pitting as a result of the concentrating power from surrounding cathodic sites. 

The specific nitrite reserve required depends on the system design, cleanliness, metallurgy, leaks, water chemistry, and LPHW temperature. The application rate must be increased when high chlorides or sulfates are present and further increased with a rise in HW temperature. 

The hydrolysis products of the hydrolyzable tannins are not dissimilar to some of the novel oxygen scavengers developed to replace hydrazine. Oxygen reaction rates and application rates are also similar. The oxygen reaction time for tannin blends varies with pH levels and temperature but at 45 °C (113 °F) is on the order of 75% complete within 5 seconds and 90% complete within 10 seconds. 

SS/MA may be structured in different ratios of sulfonated styrene to maleic anhydride. Typically, it is 3 1 (20,000 MW) or 1 1 (15,000 MW). The application rates of all calcium phosphate scale/sludge inhibitors or stabilizers vary, based on the amount of calcium present in the cooling system, with increased calcium hardness leading to higher levels of polymer required. 

Exposures of Children. Data need to be developed to properly assess the exposure of infants who eat processed baby foods containing residues of pesticides such as endosulfan. Several studies have estimated exposure based on endosulfan concentration found in foods typically eaten by infants however, no studies that directly studied infant exposure could be located. Attention should also be given to infant formulas and to the tap water used to prepare infant formulas from condensed or powdered forms. More data are also required to properly assess endosulfan exposure to children who live, play, or attend school near farmlands that are treated with endosulfan. Maps that catalog endosulfan use on crops and present average application rates would better allow an assessment of the potential for children in farming communities to be exposed. The possibility that farming parents work clothes and shoes may carry endosulfan residues into the home also should be studied. In addition, home use of endosulfan, which may result in exposure of children, needs to be investigated. 

Plant uptake is one of several routes by which an organic contaminant can enter man s food chain. The amount of uptake depends on plant species, concentration, depth of placement, soil type, temperature, moisture, and many other parameters. Translocation of the absorbed material into various plant parts will determine the degree of man s exposure—i.e., whether the material moves to an edible portion of the plant. Past experience with nonpolar chlorinated pesticides suggested optimal uptake conditions are achieved when the chemical is placed in a soil with low adsorptive capacity e.g., a sand), evenly distributed throughout the soil profile, and with oil producing plants. Plant experiments were conducted with one set of parameters that would be optimal for uptake and translocation. The uptake of two dioxins and one phenol (2,4-dichlorophenol (DCP)) from one soil was measured in soybean and oats (7). The application rates were DCP = 0.07 ppm, DCDD 0.10 ppm, and TCDD = 0.06 ppm. The specific activity of the com-... 

If we assume that the TCDD is contained in the surface 6 inches of the soil profile since it is relatively immobile (5), then the 2,4,5-T at the 947 lbs of active ingredient/acre treatment would have had to contain 2.1 ppm TCDD to be observed. At the lower application rates of 584 and 160 lbs/acre, the 2,4,5-T would have had to contain 3.5 and 12.5 ppm TCDD in the technical materials to have 1 ppb in the top 6 inches of soil. Since the soil is sandy and high rainfall occurred in the area, maximum movement of materials in soil may occur causing TCDD to be present deeper in the profile. If the TCDD moved uniformly throughout the 36 inch soil profile, then six times more TCDD would have had to be present in the original 2,4,5-T for detection. This would have required the presence of 12.6, 21.0, and 75.0 ppm TCDD in the 2,4,5-T applied in the three treatments. These calculations are based on the assumption that no degradation occurred in or on the soil. 

Since one of the key purposes of this study is to determine residue partitioning in the various processed commodities, every reasonable effort must be made to start the processing procedures with some level of residue in the RAC. If the RAC has residues present at harvest under normal GAP, then selective partitioning can be easily detected as the RAC is processed. However, if there is no residue in/on the RAC, the guideline indicates that exaggerated application rates may be required to obtain sufficient residue level to conduct a successful processing study. Usually a three- or... 

The factors of walking or tractor speed, nozzle output, pump pressure, and width of treatment can be altered to provide the most accurate application method. As a preference, it is suggested that the output of the nozzles be set to the manufacturer s recommended output, and the speed of walking or driving be adjusted up or down to achieve the desired application rate. 

Application rates in protocols can be expressed in various ways, and the field staff should be aware of these types of expressions and understand their meanings, e.g.,... 

The mathematics involved with calculating the amount of active ingredient, formulated product, adjuvants, and water to put in a spray tank to achieve the application rate specified in the protocol should be addressed prior to arrival at the field for the first application. This is also true for the calibration method. The author has found that if eight agronomists are involved in a spray application, one will encounter eight distinct calibration methods. If a calibration SOP is not written for the spray equipment to be used, the precise steps in the calibration process should be documented in the field notebook. 

Exaggerated chemical application rates may also adversely affect the crop quality. If the exaggerated rate causes the crop to be abnormal in some way at maturity, the processing applied to the crop may not result in typical fraction samples. The adverse impact may be obvious, such as slowed maturation of the crop, or the impact may be less obvious, such as a change to the internal structure of the individual fruits and vegetables, grains, nuts or roots. 

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