Draw Bar Settings Handbook To Higher
5.2 Soil and Site TreatmentsMost post-construction sites are in poor condition for plant growth and will require implementing a set of mitigation measures if good revegetation is expected. The following set of implementation guides cover the common mitigating measures for improving site conditions after construction. Fertilizers—Covers how to determine fertilizer quantity, type, and application method. Tillage—Describes the common practices of tilling the soil to improve water infiltration and root growing environment. Mulches—Seed germination, seedling survival, and surface erosion can be improved through the application of mulches. Topsoil—Outlines the removal, storage, and application of topsoil to reconstruct soils on highly disturbed sites.
For sites where topsoil is not available or in short supply, organic matter can be applied to improve post-construction soils. Organic Matter—Discusses the types of organic matter, how to determine rates, and how it is applied.
On some sites where the topsoil has been removed, pH levels may need to be raised to improve plant growth. Lime Amendments—Details materials, application methods, and how to determine liming rates. Beneficial Microorganisms—Many sites devoid of topsoil will require the introduction of mycorrhizae or nitrogen fixing plants. This section covers how to obtain and apply the appropriate sources of these important biological organisms.
Topographic Enhancements—Revegetation projects can be enhanced by integrating plants into bioengineering structures, water capture features, or planting islands or pockets.5.2.1 Fertilizers IntroductionFertilizers are used to bring soil nutrients up to levels essential for establishing and maintaining a desired plant community. When applied within a soil fertility strategy, fertilizer can be a good tool for revegetation but it should not be assumed that fertilizers are needed for every project. In recent years, the use of fertilizers on roadsides for native plant establishment has come under greater public scrutiny and more restrictive water quality laws. Many roads are adjacent to streams, lakes, or residential areas that can be affected by runoff or leaching of inappropriately applied fertilizers. In some instances, fertilizers may not be recommended for establishing native vegetation ) because of the potential of encouraging invasive species over native plants. It is important for the designer to learn how to develop fertilizer prescriptions that integrate short- and long-term site fertility goals with water quality and native plant establishment objectives.It is important to base a soil fertility strategy on the nutrient levels of found in the reference soils when considering the application of topsoil, mulch, compost, wood waste, biosolids, and/or the planting of nitrogen-fixing species. In addition, using commercial fertilizer with other methods of raising nutrient levels, can result in a greater long-term nutrient management of the revegetation project.
For the DesignerBase fertilizer recommendations on soil tests and native plant needs.This section guides the designer through the steps necessary of developing a fertilizer prescription which is the instructions for ordering and applying fertilizers. They include:. Determine nutrient thresholds and deficits. Delineate areas to be fertilized. Select fertilizer analysis. Select fertilizer release rates. Determine application rates.
Determine timing and frequency. Select application methodDevelop Nutrient Thresholds and Determine DeficitsAll sites have a minimum, or threshold, level of nutrients that needs to be met for each plant community to become functioning and self-sustaining. Threshold values can be determined by comparing soil tests from several disturbed and undisturbed reference sites.
Finding disturbed reference sites that range from poor success to good success provides a good understanding of nutrient levels and plant response. Based on nutrient values from good and poor revegetation sites, a target nitrogen range can be established between these values. Figure 5-2 provides an example of how a nitrogen threshold value was obtained by evaluating the total soil nitrogen levels from two disturbed reference sites, one considered 'fair' revegetation and one considered 'poor.'
The threshold was set between these two nitrogen levels. Threshold levels represent the minimum level of nutrients needed for a site.
In this example, the target nitrogen range for establishing and maintaining the original plant community would be between the minimum nitrogen levels and the nitrogen levels found in the undisturbed reference sites. Figure 5-2 Threshold values of nitrogenThreshold values are determined from reference sites. In this example, the threshold was established at 1,100 lb/ac, which was between the total N of a disturbed reference site with 'poor' revegetation (A) and one with 'fair' revegetation (B). Total N in post-construction soils was 650 lb/ac (C), making these soils deficient by 450 lb/ac.
The undisturbed topsoil of reference sites showed a total N of 2,430 lb/ac (D), which sets the target nitrogen range between 1,100 and 2,430 lb/ac.To determine whether nutrients are deficient, soil samples are collected from the post-construction sites and tested. The nutrient values obtained from these tests are compared against the target ranges to determine if a deficiency exists. By comparing post-construction nutrient values against threshold values, the nutrient deficit can be estimated for each nutrient. Figure 5-3 shows an example of how nitrogen deficits are calculated based on post-construction soil tests. In this example, total soil nitrogen is determined from soil tests. Because soil testing facilities report nutrients in a variety of rates, it is important to convert the rates to percentages then to pounds per acre.
Values reported as gr/l, ppm, mg/kg, and ug/g are converted to percentages by multiplying by 10,000. Converting nutrient percentage to lb/ac of the nutrient is done by multiplying percent of nutrient, soil layer thickness, soil bulk density, and fine soil fraction together with a constant (Line E). The result is the pounds of nutrient in an acre of soil on the post-construction site. To determine if the nutrient is deficit, the pounds of nutrients per acre is subtracted from the threshold level (Line F). This value (Line G) represents the nitrogen deficiency and becomes the basis for determining fertilizer prescriptions. ATotal soil nitrogen (N)0.025%From soil test of post construction soils (gr/l, ppm, mg/kg, ug/g divide by 10,000 for%)BThickness of soil layer0.5 feetThe thickness of soil represented in ACSoil bulk density1.4 gr/ccUnless known, use 1.5 for compacted subsoils, 1.3 for undisturbed soils, 0.9 for light soils such as pumiceDFine soil fraction70%100% minus the rock fragment content - from estimates made from sieved soil prior to sending to labEN in soil layerA.
B. C. D. 270 =331 lbs/acCalculated amount of total nitrogen in soil layer. To convert to kg/ha: E. 1.12FMinimum or threshold N levels1,100 lbs/acDetermined from reference sites (see )GN deficit F - E =769 lbs/acMinimum amount of N to apply to bring up the threshold.
Figure 5-3 Determining nitrogen needs from soil testsDetermining the amount of nitrogen (N) needed to bring soils up to a nitrogen threshold can be calculated from equations shown in this spreadsheet.The availability of many nutrients is regulated by soil pH. As discussed in, many nutrients are tied up in low pH and high pH soils. Calcium and magnesium are less available at low pH; phosphorus, iron, manganese, boron, zinc, and copper become unavailable in high pH soils.
It is important to compare the pH of post-construction soils with reference site soils to determine if the pH is substantially different between the two. If the pH of post-construction soils is different, then taking measures to bring the pH closer to pre-disturbance values is important when developing a nutrient strategy. Delineate Areas to be FertilizedBecause the post-construction site may differ in soil types and disturbance levels, it is important to delineated areas where fertilizer prescriptions may differ. These differences are usually based on post-construction soil type changes, topsoil salvage, organic amendment additions, or the species and plant material being grown. Areas adjacent to, or that feed into, live water are often delineated and treated with lower rates of fertilizer. Note: If seedlings of shrubs and trees are being planted, spot fertilization may be a more appropriate method than fertilizing the entire area (Inset 5-1).
Select Fertilizer AnalysisA variety of commercially available fertilizers can be used for fertilizing disturbed sites associated with road construction. The composition, or makeup, of the fertilizer is called the fertilizer analysis. Each container of fertilizer will have a label with a stated 'guaranteed analysis' that indicates the percentage of each nutrient contained in the fertilizer (Figure 5-4).
The label is the guide for determining which fertilizers to select and how much to apply. Table 5-3 and Table 5-4 provide analysis values for many common fertilizers.
Labels can also be obtained from the manufacturer or fertilizer representatives. Inset 5-1 Spot-fertilizing seedlingsFertilizing shrub or tree seedlings is done by placing fertilizer in each seedling hole or on the soil surface after each seedling has been planted.
This practice has some risks because fertilizers release salts that can damage roots. Figure 5-4 Example of a fertilizer label for an 'all purpose' fertilizerThe three numbers (21-5-20) represent the percentage of nitrogen, phosphorus, and potassium respectively (21%N, 5% P 2O 5, and 20% K 2O).
The label may also contain percentages of other nutrients in the fertilizer. Multiplying these percentages (divided by 100) by the pounds of bulk fertilizer applied per acre will give the quantity of each nutrient applied per acre. In this analysis, applying 500 pounds of fertilizer to an acre would deliver 105 lbs N, 25 lbs P 2O 5, 100 lb K 2O, 0.01 lbs B, 0.005 lbs Cu, etc.Fertilizer labels report nutrients as a percentage. The example label for a 50 pound bag of fertilizer in Figure 5-4 shows 21 percent nitrogen (N), which indicates that 10.5 pounds of material in the bag is made up of nitrogen ( 50.
21 / 100 = 10.5 ). The bag also contains 0.02 percent boron (B), which indicates that there is 0.01 pounds of boron in the bag. Calculating the amount of phosphorous and potassium is different because the convention for reporting these nutrients is P 2O 5 and K 2O instead of elemental P and K. To convert P 2O 5 to P, the analysis for P is divided by 2.29.
The percentage of P in the bag in Figure 5-4 is actually 2.2 percent, not 5 percent ( 5.0% / 2.29 = 2.2 ). K 2O is divided by 1.21 to obtain 1.6 percent K. Table 5-4 Estimated nitrogen release rates for commercially available fertilizersNutrient release rates are obtained from lab testing but how they release on-site will vary from site to site, depending on temperature, moisture, and whether the fertilizer was placed on the surface or incorporated into the soil. If slow-release fertilizers are broadcast on the soil surface, release rates are slower than if incorporated into the soil where the conditions are better for break down. Arid sites have slower rates of release than sites with high moisture; cold sites take longer to release nutrients than warm sites. First-year nitrogen release rates for fertilizers are identified with an asterisk were adapted from Claassen and Hogan (1998).Note: Non-asterisk fertilizers were based on best guess estimates.
EGDigital/Recently, Toyota showed the world the drawbar pull capabilities of one of its full-sized pickup trucks, the Toyota Tundra CrewMax. The television commercial begins with the truck on a roadway near the edge of a 180-foot cliff at the Sierra Rock Quarry in Placerville, Calif. A metal cable is attached to the truck's towing hitch, and the other end of the cable is attached to a 6,400-pound shipping container. The container is dangling in mid air more than halfway down the quarry wall, and for the moment, the weight is supported by a nearby crane. All at once, the full weight of the container is released, causing the truck to be pulled even closer to the edge. Just in time, the truck's wheels grab the road surface, the rear end squats down a bit, and somehow the Tundra CrewMax pulls the enormous shipping container - all 6,400 pounds of it - up and out of the deep quarry.Visually, the display an impressive demonstration of the pulling power of the truck; however, there are more common examples of drawbar pull all around us every day. Granted, these examples may not be as visually dramatic as the rock quarry stunt, but they're equally impressive in their own way.
足Probably the most universally familiar example of drawbar pull is displayed on rails. A locomotive pulling a long train of freight cars is demonstrating drawbar pull. The next time you're at an airport, take a moment to walk over to a window and watch the activity on the ground. The low and wide tractors that push and pull enormous jet airplanes exhibit drawbar pull as well.
Drawbar Settings Handbook To Higher Education
Another place you may see drawbar pull in action is on a farm. The tractor that pulls you and your friends or family along on that fun-filled hayride is drawbar pulling, too.These examples give us an idea of what drawbar pull looks like, but what exactly is drawbar pull, anyway? Basically, drawbar pull is the pulling force, or pulling ability, of a vehicle. The definition of drawbar pull is the towing force of a truck or other industrial vehicle, exerted at its coupler (or equivalent) in the direction of motion of the coupling point. Drawbar pull is typically expressed in pounds or Newtons source:.That's fundamentally what drawbar pull is all about; but now that you know the drawbar pull definition, perhaps you'd like to find out how to calculate the drawbar pull of a specific vehicle? Maybe even your own tow vehicle? For more drawbar information and the equation you'll need to calculate the drawbar pull of your own vehicle, read the next page.