Slide 1 LHAP 106 TESM - Fertilizer Formulations and Calculations. Developed by school of Environment Staff, adapted by E. Wheale Slide 2 Is fertilizer a contentious issue? Or is it just basic lawn care? What does this lawn need (and why?) Slide 3 Factors That Affect Nutrient Uptake 1. Health and vigor of the root system Root system must be actively growing for uptake to occur 2. Soil moisture and air content 3. pH Level of soil Alkaline soils leads to decreased uptake of Mn, Fe, Zn, B, Cu, P - ideal 6.5-7.5 4. Soil and Air temperatures y Slide 4 Natural Origins: Carbon, Hydrogen, and Oxygen. Nitrogen Taken from the Nitrogen Cycle Applied in compounds and changed easily. Phosphorous Taken from rock phosphate ores Potassium Remains in ionic form - naturally occurring Release Mechanisms: Micro-organisms (warm soil temperatures, good oxygen) Water (softens and dilutes) Chemical Reactions (natural process) Slide 5 Understanding Fertilizer Slide 6 What’s on the Bag? The Analysis is defined as the percent composition of a fertilizer. All bags must have analysis printed on them It is the percentage of actual mineral in the bag Slide 7 What’s on the Bag? Salt index High salt index + high temperatures = high foliar burn (Turgeon 174) Saline Soils become more saline with high salt index Acidifying elements Ammonium form N = acidity What’s the rest of the volume, if not fertilizer?! Fillers include salts, sand, ground corn cob and other inert materials. Slide 8 So… You have the choice between 20-20-20 (60% usable) and 10-10-10 (30% usable) Why choose a less concentrated Fertilizer? Distribution. Spreaders are tough to calibrate to really low settings. Also, it is easier to tell staff “half a bag” than “2.1 kg” since they likely don’t have a scale in the field. Do check the costs though… make sure you’re not paying the same price for a diluted product!! Slide 9 Most fertilizer programs are based on Nitrogen requirement Rates given in: Kilograms of actual Nitrogen per 100 square meters Slide 10 RULE OF THUMB: A 3:1:2 ratio throughout the growing season will produce adequate growth Slide 11 Fertilizer Formulations Slide 12 The Formulation refers to what it is made of. Key factors are release timing and release mechanism. There are 2 Broad Categories: 1. Synthetic fertilizers - man made salts soluble crystal, prill, granule - Click here to learn more about how they are Manufactured, and there are coated ones as well. 2. Organic fertilizers - carbon formations Turfgrass Fertilizer Formulations Slide 13 Type 1: Synthetic, immediate release fertilizers: Usually dyed blue, powder/crystal formation Immediately available, limited residual response Cheap per unit N Dissociate into respective ions in solution Plants absorb roughly .15 kg Nitrogen of any application (the rest is leached) Lasts roughly 2 weeks during active growth Turfgrass Fertilizer Formulations Slide 14 Synthetic Nitrogen fertilizer examples Urea (46-0-0) U of Minnesota writeup Volatilization of Ammonia (NH3) Apply during tilling or in solution When mixing, ensure granular size match to avoid striping Converts to Ammonium, and then to Nitrates Dog Urine contains urea Ammonia gas = hazardous Burns foliage and humans Ensure dog patches are watered in (do not fertilize!) Turfgrass Fertilizer Formulations Slide 15 Ammonium Nitrate (34-0-0) Restricted Component in Canada 2008 (not available in pure form for purchase). Massive explosions in Texas (1947, 2013) and Queensland Coated to prevent caking Dissolves into Ammonium (NH4+) and Nitrate (NO3-) in water Helps to maintain pH (source) Ammonium Sulfate (21-0-0-24) - crystal Ammonium phosphate (ie 11-55-0 granule). Triple SuperPhosphate (0-46-0), Potash Alum, Elemental sulphur (0-0-0-90 powder granule). Potassium Chloride (0-0-60 - granule) BEWARE OF HILLS and VALLEYS Turfgrass Fertilizer Formulations Slide 16 Foliar Fertilizers Relies on Osmosis / Stomatal openings Provides a rapid response from plants (hours) Mainly N (Not all types can be taken in through stomata due to particle size.) Susceptible to leaching Expensive (15-40% more) Susceptible to mixing error (1/10 the rates of normal applications through roots to avoid salt burning). Turfgrass Fertilizer Formulations Slide 17 Synthetic Slow Release Release mechanisms & Time vary by formation & coating N is controlled release to combat 0.15 Kg absorption rule Water insoluble Usually relies on micro-organisms or chemical processes Turfgrass Fertilizer Formulations Slowly soluble Requires a constant presence of water to dilute and move through permeable membranes. Prills & Granular form. Coated Fertilizer Coated - as the coat cracks, nutrients are released Slide 18 Slow Release Urea examples: Methylene Urea; Combination of methylated urea/formaldehyde Microbial release (as long as they are active, release rate is predictable) IBDU (Isobutylidene Diurea); Speed of release is determined by particle size Chemical reaction (pH), water Not affected by Temp. Stabilized Urea is a product with urease inhibitors (stops the enzyme / slows ammonium conversion process) Turfgrass Fertilizer Formulations Slide 19 Coated Ureas; Sulfur Coated Urea (SCU); S = Slowly Soluble. Coat Thickness=Time Delay Polymer/Sulfur Coated Urea Inner layer S, Outer layer Polymer. Slower Release (requires microbial activity as part of release) Polymer Coated Urea; Poly coat is Semi-permeable. H20 moves in and out Examples: Nutricote, Nutri-Pak, Osmocote, Polyon Release times vary by temperature - Nutri-Paks can last up to 5 years, others last between 2-9 months… read more here Turfgrass Fertilizer Formulations Slide 20 Organic Fertilizers; Derived from natural sources Broken down by soil microorganisms into useable form - slow process in cold temperatures Not readily soluble Longer Residual - less leaching No Foliar Burn Higher Cost Lower N Analysis (less than 10% often) Turfgrass Fertilizer Formulations Slide 21 Example of homeowner available “weed and feed” option. Note the photos up top: Pre-emergent dandelion and large crabgrass (Digitaria) control… Note the analysis… Note the filler… Need a starting place for your Case Study? Look on one of these more reputable manufacturer websites: Pro Turf Brett Young (better website) Slide 22 SO! What is Fertilizer Burn and How does it happen? Most Fertilizers are SALTS. Salts cause desiccation Through Roots - wilt - death (more in Physiology). Through cells - dead leaves Fertilizers provide nutrients that are necessary, but can also be toxic in the wrong proportions. Slide 23 Growth Cycles Slide 24 Turf Growth Cycles It is essential that we work WITH the growth cycle for healthy turf. Understanding the growth cycle is the key. Slide 25 Turf Growth Cycles Optimum soil temps are 10-18 C, Air Temperatures of 18-27 degrees These are related measurements. When air temps average 18-27, soil is usually 10-18 Ideal weather conditions = plant growth increase Roots deepen first, then top growth follows Typically vegetative growth occurs early in the season (cool soil, high moisture) Slide 26 Turf Growth Cycles In summer soil temps increases, moisture level drops Plants respond to this in 1 of 3 ways Escapism - seeds Avoidance - change Tolerance - dormancy Roots decrease to dormant depths, shoots do not decrease as much Top growth begins to turn brown Plants require irrigation to stay green. Slide 27 Turf Growth Cycles In the Fall, temperatures cool down and the Turfgrass recovers. Eventually shoot growth decreases, and roots follow. Slide 28 Turf Growth Cycles Growth cycles vary by species, weather, & management In the spring, just because I don’t SEE growth, doesn’t mean the grass is active. At what time is my grass the strongest? What should I do when my grass is brown in August? What happens if I fertilize hard in October? How will wind and hot weather impact growth? When would be a good time for slowly soluble? When might microbial release mechanisms be good? Slide 29 Fertilizer recap: What do my plants NEED? Soil test Growth cycle climate What is in the bag? Ratio of N:P:K Amount of usable material Salt content? What is the formulation? Release period Release mechanism Do not exceed .15 kg N if using synthetic Remember, what the grass gets, the trees (with roots beneath) and plants nearby (if there’s overspray) get too! Fertilizer will cause the plant to grow more quickly. Is the customer prepared for this, and the cost of application? Slide 30 Applying fertilizer to Turf Similar to seeding process: Select the process based on formulation Golf courses may fertigate Usually some form of slow release for sports and residential turf Calculate the required amount based on analysis, growth stage, & environment Calibrate the spreader (same process as seeding) Cross directional pattern WATER IT IN Initial solvent, helps get the product through the thatch, reduces salt “burning” Monitor the Effect Repeat when needed (based on formulation, growth stage, and environment) Slide 31 MATH Slide 32 Turfgrass Fertilizers Q1: So how much (by weight) of that bag is nitrogen? If its a 20 Kg bag… and 27% is Nitrogen? Slide 33 Nutrientin bag = Weightof bag x Percentagenutrient How much N, P, & K respectively is in a 22 kg bag of 26-13-0? 22 kg x 26 = 5.72 kg N in the bag 100 22 kg x 13 = 2.86 kg P205 in the bag 100 0 - indicates no Potassium Fertilizer Calcs Slide 34 Turfgrass Fertilizers The most common scenario: How much of this fertilizer do I need to use on my lawn? -You know your lawn area. -You know your Fertilizer Rate (KB = 0.25 - 0.75 Kg N/100m2/growing month) -You know the Analysis: 24-8-15 -AND the bag weight: 25 Kg Slide 35 Weight of fertilizer = Turfgrass Fertilizers Rate of actual N Analysis (as a decimal) Slide 36 Turfgrass Fertilizer Calc #2 You have a rate of 0.75kg N/100m2/GM and you have 26-13-0 Fertilizer. How much total Fertilizer do you need? Total Fertilizer = rate/analysis Total Fertilizer = .75 Kg/26% (or 26/100 or .26) Total Fertilizer = 2.88 Kg Fertilizer NOTE - check your #’s… do they make sense? you should always MORE fertilizer than required nitrogen! Slide 37 Rates and Areas… Using the numbers again: You figured out on the last slide that you needed 2.88 Kg of 26-13-0 fertilizer for 100m2 for one growing month. How much of this fertilizer should you put down in an area of 852 m2 in one growing month? 852m2/100m2 = 8.52 I need to apply the amount 8.52 times for this larger area. 8.52 x 2.88 = 24.54 kg Fertilizer / Growing Month Slide 38 Here are the next few steps… You are applying at a rate of 0.5 kg N/100m2/GM. How much fertilizer do you need when you’re using 25-7-15 for an area that is 375m2 over a growing season of 6 months? Total Fertilizer for 100m2 = 0.5 / 0.25 = 2 kg 2. Area = 375m2 / 100m2 = factor of 3.75 2 kg total fertilizer x 3.75 = 7.5 kg total for one month. 3. 7.5 kg x 6 months = 45 kg Slide 39 How many bags, now? You are applying at a rate of 0.1 kg N/100m2/GM. How many 23 kg bags of fertilizer do you need when you’re using 11-52-0 for an area that is 650 m2 over a growing season of 6 months? Total Fertilizer for 100m2 = 0.1 / 0.11 = .909090 kg 2. Area = 650 m2 / 100m2 = factor of 6.5 .90909090 kg total fertilizer x 6.5 = 5.91 kg total for one month. 3. 5.91 x 6 months = 35.45 kg 4. 35.45 kg total needed / 23 Kg bags = 1.54 bags needed If you go to the store, though, you’ll BUY 2 bags. Slide 40 Plant Species and N rates... Kentucky Bluegrass Poa Pratensis 0.25 - 0.75 kg N/100m2/growing month Creeping Bentgrass Agrostis stolonifera 0.25 - 0.75 kg N/100m2/growing month Perennial Ryegrass Lolium Perenne 0.1 - 0.5 kg N/100m2/growing month Creeping Red Fescue Festuca Rubra ssp. rubra 0.1 - 0.25 kg N/100m2/growing month Do not fertilize for Annual Bluegrass or Quackgrass... Slide 41 Which end of the range should I use?? It depends on the stand of turfgrass Do you want to starve out weed grasses? - use the low end (AB likes .75 Kg+) Are you applying water and able to mow regularly (high maintenance) - use the high end Is it a Polystand? - use a rate that keeps them all competitive Will it Leach? Use the low end Do they want to mow less often? Use the low end. Is it end of season? Use the low end WAIT!!!!! Slide 42 Assignment: Work through these questions - assignment is due tomorrow at 8:00 AM Slide 43 Real Life Complexity Now, though, you have to make a plan: What is your formulation? What is your release rate? How will THIS affect your calculation?! In the assignment, we haven’t really considered formulation. What we’ve done is assumed that the fertilizers stated release at a consistent rate for 4 weeks over time. In Real life, fertilizers are usually made of a certain percentage of both slow release AND immediate release. We assume that the immediate release is good for the first two weeks and the slow release kicks in at the 2 week point and lasts for whatever the remainder of the time period is that’s printed on the bag (assuming that we also have the correct conditions for release). We also assume that all fertilizers are equally good - not releasing more than 0.15 Kg of actual Nitrogen in the first two weeks and no more than that weekly throughout the growing season. What a lot of assumptions! Slide 44 What do I do with my rate over months? Let’s say you’re going to use this fertilizer for your property. We’ll say it is a Fescue blend so you will fertilize at 0.1 Kg N/100m2/growing month. Property area = 389.61 m2 Rate = 0.1 KgN, analysis = 24% (0.24) We will hope for a Mid April start, on an irrigated stand, that gives us 5 growing months (stopping at mid September) They don’t tell us the formulation of the NItrogen here, we assume there are 2 types because we see that some is Controlled Release, but not all. We see the P is in acid form (alkaline soils), and we have Sulphur and Iron included…. For max green-up. Slide 45 What do I do with my rate over months? Rate = 0.1 KgN, analysis = 24% (0.24) Weight = Rate / Analysis Weight = 0.1 / .24 = .41666 Kg/100m2/1 month. Area = 389.61 m2 / 100 = 3.8961 Total for area = .416 x 3.89 = 1.6233 Kg/1 month Growing Season = 5 months 1.6233 x 5 = 8.12 Kg Fertilizer needed for the whole season. This Fertilizer is slow release, residual 8-10 weeks Slide 46 What do I do with my rate over months? Growing Season = 5 months x 4 weeks = 20 week period. 8.12 Kg Fertilizer /20 weeks = .406 Kg/week We will go 8 weeks - it's easier to tell customers “once every two months” .406 Kg x 8 weeks = 3.25 Kg per application. Once Mid April, Once Mid June, Once Mid August. Manufacturer recommends 1.5 - 6 kg/100m2 every 8-10 weeks. Slide 47 Hold on, though… How much of my bag is slow release and how much is immediate release? So let’s figure out our percentages for this application scenario, we figure we need 3.25 Kg applied 3 times this season: When you first apply 3.25 Kg of Fertilizer, you are putting down: 3.25 Kg fertilizer x .24 = .78 Kg of Total Nitrogen 3.25 Kg fertilizer x .20 = .65 kg of SLOW RELEASE N .78 Kg - .65 Kg = .13 Kg N is immediately available to the plant over 389m2 This is good! It is less than our 0.15 Kg N/100m2 rule, so all will be used, none will be leached, residual for 2 weeks. 0.13 Kg / 3.89 = 0.033 Kg/100m2 - definitely below the 0.15 Kg! Slide 48 Continue checking… 3.25 Kg x .20 = .65 kg of SLOW RELEASE N Assuming that the slow release comes available after about 2 weeks, we are releasing .65 kg N evenly over 6 weeks .65 Kg / 6 weeks = .108 Kg / week over 389 m2 .108/3.89 = 0.028 Kg/100m2/week! This also complies with our .15 Kg N/week This is a good fertilizer to use, and our plan is good! IF we increase our rate for KB, though, it may actually be too high… you’d have to calculate it again.