TURF FERTILIZING Edited by: Vincent Mannino, County Extension Director Texas Agri. Life Extension Service
Fertilizing Your Texas Lawn Introduction continued: q This training will teach you how to best fertilize your lawn by considering: q Your Texas location and growing season q Your grass species; whether cool-season or warm season q Soil testing to determine fertilizer selection q The maintenance level and expected “quality” q Whether in open sun or shade The Take Home Message: Being able to tell a homeowner go to the garden center and pick the right fertilizer and apply it to your lawn in an environmentally sensitive seasonal program
What do I need to know to fertilize my lawn? This one question is a puzzle of many pieces!
Most homeowners ask… 1. 2. 3. 4. 5. 6. 7. 8. Why should I fertilize my lawn? What do I need know about my lawn (soil type, grass type, shade)? What do I need to know about fertilizers? How do I choose a fertilizer for my lawn? How much fertilizer should be applied? When should I fertilize when my lawn? How often should fertilizer be applied? What is this I hear about environmental issues and fertilizer application? Let’s try to answer these questions…
Why should I fertilize my lawn?
Knowing the right “ins and outs” of how to fertilize effectively almost always: Is the basic component of having a quality lawn! ► Helps you apply appropriate amounts ► Helps favor root growth and “unforced” leaf growth and limits thatch buildup ► Uses water more efficiently ► Helps lawns better tolerate moisture stress ►
What do I need know about a lawn? A: soil type, grass type, shade
How can soil testing help? How? ► You find out what nutrients in your landscape soil are either deficient or in excess. ► Soil acidity (p. H < 7. 0), alkalinity (p. H > 7. 0) and salts ► You are provided with a recommendation ► It protects from over application of Phosphorus and possible movement with storm-water ► You will know what nutrients your soil needs, if salts are a problem and fertilize recommendation? Where can I get my soil tested? ► Contact your local County Extension office. ► Or visit the following web site. http: //soiltesting. tamu. edu
Most Important Part of the Test Nitrogen (N) ► Soil test usually indicates residual N in that can contribute to plant growth and potential water contamination ► However, nitrogen is best applied according to recommended annual programs.
Let’s talk about the nutrient most often applied - Nitrogen ► Nitrogen (N) is the nutrient required in the largest quantity and it is applied most often. § Other nutrients can “come along” with the nitrogen in a “complete” fertilizer or they can be applied separately. ► Typical recommendation in irrigated situations suggest applying up to 1 LB of actual nitrogen per 1000 square feet per application. § More may lead to excessive growth or too much for the plant to use (potential leaching) ► Individual applications added together make up the annual nitrogen rate applied to lawns grasses ► Grass type, lawn quality, and maintenance level are also important considerations in determining how much and how often you apply nitrogen fertilizer
Annual Nitrogen Recommendations For Low, Medium and High Maintenance Lawns
Lawn Grass Type (species) LBS Nitrogen per 1000 sq. ft per year Warm Season Grasses Low Medium High bermudagrass (common type) 1 -2 2 -3 3 -5 Bermudagrass (hybrid) 2 -3 3 -4 4 -6 Buffalograss 0 -1 1 -2 NR* Carpetgrass 0 -1 1 -2 2 -3 Centipedegrass 1/2 1 2 Seashore paspalum 1 -2 2 -3 3 -4 St. Augustinegrass (sun) 1 -2 2 -3 3 -4 1/2 to 1 1 -2 2 -3 3 -4 St. Augustinegrass (shade) Zoysiagrass
Shade Grow turf where you can grow turf ► Grow Ground covers where you cannot grow turf ► Fertilizer requirement is 1/3 to 1/2 less for shaded sites ►
What do I need to know about fertilizers.
Nitrogen recommendation is given in pounds of actual nitrogen per 1000 square feet of lawn area Any fertilizer can be used. Fertilizer may be selected based upon a number of features including the grade (numbers on the bag: NP 2 O 5 -K 2 O) complete fertilizer or by nitrogen source (readily available or slowly available) More on this later
It All Starts With That Bag of Fertilizer… The numbers on the bag are important! ► These numbers are referred to as the “grade” or minimum guaranteed analysis ► The numbers in order represent: § Nitrogen % by weight § Phosphate (P 2 O 5) % by weight § Potash (K 2 O) % by weight ►
How do I know what nitrogen products are in the bag I am looking at at the Garden Center? Look at the other information on the bag ► It will tell you the sources of N in the container ► If slow release N sources are in the bag they will be listed. ► By the way slow release sources will cost more than readily available N sources. ►
Different forms of Nitrogen Fertilizer Which is Which? The readily available N sources: ► Readily Available N sources § Inorganic ► ammonium § Organic: Urea nitrate sulfate phosphates ► Response time to grass green-up is relatively short. ► Residual activity fairly quickly converted to “available” nitrate nitrogen. May last only 4 to 6 weeks depending upon rainfall, irrigation and clipping return ► Under good growing conditions these products may produce high leaf growth rates = more mowing!
Different forms of Nitrogen Fertilizer Which is Which? The slowly available sources: ► Slowly available nitrogen sources in lawn fertilizers § Slowly soluble: IBDU* § Slow release: ► Sulfur coated ureas ► polymer coated ureas § Microbial release dependent (needs warm soil temperatures): ► Urea formaldehyde, ► Methylene ureas ► Methylol ureas ► Natural Organics ► Processed sewage sludge ► Response time to grass green-up is delayed and product dependent. ► Residual activity may last 8 to 10 weeks depending upon grass species maintaining color, precipitation, irrigation product and clipping return Less growth surges * isobutylidene diurea ►
Knowing how your fertilizer will respond so you can use it properly! ► Nitrogen fertilizers sold can be: § All readily available N § All slowly available N § Or mixtures of readily available and slowly available N sources ► Knowing what proportion of the nitrogen that is readily available and what if any is slowly available allows you to use nitrogen wisely! All slowly available nitrogen Often homeowner-type fertilizers are a mixture of readily available N and slowly available N ► All readily available nitrogen Readily available N Slowly available N
Comparing Nitrogen Sources in Lawn Fertilizer Nitrogen Source Category Characteristic Slowly Available Readily Available Response time slow quick Burn potential low high more seldom More frequent low high greater (varies) short Cost high low Leaching potential lower high reduced potential higher potential Application Water solubility Residual Surface runoff Note: yellow are more related to water quality issues
Slowly available N in the fertilizer are stated on the label. ► In the fertilizer below some N is listed as “WIN” or water insoluble nitrogen - a type of slow release nitrogen. ► The percentage of the WIN nitrogen is 3. 6% and is also stated on a weight basis. § Therefore, 3. 6 divided by 12 as is 30% - That’s Good! § The other 70% is considered readily available nitrogen. ►
How do I choose a fertilizer for my lawn?
Don’t let all those fertilizers confuse you! 22 -3 -4
Selecting that fertilizer ► ► ► In addition to N, soil test results say: § If you need phosphorus § If you need potassium § If you need calcium, magnesium and other nutrients. Select a fertilizer ratio to meet your soil needs, but to do so you will need to soil test! Find an analysis fertilizer that supplies what is recommended by soil testing Do not apply phosphorus if not needed And, soil test will tell the p. H
Fert. Facts Ø Nitrogen sources influence cost, but also turf response Ø Fertilizer manufacturing process will affect cost Ø Consider ease of spreading Ø Only buy what is needed Ø If you have not soil tested you may use a nitrogen only fertilizer until you can soil test (more later)
How much fertilizer should be applied?
The fertilizer bag says that it will cover 5, 000 ft 2 - do I need to know anything more than that? 1. 2. 3. 4. Most people do not know how many square feet of lawn they have. You know “ 1 bag” will cover 5, 000 ft 2. L You know what the analysis is according to the bag. You do not know what nutrients the soil/plant actually need. Only testing will tell. Extension agents, specialist, fertilizer salesman are good at GUESSING recommendations. W Length X Width = sq. ft.
Measure that lawn! You only need do it once then you have it! ► ► ► 1 st Step: Measure your lawn to find out how large the turf areas are. The lawn area to the right would be the areas not taken up by the house, drive, walk, deck and landscape beds. The total lot size is 180 Ft. by 80 ft. = 14, 400 square feet The lawn area will be less than the total lot size - we just need to find out how many square feet of lawn there is! 80 Feet Landscape Plants Deck 180 feet ► House Drive Lawn
Measure that lawn! You only need do it once then you have it! ► ► ► The total lot size is 180 Ft. by 80 ft. = 14, 400 square feet Sketch the lot. Break up the different lawn areas and multiply length X width in ft. Keeping a record of each section of the yard can help you “check” your fertilizer application by section. Sections #1 through #5 are pretty easy. Lawn in areas #6 and # 7 and to the left and right of the deck also need to be measured. Add up all lawn areas. This example shows 8, 000 square feet of lawn. 80 Feet #5 #7 #8 180 feet ► #6 Deck #9 #4 House #1 #3 Drive Lawn #2
Back to That Bag of Fertilizer and Take Home Messages… Let’s talk about the nutrient most often applied - nitrogen ► Applying this to our example: § From our example we determined the lawn was 8, 000 sq. ft. § 8, 000 sq ft. divided by 1, 000 sq ft means we have 8 units of 1000 sq ft in our lawn § To apply 1 LB of N per 1, 000 sq ft to our entire lawn we would then multiply 1 lb N by 8 units of 1000 sq ft to find out our whole lawn needs a total of 8 LBS of actual nitrogen. ► Now we learn how to use this information to purchase the right amount of fertilizer.
How much of this fertilizer do we need? Your at the garden center looking at fertilizer packages of different N concentrations… ► Step 1: Know the rate of N that should be applied per 1000 sq ft of lawn area. We will use 1 LB N. More on this later… Step 2: Use the number for nitrogen on the fertilizer package of choice (20% here) ► Step 3: Divide 20% (0. 20) into 1 (rate) = 5 lbs. per 1000 sq. ft. to deliver 1 LB. N. ► Step 4: Calculate the total for the entire lawn. If we have 8 units of 1000 sq ft in our lawn. If we need 5 lbs of product for each 1, 000 sq ft that means that we should purchase 40 LBS of the product (5 times 8) and evenly apply over the lawn! ► 20% Nitrogen by Weight
Let’s try with another fertilizer at the same rate of N and the same size lawn! 12% N ► ► ► Step 1: 1 Lb N per 1000 sq ft is our goal Step 2: 12 is the % N by weight stated on the label Step 3: Divide 12% (0. 12) into 1 (rate) = 8. 3 lbs. per 1000 sq. ft. Step 4: On 8, 000 sq ft it would be 8. 3 Lbs of fertilizer product times 8 units of 1000 sq ft = 66. 7 LBS of this fertilizer is needed for the whole 8, 000 sq ft lawn. Yet some P 2 O 5 and K 2 O were also applied. The nutrient ratio here is 4 - 1 -2. So with our 1 lb of N we applied 1/3 LB of P 2 O 5 and 1/2 LB of K 2 O Did we need that much? Only a soil test will tell us that!
The amounts of various types of fertilizers required to apply certain rates of N per 1000 sq ft Fertilizer Analysis Pounds of actual nitrogen desired/1000 sq ft 1/2 1. 0 1. 5* 2. 0* Pounds of fertilizer to apply above N rate 6 -2 -0 8. 3 16. 6 25 33 10 -10 -10 5. 0 10. 0 15. 0 20. 0 12 -4 -8 4. 1 8. 3 12. 5 17. 0 16 -8 -8 3. 1 6. 2 9. 4 12. 0 20 -0 -16 2. 5 5. 0 7. 5 10. 0 23 -3 -7 2. 1 4. 3 6. 5 8. 6 28 -0 -12 1. 8 3. 6 5. 3 7. 2 31 -0 -0 1. 6 3. 2 4. 8 6. 4 38 -0 -0 1. 3 2. 6 3. 9 5. 2 46 -0 -0 1. 1 2. 2 3. 2 4. 4 * These rates only for use with slowly available N sources
When should I fertilize when my lawn?
What “growing season” zone are you in? When you start fertilizer application and when you stop depends on where you are in Texas ► It matters for both cool season and warm season grasses ► The goal is to fertilize when the grass is actively growing, and can best use the nutrients ► ► Explanation of growing season zones follow…
Knowing the “Growing Season” in your part of Texas is the first step in knowing when to apply fertilizer The length of the growing season is “roughly” the time between the last chance of frost in the spring to the first chance of frost in the fall. ► The growing season indicates temperatures are warm enough for grass growth ►
Growing Seasons as determined by Spring and Fall Frost Dates Zones Last Spring Frost First Fall Frost N Jan. 30 to Feb. 14 Dec. 16 to no freeze W Feb. 14 to March 1 Dec. 1 to Dec. 16 SE March 1 to March 16 Nov. 16 to Dec. 1 S March 16 to March 31 Nov. 1 to Nov. 15
Fertilizing the Warm Season Grasses ► ► ► ► ► Bermudagrass (common type) Bermudagrass (hybrid types) Buffalograss (only native grass) Carpetgrass Centipedegrass Seashore paspalum St. Augustinegrass (sun) St. Augustinegrass (shade) Zoysiagrass
First Spring Application to warm season grasses about the time of last frost! Zones Last Spring Frost Begin Spring Nitrogen If Needed 1 No Freeze to Jan. 30 Jan 30 2 Jan. 30 to Feb. 14 Feb 14 3 Feb. 14 to March 1 4 March 1 to March 16 5 March 16 to March 31 6 March 31 to April 15 April 1 -15 7 April 15 to May 1 April 15 -30
Last application: No later than 6 weeks prior to the first fall freeze date Zones First Fall Frost Late season ending point for Nitrogen 1 No freeze Nov 1 2 Dec. 16 to no freeze Nov 1 3 Dec. 1 to Dec. 16 Oct 15 4 Nov. 16 to Dec. 1 Oct 1 5 Nov. 1 to Nov. 15 Sept 15 6 Same as Zone 5 Sept 15 7 Oct. 15 to Nov. 1 Sept 1
Consider when, how often and how much in putting together an annual nitrogen fertilizer program for Texas lawns Soil test in winter to determine need for complete (P, K, Ca, Mg) fertilizers ► Project a total amount of N to apply per 1000 sq. ft/year. see table to ► follow… Consider use, climate, soil type and growing season Charts to follow… ► Schedule N applications during the growing seasons: timing & rate in LBS per 1000 Sq Ft ►
Annual Nitrogen Recommendations For Texas Lawn Grass Type (species) LBS Nitrogen per 1000 sq. ft per year Warm Season Grasses Low Medium High Bermudagrass (common type) 1 -2 2 -3 3 -5 Bermudagrass (hybrid types) 2 -3 3 -4 4 -6 Bahiagrass 1 -2 2 -3 3 -4 Buffalograss 0 -1 1 -2 NR* Carpetgrass 0 -1 1 -2 2 -3 Centipedegrass 1/2 1 2 Seashore paspalum 1 -2 2 -3 3 -4 St. Augustinegrass (sun) 1 -2 2 -3 3 -4 1/2 to 1 1 -2 2 -3 3 -4 St. Augustinegrass (shade) Zoysiagrass
How often should fertilizer be applied?
How often should fertilizer be applied to Warm season grasses? Using the chart on Annual Nitrogen Recommendations For Texas Lawns: -It would be appropriate to apply low annual rates of nitrogen once in the spring, and if needed again in the fall. -Split fertilizer applications are recommended. -This may require 1 to 2 applications to apply 1 to 2 LBS of nitrogen per 1000 ft 2/year. -Medium and high annual applications will likely require additional applications during the growing season. -Supplemental N if needed should be when rain is evident or irrigation can be supplied. .
What is this I hear about environmental issues (water) and fertilizer application?
Environmental Concerns in lawn fertilization Nitrate leaching into groundwater ► Nitrate runoff in stormwater ► Phosphorus stormwater runoff into surface waters ü fate from over application, ► poor timing, not using soil tests to determine need for phosphorus in your fertilizer q Take Home Message: When the grass plant is actively growing it is very effective in taking up nitrogen applied at reasonable rates!
Avoid Misapplication! Not a good thing for the lawn! Keep fertilizer off hard surfaces (reduces direct fertilizer runoff into water resources)
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