Soil test/fertilizer question

Discussion in 'Fertilizer Application' started by Bluffman, Nov 4, 2009.

  1. Bluffman

    Bluffman LawnSite Member
    Messages: 133

    I've got an approx. 3 acre lawn which I had soil tested for the first time this summer and got the results around August 1st. I glanced over them and promptly filed them away for later review...well, it's later (3 months I know) and I finally looked at them as I'm ready to do my fall application and I'm a bit confused as to where to go now. I split my samples into 3 seperate ones and marked them "West" which is irrigated. "East" which is the same and "out" which is about 1/2 of the lawn which is non-irrigated. I leave my clippings on in all cases. The tests say my "out" area should get 1lb N/1000, (33-0-0)once a season in early Sept. The "West" should get 3lb N (33-0-0) 3 times yearly May 20-June 20, August 10-Sept 10 and October 10-October 31. The "East" should get 2lb N 2 (20-0-10) 2 times yearly August 15-September 10 and October 10-October 31. I've always done my pre-em in the spring (went this year to 2 apps of 18-0-8 Dimension), a summer feed and a feed around now. All of this property kind of flows together. The East and West which are irrigated (approx 1-1/4 acre) are irrigated and are my "nice" lawn around my house. Am I over thinking this and just choose a happy medium? I could really use some advice. The lawn is pretty good the way I've been doing it though I mow (at 3-1/2-4") every 3-4 days on the irrigated stuff. I'm in Minnesota just South of the twin cities. Sorry for the long winded post.
  2. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    You are probably washing the N out of the soil with irrigation, so you need more.
  3. Bluffman

    Bluffman LawnSite Member
    Messages: 133

    I guess my question was do I try to follow the extension service advice and fertilize three diffent mixes/times which would be a pain in the butt or do my 2 pre-em dimension apps (18-0-8) in the spring equaling 36-0-16, a summer feed at say 30-0-0 and a winter/late fall 30-0-0? Again, maybe I'm over thinking this. Thanks
  4. Marcos

    Marcos LawnSite Gold Member
    Messages: 3,720

    Before I answer, a Q for you because we're in different parts of the country.

    Would you say that your lawn has reached the state of dormancy to the point that you're not mowing anymore for the sake of cutting grass, maybe just out there shredding leaves? :confused:

    If this is true & you believe the lawn to be dormant, I wouldn't recommend straight nitrogen (30-0-0) at this point in time.
    In fact, I wouldn't recommend anything for a completely dormant lawn THIS late in the fall except a compost topdressing of about 1/4", or an application of a protein meal like soybean or canola meal at 20# per 1000 sq ft.
    Both of these meals contain approx 6-1-2 fert analysis.

    But more important than JUST 'feeding the grass', protein meals and/or compost work to build the overall quality of the soil.
    Standard fertilizer doesn't, despite what you probably hear marketed every spring & fall on the radio and TV.
  5. Bluffman

    Bluffman LawnSite Member
    Messages: 133

    It is still growing somewhat although I'm sure we're fast approaching dormancy. I'm leaning toward puting down some 20-0-10 on the whole thing this weekend. Thanks for the advice and anything you can add would be appreciated.
  6. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    So I'm crious... What did you learn from your experiment?
  7. Marcos

    Marcos LawnSite Gold Member
    Messages: 3,720

    The potassium part of that (10%) should get locked into the soil easily enough, but depending upon how dormant the turf has become, some of the nitrogen component (20%) may be taken in by the roots, or a part of it may leach past the roots and into groundwater, and ultimately end up in your region's system of underground aquifers.

    But don't fret about it too much, bluffman! :waving:
    Midwest & Great Plains mega-farmers indirectly dump loads of nitrogen into drinking water aquifers year in & year out and they generally don't seem to have trouble sleeping at night! :cry:
  8. mdlwn1

    mdlwn1 LawnSite Silver Member
    Messages: 2,443

    Soil/tissue tests can be VERY misleading. Ex. when I was new, I got results back saying I needed 4lbs n/1000 3x per we all know something is off with that one..I mean I knew what I fed it, so where did it go? Turned out that the ph was so low that the N wasnt being utilized
  9. lep

    lep LawnSite Member
    from Texas
    Messages: 52

    This seems to be what I am looking for now that the temp is cooler and I am watering only once per week (St. Augustineturf, in Houston). My gut feeling was that if you haven't put down a 1/4" of compost since February (like me) and have not aerated for a year (like me), then these 2 things are crucial.

    I am getting to the point of dropping use of straightforward N-P-K ferts since I believe they are missing a lot of essential micronutients. A professional gardener (not lawn guy!) who takes care of landscape beds and lawns down the street suggested using for example and not straightforward N-P-K types.

    While I don't remember the year of botany courses I had in college, would not carbohydrates be equally important as proteins? The growth rate of our turf has really slowed now during the 50 degree nights, and my guess is that the cooler temp shuts down some of the metabolic pathways for photosynthesis and matabolism (processing nutrients -- i.e. food). Obviously, you could waste application products if the turf is not processing what you laid down due to dormancy(?)
  10. Marcos

    Marcos LawnSite Gold Member
    Messages: 3,720

    If you had sent in 5 soil samples I'll bet you would have gotten back 5 different fertilizer recommendations. :laugh:

    As far as timing of fertilizer goes, you need to look at the % of the nitrogen in the bag that's coated with sulfur, or, in other words 'sulfur coated urea', or SCU.
    The reason for this is because a sulfur coating allows for a more gradual release of nitrogen during peak growth periods, and protects to a certain degree against dessication (drying) during drought periods.
    This also helps to level off the peaks & valleys of flush top growth in rainy spring & fall periods, which helps mowing crews keep up.

    Let's look at the Dimension 18-0-8 you're considering, for example.
    Around here in S. Ohio, spring fert products are typically 25-35% SCU.
    If this holds true in MN, the bag you buy might read something like " X % Slowly Available Urea Nitrogen from Sulfur Coated Urea" at the very bottom under the heading 'GUARANTEED ANALYSIS'.
    So, if in your area Dimension 18-0-8 is 30% SCU, then 'X' would read (something very close to) 5.4%.
    .3 x 18 = *5.4
    *(By law, there is lee-way allowance in manufacturing + or -)

    Summer applications generally should contain 50% SCU or even more.
    Then in the fall, it typically drops back again, just like the temperatures. :waving:

    In the advent of fall dormancy (now), some folks thru the years have boldly theorized that applying fert with high SCU will help the turf take in the N thru the winter gradually.
    This may work in the South where turf doesn't achieve full dormancy, but in Ohio and MN I can assure you it's a waste of resources & no doubt damaging to the environment in the end.
    To be blunt & to the point, all fertilization of turf should be completed before turf reaches full dormancy, regardless of SCU %'s, unless compost topdressing or meal applications are the products being implemented.

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