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Fertilizer ratios, I need help!

Discussion in 'Fertilizer Application' started by Shady Brook, Sep 18, 2002.

  1. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Messages: 1,517

    Please bare with my ignorance. :confused:

    I am fertilizing my own personal lawn, but would like learn alot more, and maybe in the future apply to some of my customers. I have heard different suggestions from as many people I have spoken to.

    Purdue ext. says go with go with 1.0 lb nitrogen Sep, 1.5 Nov, 1.0 May, and .75 July. They suggest a 4-1-2 ratio of Nitogen, Phosphorus, and Potassium pretty much year round from what I can tell.

    Talked to an old Horticulturist who is respected in the area, and a former fert aplicator, and they both said go 13-13-13 now, Hort guy said pretty much year round unless you want to add some Iron. Ap guy said go 40-0-0 Urea later in the fall.

    Talked to another co op guy that said said go 4-1-2 now, and go 6-26-26 late fall for root development. He said it is silly to load up on Nitrogen in late fall. He also said use alot of lime since I am loaded with Oak, said results are amazing.

    Can someone give me the low down on why or why not I want a boat load of nitrogen late in the fall? Do any of these programs make sense? Any good resources to look at?

    Oh yeah, and I just did some overseeding, and applied 13-13-13 per the Horticuturist. Everybody else suggests something else so you do not burn up the seed.


    Thanks a bunch
  2. BRL

    BRL LawnSite Bronze Member
    Messages: 1,211

  3. tremor

    tremor LawnSite Bronze Member
    Messages: 1,476


    Old-schoolers can cause some confusion when their often tried & true methods conflict with modern recommendations. But think about this for a minute. If you applied 13-13-13 at 1lb N (or any other 1-1-1 ratio) right now, and then follwed it up with 46-0-0 urea at 1lb/N in 6-8 weeks, you'd have applied roughly a 2-1-1 ratio between labor day & dormancy for a total of about 2 lbs/N.

    You'd also have delivered .5 lbs/P/M & 1lb/K/M

    And that's what you want to do.

    The other option is to just run a 4-1-2 ratio all year. And that's fine too.

    Nitrogen (N) is the most used & volatile & leach prone elememt we need. So more is applied. Good selection of slow release type & content is important, but lengthy for this thread.

    Phosphorous (P) lasts too long as it is, so very little is needed since very little is actually used by established turf.

    Potash (K, potassium) is medium in it's leachability (depending on source) & will be needed in moderate amounts by turf.

    Keep in mind too that P is expressed in an inaccurate way on commercial fert bags. So a 2-1-1 ratio (20-10-10 as an example) is REALLY a 4-1-2 or 20-5-10 as far as actual elements go.

    To keep things simple, 20-10-10 all year would be fine. Of course this assumes you don't have any special needs that are borne out by a good soil test. Seeding, sandy soils, Ph issues, unusual drought or excessive moisture, & type of turf will all play a role in determining actual needs.

    Does this make sense, or did I just make matters worse?

  4. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Messages: 1,517


    Thanks, that was a super informative post!

    That makes perfect sense to me, and I gather that in some sense only %50 of the Phosphorus is actually usful to the plant or something like that, so you can halve the number indicated.

    Are area has been in a serious draught begining early July, and still continues.

    When one says established lawn, does that mean an exisiting lawn without respect for qualtity, or does it also have something to do with a lawns health?

    If you overdo it on K and P, is it just wasted, or can their be some negative effect?

    How do you know if you are buying a quality fertilizer, say from a Co op? Are their certain things to look for?

    I think a soil analysis may be smart, they do them locally for $15.

    Any other thoughts would be appreciated.

    Thanks so much
  5. Kent Lawns

    Kent Lawns LawnSite Senior Member
    from Midwest
    Messages: 870

    Nice post, Steve.

    All to often we evaluate our fertility requirements per each application, when really we do ourselves and our turf better by developing an 8 month + fertility program.

    Your post was a concise and informative evaluation on macronutrient fertility.
  6. tremor

    tremor LawnSite Bronze Member
    Messages: 1,476


    I'll try to hit'em in order.

    P is expressed improperly on a fert label as P2O5.
    P as an element (as far as plants are concerned)is actually half the amount shown on the label.

    Drought. When you do have good soil moisture again, apply a 2-1-1 or 4-1-2 as directed to promote recovery.
    If seeding, use a 1-2-1 or thereabouts. 18-24-12 as an example. Seed (& seedlings) has greater need for P than established turf.

    Established. I mean older than 3 growing months. True, grass tolerates herbicides after 2-3 mowings. But "youthful hormones" run in turf for up to 1 year. During that time (& here comes some controversy), I feel that elevated Potash levels are in order.

    Over doing any nutrient is wasteful & potentially dangerous to plants & the environment. Waste of money too.

    P can cause a toxic condition when really over-done. Also, it can occupy available soil ions, displacing other nutrients or causing other deficiencies to occur.
    Excess P is also beneficial to the developement of many common lawn weeds.
    And surplus P can move laterally ACROSS soils & polute waterways.

    K contains salts just like N. KCL (potassium chloride) makes a good de-icer & can harm any plant by reverse osmosis when over-done. KCL's salt index (or burn potential) is higher than urea.
    K2So4 (Sulfate of Potash) has a much lower salt content & can thus be applied more heavily. But more than a plant can use is still a waste. I like to elevate K levels beyond conventional thinking when drought or other stress conditions are anticipated. Potash makes for stonger cell walls & better root density. The key here is to apply the extra K a few weeks BEFORE the stress period begins. Stress can also be traffic, insect, disease, or temperature related.

    Agriculture grade ferts drive me crazy. The farmer doesn't care about fertilizer prill size when the stuff is being band applied right on the rootzone or row. In this case, it doesn't matter.
    Size always matters on turf to some extent. Really small for greens (to avoid reel mower pickup & partical shatter). Mid sized prills around SGN 100-140 (-10+20 Tyler Mesh) for golf fairways. And a standard size (about SGN 240) is fine for higher cut turf like home lawns.
    BUT, consistant sizing is very important when using agressive rotary spreaders. Big turf spreaders (over 12' swath) like PermaGreens, Lely's, Vicons, etc., are prone to striping when using AG grade fertilizers. The biggest prills travel furthest because they weigh more. (most of the ingredients have similar bulk densities) So if the biggest prills happen to be urea and the smallest prills happen to be potash then.....you get the picture.
    I call this "ballistic particle segregation". I have no idea who coined this phrase, but it fits.

    I could go on all day about this. But suffice to say, the only striped lawns I've had the pleasure to look at this year all involved improperly sized fertilizer ingredients. And all because ag ingredients are cheaper to buy. And some do work out OK. It depends on the range from smallest to largest. How small vs how big? You have to decide what works best for you.

    When practical, absolutely do the soil test. You may decide to customize the program based on results (especially Lime). But you will also instill greater confidence with your customer when you present them with the lab results & a "custom program". This can make the difference between you selling a job and someone closing the deal instead.

  7. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Messages: 1,517


    You are a Stud! :)

    Wow, I bet you could go on about the subject, you are a wealth of information. Could you share what your background and expertise are? I would find that interesting as well.

    I am not sure if the fertilizer at the co-op would be considered ag grade. He purchases the bagged material from another facility, and for the purpose of lawn use. He sells large volumes to local farmers from his facility. So, I am not really sure how I could tell. The price seems pretty good, most of the stuff is around 7 dollars a bag.

    My wife went to talk to the ext. agent who said that in Indiana you can no longer apply any fertilizer for hire, something to do with IL changing their policy on the matter. I wrote the State Chemist for more details.

    The ext. agent seems to be very knowledgeable, he made the statement that Oak leaves are not acidic, and that 99.9 percent of soil tested at their office, the lawns do not need any lime to adjust ph. He emphasised Lime is a waste for nearly every lawn. The Co op guy thinks most lawns in this area need lime, but soil analysis would confirm that. I do not know if the co-op guy is coming from a farm/ag perspective, actually I do not know what to believe. I guess analysis is the best way to find out. Only $15

    Thanks so much again, always willing to read more if you are inclined to write Steve.

  8. lawnstudent

    lawnstudent LawnSite Senior Member
    Messages: 472

    The east coast tends to have low pH or acidic soils. This is primarily due to the amount of rain that falls in that area and the fact that the soils are much older. The Midwest tends to have neutral soils because we get less rain and our soils are generally younger. The upper Midwest tends to have high pH or alkaline soils because the glaciers drop limestone till all over the place. The need for lime can occur locally anywhere. The best way to tell is to perform a soil test. Your local nursery probably sells pHydrion paper. This can be used to test the general pH of a soil. It will not be precise, but you can get a good idea of a soil's relative pH level.


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