High Nitrogen during Renovation?

Discussion in 'Turf Renovation' started by keperkey, Sep 12, 2005.

  1. keperkey

    keperkey LawnSite Member
    Messages: 33

    Just got my soil tests back from the State Extension and it suggests using high nitrogen for establishment/reestablishment. The soil had real high P and K. What do you think about the high nitrogen?

    Specifically, it was suggested 4.4 lbs of 34-0-0 or 5.0 lbs of 30-3-4. Either way, I am putting down 1.5 lbs N/1000. Can this be right?
  2. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

    If I am reading this right, Your state extention office wants you to plant seed and add high rates of nitrogen at the time of seeding. Why???? Seed needs two things to germinate and nitrogen isnt one of them. Second point. What kind of nitrogen is in the fertilizers you listed. Urea as a nitrogen source has been proven to reduce plant yeild at rates with as little as 5 lbs per acre when placed in contact with the seed. The reduction is as much a 50% for 5 lbs and as much as 75% for 10# per acre rates. Urea can also be harmful to newly germinated grass. similar results have been found using other forms of nitrogen as well. Personally, I think the nitrogen should be added after germination and then spoon fed so as to not promote top growth without a supporting root structure. I also think the 4.4 lbs is probably meant as a full years worth of nitrogen, not to be added all at one time. Any fertilizer applied should be watered in immediantly after application to reduce the harmful effects to the seed.
  3. keperkey

    keperkey LawnSite Member
    Messages: 33

    I can scan and post the report. Basically it says that my P and K is too high and that I need to use hign N to re-establish the yard. It then has numbers for what to use starting in March of next year.

    If this is wrong, how many lbs/K do I need?
  4. bobbygedd

    bobbygedd LawnSite Fanatic
    from NJ
    Messages: 10,178

    i use high nitrogen for overseeding. starter fert for seeding bare ground. excellent results every time.
  5. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

    Not knowing what the soil test says, it would be hard to suggest a fertilizer for your lawn. Even tho the P and K levels could be considered high for the soil, that doesnt mean that that P&k is available to the grass.

    Sampling at the correct depth is also important. Usually, most of the phosphorus and potassium in a soil are in the upper 6 inches. Most university soil test calibration work is based on a sampling depth of 6 inches. If the soil is dry and you can only collect a sample 3 inches deep, the levels of phosphorus and potassium will appear higher than they actually are. This can cause you to not apply these nutrients when you actually need them for optimum yield.
    On the other hand, if the soil is nice and moist and you can push the sampling probe down 9 inches, the levels of phosphorus and potassium will appear lower than they actually are since the sample is diluted with 3 inches of soil that probably has lower levels of these nutrients than did the top 6 inches. This could cause application of P and K when it wasn't really necessary.

    Your soil test probably shows available P, K, in PPM's, (parts per million), I PPM is equal to Two Lbs of nutrient per acre. Here are a couple of charts to show Low medium and high levels of P and K. This same chart is probably listed on the back of your soil test results.

    Lo = 0-50 lb/acre
    Med = 51-100 lb/acre
    High = 100+ lb/acre

    Lo = 0-120 lb/acre
    Med = 121-200 lb/acre
    High = 200+ lb/acre

    To figure your own fertilizer rates you need to convert the amounts on your soil test to lbs and substract them from the desired amounts you want for the grass you are growing. This will tell you how many lbs of P and K to add to your soil. Remember that this is acre rates so you will need to figure the lb's for the size area you are seeding. Dont want to add an acres worth of P/K to 5000 sqft. It also is going to require more math as fertilizer actually contains P2O5 and K2O so it will take more lbs of fertilizer to get the actual elemental desired weights of these two nutrients. Actual P and K are 43% and 83% of what is listed on the fertilizer bag so it will take more lbs of fertilizer to equal the desired lbs of P/K

    Application methods also have a bearing on the amount of fertilizer to apply. Most standard recommendation, even those from soil test, assumes incorporation of amendments into the upper 6 to 8 inches of the soil. No incorporation of seed and plant food occurs if you are broadcasting the fertilizer on top of the soil. All seeds are in direct contact with fertilizer and Mother Nature. Poor germination and survivability due to the contact of the seed and fertilizer are possible. The use of standard recommendations without incorporation is probably one of the main causes of a poor vegetative stands. The inability to incorporate fertilizer limits the total quantity of plant food that can be safely applied. It is also probable that the type of material applied can contribute to seedling loss. Nitrogen in the nitrate form has a much higher salt index than ammoniacal forms. Muriate of Potash has twice as much salt potential as sulfate of potash. Nitrates forms of nitrogen should be avoided when possible. Rates of both nitrogen and potash should be selected with optimum establishment of vegetation in mind rather than optimum grass production or yield. Fertilizers are salts and will injure plants in the same manner as table salt. High salt levels in the soil will draw water from the plant causing them to wilt, and in severe cases, die. Even soil test recommended rates could be considered heavy rates when just broadcasted on top of the soil.

    No nutrient can provide as many benefits as lime. Lime raises soil ph providing a more favorable environment for microorganisms. Most soils contain appreciable amounts of acidic components that can be toxic to plants. Lime can be considered the anti-acid for soil. Lime can be considered any subject with the capability of neutralizing soil acidity. . Lime is only slightly soluble in water and does not move into the soil as effectively as soluble fertilizers such as nitrogen and potassium. Lime reacts with soil acids more effectively when mixed with the soil and adequate water is present. However, if the lime cannot be incorporated into the soil, a surface application is better than none at all. Because lime is not incorporated into the soil with surface applications, care must be taken to not apply lime in such amounts as to make the nutrients unavailable to the newly planted grass. When surface applying lime it is recommended to apply no more than 50lbs per 1000 sq ft, even if your soil test recommends more. I have found reduced and slow seed germination with rates of 35lbs per 1000 sq ft even though soil testing has recommended rates of over 100lbs per 1000 sq ft. Lime rates that are applied to the surface of the soil, and not incorporated into the soil, should be reduced by approx. 70% to 80% of soil test recommendations. Soil test recommendations assume a 6 to 8 inch incorporation into the soil. Broadcasting on top of the soil is only treating the top 1 or 2 inches of the soil at best. After the seed has established, you can then follow the no more than 50lbs per 1000 sqft recommendations, but I like to split those applications and spread out the lime over several applications of 30% of recommended amounts, 6 months apart, until the total soil test recommended rate is applied. Areation, furrow slicing and other methods can speed up the translocation of the lime into the soil. Areation being the most common method for lawns.
  6. keperkey

    keperkey LawnSite Member
    Messages: 33

    Muddstopper, thanks for the info.

    My P number was 36 lbs per acre, which is just into the "high" category. My Potassium was 320 which is the start of very high. The recommendatino said no lime at this time as pH was 6.6.

    All of this being said, how much Nitrogen in pounds per K should I plan on applying now, or between now and the spring as I try to overseed and reestablish some areas that are completely bare and others that are thinning.

    Thanks again.
  7. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

    0-50lbs per acre is considered low P. At 36 lbs you can safely double your present amount. With your high K levels, I would consider using 18/46/0 ag grade fertilizer for a starter fert. Apply at the rate of one lb, P, per 1000, ( thats 23000 sqft per 50 lb bag) and not worry about the nitrogen levels ( .39 lbs N per 1000 if you cover 23000 sqft per bag) until the grass starts to germinate. After germination you can follow up with the higher nitrogen fertilizers. You will need to add the other 4 lbs your soil test recommends, split these applications but try to get about 2 apps of 1 N lb each before winter sets in and the other two before summer. The nitrogen in 18/46/0 is slower release than Urea nitrogens and also contains less salts and is a heck of a lot safer to use with new seed.The diammoniumnated Phosphate will also contain a small amount of sulfur in the sulfate form which your grass will like. A Ph of 6.6 is pretty good but I think I would still add a little lime, about 10lbs per 1000 and in your area I am pretty sure you would use dolomitic lime. this will increase your magnesium levels and your grass will like that as well. Your soil test should also tell you how much magnesium your soil contains. I dont have the chart for recommended magnesium levels in front of me and am not sure if one is listed on the back of soil test results.
  8. keperkey

    keperkey LawnSite Member
    Messages: 33

    Thank you for your help. I greatly appreciate it.
  9. keperkey

    keperkey LawnSite Member
    Messages: 33

    One more question, how late is too late to get the other nitrogen in? Need seed is going down Friday if I can, most likely Saturday.
  10. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

    I would apply nitrogen about 3 or 4 wk's after seeding, just dont use a urea nitrogen fert. the second application would be in November and depending on the weather again in dec. and another follow up in late Feb/early march. Try to have all your nitrogen applied before April. No nitrogen during the summer months, June, July and August. Some will disagee with that statement I am sure, but if you must add nitrogen in the summer, make sure it is in small amounts. Soil test again in August and set up a regular fertilization schedule.

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