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Old 04-30-2013, 01:03 AM
greendoctor greendoctor is offline
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Join Date: Mar 2008
Location: Honolulu, Hawaii
Posts: 7,302
As I have said before, soils here are in bad shape long before the incorrect materials are applied. A common construction practice is to build entire neighborhoods on top of a coral base. There is up to 12" of red clay put on top of it as "topsoil". What the coral does is contaminate the clay with salt and alkalinity. That clay is hard to leach. Chloride and salt toxicity happens even in areas getting 1+ inches of water from irrigation per week. Some of the salt and alkalinity are from the tap water used to irrigate. The coral base adds more and in windy weather there is no escaping the fine fog of salt from the Pacific Ocean. Inland deserts do not get salt spray 12 month out of the year. Leach the soil properly in a desert and the problem is fixed. Unless the subsoil is pure calcium carbonate and boron carbonate. I have heard of that situation. Grass does turn greener from rain because rain has fewer salts in it. You are right about most grasses having problems with salt. I find that zoysia is also sensitive. Centipede is normally ok because it is grown far inland away from the beaches. But throwing potassium chloride on it is not a good idea. It gets enough from the tap water used to irrigate and it does rain about 30" in those areas so people are not willing to supply the other 20". The soils there are red clay that hang on to everything applied to it. No sand or sandy loam. In many cases, the neighborhood is build on top of a coral fill. So what one would assume to be neutral or acidic and salt free is actually bad.

My preference for ammonium rather than urea stems from observing how the turf responds to each. I also know that most of the lawns I deal with need serious acidification as well. Urea dissociating into NH3 gas and CO2 explains why it does not work the same on soils with a pH of 7+. CO2 reacting with excessive calcium or magnesium forms alkaline carbonates. The NH3 is also here and gone quickly as well. Ammonium sulfate is one of the most acid forming nitrogen sources short of ammonium thiosulfate. On a soil known to be acid, my preferred nitrogen source is calcium nitrate, followed by urea. You see, I do not spread what sold as "turf fertilizer". Sure, I know there is greens grade 46-0-0 and 0-0-62. What I see sold as greens grade preblends locally contains potassium sulfate and is heavy on the ammonium for the reasons I mentioned above. Low cut bermuda has a limit on how much salt it can handle. Especially if it is a dirt fairway or pushup green. Discussions about which preblended granule is better, cheaper, etc are lost on me. I am applying according to the results of a soil test for that site. Therefore, unless it is prilled sulfur, gypsum, or dolomite, all of my nutrients are sprayed, not spread. Solutions are mixed to supply specific rates of N, P, K, S, Mg, Ca and micronutrients.

Not a doctorate. Maybe more like the old barbershop doctor/dentist in the old West. Just an undergraduate in horticulture. Rest of my schooling is from being in the industry for over 20 years or all of my adult life. By the time I was old enough to go to university, Charles Murdoch was long gone and Roy Nishimoto was retiring. That is what I meant by not having any Turf Scientists at UH. Jim was there after my time there was long past. Only person there I can relate to is Joe DeFrank. He teaches the undergraduate weed science class. To this day, we frequently talk about his research, and product trials. In spite of this poor education, I have not done badly for myself. I get grass greener even when bags of over the counter fertilizers or preblends have failed to do the job and some rather stubborn weed problems have been controlled without resorting to digging, tilling, fumigation, or RoundUp.

Which companies are you associated with? Or are you EPA?
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