Originally Posted by greendoctor
I take it that this will be a fall application on cool season grass to help maintain winter color and ensure the lawn is ready to go when spring comes. How did you arrive at the ratio of 20-0-14? What I would use as a final feeding would involve about 1/2 lb N and 1/2 lb K along with micronutrients. That translates to 100 lb soluble ammonium sulfate, 50 lb potassium nitrate and the label rate of soluble micronutrients. I have a friend in the South that applies straight potassium nitrate and micronutrients to centipede and st augustine as the final feeding in the fall. He has gotten excellent results compared to what he used to do. You do not need to apply P right? I would be one to find out via a soil test. My preferred application volume for turf not on automatic irrigation is 200 gallons per acre. I have applied this rate of fertilizer to turf with only 100 gallons per acre, but that was in cool weather with adequate soil moisture and more rain or irrigation to follow. For this application I used a boom sprayer with 1.5 GPM flood jet tips on 20" spacing and 40 PSI. Hope this answered your question.
Ted, you are right, this type of feeding need not involve some expensive stuff that only lasts a few weeks. I have an idea of what is being referred to . That is not intended for use by landscapers and lawn care operators. It is for usage on golf greens in a 14 day spray program along with whatever fungicides and PGRs they are using. Not on a lawn that gets treated only 4-6 times in a year. My usual lawn formulation costs less than $125 per acre. The granular equivalent is a high potassium greens grade granule that will cost closer to $300 per acre. There is a line of products by Growth Products Inc that I use in addition to my inorganic fertilizers. There are live microorganisms and non plant food ingredients, as well as soluble organic matter in the bottle. Again this is not a replacement for fertilizer. But it is a supplement to a good program. The other way involves 1/2 ton of compost per 1000 sq ft, the labor/machinery to transport it to the site and then spread it. Remember that some of my lawns are not accessible to normal equipment at all. There is a reason why I use an engine drive backpack sprayer and not a Z Spray or Permagreen on many of my lawns.
I do not like urea. Mostly because it does not supply what my lawns need. My lawns need sulfur or calcium. Urea and urea based granules supply neither. Not to mention the effect it has on the grass. I liken it to the maniac at the frat party, chugging tequila and doing lines. He is funny and loud, bouncing off the walls. He is also the one found crashed on the floor of the bathroom the next morning. Grass grows like mad for the first 3-4 weeks, then it gets really pale and thin. A properly formulated, balanced liquid does not do this. I use ammonia nitrogen, nitrate nitrogen, and some CRN, which is a urea polymer that is absorbed into the grass and releases nitrogen weeks later. No readily available urea except for the small amount present in the CRN. There is also lots of potassium, 1/2 lb per 1000 sq ft, which is 6 lb per year in my area. Way more than what is typically applied in the urea based granules I speak badly of. Iron and other micronutrients are also applied at much higher rates than what is found in a typical lawn granule. I get 5-6 weeks of very green grass out of this kind of formulation that does not overgrow or suddenly crash on the 6th week. The lawn actually stays acceptably green for up to 2 months, but I am getting paid to be there every month. So people get a lawn that stays consistently green. Boy, would I look stupid if my lawns only stayed green for 1-2 weeks. I had better get good at asking "would you like a large drink with that", if that was the best I could do. The industry standard here is fertilizing with slow release granules every 3 months. Which usually results in a lawn that looks green for about 45 days and looks absolutely horrible by the 90th day.
I would like to try a liquid program like yours on some of my nicer lawns. Could you clarify the individual components you use. I have access to ammoniun sulfate 21-0-0 at a reasonable price but am having trouble finding an affordable source of potassium. Could you give any brand names or sources for your mixture>