Question
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Followup To
Question -
I live in Northern Ontario Canada (ZONE 1a) I've stripped off all vegetation on my lawn that was originally sod put down right on top of sand 20 years ago and was never looked after. I put down 8" of black dirt (not top soil) and have tilled up the subsoil(sand) to get a mix of about 2/5 sand and 3/5 organic matter and very little clay sediment (maybe 2 mm settled on the top of a 1 cup soil and water mixture). I don't have enough time to send away a soil sample but did a PH and NPK home test. PH was around 6.5 but NPK all showed depleted. I have lots of crushed phosphate 38%(powder form)right from a phosphate mine and potash either sulfate or muriate. I would like to be able to till in as much of these two ferts as possible before I finish prepping my lawn for seed. I have about 10"-12" of soil now. My questions are: 1) how many lbs/1000 SF of each phosphate and potash can I safely till in? 2) do you have any suggestions of what else I could add at this time? I realize I don't have soil test results (sorry) but I would like to till in whatever I can now so I don't have to pound the chemicals to it once the lawn is established. If my P and K requirements could be met now for years to come that would be GREAT! I am very happy to have found this website. Thanks so much, Grant  
Answer -
Till in 5 lbs phosphate per 1000 sq feet. Use about 1 lb/1000 sq feet sulfate of potash or similar amount of muriate of potash, but I prefer sulfate if you can get hold of it (muriate tends to raise salt levels).

Phosphorous can be succesfully added up front, but should still be resupplied annually as required.It is still beneficial to add phosphorous (phosphate) before planting grass seeds because phosphorous moves very slowly in soil and mixing it thoroughly into the top 6" of soil will give you a great start.

Potash is more difficult to front-load. Potash dissolve easily in water and due to the negative molecular charge, it is leached easily with water. Therefore, it should be added regularily, too. If your soil is basically organic matter and sandy loam then potash will drain extremely quickly and you are probably looking at annual applications anyway.

If you add the products this fall, then have a soil test done next year (send for it.. don't use the home ones.. they are not reliable). Most county extension offices will preparre a soil test report for a nominel fee ($5-10).

Spread the nutrients evenly over the lawn are using a fertilizer spreader and then rake (or till) into the top few inches of the soil.

When sodding, or sowing seeds, using 3 lbs/1000 sq feet of UREA or ammonium nitrate. That will provide the nitrogen which is very important for grass growth.

When you get the soil test next spring, you will be able to determine the type of fertilizer to use, but it will typically be one with a ratio 4-1-1, 4-1-2, or 4-1-4, such as 20-5-10-,  20-5-5, 20-5-20, etc. You can ofcourse also use single nutrients (phosphate, sulfate of potash, urea) at that time.

My guess is that you will be adding nitrogen and potassium in same levels, e.g. using a 28-5-14 fertilizer (Scott's Turfbuilder Winterizer) on regular basis, or find yourself using urea + sulfate of potash. You probably do not need to add a whole lot of phosphorous on regular basis (a small amount yearly is fine, otherwise add only every few years)


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Hi Mr. Joergensen.

Thank you very much for your response. It was not exactly what I was hoping for, but at least now I know. I have one more question for you if you don't mind... As I mentioned in my first question I unfortunately have put down "black dirt" instead of top soil so I have approximately 1% clay once I mixed in the sub soil. I have been told that peat moss will help with the consistency of my "soil" but it will only last 5-7 years. I have read that my soil should be approximately 20% clay. I don't know if I can find 20-30 yards of clay but if I can do you think I should till it in? Of course it would have to be dry and in a powder form I'm guessing? Thank you once again for taking YOUR time to do this for others. It is a wonderful gesture for all of us out here who are lost in gardening.   

Grant.  

Answer
There is no requirement to have any clay in the soil for grass to grow. Many lawns are succesfully established on purely sandy soil bases (just take southern florida as an example).

Mixing organic matter (black dirt) into sandy soil is all you need. Peatmoss is also an alternative, but since you have mixed so much organic matter already, I would not recommend it.

I think you did ok. I would not hesitate to recommend that you establish your lawn on the surface.

The reason that you fertilize is to resupply nutrients which the grass plants use during growth. Grass use primarily nitrogen, phosphorous and potassium (in that order). You gain nothing from trying to "pre-load" the lawn. Only phosphorous can succesfully be added up front. Nitrogen (nitrate) and potassium leach easily from the soil and therefore, it is best to add fertilizer to the lawn gradually as it is being consumed. I don't know of any home owner (or farmer for that matter) who can add nutrients up front and expect them to stay in the soil for years to come. Nature does not work that way.

All you need after the lawn establishment is to fertilize 2 times per year using a regular turf type fertilizer (29-3-14 for example) to resupply nutrients.