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Soil Amendments

Q.implementing recommendations from a soils test report.

Zone Texas City Texas 77590 | Anonymous added on February 20, 2020 | Answered

I received a soils test report from Texas A & M, and it had the following recommendations for additives to the soil. I have tried contacting A & M Extension for explanations without any luck.
1 pound N/1000 sq. ft.
2.5 pounds P205/1000 sq. ft.
3.2 pounds K20/1000 sq.ft.
10.0 pounds limeston/1000sq. ft.
Do you know where I can purchase Nitrate, Phosphorus, and Potassium by the pound? I have talked to several Feed Stores in my area and they have no idea, and never heard of it being sold by the pound.
Secondly, what type of limestone would you recommend. Agricultural or Dolomite, I have no idea which one the report was referring to.
Thank you in advance for any recommendations

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Certified GKH Gardening Expert
Answered on February 21, 2020

It's hard to find small quantities of these individual mineral amendments. Do you only have one thousand square feet to treat? Because 25 or 50 lb sacks may be easier to find.

The Limestone question is a goood one, because Dolomitic lime contains a Magnesium component, which is not always appropriate in the context of balancing of the important Calcium and Magnesium ratio. So if they indicated you needed limestone but did not show a Magnesium deficiency then it is safer to use oyster shell lime or calcium carbonate. If you don't have that information, then it may be okay to use Dolomite or a combo product.

For the NPK components, I suggest going with a complete organic fertilizer product. The slight difference in percentages shouldn't make much difference. They have slow release components so it won't be detrimental to have too much. A 4-8-4 product should be easy to find at local garden centers or home improvement stores.

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Answered on February 21, 2020

John, it is possible to buy nutrients by the pound. Just do an internet search "buy nitrogen soil amendment" and options will pop up. On the other hand, I won't bend over backwards to get exact amounts. The ratio is what is important. You are looking for NPK of 1- 2.5 -3 or 10 -25-30. NPK numbers are percentages; a 10-10-10 fertilizer is 10% nitrogen, etc. If you have a 10 pound bag of 10-10-10 it contains one pound of nitrogen in the entire bag, one pound phosphorus and one pound potassium. (10% of 10 pounds is one pound.) The recommendation is one pound nitrogen for 1,000 square feet, a large garden. If your garden is 250 sq ft then you need 1/4 the amount or 0.25 pounds of nitrogen. Confusing! Look at products like "bloom booster" which tend to have higher phos and potash relative to nitrogen. It is close enough to the recommendations unless you are growing a cash crop. Or apply a balanced fertilizer, 10-10-10 or 20-20-20, that meets your nitrogen needs and supplement with extra phosphorus and potash. A large garden center will have single nutrient products but it is important to choose wisely as some amendments are not readily available to the plant. I have some links, below, which further explain nutrients/fertilizers. For local fertilizer availability and further questions understanding the soil test results, contact the Master Gardeners of your county at 281-534-3413.
This one is for applying lime. https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/adding-lime-to-soil.htm

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