# How much is too much fast release fertilizer?



## 1mjbrierley (Sep 22, 2018)

Okay so I did a "fall nitrogen blitz" last year. This is really my first full year of being a lawn nut. Soil temp in my area is almost 50. I'm going to start nutrient correcting by adding 10-20-20 (or some type of high phosphorus/ high potassium fertilizer).

How much 10-20-20 should I apply per application? How long between applications? My soil is slightly deficit in those two nutrients at 22 and 160 ppm respectively. Is it just the Nitrogen I need to worry about burning my lawn?

Thanks for help!
Matt


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## g-man (Jun 15, 2017)

The rule of thumb is to avoid going above 1lb of any (NPK) at once per rolling month. They way to calculate for 1lb is to divide 1 over the largest percentage. In your example, 10-20-20, 20 would be the largest percentage, therefore 1/0.20 = 5lb of product/ksqft.

Since these products use cheaper nutrients, their salt levels are higher, so I would suggest you use a target of 0.5lb. This will yield 0.5/.20 = 2.5lb/ksqft. Starting at half rate will also allow you to get to know your equipment for even coverage and avoid the risk of burning if you overlap.


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## 1mjbrierley (Sep 22, 2018)

g-man said:


> The rule of thumb is to avoid going above 1lb of any (NPK) at once per rolling month. They way to calculate for 1lb is to divide 1 over the largest percentage. In your example, 10-20-20, 20 would be the largest percentage, therefore 1/0.20 = 5lb of product/ksqft.
> 
> Since these products use cheaper nutrients, their salt levels are higher, so I would suggest you use a target of 0.5lb. This will yield 0.5/.20 = 2.5lb/ksqft. Starting at half rate will also allow you to get to know your equipment for even coverage and avoid the risk of burning if you overlap.


@g-man thanks!


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