Question
I'm in NW FL, zone 8, sandy soil, centipede lawn that doesn't look terrible, but could be better.  I just found out that the soil pH is 8.0 and should be about 5.0, and that the cure is iron sulphate.  Do I apply it directly on top of the grass?  Can I adjust the pH all the way down to 5.0?  How long would it take to make what adjustment is practicable, and is it permanent?  I.m a complete novice at this, and would really appreciate your help.

Answer
Hi Ed,

Most turf grasses like a slightly acidic soil.  Usually this is not as acid as pH 5, but more of the order of 6.5 to
7.
A pH of 7 is mid-point neutral; I have not known of a grass-type that liked such a low pH of 5,...some shrubs like azaleas like a soil that is so acidic.

A sandy soil is a bad soil for ALL grasses.

A high sand soil has little fertility value, poor drainage, poor root-zone microbial ecology, and a lousy buffering capacity.  Buffering capacity is critical for maintaining root-zone pH for proper root metabolism and nutrient up-take.

In my opinion, your efforts to make for a better soil and root-zone ecology for your Centipede grass lawn should involve efforts to improve the soil proper indepently of any efforts to control soil chemistry. Taking the soil from a pH of 8 to 5 is drastic and will probably be non productive and more problematic.


By 'independent efforts', I mean the soil fertility and the tilth factors.  With this accomplished,...the pH will naturally become as it should be for the turf grasses.

This is done by adding better top-soil and soil amendments like COMPOST.  

In summary, work to improve the top-soil root-zone by less drastic means than chemical-adjustmens and by adding 'Rich-Mix' top-soils from local trucking companies.  Add to this commercial composts and manures and organic matter to provide some sort of buffering system to the root zone.  Do not make your lawn into a 'cauldron' of chemical actions.

Adding the natural amendments can be failsafe and, in time should give you a suitable substrate for most grasses.  If this fails, you mamy want to consider using a more hardy grass-type like Bermuda or St. Augustine which should do fine with the sandy base and improved top-soil you can build.

With a good fertile-loamy well draining top-soil, best quality hybrid grass type(s), 1-3 inches of water per week, plenty of sun-light, ...almost anyone can have an excellent lawn with a minimum maintenance effort.
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I Hope this has answered your question(s)!

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