Lawn and Lime

twoseas – posted 08 July 2003 19:15

I live in Patterson, La and I have some bare spots in my St. Augustine grass under some pecan trees and white oaks that do not get too much direct sunlight. I tested the PH level of the soil with a direct contact probe and I’m averaging around 6 to 6.2 for a ph level. Ironically, I checked the soil under a different area where the lawn is very dense with plenty of sun and the results were around 5 to 5.5 for the Ph level. Why is the Ph level where the grass is growing nicely so low where I understand the ph level should be close to 7.0 ??I plan to core aerate my lawn and lime afterwards to bring the reading closer to 7.0 in the bare areas under the tree. Do you think it’s not too late in the summer to core aerate and lime. I plan to use “dolomitic limestone”. Should I use pelletized or ground ? Your advice is much appreciated.Ray

Will-PCB – posted 08 July 2003 19:26

Maybe you should selectively trim the bottom of the trees in such a manner as to get atleast a few hours of sunlight on the grass.

I did that with my maples and its done wonders for the St. Augustine.

twoseas – posted 08 July 2003 20:24

All the branches have been trimmed up to approx 14 feet from the bottom. These areas are not totally shaded out. It does get some sunshine in selected areas. It does seem that the areas that do not get the direct sunlight are the one’s lacking grass growth. My neighbor’s huge oak tree is the culprit if not I would get a lot more sunlight.I understand that St Augustine is somewhat shade tolerant. Therefore, I’m leaning towards increasing the ph level to see if my problem improves.Ray

Dchall_San_Antonio – posted 10 July 2003 08:30

St Augustine is incredibly shade tolerant! In fact, if I were in charge of names, I would call it “Shade Master” turf. I don’t think shade is the problem. I would suspect the pH indicator is not reading true soil pH. Can you plunge it into the ground and check it? Before I would add anything to change the pH of the soil, I would have a real soil test done.

Regardless of what the pH indicator or the soil test tells you, the solution can be had easily by applying compost to the soil and feeding with a cheap organic fertilizer. When you have a healthy herd of soil microbes, they will adjust the pH of the soil for you and keep it at about 7.0 or just under. When some of the microbes poop, they are “exuding” humic acids. These acids are pH “balanced” at or near 7.0 and are buffered to stay there for a long time. The more healthy microbes you have, the more humic acids you’ll have and the more balanced/buffered the pH will be. All you have to do is feed them and not kill them (pesticides, fungicides, and herbicides kill them).

If you could apply finished, manure-based compost (NOT fresh manure) at 1 cubic yard per 1,000 square feet, you would reestablish the microbial population in the soil. Then you need to feed the microbes. I use cheap corn meal from the feed store as my organic fertilizer. Use whatever ground feed material you can get nearby. In a pinch, you can use the cheapest generic dry dog food you can find. The ingredients in dog food are the same as in organic fertilizer except for the fats in dog food. If you use anything pelletized (alfalfa pellets or dog food), be sure you water it right away to melt the pellets down onto the soil. Otherwise I think you can guess what would happen. Apply any of the above at 10-20 pounds per 1,000 square feet to feed the microbes. Once per year is enough, but more often doesn’t hurt a thing. You cannot overdo organic fertilizers.

Then, if you haven’t done this already, weld your mower deck in the highest position. If you weld it up there, there is no chance a neighbor kid will accidentally drop it down some time when he thinks it should be lower. And mow every week. St Aug looks best and is the most drought tolerant when it is tall. And I know Louisiana has a real problem with droughts (c;

Will-PCB – posted 10 July 2003 21:58

I would not blindly start adjusting your soil’s ph levels until you know what the ph level of your soil is.

You should go to your local County (Parish) Extension office if you have one and ask them for the soil sample kit. If your Extension office is like ours here in Florida, you can mail a soil sample to a University for a minimal expense and they will analyze it for you.

If you do not have an extension office or cannot find one … let me know and I will contact you for your address, and send you a kit for you to mail off.

Make sure the ground surrounding your tree(s) is not dry. Sometimes a tree can seriously compete for water. Just stick your finger down as far as you can see how moist that dirt is.