My St Augs is starting to yellow (whole blade). What could be the cause of it (not enough nitrogen)? What do I need to do?
Have you fertilized this year?
Have you had much rain?
How much have you been watering?
There are several things that can cause yellowing in grass. One is nitrogen deficiency. Another is iron deficiency. Another is too much water.
The nitrogen deficiency can be dealt with easily. So can over watering.
If the problem is iron deficiency, it can be harder to combat.
The iron deficiency can occur even if there is a lot of iron in your soil if you have high pH soil. If your soil is high pH, it's not practical to try to lower it for a large space like a lawn. You can buffer it by adding organic matter. You can also try adding chelated iron (just adding iron sulfate doesn't help in high pH because the iron isn't available). You can also spray water soluble iron on the grass for a quick but short lived green up. But that can only be done if the highs won't be above 80 for a few days. Since you live in Texas, you should be able to get greensand (glauconite). It provides readily available iron to large areas on a sort of time release basis.
I live in Katy and have had similar issues. Like BPGreen mentioned, I have used Texas Greensand with great success.
Early march - Compost (cheap stuff from home depot), alfalfa
Early April - Texas Tee fertilizer
I try to water 1" a week. Haven't had much rain.
My turf is new (put down in November)
dao4686 where did you get the greensand?
I have found Gardenville Greensand at Houston Garden Centers, and Greensense Greensand at Southwest Fertilzer. It's cheaper at Houston Garden Centers.
Greensand is where I was headed. I was hoping you would tell me you have had a lot of rain. Rain will leach out the acidity from the surface root zone. Once the acidity is gone and the pH goes back to 8.0, then the iron is no longer available and the grass turns yellow.
Nobody knows how greensand works. Chemically it is a combination of just about everything in the Periodic Table. Once your soil loses its low pH, the grass will be yellow for the rest of the season, UNLESS you use greensand. There are no iron products that work in Texas. The application rate is high at 40 pounds per 1,000 square feet. Being a wet sand product, it is kind of hard to apply.
A few years ago, my next door neighbor never once fertilized in 5 years. Not only that but she never once watered her lawn. The only thing she used was greensand. Here I was taking care of my lawn and hers usually looked better. Life's unfair.
Is it yellowing, or just sporadic blades that are a pale green?
Both the last two years, I've had random blades, or small clumps of blades, that were pale green. I tried a little extra SMB, and they darkened to a nice deep green over a couple months. I'm not entirely sure if it was the SBM that cured them though, as they didn't darken as fast as my lawn normally does after an application of SBM. So I, too, suspected an iron deficiency, but it is so sporadic, I'm not convinced of that, either. I had thought about trying greensand last year, and after reading the above posts, think I will this weekend.
I'll keep y'all posted.
I am going to get some greensand this weekend. What is the best way to apply it (spreader?). I am also using a soaker hose a slow (dripping) rate to soften up my turf and make sure the water is penetrating the turf.
Thanks for all of your responses.
I just fling mixed greensand/lava sand around by hand. It's hard to spread greensand itself when wet. I use lava sand to break up greensand, making it easier to spread by hand.
I put down four 40 pound bags of greensand on my 4000 square foot yard (front & back)Saturday. I will post the results whenever I see them. How long should it take to see a difference? Also, sprayed the yard will fish emulsion.
Thanks for all of your help.
It will take a few weeks. Be patient... Just be glad you don't live on limestone rubbles like we do. It's worse problem to deal with... I was born and raised in Houston and I much prefer to whatever my mother has. It's probably clay based soil but it has millions of earthworms and probably 50 years old lawn so it's really nice soil. It can survive on rainfall only pretty much these days.
I normally have the same issue each summer. I too have tried Greensand, with some luck in the past. I recently had a soil test done and found out there were a few things I needed to adjust to combat this. Primarily the high pH ties up the Phosphate and micronutrients. The recommendation was to add sulfur to lower the pH. I haven't had a chance to do it yet, but will in the upcoming weeks. I'll let you know how it turns out.
DO NOT ADD SULFUR! It is fungicide and will kill beneficial fungi which is RESPONSIBLE for lowering pH (over time). Do you have any earthworm? A few or a lot? What do you feed your lawn with? Soybean meal is excellent fungal food. Which lab did the testing? A&M or Texas Plant and Soil Lab? If it is A&M, you made a mistake. Go with Texas Plant and Soil Lab which is geared for organic practice while TAMU is geared for chemical stuff.
This was the organic recommendation from TPSL. I've been organic for 2yrs - Soybean meal, alfalfa, etc. The reality is, there are several things out of ratio in my lawn and this (among other things) needs to be corrected.
Sulfur is only effective at lowering pH if you dig it into the soil, so it's not effective on a lawn. It's best used to combat high pH that is causing severe chlorosis.
If I have a tree that is dying, I'll dig some sulfur in holes around the dripline to try to save it and worry about the fungi at a later date.
Also, sulfur is a necessary nutrient, so if your soil is deficient in sulfur, you should add it.
But I would not spread it on the surface of the lawn in an attempt to lower the pH. It won't be effective and it will kill fungi.
Would you mind taking a look at the results of a soil test I posted in the TPSL results thread and letting me know what you would do. There are also pictures of the chlorosis problem I had last year. Thanks!