Question
Hi,
I have already asked the soil guys and this question is out of their range.  I am hopeing you might know something.
I live in Glendale Arizona where every day is easily over 100 degrees outside. My yard is in full sun all day. I have what appears to be mold of some kind growing all over the ground. I have lived here about six months and in that time, I have been pulling and digging up the weeds to prepare for planting grass. I have used no kind of weed killers or anything like that. What could this possibly be and how can it be fixed? It has a terrible musty odor to it.
Thank you,
Shirley

Answer
It sounds like the soil has had wooden particles incorporated which are now breaking down.

My guess is that the landscaper brought in topsoil with mulch mixed in, or that the previous owner had the area mulched with shredded hardwood rather than grass, but that is just two possible guesses.

If you find it very offensive, you would need to replace about 30-40% of the top 6" with good quality loam. However, you can just add some extra lawn fertilizer and the mulch will soon break down into wonderfull compost.

Rake it up now and apply 5 lbs per 1000 sq feet of 29-3-4 (turfbuilder) or 15 lbs per 1000 sq feet of 10-10-10. Water well. After you establish sod/seed, look for general yellowing (which not caused by lack of water) or a light green color (typical of grass growing in soil with high levels of undecomposed organic matter). Add a bit extra fertilizer everytime you fertilize.

Good news is that it takes only a season or so to break down allowing the grass to grow healthy. It enriches the soil with much needed organic matter.

I am surprised the soil guy could not answer this question.

Kenneth