Gypsum is a form of calcium that will "flocculate" clay and open the soil structure. If you live in zone 8 in Texas, your soil is already too high in calcium. Therefore I would think gypsum would not do much good.

Mulch and moisture is all you need in the problem areas.

Gypsum is useful in clearing clay soils of excess salts which too little rainfall allows to build up in the soil. The people at Texas A & M have done some studies on using gypsum in your soils, one involved using municipal sewage sludge, but I would as them if it would really help your soil. There is no sense in you spending your money on something that does little to improve your soil.

David,

There is an area somewhere in Justin, (north of Ft Worth) and I was talking to a guy about trees and he mentioned that he had the soil tested and came out with high sodium content. I think he used gypsum but I don't know if that helped. He also said that the tap water is highly sodic too. Sounds like tough job to do....

I was recently told to apply gypsum as my clay soil is sodic. I am also in Zone 8, TX. I assume it is sodic from the irrigation system - our tap water is also fairly sodic. I don't know if we usually get enough rain to wash out the sodium, but last year I did a lot of irrigation because of little rainfall, so sodium could be high because of that.

Gypsum is $10 for a 40 lb bag - I would need 7 bags to do my yard at 40lb/1000sf and it was said 2 treatments would be the minimum necessary. $70 seems like a lot for one treatment, as I can do two years of fertilizer with that money.

Lawn doesn't look bad, but it could always be better. Any visual indicators that I could use to help decide if I need to apply this gypsum?

Gypsum will do precisely nothing to break up your compaction. The compacted soil needs to be physically broken up. I would core aerate.

Who told you that your soil is sodic? The salts that cause sodic soils accumulate because of too little water, although some irrigation water has been no to increase the salinity of soils.