Question
Hello,
My husband and I have a house in southeast Texas on what used to be part of a horse pasture, the ground is very "Strange" in that it is extremely SOFT, you sink when you walk on it, it almost looks like an ant bed in the areas with scarce vegetation(but no ants). At the moment we have hardly any grass, mostly weeds and blackberry plants (small thin sticker vines). We would like to have a nice yard for our kids to play in but we aren't sure where to start. The area that we are looking at is a little low (it does not flood just gets very muddy). The dimensions are around 80ft by 50ft. We feel we need to fill in the area with dirt.

So here are our questions:
1. Do we attempt to kill the weeds before adding dirt, and if so what do u suggest we use to kill them?

2. What kind of dirt should we use?

3. Is it possible to DIY with a tractor and box blade?

4. What is the best method for getting our grass started, without spending a fortune.

Answer
Hello, Laurah -  Lots of questions.   I抣l try and knock them down for you:

You have an area that even though it doesn't flood, it is permanently wet, and not good for plants.  It probably lacks oxygen and nitrogen, two very important plant growing ingredients.
The fancy term is 揹enitrification? which can get corrected by adding fertilizer AND changing the soil structure.  You change the soil structure by adding loamy soil, organics, and powdered lime if you have clay;  You are in south eastern Texas, so yes, you have clay.   The other way soil loses nitrogen is where water moves too quickly through the soil profile, which happens with coarse-textured, sandy soils ?not your problem.  The even more rare condition is if you have a naturally occurring spring, but they usually have more vegetation around than blackberries and hardy grasses.

50?x 80?(4,000 square feet) doesn't sound like that big of an area, but if you spread as little as 1/2 foot of additional soil onto it, this adds up to be 4,000 x 0.5 = 2,000 cubic feet, or 74 yards.  A double-tandem truck only carries about 17 yards, so that would be 4-1/2 truckloads full of dirt.    

I抎 suggest any good loamy top soil that is available in your area ?In our area it runs about $20/yard, delivered, so the cost would be about $1,500.  

Can you scrape off the existing vegetation and spread this new dirt around with a hobbie-farm sized tractor ?Sure!!  Actually sounds like a lot of fun, too.  Blackberries are prickly, but tear up easily with a small tractor.  You would want to spread the topsoil around yourself as a larger truck might get stuck when it tries to delivers to your pasture.  If you are in a rural/suburban area, you may look to your neighbors that might have a tractor you can borrow.

Cheapest way to get lawn going is by seed.  At 30 pounds per acre (pretty standard), you are looking at 3 pounds of seed ?really not that much. If you buy seed from a big box, check the package for recommended coverage rates. In some  areas, the top soil comes with sprigs of grass already mixed in ?usually the kind that spread with rhizomes, like Bermuda.

I know you didn't ask about trees, but here is a bit of information from Backyardgardener.com:
Permanently wet soil is a factor that must be taken into consideration. The majority of trees will not grow in these conditions, but those that will include the numerous kinds of willow (Salix), large and small, as well as the alders (Alnus), which are mostly trees of moderate size. The handsome and uncommon swamp cypress, Taxodium distichum, is also good, though very wet conditions are not necessary for its success.  Even kids appreciate a bit of shade now and then.

A lot of info, but I hope it helps ~Marc