Last year, I battled Digitaria (crabgrass), primarily right outside my basement door, in the side yard.

We also battled fleas, thanks to the half-dozen cats and pair of dogs.

Being an engineer who whole-heartedly believes in better living through chemistry, I applied a lot of stuff to the yard last summer.  Luckily, some of it was "natural", like pyrethrins, but some of it was decidedly not.

I also happen to read Teaming with Microbes and learn about the whole soil web of life going on under my feet.  Or should be, if I hadn't killed it all off with my spraying.

I also read up on compost tea, where you take some of your rich compost, plonk it into a bucket (contained in some panty hose or other bag), feed it some molasses, and most importantly, aerate it.  Without aeration, it apparently goes anaerobic, and breeds all sorts of nasty muck.  With aeration, you're creating compost concentrate in a sprayable form.  You can easily distribute your good bacteria and fungal spores from your 2-1/2gal pump sprayer.

The supplies for making compost tea are not unlike those for entertaining fish.  It all boils down to air handling.  For that, some air stones, tubing, and an air pump is what you need.  Fishkeeping supplies.

Assemble in the obvious way, fill a 5-gal bucket with water and let it aerate for a few hours to blow off any chlorine.  Add your compost bag, some mollasses, and keep it in a warm place, with the bubbles bubbling continuously.

In a day or two, strain it out, load up your sprayer, and apply liberally.

Repeat weekly for best results, say the articles I've read.  Compost tea can also apparently not be applied "too liberally" and will not cause any burning or detrimental effects for your plants.

There are people who claim it doesn't help.  I figure nothing can be worse than doing nothing, in my yard.