Nutsedge nightmare. Is there an organic solution that will rid my lawn of ever spreading nutsedge?

Question

I have been battling purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus) as long as I've had a lawn. These weeds grow from tubers. The tuber networks are connected by a baby hair fine root system--ordinarily too fragile and deep to extract without snapping. Whether just a myth or not, I'm told that each connection I break will eventually bring forth three more terrible tubers.

I live in the southwestern part of the United States. The year we re-sodded the front lawn, I spent hours over the summer digging for tubers anytime something vaguely appearing to be nutsedge sprouted. Every year since, though, the nasty buggers return.

I'm familiar with chemical approaches to selectively controlling nutsedge in a lawn (see table 1. Controlling Nutsedge with chemicals, here); hoping someone has discovered an organic solution. I'd prefer something that didn't require me to spend every summer camped on my front lawn with a bucket and spade.

Answer 1

What is the main grass in your lawn? The type of grass will help determine the treatment to some extent.

Apparently nutsedge grows well at an optimum pH of about 4, so if it's growing really well it's an indicator that your lawn may be too acid for optimal turf grass growth; most lawn grasses grow best at at pH of about 6.5.

A soil test for pH would be very useful, as then one could work out how much (and what type) of lime is needed to lift the pH out of the range where nutsedge grows well, and into the range where grass grows best.

Answer 2

I have heard that using dried molasses can feed the beneficial microbes and they, then consume the rhizomes. I imagine the treatment must be repeated over month or two until it's eradicated.