Bermuda Lawn: Weeds' response to urea application?
I live in Knoxville, TN, and am in the slow process of deweeding a mostly Bermuda lawn. I am not 100% organic, but I prefer a non-chemical approach. I've taken a long view in my efforts to rid the yard of copious amounts of dallisgrass, content with the fact that it may take a couple of years to reach an acceptable lawn-to-weed ratio.
I maintain good cultural practices -- regularly mowing very low and watering deeply only when needed. At the start of the spring, while the Bermuda was still dormant, I applied glysophate to the lawn to attack the dallisgrass. It worked well, and the Bermuda is starting to fill in the brown spots created by the killoff. It is also very easy to pull what weeds are popping up in (or returning to) the dead areas.
Just last month, I applied my first round of urea (46-0-0), which is where my question comes in. As expected, the Bermuda responded very well to the urea. But within the last week or so, the weeds have started sending seed heads up like nobody's business.
Is the weed seeding activity because of the time of year, or because of the nitrogen application? The fertilizer application correlated to our first stretch of summer-like temperatures, so I'm assuming that's the cause. But, it'd be nice to know if the fertilizer I applied contributed to the unwanted plants' sudden desire to multiply.
Thanks for any insight you may have.