We usually only see grass burs when the land has been allowed to dry out significantly, and that usually affects its upper level fertility.
3 things that won't cost much: Keep it moist, watering about every 4 days at this point in the summer. Since we got that heavy rain over the last two days, you're still good until Tuesday.
Next, it needs fertility. I would do one application of organic fertilizer at about one 40lb bag per 2000 sq feet, then add a liquid microbial biostimulant. Hasta Gro makes one, Rhodes has one, Garrett Juice is a great option. They all do slightly different things.
Your grass is stressed, and is defending itself. The last thing is to keep it maintained, mowing weekly as opposed to weakly mowing.
I've seen this multi-step process work well. It should, on an acre, only run you about $300 or so for the materials.
Hope that helps,
Mitchell J McGowan
Dotdirt Organic Landscapes,www.dotdirt.com