I ran across this a few months ago, and I am using soybean meal this spring on 4 test lawns. Not enough time has passed to make a judgement on results, but I have made weekly visits to those lawns and have seen one single chickweed plant and no other weeds.
I liked the soybean meal, and hope it works well for 3 reasons:
1 - lower N than what is found in CGM. I really don't like the idea of applying 2 lbs. N per 1000 sq. ft. at the beginning of the season. Most of my soil tests recommended 1 - 1.5 lbs N per 1000, so applying 20 lbs soy meal per 1000 put me right in the ballpark.
2 - soybean meal is about 2/3 of the price of CGM. I haven't priced CGM this spring, but last fall, it was at around $19 for 50 lbs. I paid $12.75 for 50 lbs SBM pellets this spring.
3 - SBM is available in pelleted form. The pellets are small enough to get an even coverage, but large enough to reduce the compaction in the spreader that often comes with applying meals. The pellets that I used were about 1/8" thick and about 1/4" long.
If you haven't seen chickweed or other weeds thus far this spring, don't give all the credit to the meals, give credit to yourself
for renovating, seeding & over all developing the turf density to the point to which it can successfully crowd out such invaders before they can even get a foot-hold! :waving:
My guys like soybean meal a lot because it's the easiest spreading meal to spread out of the hoppers. Typically we'll use it twice a year.
To help gradually neutralize alkaline soil in many of our clients' turf, we'll have cotton seed meal shipped in from the South for at least one round.
Some clients get CSM and others won't, depending upon that springs' individual soil sample result.
Every so often or when the price is right we'll do a round of alfalfa meal.
This is normally done in the early fall not so much for the N, but to boost soil potasium levels.
Most folks here already know alfalfa meal is a pain in the arse to spread evenly unless the hopper has a REALLY good agitator. When we spread AM we rent a specific spreader that has a vibrator, like salt spreaders, so we can calibrate & not waste expensive product.
If you're keeping (most) potential weed break throughs in check via sheer turf density
, you shouldn't have to think of CGM anymore in terms of pre-emergent, right?
If your equipment allows you to, you can cut CGM back to 10 lb per 1000 & you'd of course just be fertilizing with it at a 1 lb N / 1000 rate.
Save that heavier 20 lb / 1000 (2 lb N) rate of CGM for specific areas where you know weeds will be historically worse as the year moves along- sidewalk & driveway edges, high-traffic areas, along decorative paver walkways, etc.