Originally Posted by ICT Bill
It may be obvious to you but I know very little about its applications
How do you apply the corn gluten is it a spray or granular?
I have heard that it has a lot of nitrogen in it and when used you need to adjust your nitrogen need down for the season
I have only used the granular type. For best results, you need to apply 40 lbs per 1000 sq ft over the course of the year for best results. 20 lbs per 1000 sq ft in the early spring and then another 20 lbs per 1000 sq ft in late summer. It does contain 10 N. CGM is 60% crude protein that converts to about 10 N.
Research shows 50-60 percent control can be achieved in the first year when applied at 20 lbs. Per 1000 ft. Studies suggest that control is improved in successive years and as use rates increase. Currently it is sold as a dry product under various trade names, including Dynaweed, Safe 'N Simple, Earth Friendly, W.O.W.!, Corn Gluten Meal Herbicide and Propac. However, I purchase from a feed and grain store and buy the animal feed granular form. It's much, much cheaper.
Portions of at least two proteins in the corn gluten meal, called peptides, are the active ingredients in corn gluten meal. Laboratory studies show the peptides themselves to be significantly more effective at preventing weed germination than the corn gluten meal itself. Unfortunately the peptides do not persist in the soil when used as a spray long enough for effective control. Current research is aimed at isolating and packaging these peptides to produce a sprayable product.
The CGM as well as soybean meal, provide the right balanced food for the microbes that keep weeds seeds roots from getting established.