40lbs should be no problem. Research from Iowa State suggests you can go as high as 80lbs before inhibiting growth of mature plants/roots.

I am assuming you are using this as a organic weed suppressant. If not, there are a lot cheaper ways to fertilizer your yard. If you are, then I would highly recommend you read "How to use Corn Gluten Meal" at the link below. It was written by Iowa State University researcher Nick Christians, who actually discovered CGM as a weed suppressant.

I normally apply in the spring, so I cannot comment on when to apply in the fall. But I can say, that timing is absolutely critical, otherwise it will just be an expensive fertilizer. In the spring, you need to put it down when the forsythia blooms or the first time there are 3 consecutive 50*+ days.

Here is a link that might be useful: Iowa State - CGM

Ah another Tennesseean. Maybe you are like me and found that cgm at a feed store is about as cheap as any other feed type of fertilizer. But to second the last post, preemergent apps aren't til spring.

"Corn gluten mealâ sold as animal feed is not the same thing. It is not licensed by Iowa State, so the university is not compensated when you buy it; and it often does not contain the right protein concentration to achieve seed death.

Products licensed by Iowa State will say something like âÂÂpre-emergent herbicideâ on the label, have the correct protein concentration, and carry complete instructions for proper use. They are more expensive than animal feed CGM because they use a much higher quality gluten�"which sells at a premium�"and the manufacturer pays that fee to the university to fund research to find more cool stuff like this. By law, animal feed gluten cannot say anything about herbicidal effects and will not have directions for any weed-killing use.

Here is a link that might be useful: Source - Gardens Alive

To answer the original question, no, there is no problem. You will have it working longer than if you had applied only 20 pounds.

CGM is a different material from corn meal. The question was about corn meal.

The only downside there may be to applying 40 pounds of Corn Meal per 1,000 square feet might be an odor and if there is that would indicate that nutrients are escaping to the atmosphere and are not being put into the soil.