I have two 1 cu. ft. bags (approx. 40 lbs.?) and want to put this through my Scott's Accugreen drop spreader (after assiduous cleansing due to the synthetic fertilizer I used last year).

It's pretty dry stuff -- I think the largest chunks are the little black pieces of lava sand (I think that's what it is).

The back of the bag says to open a broadcast spreader 100% -- I suppose I could do the same thing on my drop spreader.

Overall, is the goal to drop this as a fine powder on the yard (as I read in another post about spreading compost)?

Thanks folks!

I NEVER use the recommended spreader settings. I always calibrate whatever I'm applying for the day (humidity affects drop spreader settings). Somewhere on the bag it should tell you how many pounds per 1,000 square feet to apply. Measure 100 square feet and put the recommended amount of stuff into your spreader. Set the spreader half way open and walk the 100 square feet. After you run the 100 square feet you will have a much better idea as to what setting to use.

With organic materials I usually have to set my spreader wide open and go over it twice to get the "recommended" amount down.