Cover crops offer multiple mechanisms for helping to suppress weeds in a cropping system, from out-competing weeds to allelopathy. 

I look forward to someday sitting on my porch drinking a glass of bourbon made from corn and rye grown on my farm and smoking a cigar made entirely from tobacco I produced. To get there, I need to deliver near-perfect grains and leaves in an area that not so long ago was considered unfit for row crops.