Use manure as a biofuel?

Here’s another USDA report well worth a look.  This one looks at the use of manure in the United States.  Interesting statistics: about 5% of cropland is fertilized with manure, and about half of that goes on cornfields.  So the obvious question seems to be that if there’s all that manure around, why not use it to produce biofuels?

Why does this seem like a bad idea to me?  It makes about as much sense to use manure as corn for biofuel.   Wouldn’t it be better to use all that CAFO (Confined Animal Feeding Operations) effluent to fertilize the other 95% of cropland?  Wouldn’t composting animal waste and using it on crops instead of chemical fertilizers be more sustainable and solve a lot of problems?  Or am I missing something here?