I read
this piece about efforts to turn lignicellulosic biomass into usable fuel. It would be nice to generate fuel from nonfood sources. The drawback, however, is that right now the biomass is decaying back into the fields. If we remove even
more material from the fields, they will degrade a great deal faster than they are already doing. It's important to think beyond the immediate goal (get more fuel) to consider possible consequences (rendering large swaths of farmland useless a lot sooner). Americans have a very bad habit of thinking in fragments, because the education system trains people to think that way. This occludes the solution to many problems.
For example, there's another problem going on, where we have huge lagoons of animal excrement from farming enterprises. This spreads disease and drops property values; nobody wants live downwind from a lake of liquid pig shit. However, the traditional destination of livestock manure was ... the fields. You put the manure onto the topsoil and turn it under; that enriches the soil. The manure is then no longer a problem, but rather a valuable raw material. It is better for the soil than chemical fertilizers because it adds biomass.
Sound familiar? Yes, biomass, similar to the stuff we could be removing more of to make fuel. Livestock manure is just digested plant matter. What it puts into the soil is pretty similar to what would be there if you turned under lots of raw plant material and let it rot for a while. That's why manure is so good for soil that is used for farming, because the manure replaces what is lost when we take away fruits, vegetables ... or whole corn plants if it comes down to that.
Our planet is a complex system, every part connecting to other parts. Disconnecting the parts makes it function less effectively.
Reconnecting parts can make it function more effectively. Earth has had several billion years to figure out how to make processes cycle themselves efficiently. We've been diddling around with processes for a few thousand years. I think we'd be doing a lot better if we cribbed from the expert more often.