Some crop waste is always left in the fields.

better yeilds are usually obtained by crop rotation and, depending on the soil type: the addition of external sources of fertilizer and minerals that may be lacking in the soil.

Crop residue itself may help or in some cases even hinder production.

It really needs to be evaluated on a field by field and crop by crop basis.

GPS systems and Remote Sensing are becoming increasingly used to manage this on a meter-by-meter basis.

We are in no danger of running out of productive farmland so long as we continue to encourage sound land management practices (terraces, Planting trees on the steepest hillsides instead of row crops, CRP, etc...)

I love to criticize farm subsidies as much as the next guy, but the truth is some of those subsidies are a major factor in encouraging sustainable farm usage beacuse the subsidy programs are often built around soil conservation. What ticks me off is when the subsidies go to farms that are way to oversized to be efficient. (I passed about 2000 acres of unharvested corn just the other day...What a waste...I'm sure we the taxpayer will be buying that corn when the corporation plows it under next spring). Man that's another story...