"If humans are to have any good prospects well beyond this century, more than 90 percent of the planet's landscapes must be returned to diverse, perennial vegetation , and that entails the replacement of annual grain monocultures with polycultures of perennial grains and oilseeds. With deep, permanent root structures, those new constellations of plants, like natural plant communities, would foster vast, diverse communities of soil organisms that can micromanage ecological processes – processes we currently attempts to macro-manage with big, blunt instruments like machinery, chemicals, or truckloads of manure and mulch .
By developing perennial grain crops, plant breeders could help dramatically enlarge that portion of the agricultural landscape that is kept intact by perennial roots. With a few very small-scale exceptions, no perennial cereal, pulse, or oilseed crops currently exist. Through a well-coordinated, long-term plant breeding effort, that hole in humanity’s crop inventory can be filled." (Thanks Daniel)