This is kind of arcane but I found it of interest... I have read in a few different places that the choice to cultivate annual plants about 10,000 years ago instead of perennial plants continues to greatly impact our world today. There is much about this that I do not understand but in short perennials have longer roots which make them need less soil, water and fertilizer resulting in little negative environmental impact.
Yesterday sitting in a waiting room I read a recent National Geographic article– the following excerpt and photo below explains this concept well:
"We pay a steep price for our reliance on high yields and shallow roots, says soil scientist—and National Geographic emerging explorer—Jerry Glover of the Land Institute. Because annual root crops mostly tap into only the top foot or so of soil, that layer gets depleted, forcing farmers to rely on large amounts of fertilizers to maintain high yields. Often less than half the fertilizer in the Midwest gets taken up by crops; much of it washes into the Gulf of Mexico, where it fertilizes algae blooms that cause a vast dead zone around the mouth of the Mississippi. Annuals also promote heavy use of pesticides or tillage because they leave the ground bare much of the year. That allows weeds to invade.
Above all, leaving the ground bare after harvest and plowing it in planting season erodes the soil. No-till farming and other conservation practices have reduced the rate of soil loss in the U.S. by more than 40 percent since the 1980s, but it's still around 1.7 billion tons a year. Worldwide, one estimate put the rate of soil erosion from plowed fields at ten to a hundred times the rate of soil production. "Unless this disease is checked, the human race will wilt like any other crop," Jackson wrote 30 years ago. As growing populations force farmers in poor countries onto steeper, erodible slopes, the "disease" threatens to get worse.
Perennial grains would help with all these problems. They would keep the ground covered, reducing erosion and the need for pesticides, and their deep roots would stabilize the soil and make the grains more suitable for marginal lands. "Perennials capture water and nutrients 10 or 12 feet down in the soil, 11 months of the year," Glover says. The deep roots and ground cover would also hold on to fertilizer—reducing the cost to the farmer as well as to the environment."
After a bit of research I found that the Land Institute is investigating perennial grains that could potentially have high yields. There is quite a bit of information available on the internet and I found an interesting site called Agricultural Biodiversity that has several posts about the issue.