Bringing back the tall grass prairie
- David Porter
It’s a hot July afternoon in Kansas. The tall grass prairie stretches uninterrupted to the horizon. A vision from the past: or from the future?
When ancient man realized he could save some of the food he gathered as seed for next year and plant it near his home, he increased his food supply and reduced his work: but he made a critical mistake. By adopting annual plants he also adopted the cycle of tillage and planting, weeding and harvesting that has lead to many of the environmental problems we live with today. If he had realized that perennial plants could be domesticated to produce crops we might never have squandered the natural fertility of our soil. We would have a healthy native prairie that would support us, along with a multitude of other plant and animal species.
This is the goal at The Land Institute (www.landinstitute.org) in Salina, Kansas. There, plant geneticists are working on hybridizing native perennial plants to produce crops, which they will integrate into a perennial polyculture. This concept embodies many of the ideals environmentalist hold dear, like reduced wind and water erosion, adding organic matter to the topsoil, creating a diverse habitat for many species of plants and animals, fewer epidemics of plant diseases and predation, reduced use of herbicides, pesticides and fertilizer, and reduced fuel consumption.
Establishing this perennial polyculture will take a lot of work. The Land
Institute began 25 years ago to develop food crops from these perennials and can see another 20 years before it comes to fruition. They are developing varieties that produce a generous crop, are easy to harvest, and will work together to establish a complete and healthy ecosystem. Examples of these perennials include prairie mimosa, which is a legume native to this area. It produces a large quantity of seeds contained in a pea-like pod. Like all legumes, it has a symbiotic relationship with a soil bacterium, which allows it to produce its own nitrogen fertilizer. This allows it to flourish in poor soils, where other plants fail. As the soil is enriched other plants can also thrive. Maximillian sunflower produces seeds and oil, as well as attracting bees, birds and moths. Perennial wheat grass is being crossed with annual wheat and rye to become the breadbasket of the prairie. Members of the sorghum family not produce a large seed head; they also spread by rhizomes, which build a dense network of roots, effective at holding the soil.
Being perennials means that these plants have a head start each year. They already have an established root system that stores energy under ground, ready to burst forth in the spring. This means that the plant needs fewer nutrients from the soil to generate a crop. It also means that these plants can have very deep roots that allow the plant to find water where others can’t. These deep roots also improve the soil by adding organic matter and improving percolation. On the other hand, corn is one of our largest users of nitrogen fertilizer. It must grow the entire root system, stalk, and leaves to produce 2 or 3 ears of corn. The plant is then plowed under and you start over next year with a seed.
Today’s corn and wheat monocultures are depleting our topsoil at a rate of 5,000 pounds per acre per year. If we continue our present course, in twenty years we will be completely dependant on synthetic fertilizers, derived from fossil fuels. But, if we get busy now, to save our top soil, to begin farming and ranching for a sustainable yield, in twenty years, we will be able to put this beautiful, powerful ecosystem to work for us, and for our children. We have a choice.
