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Intermediate wheatgrass as a dual use crop for grain and grazing
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Land use practices like tilling can result in unhealthy soils and erosion. Long-lived perennial grain crops with deep roots build healthy soils, retain and efficiently use water and nutrients, and protect soils from erosion.
Modern agriculture relies on annual grain crops. These crops are commonly planted annually and maintained by tillage, or turning and breaking up the soil, which exposes the soil to erosion and releases greenhouse gases. Tilling clogs airways created by plant roots, killing beneficial microscopic life and weakening soil structure. When wind and rain come, the soil blows and washes away. Plowed farmland loses soil much more quickly than plants and people can rebuild it. A prairie would need 380 years to rebuild the soil lost in a single year from tilled cropland. Even fields that use no-till practices lose soil that would take 16 years to rebuild.
Weak and eroded soils can devastate land, food systems, and communities. Farm fields become less productive, requiring costly fertilizers to increase yields and help plants grow strong. However, crops can only absorb a small portion of the added nutrients. Whatever is left washes away into rivers and streams or seeps into the soil. Extra nitrogen and phosphorus in the water can cause over 400 dead zones globally every year, where an explosion of plant life leads to the widespread death of fish and aquatic animals due to a lack of oxygen (called eutrophication), destroying fisheries. Contaminated groundwater is also bad for humans and land animals. Properly processing contaminated water can dramatically increase the cost of living for rural communities. Plowing and erosion also release soil carbon into the atmosphere, contributing to global heating and climate change.
Perennial grain crops represent a fundamental shift, holding the potential for a truly regenerative future in which humanity and nature flourish together as a collaborative system. A future in which diverse, perennial crops—like grains, legumes, and oilseeds planted in mixtures—cover our farmlands with living plants and roots, building healthy soil, restoring waterways, and creating abundant food and economic growth for farmers and their communities.
With perennials, farmers disturb the soil much less than with annual crops. With continuous plant life and less disturbance, soils become far more functional, forming soil aggregates and root pathways, allowing water to infiltrate and storing carbon in the soil profile. Living three or more years from a single planting, perennial grain crops invest more energy below the ground in roots and root exudates. The exudates are organic compounds that roots release into the soil, fostering beneficial microbes that improve soil health.
Each gram of healthy soil contains on the order of a billion microbes, and many of these help crops defend against disease and obtain nutrients like nitrogen and phosphorus. Perennial roots are also very efficient at taking up and using water and nutrients from large soil volumes.
The next step is to rebuild and increase soil health over the long term by growing perennial grains in diverse mixtures called polycultures. Diverse perennial plant species dominate nearly all native plant ecosystems, whether in forests, prairies, deserts, savannas, or tundras. These ecosystems can regenerate and persist for centuries, feeding above and below-ground life. For example, the Great Plains prairies from Canada to Texas have a good track record of self-regeneration, persisting for 8,000-10,000 years following the recession of the last continental glacier. Those diverse perennial prairies built the soils that allowed our modern Midwest breadbasket to feed nations and the world for 160 years. Research at The Land Institute and with partners is underway to test diverse perennial grain intercropping systems that will achieve high grain yields and soil health benefits.
Various systems and organisms contribute to our understanding of “soil health,” namely, the relationship between perennial roots, carbon cycling, soil food webs, and nitrogen management. The soil food web refers to a community of organisms that interact with one another and grow in the soil. These organisms decompose organic compounds and sometimes consume smaller organisms, processes crucial to nutrient cycling and maintaining soil health.
