Managing for Multifunctionality in Perennial Grain Crops

Abstract

Plant breeders are increasing yields and improving agronomic traits in several perennial grain crops, the first of which is now being incorporated into commercial food products. Integration strategies and management guidelines are needed to optimize production of these new crops, which differ substantially from both annual grain crops and perennial forages. To offset relatively low grain yields, perennial grain cropping systems should be multifunctional. Growing perennial grains for several years to regenerate soil health before rotating to annual crops and growing perennial grains on sloped land and ecologically sensitive areas to reduce soil erosion and nutrient losses are two strategies that can provide ecosystem services and support multifunctionality. Several perennial cereals can be used to produce both grain and forage, and these dual-purpose crops can be intercropped with legumes for additional benefits. Highly diverse perennial grain polycultures can further enhance ecosystem services, but increased management complexity might limit their adoption.

Keywords: Kernza; cropping system; intercropping; multifunctional; perennial grain.

Figure 1.

The management of perennial grains can be directed toward additional functions beyond grain production. The darker shades indicate that the function is provided at a higher level. The stripes indicate that specific management would be required to achieve the function (e.g., nitrogen fixation is only provided if legumes are included in the polyculture or rotation).

Figure 2.

Perennial grain crops can be used as part of an extended rotation to regenerate soil health and reduce pest problems before rotating to annual grain crops.

Figure 3.

Compared with annual grain crops (a), perennial grain crops (b) can reduce soil erosion and protect water quality when grown on sloped land.

Figure 4.

(a) A monoculture of perennial cereal rye provides benefits, including relatively high grain yields, forage production, and improved soil health; (b) an intercrop mixture of intermediate wheatgrass and alfalfa provides additional benefits, including nitrogen fixation, improved forage quality, and nectar provisioning for pollinators; and (c) a functionally diverse perennial grain polyculture with intermediate wheatgrass, alfalfa, and perennial sunflower provides additional benefits, including biological pest control and improved habitat for wildlife.

Figure 5.

The hypothesized relationships between ecosystem services and the number of crop species included in a polyculture (a) and between management complexity and crop species (b) for scenarios with uninformed species selection (gray line) and strategic intercropping (black line).