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Alfalfa Checkoff Watch: Research Project: Identifying optimal alfalfa germplasm types and characteristics for compatibility and performance in mixed cropping systems

Published on 30 January 2019
Kernza grain with alfalfa and wheatgrass

This project received 2017 funding from the U.S. Alfalfa Farmer Research Initiative (aka Alfalfa Checkoff). Brandon Schlautman is the lead researcher from The Land Institute on this project. Email Brandon Schlautman

Q: What prompted this research project?

The goal of Progressive Forage, “not to help producers get by but to help producers get better,” is perhaps the best description of the motivation for this project. Our research group has many years of experience studying various aspects of alfalfa and perennial cropping systems, and through our work, we’ve developed two basic ideas we collectively share:

1. Long-term productivity of U.S. agriculture will likely stagnate or decrease if the management of existing corn-soybean or wheat-soybean cropping systems is not improved to reduce nutrient losses and to increase soil organic matter.

2. While most perennial crops are beneficial, alfalfa, in addition to being an excellent high-protein feed source, might be one of the best and most widely adapted perennials available for improving soil structure, nutrient cycling and cropping system fertility.

We have a central, working hypothesis that incorporating alfalfa as a living mulch into row-crop agriculture could provide some of the increases in landscape efficiency and the enhanced ecosystem services necessary for long-term sustainability and productivity in U.S. grain production. These mixed cropping systems might someday allow farmers to achieve the environmental benefits associated with growing alfalfa and perennials with the additional economic benefits of producing a grain cash crop in the same field.

Farmers and researchers in the U.S. and abroad have already begun trials with alfalfa interseeded between rows of corn, wheat and other grains. Emerging grain-alfalfa mixed cropping strategies represent untapped potential for increasing acreage planted to alfalfa and exploiting previously underutilized alfalfa germplasm.

This project intends to study alfalfa-plus-intermediate wheatgrass (IWG) mixed cropping systems. IWG is a perennial forage grass undergoing domestication as a perennial cereal grain crop. Kernza is the grain harvested from the domesticated forms of IWG.

The dual-purpose alfalfa-IWG perennial mixed cropping system has the potential to provide many of the known benefits of grass-legume mixtures (e.g., limited nitrogen losses, increased legume N2 fixation and increased grass protein content; better land use efficiency; reduced weed pressure; and increased carbon sequestration and retention in the soil) while simultaneously producing grain for human consumption and grass-alfalfa forage that can be hayed or grazed by livestock.

Q: What challenges have occurred and what progress has taken place since the research was initiated?

Alfalfa and IWG likely use resources (water, light, nutrients, etc.) in very specific and sometimes overlapping ways, and previous research in alfalfa-grain mixed cropping systems suggests success and efficiency is all in the details of how competition and compatibility between the two species is managed. For example, we found in a recent study in Minnesota that competition with alfalfa at more northern sites, where the alfalfa was seemingly better adapted and more vigorous than IWG, reduced Kernza yields when compared to other southern trial locations.

Likewise, ongoing research by Dr. John Grabber’s team at the University of Wisconsin has shown choice in alfalfa variety can be an important determinate in the stand density and yield of alfalfa interseeded into silage corn, and use of prohexadione-calcium growth regulators can help further alleviate competition between the two species.

Just as Grabber’s team found with alfalfa-silage corn, we expect choosing an alfalfa variety with a certain set of characteristics will be necessary for managing competition in the alfalfa-IWG mixtures. Our proposed work funded through NAFA USAFRI will explore how particular alfalfa traits, such as fall dormancy, root type and spring vigor, can influence Kernza grain yields, alfalfa-IWG forage yield and quality, and various soil health properties where they are grown.

To answer these questions, we’ve planted more than 25 different alfalfa varieties with contrasting traits and characteristics in mixtures with IWG at multiple sites in Minnesota, Wisconsin and Kansas. Ultimately, we hope our work can eventually assist farmers in the selection of specific alfalfa germplasm types adapted to their growing region and compatible with IWG. We also expect the study will inspire new research and breeding strategies to increase the compatibility of alfalfa with IWG and other grain crops.

Q: When can producers expect to see the final results?

This current project is just beginning and, because both alfalfa and IWG are perennial crops, we will need to collect data at least through the 2021 and probably 2022 growing seasons to get a good picture of the long-term yield potential and stability of the system as affected by the various alfalfa traits and characteristics. However, we have other ongoing alfalfa-IWG research supported by the Sustainable Agriculture Research and Education program and private food companies, like Patagonia Provisions, with results nearly ready to be shared with producers.  end mark

PHOTO: Kernza grain was combined from this field July 26, 2018, and the residue (alfalfa-intermediate wheatgrass) was swathed and baled the same week. This image shows the regrowth about 40 days after the grain-forage harvest. Photo provided by Brandon Schlautman.