Native Perennial Legumes: New Species for Grazing Systems
Native perennial legumes were once vital components of midwestern grassland ecosystems and have potential to increase diversity and productivity in modern agriculture. We propose a two-state project to begin reintroduction of two of these native plants. Grazing systems are generally sustainable, but their profitability and expansion have been limited by several factors. Reintroduction of two native perennial legumes, false indigo (Amorpha fruticosa) and Illinois bundleflower (Desmanthus illinoensis), has potential to overcome these limitations:
1. Productivity of cool-season grass pastures is uneven; two-thirds of all forage is usually produced in the first third of the growing season.
2. Legumes have the ability to fix atmospheric nitrogen and increase forage quality and yield, but are often not used because of slow establishment and lack of persistence.
3. Farmers with low-lying pastures cannot utilize current forage legumes.
4. Introduced legumes are incompatible with native, warm-season grasses.
The objectives are our research is two-fold. First, we have evaluated the establishment of two native legumes, Illinois bundleflower and false indigo, in grazing systems on four farms in Minnesota. Second, we have laid the foundation for plant breeding programs for both species using germplasm collected from the north central United States. Our evaluation and selection nurseries are located in three diverse environments in Minnesota and Iowa.
The establishment of false indigo and Illinois bundleflower in grazing systems was investigated on-farm at four sites in Minnesota. The on-farm sites varied in the time of seeding, methods of establishment, and companion species already established in the pastures. Establishment trials were initiated in western Minnesota in 1999. On-farm plot areas were identified and tested for soil fertility. Frost seeded plots were established in November 1999 and spring seeded plots were established in April 2000. Stand counts were taken in June 2000 at both on-farm sites. Establishment trials were initiated in southeastern Minnesota in 2000. On-farm plot areas were identified and tested for soil fertility. Spring seeded plots were established in May or June 2000 and stand counts were taken in September 2000.
Plant breeding programs for Illinois bundleflower and False indigo were initiated by establishing 20 populations of each species in Minnesota and Iowa. Basic genetic and agronomic information about false indigo and Illinois bundleflower for use in developing successful plant breeding strategies and agronomic research priorities was collected during 1999 and 2000.
In western Minnesota, the establishment of false indigo and Illinois bundleflower was more successful with spring seeding than with frost seeding in the fall at both on-farm sites. Stand counts for the fall frost seeding showed no established plants of either species at both farms in June 2000. The spring seeded plots showed that Illinois bundleflower established better than false indigo averaging 40 plants per square meter verses 4 plants per square meter for false indigo. The spring establishment trials in southeastern Minnesota show better success with both species. Illinois bundleflower has greater plant counts than false indigo at all on-farm sites but established poorly when competition from other companion species was not controlled.
Data analysis of the genetic and agronomic information collected during 1999 and 2000 is completed for Illinois bundleflower and is currently underway for false indigo. Three plant breeding populations of Illinois bundleflower were synthesized and are currently in seed increase for potential variety release of this native legume for grazing and restoration. Similar outcomes are anticipated for false indigo after data analysis is completed.
We expect to learn about optimal management of false indigo and Illinois bundleflower for establishment and persistence in a variety of pasture environments. These experiments will also provide further information about yield and forage quality of these legumes when grown in diverse pasture environments. We will evaluate the potential for agronomic improvement of these species through plant breeding. Through the network, all participants will come to an understanding of the strengths and weaknesses of these plants. When completed, this project should provide researchers with direction for further work with the species and give farmers familiarity with plants that were initially completely new to them. Native perennial legumes could enhance the profitability of pastures, thereby increasing the viability of pasture-based sustainable farms. The project will ultimately move agriculture toward greater diversity, sustainability and ecological soundness.