Renovating Native Grass Swards: An On-farm Trial of Improved Warm-Season Grass Varieties

Widespread adoption of native grass agriculture could diversify the landscape and rural economy.  Specifically, native grasses can improve environmental outcomes while creating new markets for sustainable bio-products.  Increasing the footprint of perennial crops on the landscape provides greater habitat for a range of insect, mammal, and bird species.  Further, deep rooted perennials can increase soil carbon and reduce soil loss and nutrient run-off.  For farmers, native grasses can be profitable by providing high-yield, low-input biomass or forage for livestock, particularly when grown on lands unsuitable for annual crops.  Promising new incentives for farmers are also being proposed through carbon offsets credits or nutrient credits.  In Pennsylvania specifically, nutrient credit programs such as Chesapeake Bay Nutrient Credit Trading program provides a model where farmers are paid for improved land management practices.

Despite these opportunities, perennial native grass adoption has been slow.  This is driven by a chicken-and-egg issue where farmers are unwilling to adopt a crop that lacks an established marketplace.   Further, without a robust community of farmers testing new methods and varieties, the best practices in native grass agronomics are uncertain.  The Association of Warm Season Grass Producers is seeking to remedy both of these issues by collaborating to recruit buyers of grass biomass and to share insights among farmers regarding best practices.  A recent opportunity has arisen because multiple member farmers have reported fields with low yields due to a combination of older varieties, weed build-up and disease pressure.  These fields were established using a “first generation” switchgrass cultivar Cave-In-Rock, along with a mixture of big bluestem and other grassland species.  Improved varieties could provide greater yield and disease resistance, but many new varieties have not been tested in the region.  Establishment and yield data on improved native grass varieties can provide current farmers with valuable information and could make native grass production more appealing to prospective farmers.

Native grass establishment is currently risky due to the risk of failed or weak grass stands.  Native grasses establish slowly and produce negligible yields during the first year and reduced yields during 2^nd and 3^rd season.  Breeding programs have focused on improving native grass germination rates and seedling vigor.  The strongest example of this is the program REAP Canada (Resource Efficient Agricultural Production) which has adopted a single-year breeding cycle based on vigorous upright growth during the establishment year.  This program has developed multiple cultivars including RC Big Rock, a selection from the Cave-In-Rock switchgrass cultivar, and RC Crazy Horse, an improved big bluestem variety.

A second major source of improved varieties is through the adoption of lowland switchgrass ecotypes.  Broadly, switchgrass occurs as two primary ecotypes: upland and lowland.  Lowland ecotypes tend to grow in the southern United States, while upland ecotypes are native to the northern United States.  The majority of farmers in the northeast region use an upland ecotype.  Agronomically, lowland ecotypes have greater yield potential and are disease resistant.  However, lowland ecotypes are prone to winterkill and poor vigor when grown in the northern United States.  Recent breeding efforts, however, have created multiple winter-tolerant lowland cultivars.  These lowland ecotypes can increase biomass yield by approximately 50%, but rigorous field comparisons have not occurred.  Further, different breeding programs have released multiple lowland populations which have not been rigorously compared in the Northeast.  This study proposes to evaluate the improved lowland switchgrass cultivars Timber, Independence, and Cedar Creek.  Timber is a cultivar generated from multiple populations native to the Northeast and was released by the Cape May Plant Materials Center.  Independence is a release from the University of Illinois and was created from individuals selected for high biomass and vigor from the cultivar Kanlow.  Cedar Creek was created in Wisconsin from a Kanlow-derived breeding population which was selected for multiple cycles of winter survival as far north as plant hardiness zone 4.

Although more research effort has been dedicated to switchgrass, multiple breeding programs have also focused on improved big bluestem cultivars.  Anecdotally, big bluestem has been successfully planted with switchgrass by farmers in the region and improves yield stability across growing seasons and fields.  This study will evaluate two new populations:  RC Crazy Horse and Empire.  The RC Crazy Horse population was described above.  The Empire big bluestem population was selected for late flowering, which extends biomass accumulation and improves fall yields.

This study can provide important yield data for farmers and may also provide information to reduce the risks of sward establishment.  Combined, this will improve confidence of farmers in the Association of Warm Season Grass Producers and can also encourage other farmers with marginal or erodible land to establish native grasses.  This work can supplement ongoing projects being carried out by Pennsylvania State University which are aimed at improving grass riparian buffer adoption and on-farm bioenergy production.