Long-term sustainability implications of diverse commercial pollinator mixtures for the conservation reserve program

Authors: Ashworth, Amanda; Adams, Taylor; JACOBS, ALAYNA - University Of Kentucky

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2022
Publication Date: 2/23/2022
Citation: Ashworth, A.J., Adams, T.C., Jacobs, A. 2022. Long-term sustainability implications of diverse commercial pollinator mixtures for the conservation reserve program. Agronomy Journal. 12(3):549. https://doi.org/10.3390/agronomy12030549.
DOI: https://doi.org/10.3390/agronomy12030549

Interpretive Summary: Insect pollinations are vital to the economic and ecologic sustainability of many food crops grown in the United States; however, populations of bees and other beneficial insects have sharply declined in recent years. As a result, the United States Department of Agriculture (USDA) has encouraged private landowners to implement conservation practices aimed at maintaining or establishing pollinator habitat, known as the Conservation Reserve Program (CRP). The USDA’s Farm Service Agency administers the CRP, which provides annual financial assistance payments for replacing environmentally sensitive agricultural land in with species that improve environmental health. One available CRP conservation practice is ‘CP42 Pollinator Habitat’, which is designed to provide better access to pollinator food sources such as blooming flowers and native plant structural support for pollinator species. Practice specifications require a seed mixture of nine pollinator-friendly species, with three species blooming during the spring, summer, and fall seasons. In addition, CP42 plantings must be maintained for 10 years, with a mid-contract management requirement, i.e., implementing a cultural disturbance to stimulate herbaceous blooming plant species and limit woody plant encroachment and reduce plant residue. However, it is largely unknown how these required disturbance regimes interact to extend bloom periods and pollinator mix persistence. Researchers set out to evaluate how ecological disturbance regimes (prescribed burning, light disking, and a fallow control) affects species growth and flowering period of commonly used CRP species mixtures. Results show that to maximize the presence of pollinator species and extend bloom counts of CRP mixtures, the 'Hamilton' pollinator mixture would need to be disking and the 'Holland' mixture would need imposed burning mid-contract. This study shows that both disturbances increased the number of blooming species, though disturbance regimes interacted with specific species mixtures. Overall, for some species and disturbance regimes, re-planting and other management strategies may be needed to maintain stand longevity long-term to fulfill CRP contract requirements and maintain ecosystem services for pollinators.

Technical Abstract: The persistence of Conservation Reserve Program (CRP) seed mixtures following planting is crucial for supporting pollinator habitat long-term; however, the role and interaction of disturbance regimes for supporting this ecosystem service is largely unknown. This study set out to evaluate how ecological disturbance regimes (prescribed burn, light disking, or a fallow control) and commercially available diverse pollinator species mixtures ('Hamilton', 'Bamert', and 'Holland') affects species growth and flowering period of commonly used CRP species mixtures. Specifically, three pollinator species mixtures were assessed for plant stand dynamics (plant density, yield, and dual-use pollinator-lignocellulosic feedstock potential); resulting soil properties; and total bloom counts during the growing-season. Following 5-years after establishment, flowering pollinator species population proportion varied by disturbance regime × seed mixture (P<0.05), with the Hamilton burned and Holland mixture disked plots having the greatest pollinator species percentage. Overall, based on plant proportion and number of blooms during the growing season, if long-term stability of pollinator blooms is a key consideration for management, the Hamilton mixture should be disturbed via prescribed burning, while the Holland mixture should be disked owing to species-specific disturbance regime preference, with post-senescence yield and soil properties not varying across pollinator mixtures and disturbance regimes. Pollinator mixtures could also be harvested as a lignocellulosic feedstock without damaging pollinator habitat and providing comparable biomass for regional feedstocks, however, seeding mixture and disturbance regime should be considered based on desired residue usage.