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Fertilizer Requirement for Native Perennial Plants Harvested for Biomass

Start Date: 2008
Principal Investigator: Craig Scheaffer
Organization: University of Minnesota, Department of Agronomy and Plant Genetics
Status: Complete

Background Info

Although corn will likely continue to be the most important energy crop, it cannot supply all the future bioenergy (ethanol) needs in the U.S. The federal government is investing heavily in cellulosic ethanol technology, and native perennial plants will be in demand as a dedicated biomass source. Therefore, basic information on practices such as soil fertilization is urgently needed to ensure profitable production. Economically and environmentally sound fertilizer recommendations are lacking for native grasses and native plant mixtures proposed for biomass cropping systems. The recommendations currently used by the University of Minnesota fall into a broad category of “pasture plantings” that includes fertilization of cool-season grasses used for hay and pasture. While native plants are considered adaptable to marginal, low-fertility land when used for no-harvest conservation programs like the Conservation Reserve Program, their yield and persistence in the biomass removal system will be compromised without consideration of soil fertility.

Objectives

Determine the N, P, and K fertilizer requirements for native perennial prairie plants used for biofuel production

Key Findings

At the initiation of the trial, unfertilized biomass yields were 2.7, 1.8 and 3.0 tons/acre at Austin, Lamberton and Rosemount, Minnesota, respectively, and were increased 45, 27 and 43% respectively by N fertilization.

Ethanol yield per ton averaged 108 gallons/ton and decreased slightly with nitrogen fertilization. Ethanol yield/acre ranged from 211 to 323 tons/acre and was increased with nitrogen fertilization.

Response to K2O and P2O5 application was less consistent and dramatic compared to N fertilizer. Producers will be able to use nitrogen fertilizer as a management tool to optimize biomass and ethanol yield.

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