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United States Department of Agriculture

Agricultural Research Service

Title: Forage and bioenergy feedstock production from hybrid forage sorghum and sorghum x sudangrass hybrids

Authors
item Venuto, Bradley
item Kindiger, Bryan

Submitted to: Grassland Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 5, 2008
Publication Date: October 5, 2008
Citation: Venuto, B.C., Kindiger, B.K. 2008. Forage and bioenergy feedstock production from hybrid forage sorghum and sorghum x sudangrass hybrids. Grassland Science. 54:189-196.

Interpretive Summary: As the bioenergy industry expands, producers choosing to shift current forage crop production to dedicated biomass crops will find it advantageous to grow low risk multi-purpose crops that maximize management options. Sorghum is a warm season annual crop that can be grown for forage or grain. Special sorghum hybrids have been developed that are capable of impressive biomass yields and that have tolerance to environmental stress. If harvested early enough in the growing season, these sorghums will re-grow and produce a second or even a third harvest within the same season. The objectives of this study were to 1) evaluate biomass production and quality characteristics of 21 sorghum cultivars using two harvest systems, and 2) provide information for identifying the best sorghum cultivars for dual-use as a forage and biofuel crop. Average yield for the single late season harvest was 12 tons per acre of dry matter per year. Average yield for a first harvest plus a ratoon crop was 11.4 tons per acre of dry matter per year. The best performing cultivar yielded almost 18 tons per acre of dry matter for a single late season harvest. However, entries varied for yield and they did not all respond the same to the harvest system. Some performed better under a single cut harvest systems and others did better when cut twice in a season. Crude protein and fiber, important components of forage quality, also varied among cultivars. The average energy value was about 7,000 Btu’s per pound and modest differences were observed among cultivars evaluated. Variations were also observed for ash and sulfur content. Results from this research demonstrate that there are sorghum cultivars that have high yield potential and can provide management options for producers that will minimize their risk while maximizing their forage or bioenergy feedstock production at the same time.

Technical Abstract: As the bioenergy industry expands, producers choosing to shift current forage crop production to dedicated biomass crops will find it advantageous to grow low risk multi-purpose crops that maximize management options. Hybrid forage sorghums (HFS) and sorghum by sudangrass hybrids (SSG) are capable of impressive biomass yields and tolerance to environmental stress. Multiple vegetative harvests (ratoon harvests) of sorghum are possible and there are photo period sensitive (PPS) sorghums that remain vegetative. However, the response of newer HFS and SSG cultivars to harvest management practices designed for forage or cellulosic feedstock production has not been fully investigated. The objectives of this study were to 1) evaluate biomass production and quality characteristics of 21 annual HFS, SSG, and sudangrass cultivars using two harvest systems, and 2) provide useful data for sorghum cultivar selection intended for dual-use as a forage and biofuel crop. Mean yield across all entries and years for a single late season harvest was 27.0 Mg ha-1 of dry matter per year. Mean total yield for a first harvest plus a ratoon crop was 25.5 Mg ha-1 of dry matter per year. The best performing entry yielded almost 40.3 Mg ha-1 of dry matter for a single late season harvest. However, entries varied for yield and interacted with harvest system. Crude protein and fiber varied among entries across all years and treatments. Mean caloric value was 16.5 Gj Mg-1 and modest differences were observed among cultivars evaluated. Variations were also observed for ash and S content. Our results indicate that existing sorghum cultivars have high yield potential and can provide management options that will minimize producer risk and maximize forage or feedstock production.

Last Modified: 8/1/2014
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