Harvest frequency effects on white clover forage biomass, quality, and theoretical ethanol yield

Authors: Springer, Timothy; Aiken, Glen

Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2015
Publication Date: 4/24/2015
Citation: Springer, T.L., Aiken, G.E. 2015. Harvest frequency effects on white clover forage biomass, quality, and theoretical ethanol yield. Biomass and Bioenergy. 78:1-5.

Interpretive Summary: White clover, an introduced, cool-season, perennial legume, is used throughout the southeastern United States. However, there is a need to understand the production of white clover under different management regimes. The objectives of this study were to determine the effect of harvest frequencies on white clover forage dry matter (DM) production, theoretical ethanol yield, crude protein (CP) concentration, and in vitro digestible organic matter (IVDOM). The results of a 4-year study indicate that harvesting four times annually (beginning on 15 May and on 15 day intervals thereafter) were consistently better than other treatments with regards to forage DM yield, theoretical ethanol yield, CP concentration, and IVDOM. Early and continuous utilization of white clover is necessary to ensure high forage production for haying, grazing, or ethanol; however, a two-harvest system should reduce harvest costs over that of a four-harvest system and would allow for two haying or grazing rotations (each with 28-30 day rest) before a decline of white clover DM production in mid-summer. Using a two-harvest system rather than a four-harvest system would reduce harvesting costs for stored forages (hay for livestock or biomass for ethanol). Regardless of the number of harvests, early utilization (15 May through 1 July) of white clover is necessary to ensure high forage production for grazing, haying, or ethanol production.

Technical Abstract: White clover (Trifolium repens L.), an introduced, cool-season, perennial legume, is used throughout the southeastern United States, however there is a need to understand the production of white clover under different management regimes and soil and climatic conditions. The objectives of this study were to determine the effect of harvest frequencies on white clover forage dry matter (DM) production, theoretical ethanol yield, crude protein (CP) concentration, and in vitro digestible organic matter (IVDOM). Frequency of forage removal, year, and treatment x year interactions had significant effects on forage quantity and quality. This 4-yr study indicated that forage DM yield, theoretical ethanol yield, CP concentration, and IVDOM with four harvests (15 May, 1 and 15 June, and 1 July) was consistently better than one, two, or three harvests. The highest seasonal DM forage production was produced from four harvests (2378 kg ha-1, a theoretical ethanol yield of 571 L ha-1). Four harvests yielded an average of 544 kg ha-1 CP and 1784 kg ha-1 digestible DM. Forage removed with two harvests (15 May and 15 June) yielded on average 493 kg ha-1 CP and 1642 kg ha-1 digestible DM. A two harvest system should reduce harvest costs over that of a four harvest system and would allow for two haying or grazing rotations (each with 28-30 day rest) before a decline of white clover DM production in mid-summer. As with the other systems, early utilization of white clover is necessary to ensure high forage production and quality.