Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 7, 2003
Publication Date: October 1, 2003
Citation: BURNER, D.M. 2003. INFLUENCE OF ALLEY CROP ENVIRONMENT ON ORCHARDGRASS AND TALL FESCUE HERBAGE. AGRONOMY JOURNAL. 95:1163-1171. Interpretive Summary: The adoption of agroforestry practices in the USA is limited in part by inadequate knowledge of crop performance in shaded tree alleys, making it difficult to choose "the best" agroforestry design for maximum production and sustainability among a wide array of potential crop-tree-livestock options. The objective of this study was to compare the yield, persistence, feed quality, and plant physiology of shade tolerant grasses (orchardgrass and tall fescue) grown in three alley crop environments (loblolly pine, shortleaf pine, and unshaded control) for three years. Orchardgrass, or a mixture or orchardgrass and tall fescue had better growth, persistence, and feed quality than tall fescue in the denser shade of loblolly pine. However, there were no large differences in basic plant physiology that definitively explained why shade-grown orchardgrass was more competitive than tall fescue. The results are useful to agroforestry producers, landowners, and researchers as they demonstrate the outstanding productivity of shade-grown orchardgrass in such close proximity to its southwestern range limit.
Technical Abstract: The design of agroforestry systems requires a thorough understanding of biological interactions that might complement or constrain production. The objective of this study was to examine effects of alley crop environment on herbage yield, nutritive value (crude protein and in vitro dry matter digestibility), botanical composition, and gas exchange of two shade tolerant forage grasses. The experiment was conducted for 3 yr in orchardgrass (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.), and the 1:1 binary forage mixture in alleys of loblolly (Pinus taeda L.) and shortleaf pine (P. echinata Mill.), and the unshaded control at Booneville, AR. Total herbage yield in pine alleys was about 30% less than the control, due in part to shading (45 and 61% of solar reception of control for loblolly and shortleaf pine, respectively). Orchardgrass persisted better in loblolly pine alleys than in the control, and yielded more than tall fescue in pine alleys. The binary mixture yielded more than tall fescue in pine alleys and yielded about the same as orchardgrass in loblolly pine alleys. Nutritive value and NO3-N increased with increasing shade. Physiological responses (CER, transpiration, and stomatal conductance) of the two grasses converged as soil moisture decreased, suggesting little difference in drought tolerance. Orchardgrass monoculture or in mixture with tall fescue, should be considered for pine alleys in the mid-south USA.