Influence of Alley Crop Environment on Orchardgrass and Tall Fescue Herbage

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 persistence, herbage yield, nutritive value, and gas exchange (CO2 exchange rate, transpiration, and stomatal conductance) of two shade‐tolerant herbage grasses. The experiment was conducted for 3 yr in orchardgrass (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.), and a 1:1 binary mixture (tall fescue and orchardgrass) in 4.9‐m‐wide alleys of 10‐yr‐old loblolly pine (Pinus taeda L.) and shortleaf pine (P. echinata Mill.), and the unshaded control at Booneville, AR. Loblolly pine was 1.5 m taller and had twice the canopy cover as shortleaf pine (52 and 25% canopy cover, respectively). Averaged across harvests, orchardgrass persisted better in loblolly pine alleys (72% stand) than in the control (44% stand) while tall fescue persisted better in the control (30% stand) than in loblolly pine (13% stand). Persistence in shortleaf pine alleys was intermediate for both herbage treatments. Yields of orchardgrass and the binary mixture did not differ in pine alleys (1300 kg ha−1) and were usually greater than tall fescue yields (≤700 kg ha−1). Crude protein was higher in loblolly pine alleys (172 g kg−1) than in the control (141 g kg−1). Gas exchange parameters were similar for tall fescue and orchardgrass across a range of volumetric soil moisture (15–30%), indicating little difference in drought response. Producers should consider using orchardgrass monocultures or binary mixtures with tall fescue for pine alleys in the midsouth USA.