Eastern gamagrass root penetration in adverse subsoil conditions

Eastern gamagrass [Tripsacum dactyloides (L.) L] (EG) is reported to exhibit acid tolerance and root penetration through claypans. To study its root growth in these conditions, a greenhouse column study was conducted under simulated soil stress conditions, using EG and sordan [Sorghum X drummondii (Stead.) Millsp. & Chase] as a comparison species. Treatments consisted of incomplete factorial combinations of plant species (EG and sordan), soil water potential (-10 and -300 kPa), lime (pH 3.5 and 4.8), and soil bulk density (D-b) (1.3 and 1.7 g cm(-3)). The treatments were arranged as a randomized complete block design (RCBD). For some of the response variables that were analyzed at different depths, depth was considered as a subplot factor. Treatments were applied to AI-toxic Tatum Bt horizon material (clayey, fine, mixed, semiactive, thermic Typic Hapludults) used in the middle 30-cm section of 15 by 60-cm polyvinyl Cl (PVC) columns. Soil strength was determined at harvest by cone penetrometer resistance. Results indicated that EG tolerated acid, Al-toxic conditions, while sordan roots were sensitive to the low pH conditions. Eastern gamagrass roots penetrated high soil strength layers that inhibited sordan root growth. The characteristics of acid, Al tolerance, and penetration of high soil strength make EG valuable in establishing grassed buffers, vegetative conservation barriers, and pastures in extremely acid or dense soils.