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Title: EASTERN GAMAGRASS ROOT PENETRATION IN ADVERSE SUBSOIL CONDITIONS

Author
item GILKER, RACHEL - UNIV OF MARYLAND
item WEIL, RAY - UNIV OF MARYLAND
item Krizek, Donald

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2001
Publication Date: 5/1/2002
Citation: GILKER, R.E., WEIL, R.R., KRIZEK, D.T. EASTERN GAMAGRASS ROOT PENETRATION IN ADVERSE SUBSOIL CONDITIONS. SOIL SCIENCE SOCIETY OF AMERICA JOURNAL. 2002. VOL. 66(3). P. 931-938.

Interpretive Summary: A greenhouse study was conducted to determine the comparative tolerance of eastern gamagrass (a warm season perennial grass known for its high forage quality) and sordan (a hybrid between sorghum and sudan grass) to acid soil and their ability to penetrate a claypan soil. Plants were grown in specially designed plastic columns containing an acid, Al toxic soil. The study showed that eastern gamagrass roots were able to penetrate soils that were strongly acid and compact and hard. These conditions keep plant roots of many crop plants from growing deep into the soil, preventing them from reaching water in times of drought. Another observation was that the presence of air spaces (known as aerenchyma) in eastern gamagrass roots, a trait associated with tolerance to water-logged conditions, may not always allow them to thrive if oxygen is in very short supply. It seems that eastern gamagrass roots are very strong, and able to grow best when the soil is hard, instead of growing when the soil is full of water and "soft". These findings mean that eastern gamagrass might be a good plant to use in fields with layers of compacted soil, because their roots can punch holes through the soil. Then, subsequent crops planted can use those holes to grow through the compacted soil layers. This is important since there are many fields in the mid-Atlantic area with acid, compact soils. These findings should be of interest to farmers interested in sustainable agriculture who are looking for plants adapted to marginal soils.

Technical Abstract: Eastern gamagrass [Tripsacum dactyloides (L.) L] 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, using sordan [Sorghum x drummondii (Steud.) Millsp. & Chase] as a comparison species. Treatment factors were: soil water (-10 and -300 kPa), soil pH (3.5 and 4.8), and soil bulk density (1.3 and 1.7 g/cm3). The treatments were applied to aluminum toxic Tatum Bt horizon material used in the middle 30 cm section of 15 x 60 cm polyvinylchloride columns. Soil strength was determined at harvest by cone penetrometer resistance. Eastern gamagrass tolerated acid, aluminum toxic conditions. Eastern gamagrass roots appeared to be inhibited by low air-filled porosity in dense soils (1.15 + 0.5 MPa), but were able to penetrate high soil strength layers that inhibited sordan root growth. These characteristics make eastern gamagrass valuable in establishing grassed buffers, vegetative conservation barriers and pastures in extremely acid or dense soils.