Location: Agroecosystems Management ResearchTitle: Phytoremediation of high phosphorus soil by annual ryegrass and common bermudagrass harvest
|GASTON, LEWIS - Louisiana State University|
Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2014
Publication Date: 1/28/2015
Citation: Gaston, L.A., Kovar, J.L. 2015. Phytoremediation of high phosphorus soil by annual ryegrass and common bermudagrass harvest. Communications in Soil Science and Plant Analysis. 46:736-752.
Interpretive Summary: Poultry production is the largest agricultural animal industry in Louisiana, so it is vital to the state’s economy. Research has shown that application of poultry litter for many years has led to a build-up of soil phosphorus (P) in some areas of north Louisiana. This P can negatively impact water quality in nearby lakes and streams. With a field study, we evaluated the potential for hay harvest to remove significant amounts of P from a Louisiana Coastal Plain soil common to the area. We measured annual ryegrass and common bermudagrass yield and P uptake as affected by the amount of plant-available P initially in the soil and the amount of poultry litter applied to the soil. During the four-year course of the study, ryegrass and bermudagrass harvests removed about 3 ppm of available P from the soil per harvest. Based on this value, a P removal rate of approximately 60 pounds of available P per acre could be attained annually. Though seemingly a slow process, the source of water enrichment with P can be depleted. Given the current emphasis on non-point source losses of P, this information will assist producers in managing and utilizing the nutrients in poultry litter.
Technical Abstract: Removal of soil phosphorus (P) in crop harvest is a remediation option for soils high in P. This four-year field-plot study determined P uptake by annual ryegrass (ARG, Lolium multiflorum Lam.) and common bermudagrass (CB, Cynodon dactylon (L.) Pers.) from Ruston soil (fine-loamy, siliceous, thermic Typic Paleudult) enriched in P by five previous annual applications of poultry litter, and related P removed to Bray 2 P in surface (0 – 15 cm) soil. Decreases in surface soil Bray 2 P were largely attributable to uptake. Phosphorus uptake was positively related to Bray 2 P, however, approached a limit. Mass of P removed in harvest closely approximated the decrease in mass of surface soil Bray 2 P. Maximum Bray 2 P drawdown per harvest (ARG and CB, average) was ~ 3 mg kg-1 at Bray 2 P ~ 300 mg kg-1, generally consistent with measured decreases in Bray 2 P.