Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2007
Publication Date: 1/14/2008
Citation: Whittington, S.F., Wood, C.W., Wood, B.H., Raper, R.L., Reeves, D.W., Brink, G.E. 2008. Tillage and forage system effects on forage yields and nutrient uptake under broiler litter amended soils. Communications in Soil Science and Plant Analysis. 38:2535-2556.
Interpretive Summary: Though a beneficial fertilizer, long-term litter application of poultry litter to pastureland can lead to accumulation of phosphorus and metals such as copper and zinc at the soil surface. This accumulation is vulnerable to losses to the environment in runoff and erosion. Phosphorus transported in surface runoff and erosion is the leading cause of fresh water algal blooms and resultant impairment of surface waters used in fisheries, industry, recreation, and sources of drinking water. Researchers with Auburn University and USDA-ARS scientists at Auburn, AL, Watkinsville, GA, and Madison, WI, conducted a field study in north Alabama to determine tillage and forage systems best suited for removing nutrients from such nutrient-overloaded pasture soils. Tillage methods evaluated included none (no-tillage), moldboard plowing, chisel plowing, and each combined with a form of deep tillage called paraplowing. Forage grasses included bermudagrass, tall fescue, and an annual rotation of ryegrass in winter and sorghum-sudangrass in summer. The annual rotation produced highest forage yields and phosphorus removal from soil. Moldboard plowing the annual rotation further increased yields and phosphorus removal. Moldboard plowing, as well as paraplowing, redistributed phosphorus from the vulnerable soil surface throughout the 12-inch depth of soil. Removal of copper and zinc followed similar patterns as phosphorus. Moldboard plowing subjects soil to erosion, but used judiciously in combination with intensive annual forage rotations, the practice may reduce the concentration of phosphorus and other nutrients at the surface of soils overloaded with these nutrients. This could reduce the potential for these nutrients to be lost to and impair surface waters. This information can be used by State Cooperative Extension Systems, USDA-NRCS, and other state and federal agencies responsible for managing lands where long-term poultry litter applications have been made in order to reduce the potential for losses of phosphorus and nutrient metals to surface waters.
Technical Abstract: Planting and harvesting high yielding forage grasses may remove phosphorus (P), copper (Cu) and zinc (Zn) from surface soils with a long history of broiler litter application. A study was conducted in Alabama’s Sand Mountain region from 1998 to 2000 to determine tillage and forage systems best suited for removing nutrients from such overloaded soils. Tillage treatments included no-tillage, moldboard plowing, chisel plowing, and each combined with paraplowing. Forage treatments included bermudagrass (Cynodon dactylon (L.) Pers.) cv. Russell, tall fescue (Festuca arundinacea Schreb.) cv. Kentucky-31, and an annual rotation of ryegrass (Lolium multiflorum Lam.) and sorghum sudangrass (Sorghum bicolor L. Moench x Sorghum vulgare sudanense). The annual rotation produced highest yields and P uptake. Moldboard plowing the annual rotation further increased yields. It appears the annual rotation best removes P, Cu, and Zn via plant uptake. Tillage reduced P concentrations in the soil surface in the following order: moldboard > chisel > no-till.