Soil and plant nitrogen cycling under tillage practices in rice-based rotations in Arkansas. (S08-anders578055-oral)
Authors:
M.M. Anders* - Univ. of Arkansas D. Olk - USDA-NSTL, Ames, IA J. Grantham - Univ. of Arkansas J. Holzhauer - Univ. of Arkansas
Abstract:
Prior to 1996 rice production in Arkansas and across the United States was regulated through
government programs that provided price supports that were tied to crop acres. This scenario evolved into a rotation sequence to rice-soybeans-soybeans over much of the Arkansas rice production area.
With passage of the 1996 farm bill farmers were free to grow as much rice as they wanted. At the same time world rice prices have fallen and there is mounting concern that the heavy tillage used in rice production is contributing to declining water quality in the region. In 1999 a study comparing six rice-based crop rotations was initiated. With each rotation conventional-and no-till comparisons were made along with fertility and variety comparisons. Rice grain yields were significantly affected by rotation, tillage, and variety in 2000. In the same year there were five interactions. By 2002, only the main effects of rotation, variety, and tillage significantly affected grain yield. Rice grain yields in the continuous rice rotation have declined from 8014 kg ha-1in 2000 to 6653 kg ha-1in 2002. At the same time rice grain yields in the rice-soybean rotation have fluctuated between 9980 and 8266 kg ha-1but with no temporal trend. In all years no-till rice yields were lower than conventional-till. Nutrient cycling and 15N data collected in this study indicate a close relationship between N uptake and grain yield.
Speaker Information: Merle Anders, Univ. of Arkansas, P.O. Box 1168, Stuttgart, AR 72160; Phone:
870-6732661; E-mail: [email protected]
Session Information: Thursday, November 6, 2003, 8:10 AM-10:30 AM Presentation Start: 9:30 AM
Keywords: Nitrogen; Organic Matter; Tillage; Rotation