Submitted to: ASA-CSSA-SSSA Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 6, 2003
Publication Date: November 6, 2003
Citation: ANDERS, M.M., OLK, D.C., GRANTHAM, J., HOLZHAUER, J. SOIL AND PLANT NITROGEN CYCLING UNDER TILLAGE PRACTICES IN RICE-BASED ROTATIONS IN ARKANSAS. ASA-CSSA-SSSA PROCEEDINGS. 2003. CD-ROM. MADISON, WI. ASA-CSSA-SSSA.
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 resulted in a rotation sequence of 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 much of the Arkansas rice production is contributing to declining water quality in the region. In 1999 a study comparing six rice-based crop rotations was initiated. Within each rotation conventional- and no-till comparisons are 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 8,014 kg ha-1 in 2000 to 6,653 kg ha-1 in 2002. At the same time rice grain yields in the rice-soybean rotation have fluctuated between 9,980 and 8,266 kg ha-1, but 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. Soil data show differences in aggregate distribution.