|Olk, Daniel - Dan|
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2011
Publication Date: 5/1/2012
Citation: Anders, M.M., Brye, K.R., Olk, D.C., Schmid, B.T. 2012. Rice rotation and tillage effects on soil aggregation and aggregate carbon and nitrogen dynamics. Soil Science Society of America Journal. 76(3):994-1004. Interpretive Summary: The Delta area of eastern Arkansas is a leading region of rice production in the U.S. The physical properties of Delta soils have degraded long-term under the normal practices of intensive soil tillage and rotation of the rice crop with a soybean crop on a yearly basis. We found that the physical properties of soil were improved by either avoiding tillage or replacing the soybean crop with rice, corn, or wheat. The improvement in physical properties included greater storage of soil carbon and nitrogen. This work identifies field management options for maintaining the health of Delta soils. It will benefit rice producers in the Delta area and scientists who are seeking approaches to improve soil health and store carbon in soil.
Technical Abstract: Rice (Oryza sativa L.) production in Arkansas and much of the Mississippi River Delta is characterized as tillage-intensive. Traditional-tillage (TT) has been shown to reduce soil quality, however, as a potential carbon (C) market emerges, no-tillage (NT) rice production practices are being considered and need to be investigated. The objectives of this study were to assess the impacts of TT and NT rice production practices and soil depth on soil aggregation and the C and nitrogen (N) concentrations contents of water-stable aggregates (WSA) over a 5-yr period in several common crop rotations containing rice. Total WSA were greater in the 0- to 5-cm than in the 5- to 10-cm soil layer pooled across all rotations. There were no differences among rotations in total WSA concentration in the 5- to 10-cm soil layer under NT and in both layers of the TT treatment. As WSA-size class decreased, the WSA concentration increased. The 1- to 2-mm WSA-size class had the greatest C and N concentrations and contents. Rotations containing soybean [Glycine max (L.) Merr.] had fewer WSA aggregates, but greater C and N concentrations than rotations without soybean. Water-stable-aggregate C and N contents were greatest in rotations that contained rice in alternate years or where rice was rotated with corn (Zea mays L.). The inclusion of wheat (Triticum aestivum L.) as a winter crop in rotation with rice resulted in the greatest WSA-C and -N contents. Including soybean in rotation with rice significantly reduced WSA-C and -N contents. No-tillage rice rotations appear to be a viable means of improving soil quality and enhancing soil C sequestration through increased soil aggregation.