Submitted to: North Carolina Agricultural Research Service Technical Bulletin
Publication Type: Proceedings
Publication Acceptance Date: June 9, 2004
Publication Date: June 9, 2004
Citation: Anders, M.M., Olk, D.C., Harper, T., Daniel, T., Holzhauer, J. 2004. The effect of rotation, tillage, and fertility on rice grain yields and nutrient flows [CD-ROM]. TB-321. Raleigh, NC. North Carolina Agricultural Research Service Technical Bulletin.
Interpretive Summary: Continuous production of rice and soybean in alternating years in eastern Arkansas has led to degradation of soil properties. This degradation might be reversed through regular addition of carbon to the soil, either through cessation of soil tillage or through continuous production of rice. Yet either option introduces new challenges in fertilizer management. In a four-year field experiment that compared rice grown every year with rice grown in alternating years with soybean and with either normal tillage or no tillage, we found that nutrient availabilities to the rice crop and nutrient losses from the field differed between the two rotations. These results indicate the need to adjust fertilizer management, including rates, under these new management strategies. Proper adjustments to fertilizer management will enable rice farmers to avoid yield loss when converting to continuous rice rotations or no tillage.
Rice (Oryza sativa L.) is one of the most intensively cultivated row crops in America. In order to move away from current tillage practices, it will be necessary to maintain current yield levels. A key to successful no-till rice production will be to maintain plant fertilizer efficiency and not increase nutrient runoff in a system that is flooded much of the growing season. A study was established in 2000 in eastern Arkansas that compared fertility, variety, and conventional- and no-till rice rotations. Rice grain yields, across all treatments, were between 140 and 195 bu a-1. Yields were most affected by rotation and tillage. Continuous rice grain yields averaged 34 bu a-1 lower than a rice-soybean (Glycine max (L.) Merr.) rotation. Plant phosphorus (P) and potassium (K) uptake varied significantly between rotation treatments but not between tillage, fertility, or variety treatments. Phosphorus concentrations in runoff water were significantly higher in the no-till plots. Total P in runoff was lower in the no-till plots because of reduced P being carried in solids. Total nitrogen (N) uptake was lower in the continuous rice rotation compared to the rice-soybean rotation with soil N uptake higher for the no-till compared to conventional-till in both rotations. Nutrient cycling differs under no tillage or under continuous rice rotation than under conventional tillage of the rice-soybean rotation, and these differences must be considered when managing fertilizer inputs.