PARENT SESSION
Monday, August 7, 5:00-6:30 pm
Poster Session 3 - Agroecosystem ecology
Exhibit Hall, Ballroom Level, Cook Convention Center
Carbon and nitrogen loss in 3 no-till agricultural systems.
Kochsiek, Amy*,1, Knops, Johannes1, 1 University of Nebraska, Lincoln, Lincoln, NE
ABSTRACT- Agroecosystems are ideal for highly controlled studies on decomposition because they are monocultures, spatially uniform, and have less nutrient and water limitation than natural systems. Because they are highly controlled, it makes it feasible to study how changing one or two environmental factors such as water availability through irrigation or changing the decomposition environment through crop rotation can affect the decomposition processes of plant material. We investigated carbon and nitrogen loss of maize tissue for 3 years in 3 no-till management regimes: irrigated continuous maize, irrigated maize-soybean rotation, and rainfed maize-soybean rotation. We found that after 3 years between 80-90% of the initial fixed carbon was lost regardless of management regime or decomposition environment. Nitrogen loss over time was variable depending upon tissue type and management regime, but overall there were no consistent significant differences in N loss due to water availability or decomposition environment. When investigating the relationship between carbon and nitrogen loss over time, we found that the C/N decreased over time for all tissues in irrigated and rainfed systems. Regression analyses showed that carbon was lost more rapidly than nitrogen in all tissues regardless of water availability or cropping environment. This work shows that in agricultural systems the processes of carbon and nitrogen loss are not necessarily linked and changes in water availability or the decomposition environment, namely crop rotation, does not have a significant effect on decomposition processes.
Key words: agroecosystem, decomposition