Wednesday, November 7, 2007
328-3

Tillage Impacts on C, N, and P Distribution in Soil Organic Matter.

Randall Reeder1, Alan Sundermeier2, Y. Raut3, Warren Dick4, and Khandakar Islam4. (1) Food, Agricultural and Biological Engineering, The Ohio State University, 590 Woody Hayes Drive, Columbus, OH 43210, (2) Ohio State University Extension, 639 S Dunbridge Road Ste 1, Bowling Green, OH 43402, (3) The Ohio State University South Centers, 1864 Shyville Road, Piketon, OH 45661, (4) 1680 Madison Ave., Ohio State University - OARDC, Ohio State University, School of Natural Resources, Wooster, OH 44691-4096

Carbon sequestration through conservation tillage may affect distribution of C, N and P fractions in soil organic matter (SOM). To evaluate the impact of no-till (NT) continuous corn on C, N and P partition in SOM, composite soil (fine, illitic, active, mesic, mollic Epiaqualfs) samples at 0-7.5, 7.5-15, 15-22.5 and 22.5-30 cm depth were randomly collected from 2 (NT2), 20 (NT20), and 40 (NT40) year NT and their adjoining conventionally tilled (CT) fields in Wood County, northwest Ohio. Soil samples were air-dried, processed and analyzed for pH, electrical conductivity (Ec), and total C and N contents. With 01M NaOH, the soil samples were extracted and fractionated for humic (HA) and fulvic (FA) acid associated C, N, and P fractions. Results showed that total, extractable, HA and FA acid associated C and N concentration at surface depth (0 to 7.5 cm) of NT soil have increased over time compared to CT soil. However, the C and N distribution in both HA and FA fractions did not change significantly. Both HA and FA acid associated P concentration had changed significantly in response to tillage. The effect was more pronounced in NT40 soil with an increase in P concentration in both HA and FA acid fractions. However, the HA acid fraction contained more P than FA acid fraction. Averaged across tillage systems, all the C, N and P fractions were significantly higher at surface than at surface depth of soil.