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Title: RAPID CHANGES IN SOIL CARBON AND STRUCTURAL PROPERTIES DUE TO STOVER REMOVAL FROM NO-TILL CORN PLOTS

Author
item BLANCO-CANQUI, HUMBERTO - OHIO STATE UNIV.
item LAL, R - OHIO STATE UNIV.
item POST, W - OAK RIDGE NAT'L LAB
item IZAURRALDE, R - JT GLOBAL CHANGE RES INS
item Owens, Lloyd

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2006
Publication Date: 6/5/2006
Citation: Blanco-Canqui, H., Lal, R., Post, W.M., Izaurralde, R.C., Owens, L.B. 2006. Rapid changes in soil carbon and structural properties due to stover removal from no-till corn plots. Soil Science. 171(6):468-482.

Interpretive Summary: Biofuel production, including that which is produced from plant residue, is seen as a possibility to reduce the use of petroleum based fuels. The question then arises whether the plant residue removal has an impact on soil carbon levels and soil properties. To evaluate some of these impacts, corn stover was removed at variable rates from three soils in Ohio. With 0, 25, 50, 75, 100, and 200% of normal corn residue, levels of soil organic carbon and soil properties, such as bulk density and aggregate stability, were measured. Changes were rapid because significant differences were measured after only one year. Changes occurred more rapidly in silt loam soils than clay soils. With only 25% removal of corn residue, soil organic carbon was reduced and soil was degraded by having increased bulk density and reduced stability of soil macroaggregates. This research indicates that the amount of plant residue that can be removed without detrimental impacts on soil properties may be limited. This information is important not only to scientists but also to farmers and biofuel industry decision makers.

Technical Abstract: Harvesting corn (Zea mays L.) stover for producing ethanol may be beneficial to palliate the dependence on fossil fuels and reduce the net CO2 emissions, but stover harvesting may deplete soil organic carbon (SOC) pool and degrade soil structure. The impacts of variable rates of removal of stover from long-term no-till continuous corn systems on SOC and soil structural properties were investigated after one year of stover removal in three soils in Ohio: Rayne silt loam (fine-loamy, mixed, mesic Typic Hapludult) at Coshocton, Hoytville clay loam (fine, illitic, mesic Mollic Epiaqualfs) at Hoytville, and Celina silt loam (fine, mixed, active, mesic Aquic Hapludalfs) at South Charleston. Soils under six treatments with 0 (T0), 25 (T25), 50 (T50), 75 (T75), 100 (T100), and 200 (T200) % of corn stover corresponding to 0, 1.25, 2.50, 3.75, 5.00, and 10.00 Mg ha-1 of stover, respectively, were studied for their total SOC concentration, bulk density, aggregate stability, and tensile strength (TS) of aggregates. Effects of stover removal on soil properties were rapid and significant in the 0- to 5-cm depth although the magnitude of changes differed among soils. The SOC pool declined with increase in removal rates in silt loams but not in clay soils. It decreased by 39% at Coshocton and 30% at Charleston within one year of complete stover removal. Macroaggregates contained 10 to 35% more SOC concentration than microaggregates, and stover removal reduced macroaggregates and increased microaggregates (P<0.01). Mean weight diameter (MWD) and TS of aggregates in T0 were 1.7 and 3.3 times lower than those in T100 across sites. The SOC was negatively correlated with bulk density and positively with MWD and LogTS. Stover removal at rates as low as 1.25 Mg ha-1 reduced SOC pool and degraded soil structure within one year of stover removal, but further monitoring is needed to establish threshold levels of stover removal in relation to soil quality.