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Title: SHORT-TERM TILLAGE EFFECTS ON BIOLOGICALLY ACTIVE SOIL ORGANIC MATTER

Author
item Cambardella, Cynthia
item DELATE, K - IOWA STATE UNIVERSITY

Submitted to: ASA-CSSA-SSSA Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/14/2002
Publication Date: 11/14/2002
Citation: CAMBARDELLA, C.A., DELATE, K. SHORT-TERM TILLAGE EFFECTS ON BIOLOGICALLY ACTIVE SOIL ORGANIC MATTER. ASA-CSSA-SSSA PROCEEDINGS. 2002. CD-ROM. MADISON, WI.

Interpretive Summary:

Technical Abstract: Soil organic C (SOC) loss after conversion of perennial pasture to annual crop rotations can be impacted by the type of tillage used to break the land out of sod. Short-term changes in soil organic matter (SOM) are difficult to detect but research has shown that biologically-active forms of SOM can function as short-term indicators of longer-term changes in SOM. Our objective was to quantify changes in particulate organic matter (POM) C three weeks after tillage of a bromegrass/alfalfa pasture prior to establishment of a corn-soybean-oats/red clover cropping system. We evaluated three commonly used tillage systems (moldboard plow (MP), Kverneland plow (KP), Howard Rotovator (R)). POM C increased after plowing in all three treatments, but the MP treatment resulted in the greatest increase in POM C. Three weeks after plowing, new C inputs into POM represented 23.4, 8.4 and 11.5 percent of total SOC in the MP, KP and R treatments, respectively. Average post-plow POM C/N was 23 indicating POM C was relatively labile. We conclude that one tillage pass can potentially result in the loss of nearly 25 percent of SOC present in a bromegrass/alfalfa pasture in a relatively short period of time.