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Title: TILLAGE INTENSITY AND CROP RESIDUE EFFECTS ON NITROGEN AND CARBON CYCLING IN A VERTISOL

Author
item Torbert, Henry - Allen
item Potter, Kenneth
item Morrison Jr, John

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Because of the high erosion potential, efforts have been undertaken to develop conservation tillage systems for the high clay soils found in Texas including the production of several different crops. This study focused on examining the effects of tillage intensity and different crops on soil organic matter and nitrogen content. The results indicated that changes in tillage systems may control soil organic C at the soil surface, but changes in the roots of different crops may control soil organic C storage at deeper soil depths in Texas vertisols.

Technical Abstract: The objective of this study was to examine the impact of tillage intensity and crop residue on C and N cycling in a vertisol. Soil samples (0-10 and 10-20 cm depth increments) were collected from a Houston Black soil (fine, montmorillonitic, thermic Udic Pellusterts) with three different levels of tillage intensity, varying from no tillage to complete residue burial. The experiment was a split plot design with 5 replications. The main plots were 3 crop species (corn [Zea mays L.], grain sorghum [Sorghum bicolor (L.) Moench], and soybean [Glycine max (L.) Merr.]) and the subplots were 3 levels of tillage intensity (chisel tillage, reduced tillage, and no tillage). Total N, organic C, inorganic N, and C:N ratio were measured on soil samples as well as the potential C mineralization, N mineralization, C turnover, and C:N mineralization ratio during a 7 and 30 d incubation. Chisel tillage reduced total N, C mineralization and C turnover at the 0-10 cm depth compared to the other conservation tillage systems. Following corn production, soil organic C increased and C mineralization and C turnover were decreased at the 10-20 cm depth compared to the other crop species. This data indicates that, in the short term, tillage systems may control soil organic C at the soil surface, while changes in plant rooting may control soil organic C storage at deeper soil depths in Texas vertisols.