137-10 Influence of Current and Previous Crop On Soil Basal and Potential Denitrification Rates.



Monday, October 17, 2011
Henry Gonzalez Convention Center, Hall C, Street Level

Xiaobin Guo1, Craig F. Drury1, Xueming Yang1, W. Daniel Reynolds1 and Renduo Zhang2, (1)Greenhouse and Processing Crops Research Centre, Agriculture & Agri-Food CanadaAgriculture and Agri-Food Canada, Harrow, ON, Canada
(2)School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, China
Soil and crop management including crop rotation and fertilization influences soil water content, available C and soil nitrate levels, which may in turn affect denitrification losses from soils. The objective of this paper was to determine how the current and previous crop affect denitrification by comparing the basal denitrification rate (BDR), denitrification rate with added nitrate (DAN) and potential denitrification rate (PDR) (amended with glucose and nitrate) of a clay loam soil under monoculture corn (C), soybean (S), and winter wheat (WW) with or without underseeded red clover (RC), and under each phase of a 2-year crop rotation (C-S), and two 3-year crop rotations (C-S-WW, C-S-WW+RC). The BDRs were greater in the 3-year C-S-WW rotation treatments than in the 2-year C-S rotation and monoculture C, S and WW treatments. The WW+RC phase of the C-S-WW+RC treatment was found to have a greater BDR and DAN than the corn phase of the rotation. Available organic C was found to limit denitrification in the BDR and DAN incubations as evidenced by the 2 to 21 fold increase in denitrification when glucose was added in the PDR assay. Further, the significant relationship between soil respiration and BDR suggests that available C was is a limiting factor. This study found that both the current crop and  previous crops in a rotation affected soil denitrification rates substantially; and that denitrification was increased when a mixture of crop residues were added to soil (i.e. from growing crops in rotation) relative to when only  a single residue was added (i.e. monoculture cropping).
See more from this Division: S06 Soil & Water Management & Conservation
See more from this Session: Agricultural Practices to Increase Nitrogen-Use Efficiency, Carbon Sequestration, and Greenhouse Gas Mitigation : II