Title: Amendment and Tillage Impacts on Water Extractable Carbon and Nitrogen in Soil Authors
Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2010
Publication Date: August 15, 2010
Citation: Zhang, M., He, Z., Zhao, A., Endale, D.M., Schomberg, H.H. 2010. Amendment and Tillage Impacts on Water Extractable Carbon and Nitrogen in Soil. Soil Science Society of America Annual Meeting. Available: http://a-c-s.confex.com/crops/2010am/webprogram/paper58005.html. Technical Abstract: Water extractable organic matter (WEOM) contains labile organic carbon (C) and nitrogen (N) and is sensitive to soil management. The objective of this study was to determine how nutrient amendment and tillage management impact the quantity and spectral properties of WEOM. Soil samples were taken from various treatments (conventional tillage, no tillage, poultry litter, and NH4NO3 application) in a 10–year tillage experiment in Watkinsville Georgia at different times and soil depths. Total C and N, absorptivity at 254 nm, fluorescence excitation and emission matrix (EEM) spectra of WEOM fractions of these soil samples were determined. Results showed that water extractable C and N increased over time. Poultry litter application accumulated high amounts of water extractable organic C and N as compared to NH4NO3 application, but tillage did not affect C or N content. Absorptivity at 254 nm decreased over time for conventional tillage and NH4NO3 application indicating accumulation of easily degradable compounds in WEOM, but the fluorescence measured humification index showed an opposite trend. For no-tillage and poultry litter application treatments, there was no difference in absorptivity over the sampling time. Parallel factor analysis (PARAFAC) of EEM data showed that the WEOM consisted of three fluorophore components: humic-, fulvic-, and tyrosine-like “compounds”, and relative distribution of these three components differed among treatments and changed over cropping times and depths. In all quantity and spectral properties of WEOM responded to types of nutrient application and tillage practices.