Submitted to: American Society of Agri Engineers Special Meetings and Conferences Papers
Publication Type: Other
Publication Acceptance Date: 5/21/2004
Publication Date: 6/30/2004
Citation: Woodbury, B.L., Nienaber, J.A., Eigenberg, R.A. 2004. Using time domain reflectometry for evaluating near-surface soil-crop dynamics of an animal waste amended soil. American Society of Agri Engineers Special Meetings and Conferences Papers. Paper #042128. Interpretive Summary: Understanding interactions between soil and crops is important to improve production, while protecting the environment. A method was developed to monitor soil-crop interactions; however, it was difficult to verify. A second method was used to verify the interpretation of the first method. It was found that the response of the first method was accurate in monitoring these interactions. The first method was most appropriately used for monitoring fields where animal waste was applied as a fertilizer.
Technical Abstract: Electromagnetic induction (EMI) mapping techniques have been demonstrated to be useful in monitoring seasonal soil-crop dynamics. These dynamics can be affected by many confounding seasonal changes in the soil profile. Time domain reflectometry (TDR) has been used to measure localized bulk soil electrical conductivity of soil horizons. The objective of this study was to use time domain reflectometry for clarifying near-surface soil-crop dynamics of an animal waste amended soil. Seasonal soil-crop EC dynamics measured by EMI and TDR were significantly (p <0.05) correlated for all treatments except commercial fertilizer without a cover crop (NCK-No-Cover) treatment. NCK-No-Cover response difference is believed to be due to placement of commercial fertilizer directly above the TDR probe. The impact of fertilizer was greater on the TDR system than EMI, primarily due to surface area and volume measurement differences used by the two methods. Significant correlations of the two systems indicate the majority of EC dynamics measured by EMI were dominated by activity in the upper 0.15 cm of soil surface. As a result, the TDR study validates EMI as a tool for evaluating soil-crop dynamics of animal wasted amended soils.