Assessment of the role of soil structure and water content in the interpretation of spatial variation in yield and yield response to nitrogen

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To, Justin

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University of Guelph

Abstract

The Least Limiting Water Range (LLWR), is defined as the range of water contents in which aeration, water and soil resistance are the least limiting for plant growth. It was hypothesized that the LLWR and water contents measured outside of the LLWR would explain much of the variation found in yield and yield response to fertilizer N. Water contents, soil properties and yields were measured on 12 sites across southern Ontario. Results showed that the LLWR parameters were poor predictors of the variability in yields. Many observed water contents were also found to be less than the wilting point. Kay et al. (1999) defined a lower water content limit based on the cessation of photosynthesis ([theta]0p). This study determined that the difference between water contents and [theta]0p (plant extractable water) correlated well with yield. Organic carbon was significantly correlated to yield and yield response, and improved yields under drought and saturated conditions.

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Least Limiting Water Range, water contents, variation found, yield, yield response, fertilizer, nitrogen

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