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Effect of Soil Water Content Variation on the Least Limiting Water Range
Author(s) -
Silva Alvaro Pires,
Kay B. D.
Publication year - 1997
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1997.03615995006100030024x
Subject(s) - tillage , transect , limiting , environmental science , agronomy , soil science , hydrology (agriculture) , mathematics , forestry , ecology , geography , geology , biology , mechanical engineering , geotechnical engineering , engineering
The least limiting water range (LLWR), a proposed structural quality index, is the range in soil water content within which plant growth is least limited by water potential, aeration, and mechanical resistance. This study tested the hypotheses that the frequency of the soil water content falling outside the LLWR ( p out ) increases with decreasing LLWR and that the relation is influenced by tillage, position (row vs. interrow), and climatic conditions. Thirty‐two paired sampling sites were located along two parallel transects in a side by side comparison of no‐till and conventional tillage. The transects crossed three soil types: Aquic Hapludalf, Psammentic Hapludalf, and Typic Hapludalf. The LLWR was calculated for the 0‐ to 20‐cm depth at row and interrow positions. The site was planted to corn ( Zea mays L.) and the study lasted three growing seasons. Logistic regression analysis, p out = exp( b 0 + b 1 LLWR)/[1 + exp( b 0 + b 1 LLWR)], showed that p out was negatively related to LLWR ( R 2 = 0.72, P > 0.01), regardless of weather, tillage, or position. Values of p out under no‐till were lower than under conventional tillage and the interrow position had a lower p out than the row position. The parameter b 1 did not vary across weather, tillage, or position but b 0 was influenced by these parameters. The analyses supported the hypothesis and emphasized the impact on p out of factors unrelated to structure.