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Effect of root systems on preferential flow in swelling soil

Mitchell, A.R. and Ellsworth, T.R. and Meek, B.D. (1995) Effect of root systems on preferential flow in swelling soil. Communications in Soil Science and Plant Analysis. 26(15&16):2655-2666.

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Permeability problems on irrigated soils may be alleviated by root
systems that increase water flow by creating macropores. Infiltration rates have been
shown to increase where plant roots decay and serve as preferential flow paths. For
low-organic-matter swelling soil, there is a question whether macropores are able to
resist the lateral swelling forces of the soil. The objective of this study was to observe
preferential water flow paths in a swelling soil under two cropping systems. A
Holtville silty clay (clayey-over-loamy, montmorillonitic Typic Torrifluvent) was
observed in situ. Two crops, alfalfa (Medicago saliva, L.) and wheat (Triticum
turgidum, L.) provided sharply contrasting root systems, with wheat possessing fine,
fibrous roots; alfalfa on the other hand, has a taproot system. Macropores were
observed after applying soil-adsorbing methylene blue dye to irrigation water.
Shrinkage cracks failed to conduct dye after 10 minutes into a flood irrigation.
Earthworm (Lubricus terrestris) channels were also not stable. However, decaying
roots of alfalfa produced stable macropores, while wheat produced no such
macropores. The influence of alfalfa-root-induced macropores was demonstrated by
the increase in final infiltration rate during alfalfa cropping which agreed with Meek
et al.'s (1989, 1990) findings on sandy loam soils.

Item Type: Article
NWISRL Publication Number: 0880
Subjects: Mass Import - unclassified
Depositing User: Dan Stieneke
Date Deposited: 20 Nov 2010 21:54
Last Modified: 23 Nov 2016 18:30
Item ID: 647