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Title: Inflow rates and interrupted flow effects on concentrated flow erosion and intake rate in two soils

Author
item JIAN, YU - INST OF WATER RES., CHINA
item LEI, T. - CHINA AGRIC UNIV, CHINA
item SHAINBERG, A. - AGRIC RES ORG, ISRAEL
item Iliasson, Amrax
item LEVY, G. - AGRIC RES ORG, ISRAEL

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2007
Publication Date: 5/1/2007
Citation: Jian, Yu, Lei, T., Shainberg, I., Mamedov, A.I., and Levy, G.L. 2007. Inflow rates and interrupted flow effects on concentrated flow erosion and intake rate in two soils. Soil Science 172:378-385.

Interpretive Summary: Efficiency of surface irrigation is often low because of poor infiltration uniformity, resulting from relatively long periods of infiltration at the upstream end and short periods of infiltration at the downstream end of the field. Intermittent supply of water to furrows may reduce soil intake rate (IR) and furrow erosion due to development of negative pressure at the soil surface during flow interruption. However, the decrease in IR and furrow erosion caused by intermittent flow is highly variable among soils. We studied the effects of inflow rates and interrupted flow on intake rates and erosion in two soils (clay and silt loam) to determine the response of soil surfaces to intermittent supply of water to the furrows. We found that increase in inflow rates had no effect on cumulative intake in both soils exposed to continuous flow. However interrupted flow reduced IR in the clay and had a small effect in the silt loam. Soil erosion in continuous flow remarkably increased with the increase in inflow rates in the clay, but small increase in the silt loam. Interrupted flow reduced erosion in both soils with the effect being more pronounced in the clay soil. Flow interruption reduced soil loss due to its increase in the cohesion forces between surface soil particles and the bulk soil underneath. This work help us further realizes interrupted flow could be effective management tool for increasing water use efficiency and reducing erosion in furrow irrigation.

Technical Abstract: Surface irrigation is the most widely used irrigation practice world wide, but its water use efficiency is low. Interrupted supply of water to furrows may reduce intake rate (IR) upstream and improve irrigation efficiency in many soils, but has an insignificant effect in others. Similarly, intermittent supply of water in furrow irrigation reduces furrow erosion in many soils but not in others. It is hypothesized that the response of soils to interrupted flow is affected by soil texture and structural stability combined with the rate of furrow wetting as determined by inflow rates. The objective of this study was to investigate the effects of inflow rate at the wetting stage of the soils and type of flow (continuous and interrupted flow) on IR and soil loss in concentrated flow. Two soils (a silt loam, Calcic Haploxeralf, and clay, Typic Haploxerert) were packed in miniflumes and were exposed to three inflow rates of concentrated (rill) flow. Cumulative intake in the clay was higher than that in the silt loam because of more stable aggregates in the clay. Increase in inflow rates had no effect on cumulative intake in both soils exposed to continuous flow because even the low inflow rate was high enough to cause aggregate disintegration similar to that in the highinflow rates. Interrupted flow reduced IR in the clay and had a small effect in the silt loam because of more soil surface compaction in the clay during the flow interruption. Soil erosion in continuous flow increased by 320% with the increase in inflow rates (and flow shear force) in the clay and only by 30% in the silt loam. Interrupted flow reduced erosion in both soils with the effect being more pronounced in the clay. Flow interruption reduced soil loss because it increased the cohesion forces between surface soil particles and the bulk soil underneath. These results suggested that flow interruption in furrow irrigation could be considered as an effective management tool for the control of water intake and erosion in furrow irrigation.