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United States Department of Agriculture

Agricultural Research Service

Title: Sprinkler Droplet Energy Effects on Infiltration and Near-Surface, Unsaturated Hydraulic Conductivity

Authors
item Lehrsch, Gary
item Kincaid, Dennis

Submitted to: International Symposium on Preferential Flow
Publication Type: Proceedings
Publication Acceptance Date: September 5, 2000
Publication Date: N/A

Interpretive Summary: Reducing the impact energy of sprinkler droplets through irrigation management should minimize 1) the breakdown of soil aggregates (naturally occurring clusters of sand, silt, and clay) at the soil surface and 2) the formation of a dense layer of surface soil while maintaining infiltration rates. From 1997 through 1999 in southern Idaho, we measured sprinkler droplet energy effects on infiltration and unsaturated hydraulic conductivity (water flow through all but the largest soil pores) near the soil surface after crop stand establishment. The treatments were droplet energies: one was a control (field plots were covered with nylon mesh to eliminate droplet impact energy) and the other was a moderate energy level from droplets produced with a low-pressure, lateral-move irrigation system. After planting sugarbeet into a Portneuf silt loam and irrigating 2-3 times, we used tension infiltrometers to measure infiltration rates through undisturbed soil surfaces at three supply potentials, each of which allowed water to flow through soil pores with different diameters. Reducing droplet energy significantly increased steady-state infiltration, averaged across years, at supply potentials of 20 and 40 mm, kept soil surfaces rougher, and minimized aggregate breakdown. Pores with diameters between 0.75 and 1.5 mm were most affected by droplet energy.

Technical Abstract: Reducing the impact energy of sprinkler droplets through irrigation management should minimize surface soil aggregate breakdown and seal formation while maintaining infiltration rates. From 1997 through 1999 in southern Idaho, we quantified sprinkler droplet energy effects on infiltration and near-surface hydraulic conductivity measured under tension after crop stand establishment. The treatments were droplet energies: 0 or 7 J/kg [0 or 7 J/(m-squared mm)], produced with a low-pressure, lateral-move irrigation system. After planting sugarbeet (Beta vulgaris L.) into a Portneuf silt loam (Durinodic Xeric Haplocalcid) and irrigating 2-3 times, we used tension infiltrometers to measure unconfined (three-dimensional) infiltration rates through undisturbed soil surfaces at three supply potentials. Reducing droplet energy significantly increased steady-state infiltration, averaged across years, at supply potentials of 20 and 40 mm and kept soil surfaces rougher with less aggregate breakdown. Pores with diameters between 0.75 and 1.5 mm were most affected by droplet energy.

Last Modified: 10/21/2014
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