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Deep subsurface drip irrigation using coal-bed sodic water: part I. water and solute movement

Agricultural Water Management

By:
, , , , and
DOI: 10.1016/j.agwat.2012.11.014

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Abstract

Water co-produced with coal-bed methane (CBM) in the semi-arid Powder River Basin of Wyoming and Montana commonly has relatively low salinity and high sodium adsorption ratios that can degrade soil permeability where used for irrigation. Nevertheless, a desire to derive beneficial use from the water and a need to dispose of large volumes of it have motivated the design of a deep subsurface drip irrigation (SDI) system capable of utilizing that water. Drip tubing is buried 92 cm deep and irrigates at a relatively constant rate year-round, while evapotranspiration by the alfalfa and grass crops grown is seasonal. We use field data from two sites and computer simulations of unsaturated flow to understand water and solute movements in the SDI fields. Combined irrigation and precipitation exceed potential evapotranspiration by 300-480 mm annually. Initially, excess water contributes to increased storage in the unsaturated zone, and then drainage causes cyclical rises in the water table beneath the fields. Native chloride and nitrate below 200 cm depth are leached by the drainage. Some CBM water moves upward from the drip tubing, drawn by drier conditions above. Chloride from CBM water accumulates there as root uptake removes the water. Year over year accumulations indicated by computer simulations illustrate that infiltration of precipitation water from the surface only partially leaches such accumulations away. Field data show that 7% and 27% of added chloride has accumulated above the drip tubing in an alfalfa and grass field, respectively, following 6 years of irrigation. Maximum chloride concentrations in the alfalfa field are around 45 cm depth but reach the surface in parts of the grass field, illustrating differences driven by crop physiology. Deep SDI offers a means of utilizing marginal quality irrigation waters and managing the accumulation of their associated solutes in the crop rooting zone.

Geospatial Extents

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Deep subsurface drip irrigation using coal-bed sodic water: part I. water and solute movement
Series title:
Agricultural Water Management
DOI:
10.1016/j.agwat.2012.11.014
Volume
118
Year Published:
2013
Language:
English
Publisher:
Elsevier
Contributing office(s):
Denver Federal Center
Description:
13 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Agricultural Water Management
First page:
122
Last page:
134
Number of Pages:
13
Country:
United States
State:
Wyoming
Other Geospatial:
Powder River Basin