Saline-Seep Reclamation in the Northern Great Plains

Abstract

ABSTRACT SALINE seeps affect extensive dry cropland areas in the northern Great Plains. Methods have been devised to reduce the subsurface flow of water to saline-seep areas. Little information is available on what methods and procedures should be used to reduce soil salinity in arrested (hydrologically controlled) saline seeps. Study objectives were (a) to determine changes in soil salinity with time; (b) to evaluate the effectiveness of soil ridges, straw mulch (20 t/ha), gypsum (11 t/ha), fallow, and check (natural revegetation with grasses and weeds) in accelerating the reclamation process; and (c) to determine potential crop yields in arrested saline-seep areas. Soil salinity of the 0- to 30-cm soil depth was reduced sufficiently 2 years after the seep was arrested to allow many crops to be successfully grown. Crop yields in the arrested saline-seep areas generally equalled average county yields after 3 to 4 years of hydrologic control. The straw mulch treatment was the most effective in reducing soil salinity in the 0- to 90-cm soil depth. The check (revegetated) treatment was the least effective in reducing soil salinity in the 0- to 90-cm soil depth. Gypsum application did not accelerate the reclamation process, probably because sufficient naturally occurring gypsum had been precipitated in the soil profile during saline-seep formation. No deterioration in soil permeability or structure was observed during the reclamation process. Seven years after hydrologic control was obtained, soil salinity was still higher in the arrested saline-seep areas than in that of adjacent nonseep areas. Rate of salt removal from arrested dryland saline-seep areas depends on distribution and amount of precipitation received. Hydrologic control in the recharge area must be maintained to prevent reactivation of an arrested saline seep.