SOIL SALINITY REDUCED BY SUMMER FALLOW AND CROP RESIDUES

Abstract

Soil salinity can frequently be reduced and controlled under dryland conditions of the Northern Plains by proper use of dryland cultural practices that promote soil water conservation. Summer fallow significantly reduced salinity in the root zone, whereas salinity increased under a small grain crop. Soil salinity reductions attributed to fallow were greater under a deeper water table regime compared to more shallow water table conditions. A straw cover or small grain stubble mulch during the winter, in conjunction with summer fallow, led to further salinity reductions. The straw mulch was more effective in reducing salinity at a more severely saline and higher water table site than at a more moderate location. Summer fallow was more effective at the more moderate site compared to the severe location. Under the combination of summer fallow and winter vegetative mulch, precipitation in excess of evapotranspiration losses supplied water for leaching. Growing a crop, except during high rainfall periods, did not leave excess water. Our findings suggest that summer fallow with winter vegetative residue management can be effectively utilized in the cultural rotation for reducing soil salinity under dryland conditions.