Contour ripping: A tillage strategy to improve water infiltration into frozen soil

Practices that combine stubble management for snow catch and contour-ripping for snowmelt infiltration have potential to increase water infiltration and soil water storage. Our objective was to investigate sod lapping to improve water infiltration into frozen soil. Infiltration studies on frozen soil were conducted at sites near Pendleton, Oregon (silt loam soil), and Culbertson, Montana (sandy loam soil). Ripping was performed with a single chisel or parabolic subsoiling shank at 6- to 8-m intervals on the contour to a depth of 0.2 to 0.3 m. Final infiltration rate on the sandy loam averaged 11 mm h-1 on the rip treatment and 1 mm h-1 on the no-rip treatment even when the soil was frozen deeper than 0.6 m. On the silt loam soils, when the average depth of frozen soil was 0.14 m, average final infiltration rate was 28 mm h-1 on the rip treatment and 2 mm h-1 on the no-rip treatment. There were no treatment differences on the silt loam when the soil was frozen 0.35 in. Soil condition at the time of ripping determined the effectiveness of tillage to improve water infiltration; there was little benefit from ripping a dry pulverized soil because loose soil flowed into the rip and obliterated the rip path. Desirable macropore structure on loose soil was achieved by deferring ripping until the soil was frozen. Infiltration measurements show that soil ripping has potential to increase water infiltration and consequently decrease water runoff, and if used in conjunction with stubble management to maximize snow trapping, may increase overwinter soil water storage