ARS | Publication request: Impact of long-term conservation tillage cropping systems on soil hydraulic properties in the Pacific Northwest

Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: October 5, 2008
Publication Date: October 9, 2008
Citation: Feng, G., Sharratt, B.S., Young, F.L. 2008. Impact of long-term conservation tillage cropping systems on soil hydraulic properties in the Pacific Northwest. Soil Science Society of America Annual Meeting.

Technical Abstract: Soil erosion can be manipulated through tillage and crop residue management as a consequence of altering the physical attributes of soil that govern soil particle detachment by water and wind. A long-term, field-scale, cropping systems experiment was initiated at Ralston, WA in 1995 to identify alternative cropping systems that would reduce windblown dust emissions from conventional winter wheat/summer fallow. The randomized, complete-block experiment included three cropping systems: 1) winter wheat/summer fallow (SF), 2) spring wheat/chemical fallow (CF), and 3) direct-seed spring barley/spring wheat (NTSW). In 2006, we assessed the impact of these cropping systems on infiltration, water retention, and saturated hydraulic conductivity (Ks). These properties were assessed in the upper 5cm of the silt loam soil profile in both spring, after sowing spring wheat or during fallow, and autumn, after harvest of spring wheat or sowing winter wheat. Infiltration was measured using a double-ring infiltrometer while water retention was assessed in-situ by measuring the temporal variation in soil water content following ponded infiltration. Saturated hydraulic conductivity was determined on extracted soil cores (7 cm in diameter) using the falling-head method. Infiltration and Ks were greater for NTSW and SF as compared with CF; this was likely due to CF having a higher bulk density than NTSW and SF. However, SF and CF retained more water near saturation and had a greater water holding capacity than NTSW. These retention characteristics suggest a larger pore size distribution for SF and CF than for NTSW. Our results indicate that hydraulic properties of a silt loam can be modified by long term management in the intermediate precipitation zone of the Columbia Plateau.