TRAFFIC EFFECTS ON WATER INFILTRATION IN CHISEL-PLOW AND NO-TILL SYSTEMS

Traffic effects on pore structure and hydraulic properties of soils may be affected by site-specific factors. The objective of this study was to determine if the effects of wheel traffic on infiltration rates in chisel-plow and no-till tillage systems differed among five Midwestern locations. Ponded and unsaturated (30-, 60-, and 150-mm water tension head) infiltration rates were measured sequentially using infiltrometers after removing surface residues and the upper 2 cm of soil. Wheel traffic reduced ponded infiltration rates in both tillage systems at all locations, ranging from 95% in the chisel-plow system in Iowa to approximately 55% in the chisel-plow system in Missouri. Tillage systems significantly affected ponded infiltration rates at only two of the locations. At the Minnesota and Nebraska locations, no-till reduced ponded infiltration rates in untrafficked interrows by 33 and 64%, respectively, compared with those in the chisel-plow system. Ponded infiltration rates of trafficked interrows did not differ between tillage systems at any location. At the Iowa and Nebraska locations, the decrease in infiltration rate with an increase in tension head was greater for untrafficked interrows than for trafficked interrows in the chisel-plow system. The large pores that drain at 30 mm of tension head accounted for a lower percentage of the water how with pending in trafficked interrows (73%) than in untrafficked interrows (88%). Infiltration rate comparisons between tillage systems should consider wheel traffic patterns.