Influence of high axle loads and tillage systems on soil properties and grain corn yield

Abstract

The effects of various tillage systems in combination with different levels of high axle load traffic on soil bulk density, penetration resistance and corn ( Zea mays L.) grain yields were studied for a 3 year period on a silt loam soil. The tillage systems were zero tillage, fall chisel plowing and fall moldboard plowing. Traffic treatments involved the annual post-harvest imposition of a 12 Mg axle weight on 100%, 25%, and 0% of the plot surface area. The 0% treatment involved controlling all field traffic with the use of a wide span tractor. Only in the third year were differences in soil bulk density resulting from loading significant within all three tillage systems at the 5–10 cm depth interval. At a depth of 20–25 cm (below the maximum depth of tillage) differences in soil bulk density resulting from loading were never significant regardless of the tillage system or year. Differences in penetrometer resistance in the 0–10 cm depth interval resulting from loading were generally only significant in zero tillage, but they were often significant within all tillage systems in the 12–22 cm depth interval. The maximum depth to which loading caused significant increases in penetrometer resistance was 35 cm. Corn grain yields were significantly higher for the traffic-free treatments within only one tillage system (moldboard) in only 1 year (1988) of the experiment. In general, axle loads of 12 Mg did not result in reduced grain corn yields regardless of whether they were imposed on 25% or 100% of the plot surface area.