Effect of different types of tractor traffic on soil physical properties and yield of winter wheat

Overuse of agricultural machinery, intensive cropping, short crop rotations and inappropriate soil management lead to soil compaction. Experiments were conducted on clay loam soil to study the effect of tractor traffic(TT) on soil properties, wheat root development and plant growth. Tractors(T) used in the experiments were wheel tractor(WT), crawler tractor(CT) and holder/ walking tractor(HT). The influence of soil compaction on wheat growth and soil structural discontinuity was discussed. Experiments showed that soil density, soil resistance, and soil moisture generally increases with the increasing of machinery passes. Possible mechanisms of wheat root-straw relations as affected by soil compaction were presented. The data on final emergence count did not show significant differences among different treatments when tested at significant level P≤0.05. However, plant heights showed significant differences at significant level P≤0.01 when they were measured at the 2nd, 4th, 6th, 8th, 10th, 12th, 18th week and the harvest time. The WT, HT produced taller plants than CT. The data of root length and density showed significant differences among different treatments at significant level P≤0.05 and P≤0.01, with WT and HT producing the high results while CT showing the lowest results. The machinery passes(MP) significantly influenced growth parameters, such as dry matter and the grain yield. However, crop yield on compacted soil largely depended on weather conditions and initial soil compactness.