Experimental study of tillage tool-soil-straw interaction

Three experiments were conducted in a soil bin and a field to study soil and straw movement and straw incorporation by tillage. The soils in the bin and the field had the same texture of sandy loam. Cereal straw was selected as a crop residue. The length of straw ranged from 5 to 25 cm, and the speeds of tillage were 5, 7.5, and 10 km/h. Tillage depth was 10 cm, and the tool was a 325-mm-wide sweep. Point tracers were used to measure soil and straw movement. Results showed that longer straws were less buried than shorter ones at the same speed. Higher tillage speed resulted in larger soil displacement and then could bury more straws. Straw displacement increased when increasing straw length. The results of the soil bin experiment indicated that the forward displacement of soil would be reduced more than 70% if tillage speed were reduced from 10 to 5 km/h no matter how long the straw was. Soil rolling in the field was greater than in the soil bin when there was no stubble in the field. Standing stubble significantly reduced soil movement. The cover percents of straw measured from the field and the soil bin were not significantly different for 10 and 17.5-cm-long straws.