Evaluation of straw spatial distribution after straw incorporation into soil for different tillage tools

Straw incorporation into the soil can effectively solve the problem of extra harvested crop residues on the surface. However, due to the lack of research on the spatial distribution effects of straw in the soil after incorporation, it is difficult to evaluate the actual straw incorporation effects of tillage tools. In this study, straw incorporation experiments were conducted via three types of tillage tools in rice stubble fields: a traditional rotary tiller (TR), a straw rotary burying and returning machine (SR) developed by our research group, and a subsoiling + straw rotary burying and returning machine (SSR). The same operating parameters, such as working speed and tillage depth, were used in the experiments. The spatial distribution of straw after tillage tool operation was measured and compared by a measuring device developed for straw three-dimensional coordinates. The results showed that after TR operation, the cutting effect on the straw was poor; more straw was left on the surface and less straw was buried into the lower layer of the tillage depth compared to SR and SSR; the average length of straw in the divided cells was small; and there were many cells without straw. Compared with that of TR, the straw average length of SR and SSR decreased by 48.2% and 52.7%, respectively. Only a small amount of straw remained on the surface. The proportion of straw in the lower layer of the tillage depth increased by 154.9% and 214.1%, the average straw length in cells increased by 114.9% and 98.6%, and the number of cells without straw decreased by 40.2% and 36.0%, respectively. On the whole, SR and SSR had more advantages for straw cutting and straw incorporation into the soil, and SSR could bury more straw into the soil of the lower layer. Therefore, for fields with excessive residue concerns, the SSR was the most desirable tillage tool.