Deep tillage combined with organic fertilizer improves the root length density of wheat in 15−30 cm soil layer

Objectives Tillage practices and organic matter affect the root growth and yield of crop. In this study, we studied the wheat root growth under different tillage practices and organic materials, aiming to create an ideal root growth environment for the efficient crop production.

Methods The field experiment was located in Shucheng, Anhui, and started since 2016. From Oct 2019 to May 2020, the wheat root growth was monitored in the treatment plots of rotary tillage + straw return (RS), deep tillage + straw return (DS), rotary tillage + organic fertilizer (RM), and deep tillage + organic fertilizer (DM). At harvest of wheat in May 2020, the wheat yields in the four treatments were investigated, and the soil compaction and the soil fertility in 0−15 cm and 15−30 cm soil layers were all determined in the wheat mature period from October 2019 to May 2020.

Results Deep tillage treatments (DM and DS) reduced soil compaction by 18.02% and increased wheat root length density by 10.23% in the 15−30 cm soil layer, compared to the rotary tillage treatments (RM and RS). DM treatment was recorded the highest organic matter, total N and available P in 15−30 cm soil layer, which were 10.42%−16.56%, 8.18%−45.12%, and 21.53%−29.13% higher than those in other treatments, respectively. In DM treatment plots, the length density of wheat root was 10.88%−22.91% higher than in other treatment plots across the whole growth stage, and for soil layer 0−15 cm, 15−30 cm, and 30−45 cm, the increases were 8.69%−18.67%, 12.29%−27.99%, and 12.62%−30.61%, respectively. The partial least squares path model (PLS-PM) analysis showed that the root growth effect of tillage methods was mainly reducing soil compaction and that of organic materials was improving soil nutrient, and the effects of soil compaction and nutrient contents on the root length density of wheat was stronger at 15−30 cm soil layer than at 0−15 cm layer.

Conclusions Deep tillage combined with organic fertilizer could reduce soil compaction and improve soil nutrient contents, thus allow wheat to develop high root length density in soil profile, especially in the 15−30 cm soil layer to attain the high and stable yield of wheat.