耕作方式与秸秆覆盖对夏玉米根系分布及产量的影响

为探究夏玉米根系分布及水分利用效率对不同耕作结合秸秆覆盖模式的动态响应,于2017年和2018年在河套灌区开展不同耕作模式田间试验。试验设置,常规(CK)、秸秆表覆(BF)、深翻结合秸秆深埋(SM)和深翻结合秸秆深埋与表覆(BFSM)4种处理。结果表明,BF处理显著提高水平向根长密度,较CK处理高24.7%,SM、BFSM处理显著提高深层根长密度,较CK处理高23.8%;2017年夏玉米根长密度与标准化根深呈显著的三阶多项式函数关系,用2018年实测值率定效果较好,可较好描述不同耕作模式根长密度分布。BF、SM、BFSM处理较CK处理根冠比显著提高3.8%、20.8%、26.4%(P<0.05),较CK处理夏玉米产量及水分利用效率分别显著提高8.6%、19.5%、19.7%和13.6%、32.3%、34.8%(P<0.05),SM与BFSM处理差异不显著。该研究为河套灌区农业耕作模式提供一定借鉴。

Effects of tillage methods and straw mulching on the root distribution and yield of summer maize

Abstract: To explore root distribution and water-use efficiency of summer maize based on different tillage depth and straw mulching, a field experiment with different tillage mode was conducted in the Hetao Irrigation district in 2017 and 2018, respectively. The experiment consisted of 4 different tillage modes. It included conventional tillage mode (CK), straw mulching tillage mode (BF), deep ploughing and straw deep-buried tillage mode (SM), deep ploughing and straw mulching and deep-buried tillage mode (BFSM). The results showed that there was significant that BF treatment increased the horizontal root length density. Compared with CK treatment, the straw mulching tillage mode significantly increased by 24.7% (P<0.05). It was beneficial to the horizontal root growth, but it led to the redundancy of the surface root system. Meanwhile, there was no significant effect on the root length density of the deep root system, and it was not conducive to the growth of the deep root system under the straw mulching tillage mode. It was significant that SM and BFSM treatments increased the root length density of deep soil and they promoted the vertical growth of roots. Compared with CK treatment, the straw deep-buried tillage mode significantly increased by 23.8% (P<0.05), but it was no significant effect on the root length density of surface soil roots. The root length density of BF treatment was only 0.85% higher than CK treatment in the straw inter-layer, which was no significant difference (P<0.05). However, the root length density of SM and BFSM treatments of the straw inter-layer was much higher than BF and CK treatments. The average root length density of BFSM treatment was 3.5% higher than SM treatment, which was no significant difference (P<0.05). It indicated that it could significantly improve the root length density of straw inter-layer and promote the growth of deep root under deep ploughing and straw deep-buried tillage mode. It showed a significant third-order polynomial function relation between root length density of summer maize and normalized root depth of soil under different treatments of 2017. The model was calibrated with the measured data of 2018, which showed good calibration effect. And the Coefficient of Determination (R2) was above 0.96 between the simulated value and the measured value, and the Root Meant Square Error (RMSE) was between 0.1 and 0.2. So, it was well to describe the distribution of root length density of summer maize under different tillage modes. Compared with CK treatment, the mean of the dry root weight and the root-shoot ratio of BF, SM, and BFSM increased by 14.2%, 32.8%, 36.6%, and 3.8%, 20.8%, 26.4% (P<0.05), respectively. There was no difference in dry root weight and the root-shoot ratio of SM and BFSM treatments in the same year, but SM treatment in rainy years (in 2018) significantly increased by 6.5% on average (P<0.05) of root-shoot ratio compared with less rainy years (in 2017). Compared with CK treatment, the yield of summer maize under BF, SM, and BFSM treatments increased by 8.6%, 19.5%, and 19.7%, and water-use efficiency of summer maize increased by 13.6%, 32.3%, and 34.8% on average (P<0.05). There was no significant difference between SM and BFSM of yield and water-use efficiency, but the difference was significantly higher than that of BF and CK treatments in rainy years (in 2018). The indicators of production increased to different degrees, but the water consumption in agriculture was incremental and the water-use efficiency under 4 treatments was decreased by 9.1%, 9.1%, 6.5%, and 4.9%, respectively. The research preliminarily revealed a response mechanism which was the effect of different depths of the straw returned and tilling on the root distribution, yield, and water-use efficiency of summer maize in the Hetao irrigation district. It could achieve the goal that was saved water and stable yield based on the deep ploughing combined with straw deep-buried tillage mode, which had certain theoretical and practical significance for suitable tillage mode for agricultural production in the Hetao irrigation district.