耕作模式对苏打盐碱土结构稳定性与玉米产量的影响

    Effects of tillage mode on structural stability and maize yield in soda saline alkali soils

    • 摘要: 为探究不同耕作模式对苏打盐碱土结构稳定性、碱化程度及玉米产量的影响,在西辽河平原开展为期2a不同耕作方式配合秸秆还田的田间试验。设置常规耕作(CK)、深翻耕作(DT)、粉垄耕作(ST)、深翻+秸秆还田耕作(DST)、粉垄+秸秆还田耕作(SST)5种处理,分析不同处理下土壤结构和玉米产量变化。结果表明,相比常规耕作CK处理,其他耕作处理显著提高各土层土壤大团聚体含量(R0.25)75.9%~334.7%,显著降低微团聚体(< 0.25 mm)含量6.1%~24.8%(P < 0.05),有效改善苏打盐碱地土壤结构稳定性;耕作层(0~20 cm)土壤水稳性团聚体平均质量直径(mean weight diameter,MWD)高于玉米根层(>20~40 cm)和心土层(>40~60 cm),耕作层以DST处理最大,提高了85.1%,玉米根层以SST处理最大,提高了104.7%,心土层以SST处理最大,显著高于其他处理10.4%~48.9%(P < 0.05);土壤钠吸附比(sodium adsorption ratio,SAR)随土壤深度增加呈增加趋势,玉米收获后CK处理土壤SAR与背景值无显著差异(P > 0.05),土壤碱化风险大,其他处理SAR降幅为0.4%~10.3%,可缓解土壤钠质化,以DST处理效果较好。4种处理2a玉米平均增产37.8%~65.7%,水分利效率(water use efficiency,WUE)平均提高46.7%~91.7%(P < 0.05),以DST处理效果最好。玉米产量与耕作层R0.25、根层MWD呈正显著相关(P < 0.05),与10~20 cm土层的SAR呈负显著相关(P < 0.05);WUE与耕作层R0.25和MWD呈正显著相关(P < 0.05),与根层SAR呈负显著相关(P < 0.05)。综上,建议深翻+秸秆还田为苏打盐碱地适宜的耕作模式,可实现改善西辽河平原苏打盐碱地土壤结构稳定性、玉米高产高效的目标。

       

      Abstract: This study aims to investigate the effects of different tillage modes on the structural stability, the degree of alkalization and maize yield. A 2-year field experiment was carried out on the different tillage modes with straw returning in the West Liaohe Plain of Northeast China. Five treatments were set as conventional tillage (CK), deep turning tillage (DT), powder ridge tillage (ST), deep turning-straw returning tillage (DST), and powder ridge-straw returning tillage (SST). The experimental results showed that the latter four tillage treatments significantly increased the soil macro-aggregate content (R0.25) by 75.9%-334.7%, whereas there was a significant decrease in the soil micro-aggregate content (< 0.25 mm) by 6.1%-24.8% (P < 0.05), compared with the CK treatment. The aggregate composition effectively improved the stability of the soil structure in soda saline soils. As such, the soil was more conducive to root growth and water-air circulation. The average mass diameter (MWD) of soil water-stable aggregates was determined in the tillage layer (0-20 cm) higher than that in the maize root layer (>20-40 cm) and the subsoil layer (>40-60 cm). In the tillage layer, the largest MWD of soil water-stable aggregates with the DST treatment increased by 85.1%, compared with the CK treatment. In the maize root layer, the largest MWD with the SST treatment increased by 104.7%. In the subsoil layer, the largest MWD with the SST treatment was significantly higher than that treated with the rest by 10.4%-48.9% (P < 0.05). The soil sodium adsorption ratio (SAR), a crucial indicator of soil alkalization, increased with the increasing soil depth. Following maize harvest, there was no significant difference in the soil SAR of CK treatment from the background value (P > 0.05), indicating the high risk of soil alkalization under conventional tillage. By contrast, the SAR of the rest treatments decreased by 0.4%-10.3%, which alleviated the soil sodicity. Among them, the more effective performance was achieved in the SST and DST treatments. It infers that the combination of tillage and straw returning was dominated in reducing the soil alkalinity. Furthermore, the average maize yield of the four treatments (DT, ST, DST, and SST treatment) for two years increased by 37.8%-65.7% and water use efficiency (WUE) increased by 46.7%-91.7% (P < 0.05) , compared with the CK treatment. The best performance was achieved in the DST treatment suitable for water-saving agriculture in the soda-saline-alkaline regions. In addition, there were the beneficial effects of various tillage patterns on the maize yield. The correlations between different indicators were further illustrated using correlation analysis. The MWD in the rhizosphere and R0.25 in the tillage layer shared a substantial and positive correlation with the maize yield (P < 0.05), indicating that the high-yield maize production benefited from the well-structured soil in these regions. In the 10-20 cm soil layer, it was also strongly and negatively correlated with the SAR (P < 0.05), indicating that the high soil alkalinity in this layer prevented the maize from growing. In the tillage layer, the WUE had a substantial and positive correlation with the R0.25 and MWD (P < 0.05). While in the rhizosphere, there was a significant and negative correlation with the SAR (P < 0.05). In conclusion, optimal cultivation was achieved in the deep turning-straw returning tillage in the soda saline-alkali land. The soil structure was also stabilized for the high yield and efficiency in maize production. The finding can offer a scientific foundation for the long-term plant growth in the soda-saline-alkaline soils of West Liaohe Plain.

       

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