旱作条件下保护性耕作对土壤结构和容重影响试验研究

Effects of Conservation Tillage on Soil Structure and Bulk Density under Dryland

    摘要
  • 摘要:
      目的  明确外源有机物和耕作方式及其交互作用对土壤容重、团聚体表征物理指标变化的影响。
      方法  依托半湿润偏旱区国家农业环境晋中长期耕作试验观测平台，设置免耕（NT）、深松（SU）、旋耕（RT）、翻耕（CT）以及耕作与秸秆耦合作用下免耕 + 秸秆覆盖还田（NTS）、深松 + 秸秆还田（SUS）、旋耕 + 秸秆还田（RTS）、翻耕 + 秸秆还田（CTS）共8种处理，连续5年进行玉米连作田间试验，通过测定和比较土壤水稳性团聚体（WSA）和容重，探讨了耕作方式及其与秸秆还田措施配合的培肥改良土壤效果。
      结果  ① 与CT相比，NT和SU土壤水稳性团聚体的平均重量直径（MWD）、几何平均直径（GMD）、> 0.25 mm团聚体含量（R0.25）分别得到了显著提升（31.94%，36.61%；23.29%，26.09%；14.42%，12.63%）。② 0 ~ 40 cm土层的容重，RTS最小，SU次之。相比CT，NT、SU、RT在土层垂直方向上，随着土层深度的增加，对土壤容重影响效果均在逐步减弱。秸秆和耕作的耦合作用，对容重的影响呈随机分布。0 ~ 10 cm表层，相比CTS，NTS、RTS措施下容重分别显著降低了21.07%和15.78%，且土壤容重升序排列为：NTS、RTS、SUS、CTS。③ 相关性MWD、GMD、> 2 mm团聚体含量，两两之间均极显著正相关。此外，NT和RT，容重与MWD、GMD、> 2 mm团聚体含量显著负相关。
      结论  深松作为改良旱地壤质黏土物理性质的重要耕作措施，连续实施不但可以促进土壤水稳性团聚体的形成，而且有助于增强团聚体的稳定性，改善土壤紧实度。因此，建议将深松耕作作为研究区普适性技术推广。

     

    Abstract:
      Objective  This paper aims to clarify the effects of exogenous organic matter, tillage methods and their interactions on the changes of soil bulk density and physical indicators of aggregate characterization.
      Method  Relying on the National Agricultural Environment Jinzhong Long-term Cultivation Observation Platform in Semi-humid and Arid Areas, 8 tillage patterns were carried on, including no-tillage (NT), subsoiling (SU), rotary tillage (RT), tillage (CT) and under the coupled action of tillage and straw, no-tillage + Straw mulching (NTS), subsoiling + straw returning (SUS), rotary tillage + straw returning (RTS), ploughing + straw returning (CTS), and continuous corn cropping was for 5 consecutive years. The effects of tillage methods, fertilization and soil improvement combined with straw returning measures were discussed by measuring and comparing soil water-stable aggregates (WSA) and bulk density (BD).
      Result  ① Compared with CT, the mean weight diameter (MWD), geometric mean diameter (GMD) and > 0.25 mm aggregate content (R0.25) of NT and SU soil water-stable aggregates were significantly increased (31.94%, 36.61%; 23.29%, 26.09%; 14.42%, 12.63%). ② Compared with CT, the effects of NT, SU and RT on soil BD were gradually weakened with the increase of soil depth in the vertical direction of soil layer. The coupling effect of straw and tillage has a random distribution on BD in 0 ~ 40 cm soil, RTS was the smallest, followed by SU. The ascending order of BD in 0 -10 cm topsoil was: NTS, RTS, SUS, CTS. Compared with CTS, the BD of NTS and RTS decreased significantly by 21.07% and 15.78%. ③ Correlation analysis showed that MWD, GMD and aggregate content > 2 mm had a significant positive correlation between them. In addition, NT and RT, BD were significantly negatively correlated with MWD, GMD and aggregate content > 2 mm.
      Conclusion  SU is as an important tillage measure to improve the physical properties of loamy clay in dry land. Continuous implementation of this tillage can not only promote the formation of soil water-stable aggregates, but also help to enhance the stability of aggregates, and also reduce the soil bulk density to a considerable extent. So it is recommended to consider SU as a universal farming promotion in the study area.

     

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