种植果树对土壤物理性状的双重效应

Dual effect of fruit tree cultivation on soil physical characteristics

  • 摘要: 在渭北果区选择不同园龄(<10 年、10~20 年、>20 年)果园, 分层测定0~60 cm 土层土壤容重、土壤坚实度、土壤含水量以及表层土壤团聚体组成等物理性状, 进一步分析了果园土壤物理性状随园龄的变化特征。结果表明: 土壤容重在0~30 cm 土层随园龄增长而降低; 在30 cm 以下土层随园龄增长而增加, 超过了健康园艺土壤的质量标准1.30 g·cm-3; 与休闲农田相比, 种植果树可降低10~30 cm 土层土壤容重; 但30 cm 以下土层土壤坚实度急剧增大, 接近或达到了限制根系延伸的土壤质量标准1 000 kPa; 与休闲农田相比, 种植果树对于降低17.5~27.5 cm 土层的坚实度具有明显作用。果园表层土壤团聚体状况整体较差, 水稳性优势团聚体直径为0.5~0.25 mm, >0.25 mm 水稳性团聚体含量随园龄增加而增大, >20 年果园比<10 年果园高1 倍。种植果树对表层土壤具有明显的保护和改善作用, 却在深层发生着紧实化和坚硬化过程。果树对土壤物理状况的双重效应体现在对0~30 cm 土层土壤结构具有改善作用, 对30 cm 以下土层土壤结构有破坏作用。果园土壤“深层的隐蔽性退化过程”影响着果树根系健康生长, 应当给予极大关注。

     

    Abstract: Soil bulk density, hardness, moisture and surface soil aggregation composition were measured in <10-, 10~20- and >20-year-old orchards in Weibei Region. The results showed that soil bulk density in the 0~30 cm soil layer decreased with increasing orchard age. However, bulk density below the 30 cm layer increased with increasing orchard age, exceeding the 1.30 g?cm-3 upper limit for healthy garden soils. Soil bulk density in the 10~30 cm soil layer was lower in orchards than in croplands. Soil hardness increased sharply below the 30 cm soil layer, almost reaching the 1 000 kPa upper limit of soil quality standard for healthy root growth. Soil hardness in the 17.5~27.5 cm soil layer is lower in orchards than in croplands. Soil aggregation status was poor in surface soil of orchards. Most water-stable aggregates in the orchard soils were in 0.5~0.25 mm range class. Contents of water-stable soil aggregates >0.25 mm increased with increasing age of orchards. Water-stable soil aggregates contents in 20-year-old orchards were two times higher than those in 10-year-old orchards. Fruit trees have a dual effect on soil physical characteristics. Soil physical conditions was generally improved in topsoil (0~30 cm), but worsen in subsoil (<30 cm) with increasing orchard age. As latent degradation of subsoil in orchards affected the healthy growth of fruit trees, any such degradation should be carefully monitored.

     

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