渭北苹果园土壤钙素退化状态

Calcium Degradation Status of Orchard Soil in Weibei Region,Shaanxi Province,China

【目的】针对渭北苹果主产区出现的随植果年限增加,果树过早衰老,苹果的苦痘病、水心病、痘斑病等生理性病害频繁发生的问题,对该区苹果园土壤钙素退化部位、退化趋势及退化程度等进行了研究,以期查明制约苹果品质和果业可持续发展的因素,为果园土壤科学管理提供依据。【方法】在渭北黄土塬区分别选取<10a、10—20 a、>20 a 3个园龄的苹果园各4个,并以土壤条件相同的农田作对照,在树冠层投影范围内距树干2/3处逐层采集剖面0—100 cm土壤样品,研究不同园龄果园土壤碳酸钙、交换性钙、水溶性钙含量及其贮量变化情况。【结果】3个不同园龄苹果园土壤碳酸钙在0—100 cm土层的总贮量随植果园龄的增加而降低,0—50 cm土层碳酸钙含量及贮量随园龄增加显著减少,50—100 cm则随园龄增大呈现逐渐增加趋势。10 a以上果园0—50cm土层的碳酸钙总贮量显著低于农田。各果园土壤交换性钙在0—100 cm土层的总贮量随植果园龄的增加呈减少趋势,0—40和60—100 cm土层土壤交换性钙含量及贮量也随园龄的增加而减少,而40—60 cm土层则随园龄的增加而稍有增加。与农田相比,果园土壤的交换性钙均有所增加。各果园0—50 cm土层水溶性钙含量及其贮量都高于50—100 cm土层,10 a以上果园10—30 cm土层的水溶性钙含量最高。与农田土壤相比,3个园龄果园土壤水溶性钙含量都有所增加。【结论】即使在富含石灰质的渭北黄土旱地,因长期植果明显加速了土壤钙素退化。随园龄增大果园土壤钙素库容及有效钙供给减小,已成为该地区土壤化学性质隐性退化的特征之一。在重视果园大量养分管理的同时,警示关注包括钙素在内的中微量养分的演化趋势。

【Objective】 Apple production contributes greatly to the economic development of Shaanxi province.But orchard soil has degraded significantly after years of fruit production,which lead to tree senescence and various diseases such as apple bitter pit,water-core and lenticel blotch pit.As a result,fruit yield and quality decreased sharply.The objective of this study was to investigate the distribution and extent of soil calcium degradation in the orchards of different ages,with the aim to facilitate sustainable development of the yield and quality of apple production.【Method】 Four replicates of 10-,10-20- and 20-year old orchards soil and farmland soil as control were selected for the study in Binxian,semiarid region of Shaanxi.Samples were taken within two-thirds of the radius of the tree canopy.Soil samples were used to measure physical and chemical properties such as soil bulk density,p H,Ca CO3,exchangeable Ca,and water-soluble Ca.【Result】 The soil Ca CO3 content and storage in 0-50 cm increased as orchard age increased,while decreased as orchard age increased in 50-100 cm.Soil Ca CO3 storage in the orchards older than 10 years were significantly lower than that of farmland in 0-50 cm.The exchangeable Ca and water-soluble Ca in all orchard soils were higher in comparison with the farmland soil.The orchard soil exchangeable Ca decreased with orchard age increasing in layers of 0-40 cm and below 60 cm,while slightly increased with orchard age increasing in 40-60 cm.The water-soluble Ca content and storage in 0-50 cm were higher than that in 50-100 cm,and the soil water-soluble Ca has a peak in 10-30 cm in the orchards older than 10 years.【Conclusion】The storage of soil Ca CO3 and exchangeable Ca in the layer of 0-100 cm decreased severely with orchards planting years increased,even in the calcareous soil of loess dry-land in Shannxi Weibei Region.The decrease of soil Ca CO3 and exchangeable Ca has become one of the characteristics of soil degradation.Calcium deficiency should be concerned in the orchard fertilization management in this region.