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草业学报 ›› 2023, Vol. 32 ›› Issue (1): 63-74.DOI: 10.11686/cyxb2022009

• 研究论文 • 上一篇    下一篇

黄土旱塬区苹果园生草覆盖对深层土壤水分和根系分布特征的影响

李惟婕(), 王立, 马景永, 王自奎()   

  1. 兰州大学草地农业科技学院,草地农业生态系统国家重点实验室,甘肃 兰州 730020
  • 收稿日期:2022-01-06 修回日期:2022-03-03 出版日期:2023-01-20 发布日期:2022-11-07
  • 通讯作者: 王自奎
  • 作者简介:E-mail: wzk@lzu.edu.cn
    李惟婕(1997-),女,四川成都人,在读硕士。E-mail: wjli19@lzu.edu.cn
  • 基金资助:
    国家自然科学基金项目(31871560);国家牧草产业技术体系(CARS-34);甘肃省科技计划项目(20CX9NA105)

Effects of a cover crop on deep soil water and root characteristics in a dryland apple orchard on the Loess Plateau

Wei-jie LI(), Li WANG, Jing-yong MA, Zi-kui WANG()   

  1. College of Pastoral Agriculture Science and Technology,State Key Laboratory of Grassland Agro-Ecosystem,Lanzhou University,Lanzhou 730020,China
  • Received:2022-01-06 Revised:2022-03-03 Online:2023-01-20 Published:2022-11-07
  • Contact: Zi-kui WANG

摘要:

研究苹果园长期生草覆盖后深层土壤水分及果树根系的分布规律,以期阐明旱作条件下果园根水互作关系,为黄土旱塬区果园生草覆盖实践的优化提供依据。试验于甘肃庆阳草地农业生态系统国家野外科学观测研究站苹果园中进行,设置果园生草覆盖(生草为鸭茅草,2014年建植)和清耕处理,以一年生作物田为对照;连续两年夏季测定果树行上和行间距离树干100和200 cm共4个位置0~500 cm土层的土壤水分和果树细根长密度,分析生草覆盖对果园深层水分亏缺及细根长密度的影响。清耕果园0~300 cm土壤水分较对照农田下降了6.7%~8.3%(P<0.01),而300~500 cm土层土壤水分与对照农田差异不显著(P>0.05);生草覆盖果园0~500 cm整个剖面的土壤水分均低于清耕果园,平均下降了11.5%~12.3%。果园生草覆盖6~7年后0~500 cm土层土壤较对照农田水分亏缺量为163.9~172.1 mm,是清耕果园水分亏缺量的3.2~4.2倍。果树根系在0~100 cm土层的细根长密度最高,平均密度为0.187 cm·cm-3,生草覆盖促进了0~100 cm土层果树根系的分布,对深层根系影响不显著。清耕果园和生草覆盖果园0~500 cm土层土壤水分的含量随果树细根长密度的增加而降低,二者呈线性负相关关系,生草覆盖后二者相关性提高,干旱年份二者相关性更高。黄土旱塬区苹果园长期生草可促进果树根系生长,降低深层土壤水分,加剧土壤干燥化,对苹果树的利用年限和农田水分循环具有负面效应。旱作条件下应加强果园生草覆盖管理以保障水分的可持续性。

关键词: 黄土旱塬, 果草复合系统, 土壤水分亏缺量, 细根长密度, 深层干燥化

Abstract:

To clarify the interaction between soil water content and root distribution and provide information for orchard cover crop management in the Loess Plateau, the distribution of apple tree root systems and deep soil moisture contents in the presence or absence of a cover crop were investigated. The experiment was conducted in the apple orchard of Qingyang National Field Station of Grassland Agroecosystems. Two planting patterns were set up, namely, orchard with cover crop (Dactylis glomerata, planted in 2014) and orchard with clean tillage, with annual crop farmland as control. Soil moisture and fine root length density in 0-500 cm soil layer were measured at four locations in the tree rows and between the tree rows for two consecutive years in summer and the effects of cover crop on soil moisture deficit and fine root length density were determined. Soil moisture levels in 0-300 cm soil horizon of orchard with clean tillage decreased by 6.7%-8.3% (P<0.01) compared to the control farmland, while soil moisture in 300-500 cm soil layer was not significantly changed (P>0.05); soil moisture levels in the whole profile of 0-500 cm of the cover crop treatment were on average 11.5%-12.3% lower than those of the clean tillage treatment. The water deficit in the 0-500 cm soil horizon of the control farmland was 163.9-172.1 mm after 6-7 years of cover crop planting, which was 3.2-4.2 times of that in the clean tillage orchard. In addition, the fine root length density of apple tree roots in the 0-100 cm soil layer was higher than that in deeper layers, and averaged 0.187 cm·cm-3 in density. Cover crop promoted root length density in the 0-100 cm soil layer. The soil moisture content in the various soil horizons from 0-500 cm decreased with increase in fine root length density and the correlation coefficient was increased by the presence of a cover crop, and was higher in the dry season.In summary, long-term cover crop planting in apple orchards in the dryland area on the Loess Plateau promoted the growth of apple tree roots, reduced deep soil moisture and aggravated deep soil drying, which would have a negative effect on the production of apple trees and water cycling in the local agricultural ecosystem. Cover crop management in apple orchard should be reviewed to ensure sustainable water use.

Key words: Loess Plateau dryland, tree-grass system, soil water deficit, fine root length density, deep soil desiccation