陇东旱塬旱作苹果园水分生产力与土壤干燥化效应模拟

Simulation of water productivity and soil desiccation effects of dryland apple orchard on the dry plateau of eastern Gansu

【目的】揭示苹果园地土壤干燥化发生规律及土壤干燥化对果园生产力的长远影响。【方法】在WinEPIC模型模拟精确度验证的基础上,应用该模型模拟研究了19601999年期间陇东旱塬旱作苹果园地水分生产力变化动态和土壤干燥化效应。【结果】（1）19601999年模拟研究期间,果树产量在10龄达到最高值26.83t/hm2后,呈显著波动下降趋势;2340龄,低产果园（年产量小于18 t/hm2）占71%,且随降水量的变化呈不稳定波动趋势,平均值为16.47 t/hm2。（2）123龄苹果园地年耗水量均高于同期降水量,010 m土层土壤有效含水量呈显著降低趋势,其中,110龄与1123龄010 m土层土壤干燥化速率分别为94.42和22.6 mm/a;2440龄苹果园地年均耗水量与同期降水量基本相当,土壤有效含水量为70240 mm,随生长期与降水量的变化稳定波动。（3）苹果园地02 m土层土壤湿度随降水量的变化波动明显;210 m土层土壤湿度逐年降低,干层逐年加深和加厚,12龄果园干层已达10 m,此后各树龄土壤湿度逐渐趋于凋萎湿度直到24龄达到稳定。（4）土壤干燥化强度由无干燥化（16龄）-轻度干燥化（7龄）-中度干燥化（89龄）-严重干燥化（1011龄）-强烈干燥化（12龄以后）而逐渐加强,以至24龄以后形成稳定的强烈干燥化状态。【结论】陇东旱塬西峰地区旱作苹果园地土壤水分合理利用年限为2324年。

【Objective】 The study was done to investigate occurrence rule of soil desiccation of apple orchards and effects of soil desiccation on apple productivity.【Method】 Based on model validation,the WinEPIC model was used to simulate the dynamic changes of water productivity and soil desiccation effects of dryland apple orchards at Xifeng on the dry plateau of eastern Gansu during 1960-1999.【Result】（1） Apple yields decreased obviously with fluctuation after 10 years’ yield reached 26.83 t/hm2 which was the highest.The yield of 71% apple orchards reached the low-yielding orchards（18 t/hm2） and fluctuated with precipitation changes in 23-24-year-old whose average yield was 16.47 t/hm2.（2） The average annual water consumption was higher than annual precipitation from 1 to 23 years,the soil desiccation rates of 1-10-year-old and 11-23 year-old orchards were 94.42 and 22.6 mm/a respectively,which made the monthly available soil water amounts decreased rapidly in 0-10 m soil profile of 1-23-year-old orchards.The average annual water consumption was equal to annual precipitation from 24 to 40 years,the monthly available soil water amounts of 24-40-year-old orchards were 70-240 mm which fluctuated with growth seasons and precipitation changes.（3） Soil moisture fluctuated obviously with precipitation changes in 0-2 m soil profile while it decreased annually in 2-10 m soil profile,therefore,the desiccated soil layers became thicker and deeper.The depth of desiccated soil layers of 12-year-old orchard reached 10 m and soil moisture gradually got close to the local soil wilting moisture and then kept steady until 24 years.（4） Soil desiccation intensified gradually until 24 years when it kept steady and was in strong desiccation state from no desiccation（1 to 6 years） to slight desiccation（7 years） to moderate desiccation（8 to 9 years） to serious desiccation（10 to 11 years） to strong desiccation（after 12 years）.【Conclusion】 The reasonable utilization period of dryland apple orchard at Xifeng on the dry plateau of eastern Gansu is 23-24 years.