不同施肥与间套绿肥对果园水热特征及硝态氮累积的影响

为了研究不同施肥与覆盖措施下苹果园水热特征及硝态氮累积量，于2012—2015年在陕西渭北旱塬白水县田家洼村进行了田间试验，探究单施化肥（农户模式FM）、推荐施肥配合树盘覆黑色膜（现有模式EM）、增施有机肥配合树盘覆黑色膜行间种植小油菜（优化模式OM）对果园水分含量、温度及硝态氮含量的影响。结果表明，与现有模式、农户模式相比，优化模式能显著提高0~200 cm土层土壤贮水量，分别平均增加6.1%、14.6%；优化模式能提高0~60 cm土层含水量随时间变化的稳定性，缓解深层（140~300 cm）土壤干燥化现象，降低土壤剖面水分垂直变异，提高土壤剖面水分垂直分布的稳定性；优化模式的三年平均产量较现有模式、农户模式分别增加20.1%、33.6%，水分利用率较农户模式、现有模式分别提高42.6%、28.9%；不同果园管理措施对土壤热量状况的影响差异显著，优化模式较现有模式能显著降低极端高温，缓冲不同时间段温度变异性，提高土壤的保温性。此外，优化模式能增加成熟期0~120 cm土层硝态氮累积量，较农户模式、现有模式分别增加277.9、183.7 kg·hm-2，优化模式可降低120~300 cm土层硝态氮累积量，较农户模式、现有模式分别降低71.3、30.0 kg·hm-2。综上所述，优化模式可明显改善土壤水热状况，降低深层硝态氮的累积量，是渭北旱地果园缓解水分和温度胁迫、改善果园生态环境、获得高产的最优果园管理模式。

Effects of different fertilizer treatments combined with green manure intercropping on water and thermal properties and nitrate accumulation in soils of apple orchard

Soil water and nutrients are two major factors limiting apple production in the Loess Plateau region in China. A 3-year field ex-periment was conducted from 2012—2015 in Tian Jia Wa village, Baishui county, Shaanxi Province, to evaluate the effects of different fertil-izer treatments combined with green manure intercropping on soil water and thermal properties and nitrate accumulation in apple orchards. There were three treatments:Farmer management pattern(FM)—nitrogen, phosphorus and potassium fertilizers only(NPK);Extension man-agement pattern(EM)—NPK fertilizers combined with swine manure(NPKM)and polyethylene black plastic film mulch(beside the tree trunks);Optimized management pattern(OM)—NPKM, polyethylene black plastic film mulch(beside the tree trunks)and rape intercrop-ping. Results showed that soil water storage in OM treatment was 14.6%and 6.1%higher than that in FM and EM, respectively. OM alleviat-ed the temporal fluctuation of soil moisture in 0~60 cm soil depth and enhance the temporal stability of soil moisture in the layer, and ef-fectively mitigated the soil desiccation in 140~300 cm soil depth. Additionally, OM also decreased the vertical variation of soil moisture in the soil profile and improved the stability of the vertical soil moisture distribution, as compared with FM and EM. In OM treatments, apple yields was increased by 20.1%and 33.6%, respectively, compared with EM and FM. The water use efficiency was highest in OM, and was 42.6%and 28.9%higher than in FM and EM . However, OM reduced the highest soil temperature, buffered different-time temperature vari-ability, increased soil thermal capacity, as compared with EM and FM. Nevertheless, OM increased NO-3-N content in 0~120 cm soil depth by 342.3 kg·hm-2 and 178.4 kg·hm-2 ,but decreased NO-3-N accumulation in 120~300 cm soil profile by 556.5 kg·hm-2 and 30.0 kg·hm-2, in comparison with FM and EM, respectively. Therefore, OM significantly improved the thermal conditions of soil, reduced the nitrate accu-mulation in deep soil, and is the best orchard management pattern for alleviating water and temperature stresses, improving the ecological environment of apple orchards and enhancing apple yields in dry land apple orchards.