塑料大棚设施菜地土壤次生盐渍化特征

以上海郊区规模化设施蔬菜园艺场为研究对象,监测了不同种植年限和不同种植模式的塑料大棚设施菜地土壤的主要理化性状,筛选了设施菜地土壤次生盐渍化特征指标,分析了不同深度土壤特征指标的变化规律。结果表明,与露天菜地相比,设施菜地土壤酸化、盐渍化、养分累积明显,田间最大持水量和土壤呼吸速率降低;各类种植年限和种植模式的设施菜地表层土壤(0~20 cm)可溶性盐分、硝态氮和全磷含量分别达到4.18 g·kg~(-1)、121.8 mg·kg~(-1)和1.38 g·kg~(-1),分别为对应露天菜地的2.9倍、1.7倍和1.6倍。综合考虑设施菜地和露天菜地土壤主要理化性状的显著性以及设施菜地土壤对作物的障碍影响和对环境的污染风险,选择p H值、可溶性盐分、硝态氮和全磷作为设施菜地土壤次生盐渍化特征指标,并采用土壤相对质量评价法进行评价。设施菜地土壤p H值随着深度的增加而升高,可溶性盐分、硝态氮和全磷则随着深度的增加而递减,其中硝态氮相对质量指数达到3.06;随着设施菜地种植年限的增加,土壤p H值逐步降低,硝态氮、全磷和可溶性盐分逐步累积,其中4~6年棚龄的p H值和可溶性盐分相对质量指数最高,7~9年棚龄的硝态氮相对质量指数最高,10年以上棚龄的全磷相对质量指数最高,茄果连作模式的可溶性盐分和硝态氮相对质量指数最高,叶菜连作模式的全磷相对质量指数最高。

Characteristics of secondary salinization of vegetable soil in plastic film greenhouse

Taking the large-scale vegetable gardens with different cropping durations and cropping modes in Shanghai suburbs as study objects, the main physical and chemical index of vegetable soil were monitored, the characteristic index for soil sec-ondary salinization were selected, and the variation patterns of the characteristic index were analyzed. The results indicated that, compared to the vegetable soil of open field, the remarkable performance of acidification, salinization and nutrient accu-mulation, and the decreasing tendency of filed moisture capacity and soil respiration rate were observed in the vegetable soil of plastic film greenhouse. The contents of soluble salt, nitrate nitrogen and total phosphorus in the vegetable soil (0~20 cm) of plastic film greenhouse reached 4. 18 g?kg-1 , 121. 8 mg?kg-1 and 1. 38 g?kg-1 , which were 2. 9 times, 1. 7 times and 1. 6 times of the contents in the vegetable soil of open field, respectively. Since the significant difference between plastic film greenhouse and open field and the consideration of obstacle effect to crop growth and pollution risk to environmental quality, the index of pH value, soluble salt, nitrate nitrogen and total phosphorus were selected as the characteristic index for the soil sec-ondary salinization, and the soil relative quality evaluation method was adopted as the assessment tool. In the different depth of vegetable soil in plastic film greenhouse, the pH values increased with the soil depth, while the contents of soluble salt, ni-trate nitrogen and total phosphorus followed the reverse pattern, and the relative quality index for nitrate nitrogen achieved the highest value of 3. 06. With the increasing of cropping duration, the pH values in the vegetable soil of plastic film greenhouse decreased gradually, while the contents of soluble salt, nitrate nitrogen and total phosphorus increased progressively. The pH value and soluble salt of 4 ~6 cropping years, the nitrate nitrogen of 7 ~9 cropping years and the total phosphorus of >10 cropping years presented the highest relative quality index, while the soluble salt and nitrate nitrogen of continuous solanaceous vegetables cropping and the total phosphorus of continuous leaf vegetables cropping appeared the highest relative quality index.