有机和常规蔬菜生产系统土壤可溶性有机氮含量及特征

Content and Characteristic of Soil Soluble Organic Nitrogen in Organic and Conventional Vegetable Production Systems

可溶性有机氮(SON)是反映耕作土壤氮矿化能力的重要指标,与氮营养供应能力密切相关。本文通过分析土壤SON、游离氨基酸(FAA)、可溶性全氮(TSN)含量,比较上海郊区有机和常规蔬菜生产系统、设施和露地栽培模式下的土壤氮素含量及特征差异。结果表明:有机蔬菜生产系统土壤中的SON(51.1±10.2 mg·kg^(-1),CV=19.9%)含量均高于常规生产系统(39.8±7.2 mg·kg^(-1) CV=18.0%),并表现为夏季>春季>冬季>秋季。设施栽培土壤的SON和FAA含量均高于露地,不同季节有机露地和大棚FAA含量、FAA/SON和FAA/TN均差异显著(P<0.05),并表现为夏季>春季>冬季>秋季。土壤SON与全氮、全碳、C/N、pH和NO_3^--N均存在显著的相关性。因此,有机和常规生产系统以及设施和露地栽培模式中,土壤SON的含量及其特性存在显著差异。

Soil soluble organic nitrogen （SON） of plastic tunnel and open-field cultivation manners in the suburbs of Shanghai was investigated by measuring the values of SON, free amino acids （FAA）, total soluble nitrogen （TSN） in the soil from organic and conventional vegetable production systems. The results showed the content of SON （51.1±10.2 mg·kg^-1, CV=19.9%） in organic vegetable production systems were significant higher than conventional vegetable production systems （39.8±7.2 g·kg^-1, CV=18.0%） with a decreasing sequence of summer 〉 spring 〉 winter 〉 autumn. Meanwhile, the values of SON and FAA content of the plastic tunnel system were higher than those of open-field system with a significant difference of FAA content, FAA/SON and FAA/TN, which decreased according to the order of summer 〉 spring 〉 winter 〉 autumn. SON was significantly correlated with soil total nitrogen, total carbon, C/N , pH and NO3^--N. Consequently, the contents and characteristics of the soil SON indicated significant difference in organic and conventional production systems, and plastic tunnel and open-field cultivation manners.