不同园艺生产系统土壤可溶性有机氮差异

运用超速离心技术和KCl浸提法测定了不同园艺生产系统（有机(OS)、转换期(TS)、常规(CS)生产系统）土壤中可溶性有机氮（SON）、溶解性有机氮（DON）、游离氨基酸（FA A）等含量及其与土壤其他性质之间的关系.结果表明：供试土壤SON含量表现为OS>CS>TS，SON含量分别为土壤可溶性总氮（TSN）的42.9%、24.5%和18.4%，分别为土壤全氮的11.1%、11.9%和7.4%；OS、TS、CS生产系统土壤DON含量分别为4.38、1.68和3.26 mg·kg ^-1，分别占TSN的47.9%、22.1%和26.1%，占土壤全氮的2.9%、2.3%和3.6%；而FAA含量则表现为CS>TS>OS，分别占TSN和SON的1%～3%和2%～10%.相关分析表明，TSN、SON及FAA与全氮、全碳、硝态氮、铵态氮等各养分之间均有极显著相关关系（P<0.01）.因此，不同园艺生产系统的管理方式改变了土壤SON的含量及其特性.

Soil soluble organic nitrogen in different horticultural production systems.

By using ultra-centrifugal technique and KCl extraction, the contents of soil soluble organic nitrogen (SON), dissolved organic nitrogen (DON), and f ree amino acid (FAA) in three horticultural production systems, i.e., organic (O S), transitional (TS), and conventional (CS), were determined, and their correla tions with some other soil properties were investigated. The results showed that SON content in the three production systems was in the order of OS>CS>TS, and t he ratios of SON to soil total soluble N (TSN) and total N (TN) in OS, CS, and T S were 429%, 245%, and 184%, and 111%, 119%, and 74%, respectively. T he DON content in OS, TS and CS was 438, 168 and 326 mg·kg-1, occup ying 479%, 221% and 261% of TSN, and 29%, 23% and 36% of TN, respect ively. FAA content occupied 1%〖KG-*2〗-〖KG-*7〗3% of TSN and 2%〖KG-*2〗-〖KG- *7〗10% of SON, and decreased in the order of CS>TS>OS. Correlation analysis sho wed that TSN, SON and FAA were significantly correlated with soil total N, total carbon, NO3--N and NH4+-N. Different management measures of horticult ural production system changed the SON content and its characters.