【摘要】 为准确测定包括硝态氮在内的设施土壤有效氮含量，采用碱解扩散法，设置标准土壤中添加NO^-₃-N的加标回收试验和设施次生盐渍化土壤有效氮检测试验，比较了硫酸亚铁和锌-硫酸亚铁2种还原剂对NO^-₃-N的还原效果。结果表明，硫酸亚铁对NO^-₃-N还原作用不明显；锌-硫酸亚铁还原能力相对较强，但不完全，加100和250 mg/kg NO^-₃-N标准溶液，回收率只有71.3%和70.9%。以锌-硫酸亚铁作还原剂，对设施土壤有效氮含量检测同样表明锌-硫酸亚铁只能还原部分NO^-₃-N,两种设施土壤中的硝态氮还原率分别为63.5%和64.8%。建议设施土壤有效氮含量用不加还原剂测得的碱解氮与紫外分光光度法测得的NO^-₃-N之和表示，可有效解决碱解扩散法测定过程中使用的还原剂对NO^-₃-N还原不完全的问题。更多还原

【Abstract】 Based on alkali hydrolysis and the Conway’s diffusion technique, the experiment compared two routine determination methods of soil available nitrogen, which differenced in the type and amount of reductants. Through a standard addition test with a certified reference material of soil（HTSB-1） and a verification test with two greenhouse soils, FeSO₄ and a mixture of Zn and FeSO₄ showed apparently different reducing efficiency. The measured results of soil available nitrogen had no obvious difference, no matter whether FeSO₄ was added, which indicated that nitrate was hardly reduced when using FeSO₄ as the only reductant. On the contrary, the mixed reductants of Zn and FeSO₄ showed relatively strong reducibility. For the spiked nitrate nitrogen at 100 mg/kg and 250 mg/kg, the recovery rates reached to 71.3% and 70.9%, respectively. For the two greenhouse soils, which contained 286 mg/kg and 180 mg/kg nitrate nitrogen, respectively, the mixture had the reducing rate of 63.5% and 64.8%. Therefore, neither of the two reductants was suitable for nitrate-rich greenhouse soils, due to their unsatisfying reducing capacity. It was suggested to use a reductant-free strategy to get the accurate content of greenhouse soil available nitrogen to measure separately the alkali-hydro nitrogen content without adding any reductants and the nitrate nitrogen content and then to add them together.更多还原