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Improved Method for Extracting Nitrites in Soil
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DOI：10.3390/agronomy14020331.png)
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摘要
En 中文
Soil nitrite (NO2-) is an important reactive intermediate in many nitrogen transformation processes, but it is unstable under acidic conditions and may be lost as gaseous N. The canonical extraction method of soil NO2- using a potassium chloride (KCl) solution greatly underestimates its concentration. To reflect the concentration more accurately, we optimized the extraction method of soil NO2- for three agricultural soils differing in soil texture and pH, an alkalic fluvo-aquic soil and acidic Mollisol and Ultisol soils, respectively. Both extractable soil ammonium (NH4+) and nitrate (NO3-) were systematically investigated to optimize the simultaneous extraction of soil inorganic nitrogen. The effects of different extractants (deionized water (DIW), un-buffered 2 mol L-1 KCl, and pH-buffered 2 mol L-1 KCl), shaking time (10 and 30 min), and storage duration of the extracts (stored at -20 degrees C for 1 day, and at 4 degrees C for 1, 3, and 6 days) on the determination of soil inorganic nitrogen were investigated. The results showed that the un-buffered KCl extractant significantly underestimated soil NO2- concentration compared to DIW. The highest recovery of NO2- was obtained by extracting with DIW at 10 min of shaking for all three soils. Compared with DIW, the concentration of NH4+ and NO3- in soil extracted from the KCl solution increased significantly. Furthermore, the soil inorganic nitrogen content of extracts stored at 4 degrees C for one day was closer to the direct measurements of fresh samples than with the other storage methods. Overall, the recommended analysis method for soil NO2- was extraction by DIW, shaking for 10 min, and filtering with a 0.45 mu m filter, while soil NH4+ and NO3- were extracted with a KCl solution and shaken for 30 min. The extract should be stored at 4 degrees C and analyzed within 24 h. Our study provides an efficient extraction method for soil NO2- and supports studies on the biogeochemical nitrogen cycle, e.g., in the investigation of soil nitrous acid (HONO) and nitric oxide (NO) emissions.
Keyword:
soil nitrites
deionized water
potassium chloride
shaking time
storage time
期刊
A
IF:
3.4
论文数:
1.7W
被引数:
5.0W
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Gross N transformation rates and related N2O emissions in Chinese and UK agricultural soils中国和英国农业土壤的总氮转化率和相关的N2O排放
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