CaCl_2和SrCl_2提取土壤氮钾的比较

为了探讨0.01mol L-1 CaCl2和0.02mol L-1 SrCl2提取土壤氮、钾能力的差异,用0.01mol L-1 CaCl2和0.02mol L-1 SrCl2提取14个土壤样品,再分别用流动分析和火焰光度法测定提取液中的硝态氮和亚硝态氮之和和钾的含量,以1mol L-1 KCl和1mol L-1中性醋酸铵提取液作为无机氮和钾的对照提取剂,同时选择部分土壤样品用盆栽试验测定提取数量与土壤氮、钾有效性的关系。结果表明,两种方法和对照方法提取氮和钾数量的相关性均达到p<0.01水平,对照提取剂、0.01mol L-1 CaCl2和0.02mol L-1 SrCl2对于14个土壤的硝态氮和亚硝态氮之和提取含量平均值分别为13.36、15.33和26.62mgkg-1,14个土样的提取钾含量的平均值分别为120.4、33.58和54.24mgkg-1。盆栽试验结果表明,对照提取剂和0.01molL-1CaCl2和0.02molL-1SrCl2提取氮的数量与植物吸氮量的相关性达到p<0.05显著水平,钾的相关性达到p<0.01显著水平。与对照提取剂的氮、钾分别提取相比,SrCl2和CaCl2提取剂均可大大降低样品提取中试剂费用。以上结果表明,0.01mol L-1 CaCl2和0.02mol L-1 SrCl2提取对土壤氮和钾的提取能力均可反映土壤硝态氮和亚硝态氮、有效钾的含量和供应能力,而提取能力以0.02mol L-1 SrCl2为高。

Comparison of CaCl2 and SrCl2 for Soil N and K Extraction

In order to assess the ability of 0.02 mol L-1 SrCl2 and 0.01 mol L-1 CaCl2 as universal extractants for soil nitrogen and potassium,14 soil samples were extracted with these two extractants,nitrate nitrite and potassium in the extracts were determined by flow analysis and flame spectrometry,respectively. Meanwhile 1 mol L-1 KCl and 1 mol L-1 neutral ammonium acetate were as the reference extractants for nitrogen and potassium,respectively. Some of the soil samples were used for pot experiment to determine nitrogen and potassium bioavailabilty. The results showed that extractable nitrate nitrite and potassium by those two extractants correlated with that of reference extractants significantly(p<0.01). Average extractable nitrate nitrite of reference extractant,0.01 mol L-1 CaCl2,0.02 mol L-1 SrCl2 were 13.36,15.33 and 26.62 mg kg-1,respectively,average extractable potassium were 120.39,33.58 and 54.24 mg kg-1,respectively. Extractable nitrate nitrite of the three extractants correlated with plant nitrogen uptake significantly (p<0.05),while extractable potassium correlated were significant at p<0.01 level. Compared with extracting nitrogen and potassium with different solutions,extracting nitrogen and potassium with universal extractants can reduce the cost of reagents considerably. The results suggested that extractable soil nitrogen and potassium with both 0.01 mol L-1 CaCl2 and 0.02 mol L-1 SrCl2 could be used to judge soil nitrogen and potassium concentration and availability,0.02 mol L-1 SrCl2 could extract more nitrogen and potassium than 0.01 mol L-1 CaCl2.