Mehlich 3-连续流动分析仪在砖红壤有效磷和有效钾测定上的应用

Simultaneous Measurement of Available Phosphorus and Potassium in Latoso Soil by Continuous Flow Autoanalyzer with Mehlich 3 Extractants

以采自海南省橡胶园的5种母质51个土壤样品为对象,研究了Mehlich3法浸提-AA3型连续流动分析仪（M3-AA3）联合测定砖红壤有效磷（P）和有效钾（K）的可行性。结果表明,M3法提取的有效磷（y）与常规Bray2-P（x）呈极显著相关（y=0.626 6 x＋0.934 1,R2=0.980 6,p〈0.01,n=50）,且M3-P比常规Bray2-P低,但其变幅仍较宽,有利于有效磷水平的分级;M3-K（y）与常规醋酸铵提取态钾（x）亦呈极显著相关（y=1.030 1 x-0.376,R2=0.994 7,p〈0.01,n=51）,且方程斜率接近1,两法测定结果相近;AA3低浓度进样管路同时测定M3-P、M3-K混合标准曲线决定系数R2分别达0.999 9和0.999 7;平均加标回收率分别为98.23%、101.17%;P（4mg/L）、K（5.04 mg/L）混合标准8次重复测定值变异系数均〈0.5%,且经t检验与理论值差异不显著;M3法土壤待测液中P、K含量检出限分别为0.033和0.018 mg/L,线性范围分别为0~7 mg/L和0~8.82 mg/L。说明M3法浸提-AA3联合测定适合于海南橡胶园砖红壤有效磷、有效钾养分的快速测定,3 d可测250~300个样次,提高工效2~3倍。

The content of available phosphorus（P）,potassium（K）of 51samples from acid latoso soils under rubber plantations in Hainan were measured simultaneously by Continuous Flow Autoanalyzer 3 High Resolution（AA3） with Mehlich 3 extractants（M3-AA3）.The results were compared with that of the routine method,Bray 2-P and ammonium acetate-K.The precision and accuracy of the measurement method of M3-P and M3-K simultaneously by AA3 were studied.The results showed that strong correlation was found between Mehlich 3-P（y）and Bray 2-P（x）（y=0.626 6 x＋0.934 1,R2=0.980 6,p〈0.01,n=50）,and the M3-P was lower than Bray 2-P,but the range of M3-P was still wide,and would be benefit for the classification of phosphorus.The M3-K（y）was linearly related with the ammonium acetate-K（x）（R2=0.994 7,p〈0.01,slope=1.030 1,and intercept=-0.376）,with almost the same value.The linear correlation coefficient of P and K mixed standard curve of M3 method reached to 0.999 9 and 0.999 7 respectively sampled from low concentration pipeline,and the average recovery was 98.23%,101.17%,respectively,and the P and K detection limit in soil analytical solution was 0.033 and 0.018 mg/L,the liner scope of M3-P and M3-K was 0~7mg/L and 0~8.82 mg/L,respectively.The average values of P and K mixed standard measured with eight replicates were not different significantly with the theory values（4 mg/L as P and 5.04 mg/L as K accordingly） by t test and the coefficients of variation were less than 0.5%.Therefore M3-AA3 were suitable for the assessment of the available P,K in Latoso soil under rubber plantations in Hainan and 250~300 samples could be measured in three days by AA3（including reagent preparation,sample weighting,sample extraction,etc）,and the efficiency could be improved 2 to 3 times when compared with the routine methods.