Preliminary study of three methods for simultaneous determination of soil nitrogen and phosphorus
1997
Lim, C.K. | Lau, C.H. | Mohd Napi D.
Nitrogen and phosphorus in soils under Hevea cultivation were determined three chemical extraction procedures which are : (I) H2O2 oxidation followed by digestion with Se + H2SO4 + salicylic acid mixture, (II) digestion with Se + H2SO4 + salicylic acid mixture and (III) digestion with HClO4 + H2SO4 mixture. Analytical results of sixteen randomly selected surface soils showed that P determined by (III) were comparatively higher than those obtained from (I) and (II). Nitrogen values by (I) and (II) are in fairly good agreement and they are generally higher than the corresponding values derived from (III). With the exception of N by (I), mean coefficients of variation of N and P over all samples are less than 8.1% suggesting that the precision and accuracy of the three methods are reasonably good. Linear regression analysis of data obtained from 57 different soil samples showed that P by (I), (II) and (III) are closely interrelated with correlation coefficients., r 0.96. For N, only (I) and (II) are highly correlated (r 0.96). Since total N is routinely determined by (II) and P by (II) is also closely related to total P commonly determined by (III), it appears that (II) can be used for the simultaneous determination and assessment of total soil N and P status. Although (I) can be an alternative, the relatively more simple method (II) is preferred.
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