The identification and quantification of different soil organic phosphorus (P) compounds is crucial for a better understanding of soil P dynamics. Phytic acid (PA) accounts for 50-60% of the total organic phosphorus in soils, thus it is especially important to accurately determine its content using lower cost techniques. Therefore, the aim of the study was to compare two commonly used characterization methods ³¹P NMR spectroscopy and enzymatic hydrolysis assay. The same anion exchange resin water, 0.5 M NaHCO3, 0.1 M NaOH and 0.1 M HCl extracts of tropical wetland topsoils was analyzed by two methods. The results showed that the phytate content determined by ³¹P NMR spectroscopy was higher than that determined by enzymatic hydrolysis assay. This may be attributed to that the extractant of the continuous extraction method also extracts organic matter from soils. Specifically, fulvic acid (FA) and humic acid (HA) can be extracted by strong extractants HCl and NaOH. For the enzymatic hydrolysis method, the effect of soil humus on phytase activity in continuous extract solutions and pros and cons with respect to ionic strength, cultivation time and PA:HA/FA mass ratio were examined. The results showed that extractable soil organic matter inhibits phytase activity, and even at low PA:HA/FA mass ratios, the activity of phytase was reduced by 40-50% compared to the control. Both organic matter and phytase were negatively charged, and the electrostatic repulsion between them affects organic matter polymerization. The hydrophobic action of humus increases with the increase of mass ratio, leading to the blocked electrostatic repulsion between organic matter and phytase, and the formation of polymer affects the active sites on phytase surface. The objective of this study was to measure the inhibition of phytase activity in extract solution and to attempt to establish a link with the quantity and quality of dissolved organic matter.