As a natural macromolecular organic matter, humic acid has various effects on soil, the most critical of which is to regulate soil enzyme activity. The effect of humic acid on urease is an important aspect of its influence on soil enzymes. Studies have shown that humic acid can inhibit soil urease activity in the early stage of addition, reduce the hydrolysis rate of urea, thereby reducing the volatilization of ammonia, the hydrolyzate product; but in the later stages of addition, it can stabilize urease activity, allowing urea to continue to be converted into ammonia at a relatively stable rate to supply plants. grow.
In addition, the effects of humic acid on other enzymes include:
(1) In soil containing a large amount of organic matter, humic acid can strongly inhibit the activities of urease, acid phosphatase, and N-acetylglucosaminidase;
(2) Studies have shown that applying humic acid compound fertilizer to cinnamon soil where rapeseed is grown can increase soil alkaline phosphatase activity and catalase activity more than ordinary compound fertilizer, thereby activating phosphorus in the soil and increasing the effective Phosphorus content;
(3) It was confirmed through plot experiments that humic acid has the effect of increasing soil acid phosphatase and sucrase activities;
(4) Research shows that the combined application of humic acid and fertilizer has an effect on improving the activities of catalase, dehydrogenase and alkaline phosphatase in the soil, and as the amount of humic acid added (10~40 kg/hm2) increases , the effect first increases and then weakens.
In summary, humic acid can achieve its role in promoting crop growth by regulating soil enzyme activity, providing a good environment for plant root growth and the preservation of fertilizer nutrients.