Active Effect and Impacting Factors of Organic Acid on Red Soil Phosphorus
Red soil has the high capacity of fixed phosphorus,so the content of phosphorus in red soil is very poor.Yunnan red soil treated with oxalic acid and citric acid was tested to study active effect and impacting factors of Red Soil phosphorus.The results showed that：（1） Soil Available phosphorus（AP） value of Red soil after oxalic acid and citric acid treatment was higher than the control;at the same concentration,active effect of oxalic acid on soil phosphate was better than citric acid.（2） With the concentration of organic acid increasing,the active effect on soil phosphorus in Yunnan red soil was also better.But when the concentration of oxalic acid was in the range from 2 mmol L-1 to 10 mmol L-1,the available phosphorus contents decreased,but the trend in citric acid treatments changed in the opposite way.（3） The experiment set the solid-liquid ratios respectively at 1∶1 and 1∶5t,he results showed that 1∶1 had the better effect on release of fixed phosphate than 1∶5.Among the experiment,active effect of citric acid was better than oxalic acid to Al-P,Fe-P,Ca2-P and Ca8-P,but was lower to O-P.
Red soilOxalic acidCitric acidAvailable phosphorus
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