Hydrotalcite-like Compounds (ldh) On Soil Phosphorus Behavior Of Experimental Research

The phosphorus in soil Occupies an important position in the agricultural production. The quantity and conformation of phosphorus may affect not only the quality of the soil but the growth of plants. Some wrong actions, such as deforestation, expansion of building and overfertilization, lead to soil degradation and erosion of phosphorus in the soil. At the same time, the phosphorus in soil may flow into the waters with rainwater. Therefore, the increase of phosphorus intensifies the pollution of the rivers, lakes and the underground water. In order to solve those problems, coated fertilizer and all kinds of Soil conditioner were invented and used. But there are some shortcomings on those inventions. In order to provide more solutions solve those problems, LDH that has exchangeable property of anion was synthesized in the lab and was mixed in the soil. Phosphate was adsorbed and desorbed by LDH. As a result, some phosphorus that were fixed in soil and taken by the rainwater are reduced. At the same time, LDH can release phosphorus to soil, regulate the content of phosphorus at the different period, and improve the validity of the phosphorus for the growth of the plant.Test procedures follow like this. First, Mg/Al-CO3-LDH was synthesized on conditions that moore ratio of Mg/Al was 3:1, that solution temperature was 75℃and solution pH was 11. Second, the sample was proved and analysised by XRD and SEM. The results of analysis showed that the sample with better lameller structure and characteristic peak of hydrotalcite is LDH. Third, LDH and phosphorus were fixed into soil. Then readily desorbable phosphorus (RDP) in the soil was determined under conditions of water saturated soil and At the different time. And the result was compared with the soil withou LDH. Forth, some anions were taken as effective factors, Ca2+,Cl-,CO32-,NO3-,SO42-,pH and Humic Acid, and were mixed separately with solution and soil in the lab. So as to research the relationship and effect between LDH and phosphate in solution and soil. Finally, LDH was mixed in experimental fields and was researched the relationship with phosphorus for a long time. And the result was compared with soil without LDH.LDH has the abilities of adsorption and desorption according to the exchangeable property of anion in the LDH. For example, PO43-,HPO42- and H2PO4- may be adsorbed by LDH and were displaced by other active anions such as CO32-. According to the property, It was found that Mg/Al-CO3-LDH can raise the content of the RDP to three times. After put LDH into soil, the results showed that Ca2+,CO32-,pH and Humic Acid have a stronger influence on the adsorption and desorption of LDH than other effect factors in the lab. In fields, the soil had more. RDP in the experimental fields with LDH (L-soil) than the experimental fields without LDH (Soil). The large discrepancy of RDP is about 1.5 times. And RDP was kept for longer time in the L-soil and availability of RDP was improved.The propertiesof LDH in the soil make positive contribution that phorphosus are slow-released and saved, that plants may get more phorphosus which can preserve the soil and reduce eutrophication to water.