Biological Availability And Mechanism Of Phosphorus Rock Powder

As well known, elemental phosphorus is key and indispensable to agricultural production.it has effect on the output of the crop and certain effect on the toots,And can release the harmfulness of metal.Using enough phosphate can reduce the solubility of the metal. Phosphorus composed many compound,so phosphorus plays a very important role in agriculture. As we know well, the phosphorous in the low-grade phosphorite is difficult to utilize because they strongly combine with minerals, so how to make full use of them, to accelerate their release from the low-grade phosphorite andimprove their effect almost same to the chemical fertilizer have the outstanding significance for the fullusing of China's phosphorite source and the sustainable development of agriculture. Based on this point,a study was proposed and conducted aiming at probing the techniques how to efficiently and fully utilize the phosphorus in low-grade phosphorus. First, the low-grade phosphate rock was remodeled to be phosphorus rock powder, and then three kinds of phosphate rock powder were applied to soil and the effects were investigated and studied systematically. The main results and conclusions are followings:1.Physical and chemical characteristic of phosphorus rock powderThe phosphorus rock powder was tested by the X-ray diffraction (XRD) and the laser granularity. It was verified that more than 90% of the superfine and exiguous phosphorus rock powder(J1) have a less than 16.51μm of particle size, and more than 90% of activated phosphorite powder have a less than 8.64μm of particle size of superfine and exiguous phosphorus rock powde(J2).2.Plant availability of activated phosphorite powderThe conformation and the source of phosphorus fertilizer affected the growth of corn seedling and rape seedling. The results showed that the assimilated rate of nitrogen, phosphorus and pot ash in the seedling were the highest in the treatment of super calcium phosphate, and the next was the treatment of phosphorus rock powde, nevertheless, there were not significant difference between these two kinds of phosphorus fertilizer. Furthermore, outfield experiment showed that the conformation of phosphorus affected the yield of rapeseed and the efficiency of phosphorus fertilizer.3.All three tested phosphorite powder (natural phosphorite powder, superfine and exiguous phosphorus rock powder(J2,J2)) positively affected the physical and chemical properties of brown soil at different degree, In general, the DPR dissolution increased with incubation time in the first 20d, and then the dissolution rate leveled off.4. Effect of three different kinds of low-molecular-weight organic acids on the release of phosphorus were studied in laboratory. The results showed that the organic acids could all improve release of phosphorus powder and the ordinary phosphorite powder.The smaller size of phosphorite powder, the more mobilization of phosphorus, but the release of phosphorus increased not obviously when the size of rock phosphate decreases to a certain degree . the release of phosphorus of phosphorite powder varied with the concentration of organic acids and type. The pH-value increased after organic acids were added. The smaller size of rock phosphate, the more the pH-value increased. The pH-value was increased obviously at low concentration of acid, while it was not significant at high concentration of acid.