Study On The Properties And The Utilization Ratio Of Phosphate Fertilizer Of The Synthetic Starch Super Absorbeznt Polymer With Phosphorus

Super absorbent polymer is a new multi-functional polymer material which has a wide range of applications. Most of the existing studies focus on the improvement of synthetic methods and conditions of super absorbent polymer. For fertility-keeping ability of super absorbent polymer, current studies primarily focus on the interaction and the effects between super absorbent polymer, water and fertilizer. The synthesis and study about sustained-release phosphate super absorbent polymer have not been reported. Mainly by improving the synthesis method of super absorbent polymer and adding rapidly-available phosphorus fertilizer in different way, this study aims at synthesizing a starch phosphatic super absorbent polymer with phosphate sustained-release effect. The performance of synthesized super absorbent polymers and the phosphate sustained-release effect have been studied by determination of property indexes and pot experiments. The results are as follows:1. The synthesized super absorbent polymer has good water absorption，water retention and reproducibility. SEM images show that it has irregular three-dimensional network micro-structure. There exist large gaps between the microscopic particles and smaller pores on the single particle which lead to capillary effect. The absorbency of the seven type of synthesized super absorbent polymer is larger than160g/g. Compared with the control sample, the moisture retention of each agent began to show advantage from the fifth day, with no significant difference between each other. In regeneration test, the water absorbency increased gradually with time. The absorbency reached398.53g/g when the agent reached the fifth saturation. Then it started to reduce after that.2. The WP3sample presents the best salt tolerance and the largest dissolution of phosphorus. The salt tolerance test on super absorbent polymers showed that the fluid absorption rate of WP3sample in0.3%NaCl solution was51.95g/g, which is121.60g/g less than the water absorption rate (173.55g/g) in distilled water, a70.07%decrease. In the NaCl solutions with the concentration0.6,0.9,1.2and1.5%, the fluid absorption rates of WP3samples were44.72,35.28,31.81,29.29g/g, respectively. In three different salt solutions, the order of absorbency regarding the WP3sample was Na+>K+>Mg2+. The WPS samples had the highest absorbencies in these three solutions, which reached36.43,42.18,6.71g/g. In the content determination of the phosphorus in dissolution liquid, the content of the dissolved phosphorus in WP3sample was also the highest, which was49g/kg.3. The synthesized super absorbent polymers present excellent phosphate sustained-release effect. The pot experiment showed that:in the early period of the experiment (the30th day after the emergence), the application of single phosphate had the best performance—the content of phosphorus in plants was obviously higher than it under the application of WP3agent and the mix of agent and phosphate (WPO+P). However, in the middle and late period of the experiment (the60th day after the emergence to the end of the experiment), the content of phosphorus in plants was obviously lower than it under the application of WP3agent and the mix of agent and phosphate (WPO+P). This means that, at the early stage of the planting, the fertilization with single phosphate had the best effect for the absorption and utilization of the plants. Yet as time goes on, under the effect of watering, the leaching and immobilization of phosphorus was strong without the super absorbent polymer, which resulted in the bad absorption of the plants. The difference of the WP3and WPO+P on fertilization was unobvious during each period, which indicated that they had the similar effect on plant absorption at most of the time, with WP3performed better occasionally probably due to temperature and moisture.4. The phosphorus loaded super absorbent polymer significantly affects the level of rapidly-available phosphorus in the soil. At the30th day after the fertilization of super absorbent polymer or phosphorus, the contents of rapidly-available phosphorus under the treatment of P and WPO+P were obviously higher than those under the treatment of WP3. The content under P treatment was the highest which reaches21.51mg/kg, indicating that directly fertilizing with phosphate was the best way in the early stage of the growing. In all stages that follow, the content of rapidly-available phosphorus under the treatment of P and WPO+P decreased gradually. While under the treatment of WP3, the content level of rapidly-available phosphorus remained constantly. It is still14.72mg/kg even at the150th day after the fertilization of super absorbent polymer or phosphorus, which was significantly higher than those under the other two treatments. This demonstrated that the synthesized phosphorus loaded super absorbent polymer exhibited great phosphate sustained-release effect.5. The fertilization of phosphorus loaded super absorbent polymer improves the productivity of the rape plant. As the elongation of the growing time of the rape, the dry weight of the rape under the treatment of WP3super absorbent polymer was gradually larger than those under other treatments, which was coincident with the release result of phosphorus in the plants and the soil, indicating the great phosphate sustained-release effect of our synthesized phosphorus loaded super absorbent polymer.6. The treatment of the phosphorus loaded super absorbent polymer (WP3) can improve the water utilization and phosphorus utilization. The rape water utilization can reach35.782kg·hm-2mm-1during the experimental which used the phosphorus loaded super absorbent polymer (WP3). The water utilization of rape became larger with the increase of the phosphorus. When the content of phosphorus was0.09g/kg, the treatment of WP3had the best performance, which was better than the other two treatments. The order of phosphorus utilization in this experiment was:the mix treatment of super absorbent polymer and phosphorus (WPO+P)> the treatment of phosphorus loaded water-retaining treatment (WP3)> the treatment of single phosphorus. The utilization of phosphorus decreased with the increase of the phosphorus amount. However under the largest phosphorus amount (0.36g/kg), the treatment of phosphorus loaded super absorbent polymer had the highest phosphorus utility ratio.