Study On The Water Retention And Availability Of Phosphate Of The Starch-based Super Absorbent Polymer

Annual rainfall of Southeast Hubei is abundant, but seasonal drought was more severe. Drought not only limits the crop absorption of moisture, but also reduces the effectiveness of the soil phosphorus. Red soil is zonal soil of Southeast Hubei, which with a strong ability like phosphorus fixation. In order to solve the reduction effectiveness in phosphorus of red soil by drought-induced, people have done a lot of research, but mostly from single to improve soil drought tolerance or fertilizer effectiveness. This research attempts to improve the soil’s water-holding capacity, on the same time improve the effectiveness of phosphate fertilizer.In this study, the test material is red soil sampled from southeastern Hubei. Experiment design is as follows: control(CK, no fertilizer and SAP), starch-based SAP(W, only starch-based SAP applied in the soil), phosphorus loaded with starch-based SAP(WP, applying phosphorus loaded starch-based SAP applied in the soil), phosphate fertilizer(P, only phosphate fertilizer applied in the soil, same phosphorus amount with WP), starch-based SAP plus phosphate fertilizer(W+P), five treatments in total with 3 levels, and 3 repeats. Soil WUE, the soil phosphorus content and the phosphorus content of plants are studied. The main results are as follows:1)SAP or phosphate fertilizer applied in the soil will affect the soil moisture conditions and the water requirements of plant. In the same time of interval, the water required demand of SAP treatment is higher than the treatment of no SAP in the initial test, lower than the treatment of no SAP in the late, the water demand of phosphate fertilizer treatments(WP, P, W+P) has been higher than the treatments of no phosphate fertilizer(W, CK) throughout the trial process. Soil WUE is also affected by SAP, at the beginning of the trial, has lower WUE of SAP treatment, later has higher WUE.2)Phosphorus loaded starch-based SAP applied in the soil will significantly affect the phosphorus content of soil. In the pot experiment, only SAP has no significantly effect on soil phosphorus content, but applying Phosphorus(WP、W+P、P)had significant effects on soil phosphorus content, and the higher the amount of Phosphorus applied in the soil, the more phosphorus content: When rapeseed ripe, WP, W + P, P in high level(level 3), the soil phosphorus contents were 10.90 mg / kg, 9.39 mg / kg, 8.96 mg/kg, significantly higher than those without fertilizer treatment, It is also significantly higher than the low level(level 1)(soil phosphorus contents were 4.71 mg / kg, 4.51 mg / kg, 4.14 mg / kg). In the simulated test conditions, soil moisture content in 20%-40%, phosphorus loaded starch-based SAP(WP) has higher soil phosphorus content than other treatments in most period, and the longer the more obvious differences.3)Phosphorus loaded starch-based SAP applied in the soil will significantly affect the phosphorus content of rapeseed plants. Single SAP applied in the soil has an impact on total phosphorus of rapeseed plants, but the impact was not significant, and phosphorus treatments(include phosphorus loaded starch-based SAP) have significant effect on total phosphorus and Phosphorus cumulative volume of rapeseed plants, the cumulative amount of phosphorus each treatment in the order of WP> W+P> P> W, CK, Level 3> Level 2> Level 1, there were no significant differences among the three levels of SAP treatments, there were significant differences among the three levels of fertilizer treatments. Fertilizer use efficiency by more phosphate fertilizer(level 2 and level 3) was significantly higher than other treatments, and WP’s was higher than W + P’s and P’s, fertilizer use efficiency of WP up to 16.85%, W + P’s and P’s were 14.06%, 11.10%, fertilizer use efficiency of WP, W + P, P under level 1 were 6.40%, 7.12%, 8.48%, significantly below the level 2 and 3.4)SAP or phosphate fertilizer applied in the soil will significantly affect the growth conditions of rapeseed. Fertilizer has significant impact on root diameter, stem length, leaf index of rape, has significant effect on biological yield of rape too, and because the sustained-release phosphate fertilizer of SAP, making the rapeseed biomass of W+P and P higher than other treatments, but the rapeseed biomass of WP is the highest in later test, economic output of WP reached 533.73 kg/hm2, higher than W+P(527.24 kg/hm2) and P(508.05 kg/hm2).