| In recent years, water consumption in city landscaping has increased with the rapiddevelopment of city landscaping and the influence of the arid climate, less rainfall and so on,many lawns,flowers and seedling grow bad due to the water shortage.Meanwhile, lowfertilizer use efficiency and environmental problem with fertilizer leaning have becomeanother prominent problem. In order to solve the two problems and maximize the water andfertilizer use efficiency, Super Absorbent Polymer (SAP) has become the important topic ofwater saving and fertilizer.preserving. In this dissertation, three types of SAP, P(AA-AM)、P(AA-AMPS) and P(AA-AM-AMPS) with different composition and structure,were usedas the tested materials to study their absorbing water and CO(NH2)2,NH4+and K+adsorptionand desorption characteristics by SAP in different solutions, and their recycling useperformance. further research about the interaction between SAP and nutrient throughcolumn-leaching and pot experiment were conducted. The main conclusions were asfollows:The relative water of SAP decreased with the increase of concentrations of CO(NH2)2,NH4+and K+respectively, but the nutrient adsorption capacity increased. The reductionpower function could better characterize the relationship of solution concentration and therelative water absorbency of SAP, Freundlich adsorption model could better characterize theadsorption characteristic.The neutral molecule CO(NH2)2had little influence on waterabsorbing capability of SAP, so the relative water absorpency of SAP declined less inCO(NH2)2solution. The effects of different solutions on the relative water absorpency ofSAP were in the following order: NH4+>K+> CO(NH2)2+NH4++K+.>CO(NH2)2In thecoexistence system of NH4+and K+, the amount of adsorpted CO(NH2)2was less than that insingle system of CO(NH2)2, but the amount of NH4+and K+adsorption were more than thatin single system of NH4+and K+respectively.Three kinds of SAPs performance varied according to the different monomer com--position and structure,the effects of solution concentration on SAP and nutrient adsorption capacity by SAP were in the following order: P(AA-AMPS)>P(AA-AM-AMPS)>P(AA-AM).With the increase of the concentration CO(NH2)2,NH4Cl and KCl, at the early stage, thewater absorption rate of SAP decreased, but the CO(NH2)2, NH4+and K+adsorption rateincreased on the contrary, then flatten out later. The water absorption and nutrient adsor--ption dynamics could be characterized well by First order kinetics equation or Elovichequation.The weight of gel which had adsorbed nutrient increased after desorption, it neededabout2-4days for80%nutrient released,and the nutrient desorption rate of gel with higherconcentration solution was larger. Compare three kinds of SAPs, the water absorption rateexpressed P (AA-AM)> P (AA-AM-AMPS)> P (AA-AMPS); the nutrient adsorption ratestepped up through P (AA-AM), P (AA-AM-AMPS),and then P (AA-AMPS);the nutrientdesorption rate expressed P (AA-AM)> P (AA-AM-AMPS)> P (AA-AMPS).The water absorption and nutrient adsorpency of P(AA-AM)、P(AA-AMPS) andP(AA-AM-AMPS) in deionized water and CO(NH2)2, NH4Cl,KCl solutions were decreasedas the use times rose, the water absorpency of P(AA-AMPS) declined least.Three kinds ofSAP still maintained high water and nutrient absorbency and had good reusability in thesecond and third repeated use,The application of SAP could effectively reduce the leaching of nitrogen and potassiumin the soil, the CO(NH2)2leaching declined most in combination with SAP. Theanti-leaching effect of three kinds of SAP on fertilizer which was affected directly by thewater and nutrient absorbtion ability stepped up through P(AA-AM), P(AA-AM-AMPS),and then P (AA-AMPS).Under middle conditions of water stress, the application of SAP could increase thebiomass of carpet grass（Axonopus compressus (Sw.) Beauv.）and effectively improved thewater and fertilizer use efficiency. It could get a better effect on increasing water andfertilizer use efficiency when SAP used in combination with CO(NH2)2than SAP used incombination with NH4Cl and KCl. |
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