Studies On The Preparation Of New Kind Of Slow-release Fertilizers With Water-retaining Property And Its Application On Lawn

Insufficient water resources and low utilization rate of fertilizers are the major problems that need to be solved urgently in China’s agricultural development.In order to improve the usage efficiency of water and fertilizer,in this paper,a kind of low-cost superabsorbent composites with good salt resistance property was synthesized via aqueous solution polymerization method,with acrylic acid(AA)as monomer,natural resources,such as wheat bran,corn bran,tourmaline as additives.And then a kind of slow-release fertilizer with water-retaining property was prepared by chemical reaction method on the basis of preparation of superabsorbent composites.A series of coated slow-release fertilizers with water retaining property were prepared,using urea as fertilizer source,natural resources,such as humic acid,sodium alginate,montmorillonite(MMT),egg shell powder,ethylcellulose(EC)as auxiliary materials.The water absorbency,water retention,sustained release properties and physical properties of soil,the growth of lawn plants were measured and investigated,the specific research contents and conclusions were drawn as following:(1)PAA/wheat bran/tourmaline superabsorbent polymers were synthesized by aqueous solution polymerization method: The absorption ratio of superabsorbent polymers in distilled water,tap water and 0.9% NaCl solution were 720.4 g/g,235.9g/g and 90.3 g/g,respectively,when the content of tourmaline was 5% and the content of wheat bran was 15%.And the absorption ratio in 0.9% NaCl solution were 35.5%and 52.3% higher than the control groups with 0% tourmaline and 0% wheat bran.A series of superabsorbent composites with different contents of tourmaline were applied to the soil,and results showed that when the tourmaline content was 5%,the maximum water holding capacity,capillary water holding capacity,field water holding capacity and pore ratio were 12.3%,10.1%,13.6% and 40% higher than the control group,respectively.PAA/wheat bran/tourmaline/urea slow-release fertilizers with water retaining property was prepared by chemical reaction method: the distilled water absorption ratio was 338.9 g/g,the time of slow-release of urea were more than7 days and 10 days in distilled water and sand respectively when the content of urea was 9%.(2)EC aqueous dispersion was prepared by phase transition method: Theaddition of 3% MMT not only reduced the amount of oleic acid but also increased the stability and dispersion of the aqueous dispersion.Slow-release fertilizer with water-retaining property based on EC aqueous dispersion was prepared by coating method: The absorption ratio of coated slow-release fertilizers with water-retaining property in distilled water was 44.6 g/g,and the time of slow-release of urea in distilled water and sand was 8 days and 20 days respectively,when the intermediate layer was wrapped by fluidized bed process.(3)Urea-humic acid-MMT slow-release fertilizer with water-retaining property was prepared by coating method: The slow-release time in sand reached more than 25 days.The germination rate,germination potential,germination index and vigor index of tall fescue were 29.0%,85.9%,52.4%,36.7% higher than the blank soil group in the plant growth experiment.Urea-humic acid-EC slow-release fertilizer with water-retaining property was prepared using film-forming technology of EC aqueous dispersion.In the plant growth experiment,the content of chlorophyll in the leaves of tall fescue in the group of urea-humic acid-EC slow-release fertilizer with water-retaining property were17.9% and 41.4% higher than the group with equal amount of urea and the group of blank soil,respectively.