Effects Of Humic Acid Phosphate Fertilizer On Growth And Development Of Tomato,phosphorus Transformation And Availability

In the process of phosphate fertilizer production,adding humic acid to produce humic acid value-added phosphate fertilizer can improve fertilizer efficiency and promote crop growth.Studies on humic acid added phosphate fertilizer mainly focus on the influence of humic acid structure and function on phosphorus availability,but few studies on the regulatory effect of phosphorus fertilizer structure and the synergistic mechanism of microorganisms.Therefore,this study set up humic acid phosphate fertilizer treatment with different combination processes,namely physical blending of humic acid phosphate fertilizer（HA+P）,chemical synthesis of humic acid phosphate fertilizer（HAP）,commercial humic acid phosphate fertilizer（SHAP）,ordinary phosphate fertilizer（P）and no phosphate fertilizer blank control（CK）treatment,to study the chemical and biological mechanism of increasing the efficiency of humic acid added phosphate fertilizer.It is of great significance to improve the synergistic mechanism of humic acid added phosphate fertilizer.The main innovation results are as follows:（1）SEM and FT-IR characterization showed that there was no structural change during the preparation of HA+P,while HAP showed a network structure,with a larger surface area and more binding sites than HA+P.HAP generated a new absorption peak at 1101 cm^-1 and a new chemical bond-O-formation,which indicates that-OH cleavage in humic acid combines with phosphoric acid to form a phosphate ester（P-O-C=O）structure.（2）SEM-EDS analysis of HA+P and HAP treated dialysis bag residues in pot test showed that the HAP-treated surface showed aggregation and loaded with more soil minerals.FT-IR,¹³C-NMR and other advanced technologies showed that the absorption peak of HAP at1114 cm^-1 disappeared,the content of oxygen-containing functional groups with high activity such as aromatic C-O,carboxyl amide/amide carbon and carbonyl carbon increased significantly,and the content of alkyl carbon,oxy alkyl carbon and aromatic carbon decreased.HAP has more C=O in XPS and 5.62%more H₂PO₄^-in HAP than HA+P treatment.The results showed that after the combination of HA and potassium phosphate,the content of carboxyl and other active functional groups in the complex increased,which could increase the content of soluble phosphate（H₂PO₄^-）in soil,and the available phosphorus content in HAP treated soil increased by 13.8%～47.7%compared with HA+P treatment（P<0.05）.The plant height,stem thickness and aerial biomass of tomatoes treated with HAP increased by 21.3%,15.31%and 61.02%,while the total accumulation of N,P and K nutrients in tomatoes increased by 6.71%,31.13%and 41.40%,respectively,compared with the control treatment.（3）In this experiment,a total of 8 phosphorus-solublizing bacteria that could produce obvious phosphorus-soluble circles were isolated from tomato rhizosphere soil.The phosphorus-dissolving capacity of 8 phosphorus-solublizing bacteria obtained by screening was 30.42～1201.62 mg·L^-1,the HAP1 strain had the highest phosphorus-soluble ability,with a phosphorus-soluble capacity of 1201.62 mg·L^-1.Through sequence alignment,the 8phosphorus solublizing bacteria had high sequence similarity with Burkholderia cepacia,Leclercia sp.and Sporolactobacillus laevolacticus.The microbial structure of soil treated with HAP and HA+P changed,and the diversity of bacterial communities increased.The number of genes encoding phytase and alkaline phosphatase associated with organophosphorus solysis increased by 3.23%and 2.90%in HAP treatment,while HAP promoted soil phytase and alkaline phosphatase activity.The above results showed that phosphorus humate fertilizer could change the soil microbial community structure,improve the utilization of phosphorus by microorganisms,increase the root biomass of tomato treated with HAP by 177.18%,and increase the total root length of the root system by 73.36%.In conclusion,humic acid phosphate fertilizer can form phosphate ester in the process of chemical preparation,reduce the fixation of phosphorus in soil,and complex metal ions in soil to increase the content of soluble phosphate.Humic acid phosphate fertilizer also promoted tomato’s absorption of soil nutrients by changing soil microbial community structure and improving soil enzyme activity related to phosphorus transformation,thus promoting tomato plant growth and nutrient accumulation.