Abstract
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. Although studies have primarily focused on investigating the impact of humic acid’s structure and function on phosphorus availability in humic-acid-added phosphate fertilizers, there is limited research on the regulatory effects of phosphorus fertilizer structure and the synergistic mechanisms involving microorganisms. Therefore, this study aimed to examine the chemical and biological mechanisms underlying the increased efficiency of humic-acid-added phosphate fertilizers by implementing various treatment processes. These processes included physically blending humic acid with phosphate fertilizer (HA+P), chemically synthesizing humic acid phosphate fertilizer (HAP), using commercially available humic acid phosphate fertilizer (SHAP), employing ordinary potassium phosphate fertilizer (P), and implementing a control treatment with no phosphate fertilizer (CK). Investigating the synergistic mechanism of humic-acid-added phosphate fertilizers holds significant importance. The results showed that during the preparation of HAP at high temperature, a new absorption peak appeared at 1101 cm−1, and a new chemical bond -O- was formed. The hydroxyl fracture in humic acid combined with phosphoric acid to form a phosphate ester (P-O-C=O) structure. HAP residues were concentrated on the surface and loaded with more soil minerals. The content of highly active oxygen-containing functional groups—such as aromatic C-O, carboxyl/amide carbon and carbonyl carbon—increased significantly, while the content of alkyl carbon, oxyalkyl carbon, and aromatic carbon decreased. Upon combining humic acid with potassium phosphate, the carboxyl group and calcium ions formed the HA-m-P complex, increasing the content of soluble phosphate (H2PO4−) in the soil by 1.71%. Compared to HA+P treatment, HAP treatment significantly increased the soil’s available P content by 13.8–47.7% (P < 0.05). The plant height, stem diameter, and above-ground biomass of HAP treatment were increased by 21.3%, 15.31%, and 61.02%, respectively, and the total accumulations of N, P, and K nutrient elements were increased by 6.71%, 31.13%, and 41.40%, respectively, compared to the control treatment. The results of high-throughput sequencing showed that the rhizosphere soil of HA+P and HAP treatment was rich in bacterial groups, the soil microbial structure was changed, and the bacterial community diversity was increased under HAP treatment. The number of genes encoding phytase and alkaline phosphatase associated with organophosphorus dissolution increased by 3.23% and 2.90%, respectively, in HAP treatment. Humic acid phosphate fertilizer forms phosphate esters in the process of chemical preparation. After application, the soil’s microbial community structure is changed, and soil enzyme activity related to phosphorus transformation is improved to promote tomatoes’ absorption of soil nutrients, thus promoting tomato plant growth and nutrient accumulation.
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Claims 13
Claim · model-written summary
A new absorption peak appeared at 1101 cm−1 during preparation of humic acid phosphate fertilizer at high temperature.
- Taxon
- tomato
Solanum lycopersicume2 - Treatment
- during the preparation of HAP at high temperaturee1
- Outcome
- absorption peake1
- Value
- 1101 cm−1e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The results showed that during the preparation of HAP at high temperature, a new absorption peak appeared at 1101 cm−1, and a new chemical bond -O- was formed”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
A new chemical bond -O- formed during preparation of humic acid phosphate fertilizer at high temperature.
- Taxon
- tomatoSolanum lycopersicume2
- Treatment
- during the preparation of HAP at high temperaturee1
- Outcome
- chemical bond -O-e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The results showed that during the preparation of HAP at high temperature, a new absorption peak appeared at 1101 cm−1, and a new chemical bond -O- was formed”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
Humic acid combined with phosphoric acid to form a phosphate ester (P-O-C=O) structure.
- Taxon
- tomatoSolanum lycopersicume2
- Compound
- humic acide1
- Outcome
- phosphate ester (P-O-C=O) structuree1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The hydroxyl fracture in humic acid combined with phosphoric acid to form a phosphate ester (P-O-C=O) structure”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
HAP residues were concentrated on the surface and loaded with more soil minerals.
- Taxon
- tomatoSolanum lycopersicume2
- Outcome
- HAP residuese1
- Qualifier
- concentrated on the surface and loaded with more soil mineralse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“HAP residues were concentrated on the surface and loaded with more soil minerals”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
The content of highly active oxygen-containing functional groups increased significantly in humic acid phosphate fertilizer.
- Taxon
- tomatoSolanum lycopersicume2
- Outcome
- content of highly active oxygen-containing functional groupse1
- Direction
- increasede1
- Qualifier
- such as aromatic C-O, carboxyl/amide carbon and carbonyl carbone1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The content of highly active oxygen-containing functional groups—such as aromatic C-O, carboxyl/amide carbon and carbonyl carbon—increased significantly”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
Combining humic acid with potassium phosphate formed the HA-m-P complex.
- Taxon
- tomatoSolanum lycopersicume2
- Treatment
- combining humic acid with potassium phosphatee1
- Compound
- calcium ionse1
- Outcome
- HA-m-P complexe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Upon combining humic acid with potassium phosphate, the carboxyl group and calcium ions formed the HA-m-P complex”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
Combining humic acid with potassium phosphate increased soluble phosphate in soil by 1.71%.
- Taxon
- tomatoSolanum lycopersicume2
- Treatment
- combining humic acid with potassium phosphatee1
- Outcome
- content of soluble phosphate (H2PO4−) in the soile1
- Direction
- increasinge1
- Value
- 1.71%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Upon combining humic acid with potassium phosphate, the carboxyl group and calcium ions formed the HA-m-P complex, increasing the content of soluble phosphate (H2PO4−) in the soil by 1.71%”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
HAP treatment significantly increased soil available P content by 13.8-47.7% compared with HA+P treatment.
- Taxon
- tomatoSolanum lycopersicume2
- Treatment
- HAP treatmente1
- Outcome
- soil’s available P contente1
- Direction
- increasede1
- Value
- 13.8–47.7%e1
- Qualifier
- P < 0.05e1
- Comparator
- HA+P treatmente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Compared to HA+P treatment, HAP treatment significantly increased the soil’s available P content by 13.8–47.7% (P < 0.05)”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
HAP treatment increased rhizosphere bacterial community diversity in tomato.
- Taxon
- tomatoSolanum lycopersicume2
- Treatment
- HAP treatmente1
- Outcome
- bacterial community diversitye1
- Direction
- increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“the bacterial community diversity was increased under HAP treatment”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
Rhizosphere soil under HA+P and HAP treatment changed soil microbial structure.
- Taxon
- tomatoSolanum lycopersicume2
- Treatment
- HA+P and HAP treatmente1
- Outcome
- soil microbial structuree1
- Direction
- changede1
- Qualifier
- rich in bacterial groupse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“the rhizosphere soil of HA+P and HAP treatment was rich in bacterial groups, the soil microbial structure was changed”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
HAP treatment increased the number of phytase-encoding genes by 3.23%.
- Taxon
- tomatoSolanum lycopersicume2
- Treatment
- HAP treatmente1
- Gene
- phytasee1
- Outcome
- number of genes encoding phytase and alkaline phosphatasee1
- Direction
- increasede1
- Value
- 3.23%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The number of genes encoding phytase and alkaline phosphatase associated with organophosphorus dissolution increased by 3.23% and 2.90%, respectively, in HAP treatment”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
HAP treatment increased the number of alkaline phosphatase-encoding genes by 2.90%.
- Taxon
- tomatoSolanum lycopersicume2
- Treatment
- HAP treatmente1
- Gene
- alkaline phosphatasee1
- Outcome
- number of genes encoding phytase and alkaline phosphatasee1
- Direction
- increasede1
- Value
- 2.90%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The number of genes encoding phytase and alkaline phosphatase associated with organophosphorus dissolution increased by 3.23% and 2.90%, respectively, in HAP treatment”
e2“promoting tomato plant growth and nutrient accumulation”
Claim · model-written summary
Humic acid phosphate fertilizer improved soil enzyme activity related to phosphorus transformation in tomato soil.
- Taxon
- tomatoSolanum lycopersicume3
- Treatment
- Humic acid phosphate fertilizere2
- Outcome
- soil enzyme activity related to phosphorus transformatione1
- Direction
- improvede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“After application, the soil’s microbial community structure is changed, and soil enzyme activity related to phosphorus transformation is improved”
e2“Humic acid phosphate fertilizer forms phosphate esters in the process of chemical preparation”
e3“promoting tomato plant growth and nutrient accumulation”
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