Pedosphere 35(6): 1065--1077, 2025
ISSN 1002-0160/CN 32-1315/P
©2025 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Nano-sized humic acid improves phosphate fertiliser efficiency in chilli pepper |
Qizhong XIONG1,2, Shaojie WANG1,2, Xuxiang CHEN1,2, Jianyuan JING1,2 , Yonglin JIN1,2, Hongying LI3, Chaochun ZHANG1, Yuji JIANG4,5, Xinxin YE1,2 |
1 Anhui Province Key Lab of Farmland Ecological Conservation and Nutrient Utilization, Engineering and Technology Research Center of Intelligent Manufacture and Efficient Utilization of Green Phosphorus Fertiliser of Anhui Province, College of Resources and Environment, Anhui Agricultural University, Hefei 230036 (China);
2 Key Laboratory of Jianghuai Arable Land Resources Protection and Eco-Restoration, Ministry of Natural Resources, College of Resources and Environment, Anhui Agricultural University, Hefei 230036 (China);
3 Institute of Soil and Fertiliser, Anhui Academy of Agricultural Sciences, Hefei 230001 (China);
4 State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135 (China);
5 College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002 (China) |
| ABSTRACT |
| Humic acid (HA) prevents phosphorus (P) fixation and promotes P absorption by plants, thereby effectively increasing the efficiency of phosphate fertiliser utilisation. Although nano-sized HA (NHA) might exhibit superior effects compared to conventional-sized HA (CHA), evidence is limited. Therefore, we investigated the effects of CHA and NHA applied with conventional phosphate fertiliser (CHA+CP and NHA+CP, respectively) on chilli pepper biomass, P uptake, and root morphology, as well as soil available P content, and evaluated CHA, NHA, and their residues in the soil for differences in specific surface area, functional groups, molecular weight distribution, and surface elemental compositions in a 40-d pot cultivation experiment. Results showed that the CHA+CP and NHA+CP treatments significantly increased pepper biomass and P uptake by 15.2%–24.7% and 37.9%–49.0%, respectively, compared to the conventional phosphate fertiliser applied alone (CP) treatment (P < 0.05), with NHA exhibiting a greater effect than CHA. This was primarily related to NHA's stronger ability to reduce P fixation than that of CHA. Soil available P content significantly increased by 5.8% and 3.8% in the NHA+CP treatment compared with CHA+CP on days 22 and 40 of cultivation, respectively (P < 0.05). Nano-sized HA contained more small-molecule components and carboxyl groups than CHA, which can more stimulate root elongation and thus promote root P uptake. Furthermore, fertiliser-derived P gradually entered the structure of CHA or NHA during cultivation. The presence of more plant-available forms (e.g., H2PO4- and HPO42-) in NHA compared to CHA also contributed to better regulation of phosphate fertiliser efficacy. In conclusion, NHA is superior to CHA in improving phosphate fertiliser efficiency, making it a potential alternative material for the development of high-efficiency phosphate fertilisers. This presents an excellent opportunity to minimise P resource waste.
Microplastics (MPs), fluoride (FR), and fungicide mancozeb (MZ) are common contaminants in soil. However, there is no information about the combined impacts of MPs, FR, and MZ on tomato plant growth features in the literature. This study aimed to investigate the effects of combined application of MPs, FR, and MZ (both analytical grade and commercial) on the growth and development of tomato plants and metagenomics of rhizosphere soil. A pot experiment was set up in an artificial greenhouse with two sets of treatments. One set was the combined application of MPs, FR, and analytical grade MZ (B2) and a control without the application of MPs, FR, and MZ (W2), and the other set was the combined application of MPs, FR, and commercial MZ (B3) and a control without the application of MPs, FR, and MZ (W3). No detrimental effects of MPs, FR, and MZ were detected on the growth parameters of tomato plants, including the number of leaves and chlorophyll concentration. However, tomato roots showed knot and nodulation-type structures, and metabolomic profiling revealed that combined exposure to MPs, FR, and MZ profoundly reprogrammed the primary metabolism in tomato roots, with marked alterations in carbohydrate and amino acid pathways. Metagenome whole genome sequencing showed that the B2 and B3 treatments profoundly affected soil microbial community composition, diversity, gene abundances, and functional gene variations compared to W2 and W3. Proteobacteria became the dominating phylum in B2 and B3, causing a significant shift in the microbiome. Its abundance soared to 66.7% in B2 and 75.4% in B3, compared to only 35.9% in W2 and 28.9% in W3. On the other hand, Actinobacteria decreased significantly from 55.6% in W2 and 63.8% in W3 to 18.1% in B2 and 9.6% in B3. This study highlights the microbial shifts due to combined application of MPs, FR, and MZ, providing evidence for understanding their environmental risks. |
| Key Words: available phosphorus|fertiliser performance|phosphorus use efficiency|phosphorus fixation|plant growth |
| Citation: Xiong Q Z, Wang S J, Chen X X, Jing J Y, Jin Y L, Li H Y, Zhang C C, Jiang Y J, Ye X X. 2025. Nano-sized humic acid improves phosphate fertiliser efficiency in chilli pepper. Pedosphere. 35(6): 1065-1077. |
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