[Effects of large-grained activated humic acid fertilizer on soil aggregates and organic carbon in apple orchard soil]. / å¤§é¢—ç²’æ´»åŒ–è æ¤é ¸è‚¥å¯¹è‹¹æžœåœŸå£¤å›¢èšä½“å’Œæœ‰æœºç¢³çš„å½±å“.

The new large-grained activated humic acid fertilizer (LAF) can significantly reduce the amount of chemical fertilizer application and stable fruit yield. Understanding its impacts on soil aggregates and organic carbon is an important basis for revealing its role in driving soil structure of apple orchard. There were four LAF treatments: LAF1 (full fertilization, fertilization period and mass ratio (the same below), germination stage: fruit expansion stage: maturity stage=3:4:3), LAF2 (full fertilization, germination stage: fruit expansion stage: maturity stage=2:3:5), LAF3 (fertilizer application reduction by 1/4, germination stage: fruit expansion stage: maturity stage=2:3:5), LAF4 (fertilizer application reduction by 1/3, germination stage: fruit expansion stage: maturity stage=2:3:5); with no fertilization as control (CK). In a four-year pot experiment, we examined the composition, stabi-lity and organic carbon content of soil aggregates under different fertilization treatments. The results showed that: 1) compared with CK, each treatment of LAF increased the content of >2 mm and 2-0.25 mm aggregate by 53.4%-77.5% and 12.3%-17.0%, respectively. The application of LAF significantly increased the content of soil water stable aggregates, and such effects were positively related with application amount. The content of soil water stable aggregate was the highest in the LAF1 treatment. 2) There was no significant difference in aggregate content of each particle size among LAF treatments, with the proportion of aggregate content of 2-0.25 mm particle size being the highest. 3) Compared with CK, all LAF treatments significantly increased the average weight diameter (MWD) and geometric mean diameter (GMD), and reduced the fractal dimension (D). LAF1 treatment had the highest MWD and GMD values, and had the strongest effect on the stability of soil aggregates. 4) Except for LAF4 treatment, the content of soil organic carbon in other LAF treatments was significantly higher than that in CK, and the content of soil organic carbon in LAF2 treatment was the highest. All LAF treatments increased the organic carbon content of soil aggregates with each particle size. LAF1, LAF2, and LAF3 treatments significantly increased the organic carbon of aggregates with particle size >2 mm. Particle size >2 mm had the highest contribution to the total organic carbon. The contribution rate of water stable large aggregate organic carbon to total organic carbon of LAF treatment was significantly higher than that of CK, which was all higher than 66.0%, and that of LAF1 treatment was the highest. In conclusion, the application of LAF enhanced the formation and stability of water stable aggregates and increased organic carbon content of aggregates in apple orchard soil, with the best performance of the full application. The application of LAF could be used as an effective measure to improve soil structure and fertility in apple orchard.

Fabrication of antimicrobial composite films based on xylan from pulping process for food packaging.

A facile and green route is introduced to fabricate antimicrobial composite films in this article from xylan (XL) and hydroxyethyl cellulose (HEC) with citric acid (CA) and polyethylene glycol 400 (PEG-400) as crosslinker and plasticizer, respectively. XL was obtained by precipitating wood hydrolysate (WH) produced during pulping process with ethanol. Antimicrobial activity was constructed by incorporating ß-cyclodextrin/sodium benzoate (ß-CD/NaBz) complex into the composite matrix. The interactions, including hydrogen bonds and covalent bonds, between the polymers were confirmed by FT-IR spectroscopy. Morphology and crystallinity of composite films at different curing time were investigated by AFM and XRD, respectively. The composite film cured for 40 min exhibits tensile strength up to 62.3 MPa and oxygen permeability (OP) as low as 1.0 cm3·µm m-2·d-1·kPa-1. Finally, the antimicrobial test against Staphylococcus aureus reveals superior antimicrobial activity of composite films with complex. In conclusion, the XL/HEC antimicrobial film has great potential in the field of sustainable food packing materials.

Improving the quality of polymer-coated urea with recycled plastic, proper additives, and large tablets.

Polymer-coated urea (PCU) has great potential for increasing crop production and enhancing nitrogen (N) fertilizer use efficiency, benefiting the ecosystem. However, current PCUs are used only in a limited market, and the main obstacle to the wider use of PCUs is high cost compared to that of conventional N fertilizers. In this study, the low cost PCU and large tablet polymer-coated urea (LTPCU) were prepared by using recycling polystyrene foam and various sealants as the coating materials. The structural and chemical characteristics of the coating shells of the coated fertilizers were examined. The N release characteristics of coated fertilizers were determined in 25 °C water under laboratory conditions. The relationship between the N release longevity and the amount of coating material and the percentage of different sealants were evaluated. The results indicated that recycling polystyrene foam was the ideal coating material of the controlled release fertilizer. The polyurethane that was synthesized by the reaction of castor oil and isocyanate was better than the wax as the additive to delay the N release rate of coated urea. The coating material used for LTPCU was 70-80% less than those used for commercial PCUs under the same N release longevity. The cost of the recycling polystyrene foam used for coating one ton of pure N of the LTPCU was about one-seventh to one-eighth of the cost of the traditional polymer used for the commercial PCU. The experimental data showed that the LTPCU with good controlled-release capacities, being economical and eco-friendly, could be promising for wide use in agriculture and horticulture.