在湖南农业大学实验基地进行了长达5年的长期定位实验，研究施用90天释放期的聚乙烯包膜尿素对双季稻产量、氮肥利用率、土壤残留无机氮、土壤-植株系统氮平衡和经济效益的影响。本研究共设置了四个不同的施氮肥处理，包括CK（不施氮肥）、U（全量施用普通尿素）、CRU1（全量施用聚乙烯包膜尿素）、CRU2（减氮20%施用聚乙烯包膜尿素）。研究结果表明相比较全量施用普通尿素而言，全量施用控释肥能够分别提高作物产量和氮肥利用率11.0、13.5%。CRU1在晚稻上的产量和氮肥利用率的应用效果要优于早稻。研究结果表明全量施用控释肥可以提高早稻产量6.0%，可以提高早稻氮肥利用率10.2%；提高晚稻产量15.4%；，提高晚稻氮肥利用率13.8%。除此之外，CRU1与CRU2的双季稻产量和氮肥利用率没有明显的差异。此外施用控释肥处理（包括CRU1和CRU2）相较于U有较高的表观土壤残留率和作物表观氮素回收率，同时有较低的表观氮素损失，且CRU2相比较CRUI呈现出较好的的效果。在收获后，控释肥处理（包括CRU1和CRU2）能够维持土壤耕层（0-20 cm）较高的铵态氮和硝态氮浓度，并且能够减少深层土层（40-60 cm）的铵态氮和硝态氮浓度。此外，据估算施用控释肥处理还能获得较好的经济效益。总得来说，施用控释肥要比施用普通肥料在水稻产量、氮肥利用率、土壤-植株氮素平衡、经济效益上表现得更加优越，并且其中减氮施用20%控释肥处理有最优的综合效益。因此，我们认为施用控释肥能够有效解决水稻生产中的氮素管理所面临的挑战。

Polyimide (PI) is a type of important membrane material. A soluble polymer was synthesized from 4,4´-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 2,2-bis[4-(4-aminophenoxy) phenyl] hexafluoropropane (BDAF) by the two-step polymerization method. The polymer was proved to be polyimide 6FDA-BDAF by the Fourier transform infrared (FT-IR), the 1H-NMR and 19F-NMR spectra. An asymmetric membrane was prepared with the synthesized polyimide 6FDA-BDAF, it was porous in the 50 μm height bulk and dense in a 3–5 μm height surface. The membrane was used to separate n-heptane/ thiophene mixtures by pervaporation with sulfur (S) contents from 50 to 900 μg g–1. The total flux was enlarged from 7.96 to 37.61 kg m–2 h–1 with temperature increasing from 50 to 90°C. The membrane’s enrichments factor for thiophene were about 3.13 and dependent on the experimental conditions. The experimental results demonstrated that polyimide 6FDA-BDAF would be a potential membrane material for desulfurization and controlled release of the S-containing fertilizer.

Exploration of soil environmental characteristics governing soil microbial community structure and activity may improve our understanding of biogeochemical processes and soil quality. The impact of soil environmental characteristics especially organic carbon availability after 15-yr different organic and inorganic fertilizer inputs on soil bacterial community structure and functional metabolic diversity of soil microbial communities were evaluated in a 15-yr fertilizer experiment in Changping County, Beijing, China. The experiment was a wheat-maize rotation system which was established in 1991 including four different fertilizer treatments. These treatments included: a non-amended control (CK), a commonly used application rate of inorganic fertilizer treatment (NPK); a commonly used application rate of inorganic fertilizer with swine manure incorporated treatment (NPKM), and a commonly used application rate of inorganic fertilizer with maize straw incorporated treatment (NPKS). Denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA gene was used to determine the bacterial community structure and single carbon source utilization profiles were determined to characterize the microbial community functional metabolic diversity of different fertilizer treatments using Biolog Eco plates. The results indicated that long-term fertilized treatments significantly increased soil bacterial community structure compared to CK. The use of inorganic fertilizer with organic amendments incorporated for long term (NPKM, NPKS) significantly promoted soil bacterial structure than the application of inorganic fertilizer only (NPK), and NPKM treatment was the most important driver for increases in the soil microbial community richness (S) and structural diversity (H). Overall utilization of carbon sources by soil microbial communities (average well color development, AWCD) and microbial substrate utilization diversity and evenness indices (H’ and E) indicated that long-term inorganic fertilizer with organic amendments incorporated (NPKM, NPKS) could significantly stimulate soil microbial metabolic activity and functional diversity relative to CK, while no differences of them were found between NPKS and NPK treatments. Principal component analysis (PCA) based on carbon source utilization profiles also showed significant separation of soil microbial community under long-term fertilization regimes and NPKM treatment was significantly separated from the other three treatments primarily according to the higher microbial utilization of carbohydrates, carboxylic acids, polymers, phenolic compounds, and amino acid, while higher utilization of amines/amides differed soil microbial community in NPKS treatment from those in the other three treatments. Redundancy analysis (RDA) indicated that soil organic carbon (SOC) availability, especially soil microbial biomass carbon (Cmic) and Cmic/SOC ratio are the key factors of soil environmental characteristics contributing to the increase of both soil microbial community structure and functional metabolic diversity in the long-term fertilization trial. Our results showed that long-term inorganic fertilizer and swine manure application could significantly improve soil bacterial community structure and soil microbial metabolic activity through the increases in SOC availability, which could provide insights into the sustainable management of China’s soil resource.