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Zhang H.,Shanghai JiaoTong University | Zhang H.,Key Laboratory of Urban Agriculture | Lu Y.,Key Laboratory of Urban Agriculture | Cao L.,Key Laboratory of Urban Agriculture
Fresenius Environmental Bulletin | Year: 2011

Based on the lysimeter method, a long-term fertilization experiment was carried out to investigate the effect of fertilization on paddy soil bacterial diversity. Paddy soil was treated with urea (UT) and mixed fertilization (MT) (20% commercial organic fertilizer and 80% urea). The Polymerase Chain Reaction (PCR) and Denaturing Gradient Gel Elecrophoresis (DGGE) analysis were used to determine the bacterial diversity. The results suggested that with increasing soil depth, bacterial diversity with UT decreased, and with MT in 0-10 cm was the highest but in 10-20 cm was the lowest. The samples in 10-20 and 20-30 cm with MT had significantly higher bacterial diversity than those with UT. The correlation analysis revealed that H and E had significant positive correlation with organic matter content and significant negative correlation with pH in both fertilization treatments. According to PCR-DGGE analysis, there was one specific clone found only in each treatment (#2 in UT, #15 in MT) which had high similarity with Escherichia-Pseudomonas (97%) and Burkholderia cenocepacia (99%), and there were two clones that MT was in dominant position (#5, #16) which had high similarity with Enterococcus faecalis D6 (100%) and Streptomyces ghanaensis (95%). These above results indicated that MT had more positive impact on bacterial diversity in the paddy soil than UT, especially in the depths of 10-20 and 20-30 cm. © by PSP. Source


Zhang H.,Shanghai JiaoTong University | Zhang H.,Key Laboratory of Urban Agriculture | Zhao Z.,Key Laboratory of Urban Agriculture | Yi X.,Technical Center for Food | And 2 more authors.
Plant, Soil and Environment | Year: 2012

Dissolved organic nitrogen (DON) has high bioavailability and is an important source of soil nutrients. In order to determine the concentrations and the composition of DON in different depths (0-30 cm), and provide a theoretical basis for further deep research into the paddy soil nitrogen supply, experiments based on the lysimeter method were carried out to investigate the effect of fertilization on composition and spatial distribution of DON in paddy soil. Paddy soil was treated under chemical fertilization treatment (CT) and mixed fertilization treatment (MT). With methods of PCR-DGGE and HPLC-MS, the results of the experiments suggested that the samples in 10-20 cm and 20-30 cm under MT had significantly higher bacterial diversity than those under CT except in 0-10 cm. DON had a high percentage (63.1-79.9%) in N tot of soil solution. The results of the correlation analysis revealed that DON had a significant positive correlation with organic matter content, Shannon-Wiener diversity index (H') and a significant negative correlation with pH. The possible results of HPLC-MS identification of DON from paddy soil solution were that (a) 3-(4-thiazolyl)-l-alanine; (b) 2-phenylbenzimidazole-5-sulfonic acid; (c) 4-(2, 4-difluorophenyl)-3-nitrobenzene carbaldehyde; (d) fendizoic acid. Source


Zhang H.,Shanghai JiaoTong University | Zhang H.,Key Laboratory of Urban Agriculture | Zhao Z.,Key Laboratory of Urban Agriculture | Lu Y.,Key Laboratory of Urban Agriculture | And 2 more authors.
Fresenius Environmental Bulletin | Year: 2012

In the upper reach of Huangpu River Basin, based on the lysimeter method, the behaviors and fluxes of dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) in rice field leakage were determined, and two 28days incubations under chemical treatment (CT) and mixed treatment (MT) were conducted to investigate the bioavailability of DON and DOC. Based on the trends of DON and DOC concentrations, water samples in 1-7 days as well as 8-28 days were evenly mixed for use in degradation experiments I (DE I) and II (DE II). The results of the experiments suggested that samples under CT had 49.5% higher TN flux and 19.5% higher DON flux than samples under MT, respectively. The trends of DON and DOC concentrations had a rapid increase and decrease in the first 7 days after fertilization, and then stabilized slowly. Rates of DON/TN (total nitrogen) and DOC/TC (total carbon) were around 32.5-91.9% and 14.9-18.6%, respectively. In DE I and DE II experiments, DON28 (degraded DON after 28 days) accounted for 31.9-46.7% of initial DON, whereas DOC28 accounted for 27.8-37.2% of initial DOC, in the two treatments. The rice field leakage had a high degradation rate of DON and DOC, and biodegradation method was feasible as a source control in upper reach of Huangpu River Basin. © by PSP. Source


Zhang J.,Shanghai JiaoTong University | Zhang J.,Key Laboratory of Urban Agriculture | Zhang Y.,Key Laboratory of Urban Agriculture | Cao L.,Shanghai JiaoTong University | Cao L.,Key Laboratory of Urban Agriculture
Communications in Soil Science and Plant Analysis | Year: 2016

Water scarcity and nitrate contamination have caused considerable attention to environmental matters. Water and nitrogen interactions have critical impacts on their use efficiency, plant growth, and quality. In a field experiment, a combination of three water treatments and three nitrogen rates was applied to determine their interactive effects on the growth of spinach. Soil water supply that was too low [W3N1 (the combination of water treatment 3 and nitrogen treatment 1), W3N2] could cause an increase in nitrate content. Oxalate contents would increase when water and nitrogen were either inadequate (W3N0, W3N1) or too high (W2N2). The most profit from spinach was obtained in plots that received water treatment 2 and nitrogen fertilizer 78 kg N ha−1. However, considering nitrogen treatments could affect the nitrate and oxalic acid, application of water treatment 2 and 39 kg N ha−1 nitrogen fertilizer could get better spinach quality. © 2016 Taylor & Francis. Source


Zhang J.,Shanghai JiaoTong University | Zhang J.,Key Laboratory of Urban Agriculture | Sha Z.,Key Laboratory of Urban Agriculture | Zhang Y.,Key Laboratory of Urban Agriculture | And 3 more authors.
Canadian Journal of Plant Science | Year: 2015

Water and nitrogen (N) are important factors that affect crop yield. The objective of this study was to explore the interactive effect of water and nitrogen on biomass production, yield and growth responses, water and nitrogen use efficiency of winter-grown spinach. A field experiment was grown with treatments of varying water (W) and nitrogen (N) levels near Shanghai, China. Leaf area, shoot biomass and height of spinach increased with the application of N in the well-watered treatment. The highest chlorophyll content was found in spinach treated with N2 (170 kg ha−1 nitrogen). A response surface analysis was done on plant height, leaf number, leaf weight, and plant yield of each spinach plant at different water and nitrogen levels. The equation for each of the response surfaces was taken and solved for the mathematical optimum of the curves. Abundant water supply resulted in the highest spinach yield. Yield of spinach increased with N application rates but decreased when the N was excessive. Compared with the low water treatment (W3), a higher N leaching ratio was observed in the high water treatment (W1), regardless of N treatment. With the increase of N application, N use efficiency of spinach significantly decreased, while water use efficiency of spinach increased. In conclusion, water levels between 36.15 cm and 42 cm, and nitrogen applications between 86 and 152.74 kg ha−1 could be recommended as the optimal treatment for spinach growth. Source

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