| Greenhouse vegetable planting has become an important approach to offset the problem of vegetable's lackless in the off-season, and the contradiction of a large population with relatively little land. Nevertheless, the chemical and microbial processes of greenhouse vegetable soil were different from the natural soil, affcected by the factors such as environmental conditions and unscientific human management. In the research, we used the greenhouse vegetable soil from Wuhan suburb as the research object, and studied in a method that combines field sampling analysis and laboratoory incubation, furthermore, analysises dynamics of soil P under the variety of areas, ages, cropping models and profile. We studied dynamics of soil P under different environmental conditions, and compared the impact of these conditions. Acquired the following progress:(1) The results of field sampling analysis showed that greenhouse vegetable soil P from Wuhan suburb was surplus, soil available P(Olsen-P) and microbial biomass P(MBP) were higher than open-air vegetable soil, the differences was significant at esurbs. As the ages increasing, soil P increased overall at inner suburbs. Soil total P(TP) accumulated from 1.92 g/kg to 2.99 g/kg during 20 years. Olsen-P were increased at three samples time(2011.12, 2012.04, and 2012.12), comparatively, MBP increased slightly. In shot, a turning point in the dynamics of soil P appear in the age of 5. Crop rotation model of water spinach-garlic reduced Olsen-P by average 7.93 mg/kg in 2011.12 and inceased by 23.21% in 2012.04 and 40.62% in 2012.12 than model of water spinach-celery, dynamics of MBP were opposite.(2) From Tiessen P fractions, greenhouse vegetable topsoil based on with inorganic P, more than 72.94% of TP, then organic P were less than 22.65%. According to the activity of P, HCl-P were the main of average 85.36%, the second were NaHCO3-P of average 9.32%, Residual-P were the last, only 5.32% of TP. As the extension of age, the tend was the conversion of HCl-Pi and Residual-P to NaHCO3-P.(3) Soil P significantly reduced with the profile from 0 to 100 cm, was higher than open-air vegetable soil at topsoil of 0~40 cm. Under profile of 60 cm, Olsen-P stop migrating down, the same to MBP under 40 cm.(4) The results of laboratoory incubation showed that Soil MBP significantly increased with the temperature of 4? up to 10? and 25?, Olsen-P and CaCl2-P were highest at 10?. MBP have been most impacted on temperature. NaOH-Pi reduced as temperature rise, while HCl-Pi and Residual-P increased. At pH 6.89, soil MBP significantly was highest, while Olsen-P was lowest. Olsen-P was highest at pH 5.30, CaCl2-P significantly increased with soil pH rise. and lower pH enhanced the conversion of HCl-Po to Resin-P or NaHCO3-P, pH 8.34 could promoted the conversion of Residual-P to inorganic P. Soil MBP were highest on light salinization, Olsen-P increased with salinization degree aggravating after 25 days incubation, With heavier salinization, NaHCO3-Pi and NaOH-Po increased, while NaHCO3-Po, NaOH-Pi and C.HCl-Po reduced.(5) The results of the orthogonal experiment showed that factor of pH were greatest influence on soil P, the second were the temperature and the carbon species, and the difference of influence of these facrors reached statistical significant at P < 0.05 level. The factors of humidity and P species were minial influence on soil P. The inorganic P, associated with soil P fractions, affected by factor of pH significantly, however, organic P done little significantly. The second factor was temperature. Comparatively, factors of the interaction of carbon species and humidity has greatest influence on soil organic P, as the same as factor of carbon species. Secondly, factors of temperature and P species had greater influence on soil organic P. |
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