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Vegetables is a year-high cropping index, fertilizer requirement, big investment and a high output of economic crops. Fertilizing vegetable production, a key agronomic measures, but excessive partial nitrogen has become one of the most prominent problem in the current vegetable fertilization. Unreasonable fertilization and lead to the garden soil quality degradation, soil nutrient imbalance, soil microbial community diversity reduce the decline in yield and quality of vegetables. Nitrogen is one of the large number of the most important elements in the process of growth and development of vegetable crops. Soil nitrogen mainly to the presence of organic crops absorb nitrogen, inorganic-based, it is inherent in the soil organic nitrogen and organic nitrogen fertilizer was applied to need into inorganic nitrogen in order to effectively absorption by crops, but when inorganic nitrogen is likely to accumulate in the soil through leaching, volatilization and denitrification pathways lead to nitrogen loss and caused ecological problems. Therefore, the study of soil nitrogen the form transformation process, not only conducive to to understand soil nitrogen supply and to determine the reasonable amount of nitrogen, and has great significance for improving nitrogen use efficiency, reduce nitrogen losses and protect the ecological environment. At home and abroad on the impact of environmental factors on soil nitrogen transformation have been many reports, but mostly for moisture or temperature of a single factor, less considering the interaction of moisture and temperature on soil nitrogen transformation, and often the water treatment is set to a constant moisture content, and there are significant differences in the actual situation of the agricultural production, soil moisture fluctuations. Therefore, in this paper a typical garden soil study, frequent irrigation and climate change caused by alternating wet and dry, and the practical problems of low temperature stress for intensive vegetable production, indoor culture test moisture, temperature and other environmental factors on the dish. soil nitrogen transformation in its biological mechanism, designed to provide a theoretical basis and technical support for synergies play nutrients and environmental factors, increase fertilizer use efficiency. The main results are as follows: 1. Indoor culture experiments, three kinds of water status the [Hang dry (CDC, maintained at 30% WHC), constant humidity (CWC maintained at 75% WHC), alternating wet and dry (DW, 30% -75% WHC)] for different types of vegetable plots soil (Chao soil, small silt, bruising mud) on nitrogen transformation and its related activity. The results show that the alternating wet and dry processing (DW) soil nitrate, inorganic nitrogen content higher than Hang dry (CDC) and the constant wet processing (CWC); net mineralization of soil nitrogen mineralization rates, net nitrification and The nitrification rate the size of the performance of DW> CWC> CDC. Urease, asparaginase, glutaminase arylacylamidase, N-acetyl-based-β-glucosaminidase (NAG) activity on the response of the water due to different soil types vary, but the overall trend DW> CWC. Soil days asparaginase, glutaminase, arylacylamidase, NAG and other activity of the enzyme with the soil nitrogen transformation process has a close relationship. Shows alternating wet and dry process conducive soil nitrogen mineralization and nitrification, the impact on soil nitrogen transformation and its impact on soil activity. Adopted the carbon utilization Law (BIOLOG) and phospholipid fatty acids (PLFA) method compares the three kinds of water status [Hang dry (maintain 30% WHC), constant humidity (maintained at 75% WHC), alternate wetting and drying (30% -75 % WHC)] of the different types of vegetable soil (earth tide, small silt, the bruising mud) microbial community diversity. The BIOLOG the results show that the average absorbance values ??(AWCD) of the different types of soil microbial communities there are significant differences in response time, damp soil, small silt, and bruising mud AWCD values ??at 48h, 96h and 60h after With prolonged incubation time gradually increased; performance the small silt AWCD value for DW> CWC> CDC, damp soil and bruising mud in the early stage of incubation DW> CWC, but training late compared to the CWC> DW; constant wet conducive to to maintain microbial community richness and evenness; alternating wet and dry the aquic soil microbial utilization of the the phenolic mixture of sugars and amines, and promote microbial bruising mud amino acids, carboxylic acids, and polymerization substance use. PLFA results found alternate wetting and drying can significantly improve the characterization of fungal and bacterial characteristics relative content of phospholipid fatty acids. Show that moisture conditions significantly affect the microbial community functional diversity and structural diversity, its impact is different due to the different soil types. 3. Incubation test temperature (30 ℃ and 5 ° C), moisture humidistat [to maintain 75% WHC) and alternating wet and dry (30% -75% WHC)] and different fertilizer treatments (control, urea, pigs dung) vegetable soil nitrogen transformation and dynamic. The results showed that the soil nitrate, inorganic nitrogen mineralization amount, nitrification, mineralization rate and nitrification rate performance at 30 ℃> 5 ℃ treatment, alternating wet and dry processing (DW)> the humidistat processing (W) no fertilizer soil inorganic nitrogen content of 30 ° C than 5 ℃ 21.4% urea inorganic nitrogen content DW (244.0 mg · kg -1 ) than the CWC (194.2 mg · kg -1 ) 20.4%; application of the average soil nitrogen mineralization and nitrification of urea to 51.1 mg · kg -1 and 59.5 mg · kg -1 no fertilizer control 3.25 times and 2.68 times the amount of soil nitrogen mineralization and nitrification of organic fertilizer were 2.0 times and 1.8 times the no fertilizer control; temperature, water, fertilizer and soil interaction on factors mineralization nitrification volume has a very significant impact. Visible, high temperature, and wet and dry (DW) alternately beneficial soil nitrogen mineralization and nitrification, reasonable regulation of environmental factors such as moisture and temperature can promote soil nitrogen form transformation process. The adopted the carbon utilization Law (BIOLOG) and phospholipid fatty acids (PLFA) method to study the temperature (30 ℃ and 5 ° C), moisture [humidistat (WHC) and alternating wet and dry to maintain the 75% (30% -75% WHC) ] and different fertilizer treatments (control, urea, pig manure) Hebei aquic soil microbial community functional diversity and structural diversity. No fertilizer control The BIOLOG the results show that the low temperature processing improve AWCD value, indicating that the low temperature increased microbial activity; AWCD rich degrees (S), Shannon index (H), evenness index (E) showed organic fertilizer processing> > urea treatment similar trend; PLFA and Biolog 5 ° C cultivate soil PLFA were significantly higher than 30 ° C to cultivate the soil PLFA content; fertilization significantly improve the content of each PLFA increase the richness of the soil PLFA; principal component analysis of the results showed that the pig manure soil microbial communities to a low-carbon atoms of microbial urea to improve soil Gram-positive bacteria, fungi and actinomycetes content; dominant species, no fertilizer control treatment did not significantly dominant populations. The same temperature, alternating wet and dry handling is not conducive to the maintenance of the microbial community richness and evenness, reduce the polyunsaturated fatty acid content, but increase PLFIA total, characterization of the fatty acid content of fungi, bacteria and actinomycetes, and Gram positive bacteria (G), Gram-negative bacteria (G-), total saturated fatty acids, fatty acid cy17: 0 content of hydroxy fatty acids and cyclopropyl. Visible, fertilization, temperature and moisture and their interaction on the Supply and soil microbial activity, community structure and functional diversity.
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