昆明近郊水稻土、菜园土、大棚土养分调查

2002年5月对昆明近郊水稻土、菜园土、大棚土136个土壤样品进行了测试分析,了解昆明近郊水稻土、菜园土、大棚土3种土壤肥力现状。结果表明:有机质、全N、全P、碱解N、速效P在耕作中不存在缺乏现象。全K3种土壤全层都缺乏。速效K在水稻土、菜园土的20～40cm、40～60cm土层中缺乏,其余土壤的土层不缺乏。

平菇大棚覆土栽培技术

从菇房准备、原料科学配方、菌柱培养、菌柱栽培、棚内管理、适时采收等方面介绍了平菇大棚覆土栽培的技术措施。平菇大棚覆土栽培能灵活地解决水分调控问题,能保持棚内的最佳湿度,有效地提高了平菇的生产质量和产量。此项栽培技术适合在广大农村规模种植,也便于在农村广泛推广。

Salt Contents in Soils Under Plastic Greenhouse Gardening in China

Field experiments were conducted on three main soils, brown soil, meadow soil and cinnamon soil, of Shandong Province to study the effect of plastic greenhouse gardening on soil salt contents. As compared to the open fields, the soil nutrient contents in the fields under plastic greenhouse gardening all increased significantly. The organic matter, quickly available N and P increases were extremely significant and the quickly available K increase was also significant. Along with the nutrient increases the soil salt contents increased clearly in all the soils investigated not only in the top layer but also in the deeper layers, being extremely significant in the 0～10 cm layer and significant in the 10～40 cm layers. The salt contents in the plastic greenhouses had significant correlations with the soil available nitrogen and phosphorous. Soils with longer plastic greenhouse gardening time tended to have more salt. The plastic greenhouse soils contained less CO-3～(2-) and much more NO-3 than the open soils, which indicated a higher influence of human intervention in plastic greenhouses. Among the constituent ions, Cl～(-), NO-3～(-) , Ca～(2+) and Mg～(2+) had positive while HCO-3～(-) had negative significant or extremely significant correlations with total salt, with correlation coefficients being 0.66*, 0.80**, 0.92**, 0.80** and -0.64* , respectively. Nitrate decreased from the top to deeper layers both in the plastic greenhouses and in the open fields. The plastic greenhouse soils contained much more nitrate than the open fields in every layer and even the nitrate contents of the 80～l00 cm layer were still several times those of the top layer in the open fields. The main reason for the salt increases was considered to be the inappropriate fertilization and selective absorption of nutrients by plants in the plastic greenhouses. The methods recommended to avoid soil salt increase in the plastic greenhouses were to apply fertilizers rationally according to the soils, vegetables and fertilizer properties and to adopt a good intercropping or rotation system.

Determination and Analysis of Soil Organic Matter Content in Greenhouses around Lhasa City

The soil organic matter content in the greenhouses around Lhasa City was determined by potassium dichromate-sulfuric acid digestion method. The results showed that the soil organic matter content differed among different soil layers of the greenhouses around Lhasa City, and it was relatively low in the deep soil. The soil organic matter content also differed among greenhouses with different cultivation modes. In the same soil layer, the organic matter content in arched greenhouse was lower than that in semi-arched greenhouse. Among all the soil samples, the samples with organic matter content below the critical value （20 g/kg） accounted for 61.33%, and the samples with higher organic matter content （≥30 g/kg） accounted for 10.64%. The soil organic matter content in the greenhouses of different counties of Lhasa City ranked as Dazi County＇s〉Duilongdeqing County＇s〉Qushui County＇s. In overall, the organic matter content in the soil of greenhouses around Lhasa City was medium-low, and the fertility of the greenhouse soil was at the middle level.

土大棚也能养好蝴蝶兰

笔者养蝴蝶兰多年，都是在温室环境下培养。前年尝试在土大棚中养植，效果也不错。

Analysis of mechanical behaviors of big pipe roof for shallow buried large-span tunnel

A series of researches on mechanical behaviors of big pipe roof for shallow large-span loess tunnel were carried out based on the Wenxiang tunnel in Zhengzhou—Xi'an Special Passenger Railway. The longitudinal deformations of the pipe roofs were monitored and the mechanical behaviors of the pipe roofs were analyzed at the test section. A new double-parameter elastic foundation beam model for pipe roof in shallow tunnels was put forward in Wenxiang tunnel. The measured values and the calculation results agreed well with each other,revealing the force-deformation law of big pipe roof in loess tunnel:At about 15 m in front of the excavating face,the pipe roof starts to bear the load;at about 15 m behind the excavating face,the force of the pipe roof tends to be stabilized;the longitudinal deformation of the whole pipe roofs is groove-shaped distribution,and the largest force of pipe roofs is at the excavating face. Simultaneously,the results also indicate that mechanical behaviors of pipe roof closely relate to the location of the excavation face,the footage of the tunnelling cycle and the mechanics parameters of pipe roof and rock. The conclusions can be reference for the design parameter optimization and the construction scheme selection of pipe roofs,and have been verified by the result of numerical analysis software FLAC3Dand deformation monitoring.

Effects of Arbuscular Mycorrhizal Fungi Communities on Soil Quality and the Growth of Cucumber Seedlings in a Greenhouse Soil of Continuously Planting Cucumber

A pot experiment was performed to determine the effects of arbuscular mycorrhizM fungi （AMF） communities on soil properties and the growth of cucumber seedlings in a degraded soil that had been used for continuous cucumber monoculture in a greenhouse for 15 years. In the experiment, AMF communities （created by combining various AMF species that were found to be dominant in natural farm soil） were inoculated into the degraded soil, and then the soil was planted with cucumber. Inoculation with AMF communities did not affect soil pH but increased soil aggregate stability and decreased the concentrations of salt ions and electrical conductivity （EC） in the soil. Inoculation with AMF communities increased the numbers of culturable bacteria and actinomycetes but reduced the number of fungi. AMF communities increased plant growth, soluble sugar content, chlorophyll content, and root activity compared to non-mycorrhizal or a single AMF species treatments. Improvements of soil quality and plant growth were greatest with the following two communities： Glomus etunicatum ＋ G. mosseae ＋ Gigaspora margarita ＋ Acaulospora lacunosa and G. aggregatum ＋ G. etunicatum ＋ G. mosseae ＋ G. versiforme ＋ G. margarita ＋ A. lacunosa. The results suggested that certain AMF communities could substantially improve the quality of degraded soil.

Effect of Land Use on Soil Phosphorus Sorption-Desorption Under Intensive Agricultural Practices in Plastic-Film Greenhouses

With rapid urbanization and economic growth, Chinese traditional rice-legume production is increasingly replaced by vegetable and horticultural flower production, which could affect soil properties. This study was conducted near Kunming City, Yunnan Province, Southwest China to investigate how soil phosphorus （P） sorption and desorption processes respond to land use changes and to relate P sorption and desorption parameters to soil properties. Soil samples （0-20, 20-40, 40-60, 60-80 and 80-100 cm） were collected from five sites representing four land use types： rice-legume production in a two-crop, one-year rotation （Rice）, vegetable production in open fields （Vegetable）, recent （〈 3 years） conversion from open fields to plastic-film greenhouse vegetable and flower production at two sites （VFCS1 and VFCS2）, and longer-term （〉 10 years） plastic-film greenhouse vegetable and flower production （VFCL）. The changes in land use affected soil pH, electrical conductivity, available N and P and organic carbon content in topsoil and subsoil. In turn, these changes of soil properties influenced soil P sorption capacity. The P sorption maximum （Smax） was affected by land use types, soil sampling depth and their interactions （P 〈 0.0001）. For surface soil, Smax was in the order of Rice （1 380 mg kg-1） 〉 VFCL （1 154 mg kg-1） 〉 VFCS2 （897 mg kg-1） 〉 VFCS1 （845 mg kg-1） 〉 Vegetable （747 mg kg-1）. The lowest Sm^x generally occurred at the surface （except for Rice at 80-100 cm） and increased with depth. The amount of P desorbed during the 8 successive extractions was in the range 23%-44% of sorbed P, and was not affected by land use types or sampling depths. The decreases in Smax suggested that soil P sorption capacity decreased when rice-legume production converted to more intensive vegetation and flower production and caution should be exercised when applying P fertilizer to minimize potential leaching and runoff P loss to the environment.

Effect of Intensive Greenhouse Vegetable Cultivation on Selenium Availability in Soil

Soil properties dramatically change after long-term greenhouse vegetable cultivation, which further affects soil selenium （Se） nutritional status and plant Se uptake. An evaluation of Se availability after long-term greenhouse vegetable cultivation （CVC） can help in better understanding its influential factors under GVC conditions and will also facilitate further regulation of soil Se nutrition in GVC systems. Two typical GVC bases were chosen： one with clayey and acidic soil in Nanjing, southern China, and the other with sandy alkaline soil in Shouguang, northern China. Twenty-seven surface soil samples at the Nanjing base and 61 surface soil samples at the Shouguang base were collected according to cultivation duration and cultivation intensity. Soil properties including soil available Se （PO4^3--Se） and total Se （T-Se） were analyzed. The results showed that soil PO4^3--Se was significantly and negatively correlated with soil Olsen-P, available K （A-K）, and electrical conductivity （EC） at the Nanjing base. At the Shouguang base, however, no significant correlation was found between soil PO4^3--Se and Olsen-P and EC, and soil PO4^3--Se increased with increasing soil organic matter （OM）. Intensively utilized greenhouse vegetable cultivation caused significant changes in soil properties and further affected soil Se availability. Due to different management practices, the dominant factors affecting Se availability varied between the two GVC bases. At the Nanjing base, the dominant influential factor on soil Se availability was soil nutritional status, especially Olsen-P and A-K status. At the Shouguang base, where organic fertilizers were applied at high rates, soil OM was the dominant influential factor.

Effects of Soil Depth and Season Variation on Community Structure of Arbuscular Mycorrhizal Fungi in Greenhouse Soils Planted with Watermelon

The characteristics of arbuscular mycorrhizal fungal (AMF) community structure in various soil depths and growing seasons of watermelon (Citrullus vulgaris) grown in commercial greenhouses in Daxing of Beijing and Weifang and Laiyang of Shandong, China were investigated using both morphological identification and denaturing gradient gel electrophoresis. The sampled soils had been used for continuous greenhouse production of watermelon for 0, 5, 10, 15, or 20 years. Glomus claroideum was the dominant species in the greenhouse soils planted for 5, 10, and 15 years in Laiyang, while Glomus mosseae and Glomus etunicatum were dominant in the nearby open farmland soil. Sorenson's similarity index of AMF community composition ranged from 0.67 to 0.84 in the soils planted for 5 years, and from 0.29 to 0.33 for 20 years among the three locations. Spore abundance, species richness, and the Shannon index were highest near the soil surface (0-10 cm) and decreased with soil depth, and higher in June and October than in August and December. Canonical correspondence analysis showed that available P and the number of years that soil had been used for greenhouse production were the main factors contributing to the variance of AMF community composition. It was concluded that the community structure of AMF was mainly influenced by soil available P and planting time of watermelon as well as by soil depth and seasonal variation in the commercial greenhouse.

Short-Term Responses of Nitrogen Mineralization and Microbial Community to Moisture Regimes in Greenhouse Vegetable Soils

Soil drying and wetting impose significant influences on soil nitrogen (N) dynamics and microbial communities. However, effects of drying-wetting cycles, while common in vegetable soils, especially under greenhouse conditions, have not been well studied. In this study, two greenhouse vegetable soils, which were collected from Xinji (XJ) and Hangzhou (HZ), China, were maintained at 30% and 75% water-holding capacity (WHC), or five cycles of 75% WHC followed by a 7-day dry-down to 30% WHC (DW). Soil inorganic N content increased during incubation. Net N mineralization (Nmin), microbial activity, and microbial biomass were significantly higher in the DW treatment than in the 30% and 75% WHC treatments. The higher water content (75% WHC) treatment had higher Nmin, microbial activity, and microbial biomass than the lower water content treatment (30% WHC). Multivariate analyses of community-level physiological profile (CLPP) and phospholipid fatty acid (PLFA) data indicated that soil moisture regime had a significant effect on soil microbial community substrate utilization pattern and microbial community composition. The significant positive correlation between Nmin and microbial substrate utilization or PLFAs suggested that soil N mineralization had a close relationship with microbial community.