福建烟区土壤肥力状况

福建烟区 72 2个土壤样品的分析结果表明 ,土壤 p H平均为 5 .0 4.各成分的质量分数为 :有机质 2 8.93 g· kg- 1 、物理性粘粒 (<0 .0 1 mm) 3 3 %、全 N 1 .446g· kg- 1 、碱解 N 1 41 .9mg· kg- 1 、全 P 0 .482 g· kg- 1 、速效 P 2 0 .5 mg· kg- 1 、全 K2 0 .89g·kg- 1、速效 K1 2 2 mg·kg- 1、缓效 K2 94mg· kg- 1、交换性 Ca5 99.3 mg·kg- 1、交换性 Mg2 9.5 3 mg·kg- 1、有效S2 6.8mg·kg- 1、有效 Cu2 .1 1 mg·kg- 1、有效 B0 .2 42 mg·kg- 1、水溶性 Cl- 1 4.7mg·kg- 1 .烟区土壤 p H普遍偏低 ,应重视调节土壤酸度 ;注意适量施用 N肥 ;合理施用 P肥 ,减少土壤固定 ;重视施用 K肥 ;增加 Mg、B营养 ;施用石灰调节土壤酸度的同时应避免影响烤烟对 Mg、B的吸收     

亚里士多德的明智观

在亚里士多德的德性论中,明智占有非常突出的地位,它是欲望所应遵循的正确的逻各斯,是严格意义上的道德德性形成的一个重要因素;明智是一种理智德性,但又与其他的理智德性不同,是一种同善恶相关的,合乎逻各斯、求真的实践品质,是实践理智的德性。     

河北平原水环境状况初步研究

系统调查研究了河北平原水资源的条件和利用状况，包括地表水资源，地下潜水资源和地下深水资源，重点研究了由于各种水资源过量开采所造成的河北平原水环境恶化，主要包括地表水资源的污染，萎缩和由此产生的环境问题；地下潜水资源的过量开采所造成的诸多地质灾害及深层地下水超量开采造成的水位大幅度下降和地面下沉等，针对河北平原的特点和目前存在的突变问题提出了合理利用河北平原水资源和保护其水环境急需解决的问题。     

黄土丘陵区水土保持型生态农业的理论与实践

安塞县纸坊沟小流域通过水土保持型生态农业建设,将农林牧用地比例由1983年的1:0.3:0.5调整到1990年的1:0.98:1.2,使生态环境和农业生产条件得到改善,扭转了整个农业生态系统的恶性循环。年土壤侵蚀模数由1.4万t/km2减少为6500t/km~2,粮食产量达2175～3225kg/hm~2,人均产粮由420.2kg提高到601.5kg,1990年人均纯收入达667元。该文以纸坊沟为例,论述了黄土丘陵区水土保持型生态农业建设的意义、指导思想、结构和功能及实施途径,提出了水土保持型生态农业建设的三个阶段和每个阶段要求达到的指标,为该地区生态农业建设提供了进一步治理开发的意见。     

保水剂的开发及应用进展

保水剂的开发及应用进展赵永贵（河南省科学院生物研究所，郑州４５０００３）水土资源是人类赖以生存和发展的物质基础。如何经济有效地利用土壤水分，克服干旱对植物生长的不利影响，是一项具有国际影响的科学研究课题。美国在６０年代初期首先研制和应用保水剂，作为“...     

优化与模拟耦合模型在水资源合理配置中的应用

随着水资源供需矛盾日益加剧,合理配置已成为实现水资源可持续利用的重要手段,本文系统地阐述了我国水资源配置方面取得的研究和应用成果,分析了常用的两种配置模型——优化模型和模拟模型。结合工程实际,研究优化与模拟耦合在水资源合理配置中的应用,实现了水资源合理配置时间和空间的有机耦合。     

Effect of fungal to bacterial biomass ratio on the relationship between CO2 evolution and total soil microbial biomass

The relationship between the fungal: bacterial biomass ratio and the metabolic quotient (qCO₂) was studied in three different soils. In addition, the effect of the fungal: bacterial biomass ratio on the relationship between CO₂ evolution and the size of the soil microbial biomass was examined. Soil samples were collected from three experimental fields amended with various organic materials (Yatsugatake, Ibaraki, and Tochigi fields). The range of the fungal:bacterial biomass ratio in the Yatsugatake and Ibaraki fields was small (1.54–2.24 and 1.11–1.71, respectively), but it was large in the Tochigi field (1.18–3.75). We found a high negative correlation between this ratio and the metabolic quotient (qCO₂=2.10–0.361 (fungal:bacterial biomass ratio), R=–0.851, P<0.01) in the Tochigi field. Therefore, we suggest tha qCO₂ decreases with an increase in the fungal:bacterial biomass ratio, which may be due to a higher efficiency of substrate C use by fungal flora in comparison with bacterial flora. In the Yatsugatake and Ibaraki fields, there was a high positive correlation between CO₂ evolution and total microbial biomass. In contrast, no correlation was observed between these two parameters in the Tochigi field, probably reflecting the wide range of values for the fungal:bacterial biomass ratio. From the results obtained, we suggest that the fungal: bacterial biomass ratio is an important factor regulating the relationship between CO₂ evolution and the size of the microbial biomass.     

Effect of green manuring,blue-green algae and neem-cake-coated urea on wetland rice (Oryza sativa L.)

Summary A field trial was set up to examine the effect of green manuring, blue-green algae, and neem-cake-coated urea on a rice crop. Summer green manuring using Sesbania aculeata increased the crop yield. Inoculation of blue-green algae increased the rice grain yield when 60 kg N ha^-1 was applied as prilled urea, but the increase in grain yield was greater when 60 kg N ha^-1 was applied as neem-cake-coated urea. The results of the present study show that applications of green manure, neem-cake-coated urea, and blue-green algae are complementary and that the three treatments can be used together in the rice ecosystem. The green manure and the fertilizer treatments had no effect on the algal flora of the soil.     

Interactions between nematodes and microbial communities in a tropical soil following manipulation of the soil food web

The carrying capacity for microflora and nematofauna was manipulated (using a bactericide, a fungicide, manure or a growing millet plant) in a poor tropical soil, in order to identify relationships between the soil microbes and nematodes and to assess the influences of these organisms on nitrogen flux. The experiment was conducted for 4 months in containers under greenhouse conditions, with analyses of soil, nematofauna and microbial characteristics at regular intervals. Manure input and initial bactericide application led to a significant increase in bacterial-feeding and fungal-feeding nematodes of coloniser-persister classes 1 and 2, respectively, whereas high manure input stimulated omnivorous nematodes (i.e. Microdorylaimus rapsus) which became the dominant trophic group. Changes in abundance of the different bacterial-feeding nematode taxa between treatments seemed to be more related to changes in the structure of the microbial communities than to the total amount of micro-organisms, as suggested by the RISA fingerprint analysis of the bacterial communities. Canonical analysis of nematode feeding guilds, combined with soil microbial and mineral nitrogen parameters as well as multiple regression showed that the bacterial-feeding nematodes influenced the inorganic N content in the soil whereas microbial biomass was determined by total nematode abundance and not by any specific trophic group.     

Effects of Sesbania rostrata and Azolla microphylla incorporation on transformation of applied zinc and copper in lateritic rice soils with different flooding regimes

Fixation of Zn and Cu applied to tropical rice-growing lateritic soils rich in Fe-oxides may be reduced if the soils are kept flooded for a few days before their application. There may be a further reduction if such flooding is combined with incorporation of green manures. To investigate this effect, a laboratory experiment was conducted to study the effect of different periods (0 and 15 days) of preflooding combined with (0 and 0.50% of soil weight) Sesbania rostrata and Azolla microphylla incorporation as green manures on the transformation of applied Zn and Cu in two lateritic rice-growing soils. Recovery of added Zn/Cu in DTPA (diethylene triamine pentaacetate)-extractable form was always found to be higher when they were applied after the soils were maintained in a flooded state for 15 days than when applied immediately after flooding; this effect was more prominent in respect of Cu. Contrary to expectations, green manure incorporation along with preflooding caused a significant decrease in recovery of Zn/Cu; the effect, however, showed a decreasing trend as incubation progressed. The effect was more marked with A. microphylla than with S. rostrata, particularly with Cu. Possible causes of such changes and their implications on the Zn/Cu nutrition of rice are discussed. Received: 7 August 1995