Bioturbation Effects of Benthic Fish on Soil Microorganism of Paddy Field

[Objective]The research aimed to explore the bioturbation effects of benthic fish Misgurnus anguillicaudatus on soil microorganism（microflora,biomass,and special physiological groups） of paddy field.[Method]The experiments were conducted locally and quantitatively in field,using plate count and MPN methods.[Result]In the microflora of paddy soil tested,the quantity of bacteria is the largest,followed by actinomycetes and fungus.Compared with the control paddy fields,in rice-fish paddy fields the quantities of bacteria,actinomycetes and fungus were higher,at significance level P 〈0.05,P 〈0.01,and P 〈0.01 respectively.The microbial biomass C and N in rice-fish paddy fields is remarkably higher than those in control paddy fields,both at significance level P 〈0.01;the microbial biomass P in rice-fish paddy fields is higher than that in control paddy fields,but at significance level P 〈0.05.Benthic fish promotes the growth of soil azotobacter,cellulolytic bacteria,nitrobacteria,sulfur bacteria,and ammonifying bacteria,restricts the reproduction of nitrate reducing bacteria and sulfate reducing bacteria.[Conclusion]The benthic fish had important effects on microflora,microbial biomass,and special microorganism physiological groups of paddy soil,improves the living conditions of soil microorganisms,promotes the soil fertility and bio-chemical activity,which is beneficial for improving the supply ability of soil nutrients such as N,P,S,as well as the efficiency of nutrient utilization.

Bioturbation Effects of Branchiura sowerbyi (Tubificidae) on the Vertical Transport of Sedimentary Particles in Paddy Field

[Objective] The research aimed to investigate the bioturbation effects of Branchiura sowerbyi （Tubificidae） on the vertical transport of sedimentary particles in paddy field,and explore the bioturbation effects and mechanism of benthic Annelida in coupling process of benthic-pelagic interface.[Method]Using chemically stable glass beads as tracers,the vertical transport of sedimentary particles in paddy field was analyzed comparatively with and without B.sowerbyi.[Result]After 10 days＇ bioturbation of B.sowerbyi,41.3% of the glass beads on the surface of sedimentary particles were transferred downward to the maximum depth of 9.4 cm,and the vertical transportation rate of sedimentary particles was 1.370×10-3/（g·cm2·d）. 25.8% and 17.3% of glass beads at a depth of 6 cm were transferred upwards and downwards respectively after bioturbation,to the maximum depth of 5.2 and 2.7 cm respectively,and the vertical transportation rates of sedimentary particles were 8.557×10-4 and 5.738×10-4/（g·cm2·d） respectively.[Conclusion]The sedimentary particles on the surface and deep layer of the paddy field were vertically shifted by the physical activities of B.sowerbyi,thus changed the sedimentary environment.

The Effects of Increasing Production of Endophytes Phomopsis B3 on Rice

After insufflating extended endophytes phomopsis B3 ferment diluent on seedling bed of rice, the effect of microbial inoculum on rice growth was studied. The investigation result of seedlings before transplanting seedling showed that leaf age,the number of green leaves,the number of tiller of individual plant and the weight of per 100 fresh plants in microbial inoculum treatment group increased 0.11,0.12 ,0. 03 and 2.6 g respectively compared with those of control group. 20 days after transplanting, increased tiller number in microbial inoculum treatment group was 55 500 hm^2 more than that in control group. 30 days after transplanting, tiller number in microbial inoculum treatment group was 42 000 hm^2 more than that in control group. In harvest season, the yield ,weight of I 0130 grain and seed-setting rate increased 300 kg/hm2, 0. 7 g and 0. 23% respectively compared with these in control group. The result of preliminary study demonstrated that microbial inoculum confected by endophytes phomopsis B3 could increase the number of strong seedling and yield.

Bioturbation Effects of Benthic Fish on the Phosphorus Dynamic in Overlying Water of Paddy Field

[Objective]The research aimed to investigate the bioturbation effects of benthic fish Misgurnus anguillicaudatus on phosphorus dynamic in overlying water of paddy field,as well as to explore the bioturbation mechanism.[Method]Based on simulation experiment,the phosphorus contents in overlying water were analyzed comparatively with and without Misgurnus anguillicaudatus by the using of ion chromatography and spectrophotometry.[Result]The concentrations of total phosphorus(TP),dissolved total phosphorus(DTP)and particular phosphorus(PP)in bioturbation group had no significant differences with those in control group in initial stage of experiment,and became significantly higher than control group in middle and late stages of experiment(P<0.05). The PP/TP ratios in bioturbation group were bigger than those in control group,the increase of TP concentration in bioturbation group was mainly due to the increase of PP. The ratios of dissolved inorganic phosphorus(DIP) to DTP (DIP/DTP) were significantly bigger than those in control group in middle and late stages of experiment(P<0.05).[Conclusion]The benthic fish had bioturbation effects on phosphorus in overlying water of paddy field,which increased the available phosphorus for rice growth.

Sugarcane Requirement of Water and Effect of Fertigation on Sugarcane

The sugarcane is a main sugar crop in China. The seasonal drying is one of the problems that influence the improvement of output and quality of sugarcane in China. The experimental results for the water requirement and fertigation of the sugarcane showed, that the distribution of the rainfall in spring, autumn and winter, all could not suit the requirements for sugarcane growth. Detailedly, it can suit that sugarcane requirement of 74.4%, 68.6% and 35.7% respectively at seedling emerging stage, tillering stage and mature stage according to sugarcane growth. The drought has already limited the yield of sugarcane. Application of fertigation can enhance the fertilizer use efficiency, and it is also a water saving technique in sugarcane production.

Effects of Nitrogen Fertilizer Regulation with Straw-return on Wheat Yield and Different Forms of Potassium in the Soil

In order to study the effects of nitrogen fertilizer application methods and nitrogen fertilizer regulation with straw-return on wheat yield and potassium forms in the soil, field experiment was arranged in Pinyuan County, and the effects of the regulation of different ratios of basal to topdressed nitrogen on the yield of wheat and the contents of different forms of potassium in the soil were studied. The re- sults indicated that in the condition of straw-return, the yield of wheat was the high- est after the treatments of the ratios of basal to topdressed nitrogen of 7：3 and 6：4. As to the contents of different forms of potassium, the contents of water-soluble potassium, exchangeable potassium and total potassium treated by the ratios of basal to topdressed nitrogen of 7：3 and 6：4 were the highest, and the differences of non-exchangeable potassium among all treatments were not significant. Under the experiment condition, the ratios of basal to topdressed nitrogen of 7：3 and 6：4 were the best treatments, they can increase the wheat yield and the contents of available potassium and total potassium in the soil.

Real-time Monitoring Scheme of Soil Moisture Content in Paddy Field

The monitoring of soil moisture content in paddy field is one of important parts and contents of regional soil moisture monitoring. But a good monitoring scheme hasn’t been established. A real-time monitoring scheme of soil moisture content in paddy field was put forward from two key links of soil moisture content monitoring and field water-layer monitoring. This scheme could meet the alternative monitoring requirements of soil moisture content in water layer and none-water layer. It had a good maneuverability and could provide references for practical work.

贺贻孙生卒年小考

明末清初著名文人贺贻孙的生卒年未详,可通过其《水田居文集》中若干文献考得其确切生年及大致卒年,为1603至1685后不久。

The Effect of Three New Fungicides against Rice Sheath Blight in Field Experiment

[Objective] The aim was to study the effect of three new fungicides against rice sheath blight in field experiment. [Methods] The experiment set up 7 treatments with three times of repetition and designed by random grouping. By using 5 sampling points in each plot, and investigating continuous 4 holes of each point, total plants, diseased plants and disease degrees were recorded. Then disease index and control efficiency were calculated, and variance analysis was carried out. [Results] 300 or 450 ml/hm^2 azoxystrobin ＋ difenoconazole 325 g/L SC had better control efficiency to rice sheath blight and had no phytotoxicity effect, we should use it at the initial disease stage and continuously spray 2-3 times. [Conclusion] The experiment provided a theoretical basis for controlling rice sheath blight using fungicides.

Effect of Irrigation on Groundwater Dynamic Change in the Typical Irrigated Area of Qinghai Province

Under the influence of the natural and human factors, water table of irri- gated area Changes frequently, but it is mainly affected by irrigation water infiltration replenishment during the irrigation. 5 groundwater observation wells were constructed in experimental plot of the Daxia irrigated area to carry out the experiment of the effect of irrigation on groundwater dynamic change in this research. The results showed that the groundwater stage dynarnic change rule of spring and seedling irri- gation stage in the typical plot was fit to the hydrological geology condition of grade- I terrace of Huangshui river valley. On the whole, lateral canal water direction formed a line effect. The No. 1 and No. 2 observation well were the closest to the lateral canal, which received more supplies, and the water level was the highest; the No, 3 observation well took the second place; The No. 4 and No. 5 observation well accepted least supplies, and the water level was the lowest. The rangeability of water table of spring irrigation period was significantly higher than that of seedling irrigation period, this is mainly due to the difference value of intake water volume and drainage water volume of spring irrigation phase was significantly higher than the seedling irrigation phase.

The Estimation of Cultivated Land Threshold Value in Hotan Oasis

[Objective] Water shortage is a key natural factor limiting arid economic development and ecological security.However,the large-scale land reclamation against natural laws has been speeding up water consumption,and the ecological water use which is the primary condition for maintaining ecological security was squeezed.Moreover,the fragile oasis ecosystem would be destroyed dramatically.In order to maintain ecological security,it is urgent to evaluate the threshold value of cultivated land.[Method] The method of water-soil balance was used to evaluate the threshold value of cultivated-land on the premise of allocating downstream ecological water demand.[Result] Under the frequency of 75%（P =75 for short） in Hotan River,the threshold value of cultivated-land in Hotan Oasis would be 13.83×10^4,16.78×10^4and 16.50×10^4hm^2in 2010,2020 and 2030 respectively.Under the frequency of 50%（P=50 for short）,the threshold value of cultivated land in Hotan Oasis would be 14.95 ×10^4,18.08 ×10^4and 17.78 ×10^4hm^2in 2010,2020 and 2030 respectively.If effective measures are not taken to control cultivated-land expansion,the cultivated land area will be 2.78×10^4and 5.07×10^4hm^2more than the threshold values of cultivated land at P =75 in 2020 and 2030 respectively.Even if the efficient water-saving technique are adopted,the water requirement of crop use will increase from 19.77×108to 20.82×108and 21.95×108m3during 2010-2030,and then the ecological water use cannot be guaranteed.[Conclusion] The cultivated-land expansion would threaten the ecological security in Hotan River and Tarim River.Therefore,some strict measures should be taken to protect desert-oasis ecotone,an important constituent of oasis ecosystem which has vital role in maintaining the stability of oasis,and to prohibit cultivated-land expansion.

Prediction of Injection-Production Ratio with BP Neural Network

Injection of water to enhance oil production is commonplace, and improvements in understanding the process are economically important. This study examines predictive models of the injection-to-production ratio. Firstly, the error between the fitting and actual injection-production ratio is calculated with such methods as the injection-production ratio and water-oil ratio method, the material balance method, the multiple regression method, the gray theory GM (1,1) model and the back-propogation (BP) neural network method by computer applications in this paper. The relative average errors calculated are respectively 1.67%, 1.08%, 19.2%, 1.38% and 0.88%. Secondly, the reasons for the errors from different prediction methods are analyzed theoretically, indicating that the prediction precision of the BP neural network method is high, and that it has a better self-adaptability, so that it can reflect the internal relationship between the injection-production ratio and the influencing factors. Therefore, the BP neural network method is suitable to the prediction of injection-production ratio.

Effects of Ploughing Astragalus sinicus at Maturity Stage on Rice Yield and Soil Properties of Paddy Field

[Objective] The effects of ploughing Astragalus sinicus at maturity stage as green manure on paddy soil properties were studied to provide references for ad- vancing the green manure production and field sustainable development. [Methods] A three-year field positioning experiment was carried out. In the first year, five differ- ent levels （0, 2.81, 5.61, 8.42, 11.23 t/hm~） of Astragalus sinicus ploughed at matu- rity stage were designed. And in the next two years, the amounts of ploughed As- tragalus sinicus at maturity stage were based on the natural growth amounts of As- tragalus sinicus at maturity stage of the former year in each plot field. The yields of Astragalus sinicus at maturity stage were estimated and ploughed directly before rice transplanting. Rice yield, soil nutrients, biological properties and water-stable aggre- gates of paddy fields were measured as well. [Results] The effective panicles and rice yields increased significantly after ploughing Astragalus sinicus at maturity stage. Meanwhile, the organic acid content in paddy field increased and the activities of soil phosphatases, invertase and catalase were higher. The soil dissolved organic carbon also increased with the increasing application of green manure. However, excess amount of green manure inhibited the soil microbial biomass carbon content. The macro aggregates and micro aggregates gathered to middle aggregates. [Conclusion] As green manure, the use of Astragalus sinicus at maturity stage could improve soil physiochemical and biological properties, improve soil fertility and increase rice yield significantly. But the ploughing amount of Astragalus sinicus at maturity stage before rice transplanting should be less than 8.42 t/hm2 （dry weight.

Research on Modification of Non-limiting Water Range of Soil

[Objective] The paper was to study and modify non-limiting water range （NLWR） of soil. [Method] The water content when total soil water potential was -0.3 MPa or soil mechanical resistance was 0.85 MPa was selected as the lower limit of NLWR to replace the original water content of permanent wilting point or the water content under soil mechanical resistance of 2.0 MPa. NLWR could be calculated us-ing the minimum value of upper limit minus the maximum value of lower limit. [Re-sult] Compared with original NLWR or least limiting water range （LLWR）, the modi-fied NLWR had more practical significance. When Db〉Db-thr, soil physical properties hindered the growth of crops, so the soil should be improved; when Db〉Db-thr, soil physical properties hindered the growth of crops, so-the soil should be improved; wtlen Db〈Db-thr, as long as the soil water content is within NLWR, soil physical properties had no effect on crop growth. NLWR at this time could be used as the basis for irrigation man- agement in farmland. [Conclusion] The study provides theoretical support and scientific basis for relevant researches about evolution rule and regulatory mechanisms of soil physical quality, relationship between soil physical quality and crop growth and yield, water-fertilizer-salt management of soil.

Nitrogen Losses from Flooded Rice Field

A field microplot experiment was conducted during the tillering stage of paddy rice to investigate nitrogen(N) Iosses from flooded rice fields following fertilizer application. After application of ammonium bicarbonate,most of nitrogen in the floodwater was present as NH4-N and its concentration varied widely with time.Concentrations of both NO3-N and NO2-N in the floodwater were low due to the weakened nitrification.Under flooded anaerobic reducing conditions, soil solution concentrations of NO3-N and NH4-N were nothigh, ranging from 0.6 mg L-1 to 4.8 mg L-1, and decreased with soil depth. However, the groundwater wasstill contaminated with NO3-N and NH4-N. Rainfall simulation tests showed that the N losses via runoff inrice fields were closely related to the time intervals between fertilizer applications and rainfall events. Whena large rain fell for a short period after fertilizer application, the N losses via runoff could be large, whichcould have a considerable effect on surface water quality. Both irrigation and N fertilizer application mustbe controlled and managed with great care to minimize N losses via runoff from agricultural land.

Ammonia Volatilization and Nitrogen Utilization Efficiency in Response to Urea Application in Rice Fields of the Taihu Lake Region,China

Ammonia volatilization losses, nitrogen utilization efficiency, and rice yields in response to urea application to a rice field were investigated in Wangzhuang Town, Changshu City, Jiangsu Province, China. The N fertilizer treatments, applied in triplicate, were 0 （control）, 100, 200, 300, or 350 kg N ha^-1. After urea was applied to the surface water, a continuous airflow enclosure method was used to measure ammonia volatilization in the paddy field. Total N losses through ammonia volatilization generally increased with the N application rate, and the two higher N application rates （300 and 350 kg N ha^-1） showed a higher ratio of N lost through ammonia volatilization to applied N. Total ammonia loss by ammonia volatilization during the entire rice growth stage ranged from 9.0% to 16.7% of the applied N. Increasing the application rate generally decreased the ratio of N in the seed to N in the plant. For all N treatments, the nitrogen fertilizer utilization efficiency ranged from 30.9% to 45.9%. Surplus N with the highest N rate resulted in lodging of rice plants, a decreased rate of nitrogen fertilizer utilization, and reduced rice yields. Calculated from this experiment, the most economical N fertilizer application rate was 227 kg ha^-1 for the type of paddy soil in the Taihu Lake region. However, recommending an appropriate N fertilizer application rate such that the plant growth is enhanced and ammonia loss is reduced could improve the N utilization efficiency of rice.

Kinetic Performance of Oil-field Produced Water Treatment by Biological Aerated Filter

The biological aerated filter （BAF） was used to treat the oil-field produced water. The removal efficiency for oil, COD, BOD and suspended solids （SS） was 76.3%-80.3%, 31.6%-57.9%, 8.6.3%-96.3% and76.4%--82.7%, respectively when the hydraulic loading rates varied from 016m·h^-1 to 1.4m·h^-1. The greatest partof removal, for example more than 80% of COD removal, occurred on the top 100cm of the media in BAF. The kinetic .performance of BAF indicated that the relationship of BOD removal efficiency with the hydraulic loadingrates, in biological aerated filters could be described by c1/c1=l-exp（-2.44/L^0.59）. This equation could be used topredict the B OD.removal efficiency at different hydraulic loading rates.

Estimate of Methane Emission from Rice Paddy Fieldsin Taihn Region, China

Methane fluxes from late rice and single cropping rice fields in Taihu region were measured using closedchamber method in 1992 and 1993 and CH_4 emission from this region (total area of paddy soils was about1.88 million hectares, of which 0.63 million hectares are distributed in the south of Jiangsu Province) wasestimated on the basis of the mean CH_4 fluxes observed. The results showed that the mean CH_4 flaxes fromlate rice and single cropping rice field were quite similar under the prevailing cultivation practices in theregion, being around 5 mg CH_4/m￣2/h (4.31-5.31 mg CH_4/m￣2/h for various cultivars of the late rice and3.20-6.22 mg CH_4/m￣2/h for various treatments of the single cropping rice). Total CH_4 emission from paddysoils in the region was estimated to be 0.185-0.359 Tg CH_4 per year. Continuously flooding the soil witha water layer till ripening caused higher mean CH_4 flux; and addition of nitrification inhibitor (thiourea)stimulated CH_4 emission. There was no simple relationship between CH_4 flux and either soil temperature orsoil Eh.

Greenhouse Gas Emissions from Northeast China Rice Fields in Fallow Season

CH4, N2O and CO2 emissions from northeast Chinese rice fields were measured in the fallow season （November to March） to investigate the effects of freezing-thawing on the emissions. Both CH4 emission from and atmospheric CH4 oxidation by the soil occurred, but the flux was small. During the fallow season, rice fields acted as a minor source of atmospheric CH4, which accounted for about 1% of the CH4 emission during the rice growing period. The field was also a substantial source of atmospheric N20, which ranged between 40 to 77 mg m-2 and eu=counted for 40%-50% of the annual N20 emission. The largest N20 flux was observed in the thawing period during the fallow season. Laboratory incubation tests showed that the largest N20 flux came from the release of N20 trapped in frozen soil. Tillage and rice straw application （either mulched on the soil surface or incorporated in the soil） stimulated the CH4 and CO2 emissions during the fallow season, but only straw application stimulated N2O emission substantially.

Effect of Waterlogged and Aerobic Incubation on Enzyme Activities in Paddy Soil

An incubation experiment with soil water content treatments of 0.15 （W1）, 0.20 （W2）, and 0.40 （W3） g g^-1 soil was carried out for two months to investigate the activities of important enzymes involved in C, N, P, and S cycling in a paddy soil from the Taihu Lake region, China, under waterlogged and aerobic conditions. Compared with air-dried soil, waterlogging resulted in a significant decrease （P ≤ 0.05） of fluorescein diacetate （FDA） and /3-D-glucosidase activities, and this effect was enhanced with increasing waterlogging time. Waterlogging also significantly inhibited （P ≤ 0.05） arylsulfatase as well as alkaline and acid phosphatase activities, but did not decrease the activities with the increase in waterlogging time. Short-term waterlogging did not affect urease activity, but prolonged waterlogging decreased it markedly. In contrast, the aerobic incubation （W1 and W2 treatments） significantly increased （P ≤ 0.05） FDA, alkaline phosphatase, and /3-D-glucosidase activities. With aerobic treatments the activities of FDA and alkaline phosphatase increased with incubation time, whereas /3-D-glucosidase activity decreased. A significant difference （P ≤ 0.05） was usually observed between the W1 and W2 treatments for the activities of FDA as well as alkaline and acid phosphatase; however,/3-D-glucosidase and urease were usually not significant （P ≤ 0.05）. No activity differences were observed between waterlogging and aerobic incubation for arylsulfatase and urease.