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Soil Water Balance Measurement in field scale

Pedosphere 1992年第2期2卷 115-124页

作者： CHEN ZHI-XIONGInstitute of Soil Science, A cademia Sinica, P.O.Box 821. Nanjing 210008 (China)

A 5-year experiment on water balance has been conducted in a flat rainfed wheat field with an area of 66 × 100 m2 in Fengqiu, Henan Province in China. Based on the analysis of semi-variance functions conducted with soil moisture samples taken from 77 nodes of a 10 × 10m2 grid, the soil moisture distribution in the field was structural with a temporal stability. According to the autocorrelation range of the semi-variance function, S sites were selected for the determination of soil water conditions. The characteristic of probability density function of the differences of water storage in two sets of measurements showed that the distribution of these variables in the field was a normal one. The error in the estimation of the average of S random samples was 14% (α = 0.10), and the errors of water consumption by wheat during the experiments were estimated to be 6-13%.Since the experimental field was large enough to avoid any edge effect, the results obtained should tally with the actual situation. Yet the soil system was heterogeneous, so we must follow the principles of statistics and geostatistics when describing the system 's status with the average of the samples.

关键词： field scale water balance

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维普期刊数据库

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field-scale Contaminant Transport Through Soils:Current Understanding and Open Questions

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Pedosphere 1999年第4期9卷 339-350页

作者： ZHANGJIABAO K．ROTH InstituteofSoilScience theChineseAcademyofSciencesNanjing210008China InstituteofEnvironmentalPhysic

Agro-chemical transport processes at different scales are discussed and relevant opening questions areidentified by literature review to make some suggestions concerning the improvement of research methods forfield scale solute transport by aid of evaluation of existing models, and examining transport behaviors of solutein vadose zones on different scales. The results indicate that present research progress and understanding onfield scale solute transport have not yet been enough to guarantee the use of our models for the management offield solute movement. Much more research work needs to be done, particularly, in aspects of high resolutionof spatial structures relevant to the hydraulic and transport properties, explicit numerical simulation of actualstructure on field scale and field measurement corroborated with model development.

关键词： contaminant transport field scale modeling

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维普期刊数据库

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Assessing field vulnerability to phosphorus loss in Beijing agricultural area using Revised field Phosphorus Ranking Scheme

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Journal of Environmental Sciences 2007年第8期19卷 977-985页

作者： LI Qi CHEN Li-ding QI Xin ZHANG Xin-yu MA Yan FU Bo-jie State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Guanting Reservoir, one of the drinking water supply sources of Beijing, suffers from water eutrophication. It is mainly supplied by Guishui River. Thus, to investigate the reasons of phosphorus （P） loss and improve the P management strategies in Guishui River watershed are important for the safety of drinking water in this region. In this study, a Revised field P Ranking Scheme （PRS） was developed to reflect the field vulnerability of P loss at the field scale based on the field PRS. In this new scheme, six factors are included, and each one was assigned a relative weight and a determination method. The affecting factors were classified into transport factors and source factors, and, the standards of environmental quality on surface water and soil erosion classification and degradation of the China were used in this scheme. By the new scheme, thirty-four fields in the Guishui River were categorized as ＂low＂, ＂medium＂ or ＂high＂ potential for P loss into the runoff. The results showed that the P loss risks of orchard and vegetable fields were higher than that of corn and soybean fields. The source factors were the main factors to affect P loss from the study area. In the study area, controlling P input and improving P usage efficiency are critical to decrease P loss. Based on the results, it was suggested that more attention should be paid on the fields of vegetable and orchard since they have extremely high usage rate of P and high soil test of P. Compared with P surplus by field measurements, the Revised field PRS was more suitable for reflecting the characteristics of fields, and had higher potential capacity to identify critical source areas of P loss than PRS.

关键词： phosphorus loss risk assessment field scale revised phosphorus ranking scheme management strategy

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维普期刊数据库

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The Effect of Precision Variable Fertilization on Wheat Based on Prescription Map

The Effect of Precision Variable Fertilization on Wheat Base...

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作者： Guo Jianhua Chen Liping Wang Xiu Chen Tianen Ma Wei Meng Zhijun Fu Weiqiang National Engineering Research Center for Information Technology in Agriculture

Precision fertilization is one of the important measure in precision *** carries out different fertilizer management according to the differences of soil *** core of precision fertilization is to get the largest fertilizer *** this study,we carried out precision fertilization of wheat through the topdressing by intelligent spatial decision,which is based on the variability of soil fertility and spatial variability of production for many years to form prescription map which is to be set up in precision rate fertilizer *** results showed that the yield coefficient of precision fertilization had a decrease of 1.08-1.23 percentage points and the precision fertilization which is decision-making based on spatial variability of soil fertility can save 9.82%of fertilizer than the farmer which uniform fertilization,it also can increase income by 227.35 Yuan per *** fertilization can increase the content of chlorophyll during the green stage to the jointing stage,2-3.79%for chlorophyll a;2.3%for chlorophyll b.

关键词： Variable Fertilization Prescription Map field scale Nitrogen

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