A Preliminary Analysis On Vertical Distribution Of Certain Physical And Chemical Properties Of Soil Of Field Scale In Sewage Irrigation Farmland

The North China Plain’s land is fertile and suitable for agriculture in economicdevelopment; it is also an important area for graining production. Although sewageirrigation can solve the shortage of agricultural water in northern China, it makesthe habitat of soil to be polluted in varying degrees. For this reason, knowing physicaland chemical properties of sewage irrigated soil in some spatial variability, which canunderstand the spatial distribution of pollutants intuitively and accurately, and then it willprovide some references for the restoration of degraded soils and integrated control.The thesis carried out experimental work in Niangniangmiao plot of FarmlandIrrigation Research Institute, on an area of42m×7.2m plots in the uniform distributionof fourth sampling method, it applied classical statistical and geostatistical analysismethods, which gave a preliminary analysis to determine soil moisture, pH, organicmatter and available contents of Cadmium in vertical cross-section of space distributionof features in field scale;The main findings are as follows:1.Classical statistical analysis showedthe average of soil moisture and organicmatter increase in varying degrees, the average of pH and available contents of Cadmiumreduce.the coefficient of variation of the four parameters were weakened, soil moistureand pH showed a weak variability, soil organic matter and availableCadmium showed amoderate variability.2. The optimal fitting of semivariance modelshowed that: After irrigation,soilmoisture increased from weak spatial correlation to strong in the cross-section A, andthe related distance decreased; the others changed from weak to moderate, itmeans aincreased variability caused by the random factors. The pH value of cross-sectional A andD changed from strong spatial correlation to moderate; except the cross section A, thesteps had increased. All soil sections of organic matter both in the front and afterirrigation exhibited a strong spatial correlation; the relevant distance of cross-sectional A,B and D increased slightly. Spatial correlation of the available contents of Cadmiumof soil profile Benhanced, step was decreased significantly, and the restskeepped in a strong spatial correlation, step was variable range in degrees.3. Correlationanalysis showed that: soil moisture of section B that in front of theirrigation and the section A and C that after irrigation respectively and positivelycorrelated with soil organic matter and available contents of Cadmium,they had R（2Cd）>R2（OM）;It was significantly negatively correlated with pH.4. Kriging optimal interpolation intuitively reflects the striped distribution pattern ofthe four parameters in vertical profile,some appeared high and low value centers; soilmoisture and pH in the vertical cross sectionexhibited the closer surface,the low value,the soil organic matter and available contents of Cadmium reflected surface ofaccumulation and aggregation.