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ISSN 1811-0231 / ISEIS Publication Series Number P002

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  Paper EIA06-033, Volume 4 (2006), Pages 361-369 = complimentary

Temporal and Spatial Variability of Soil Nitrogen in Wulate and Yichang Irrigation District of Hetao Irrigation Area Inner Mongolia

P. Li*, F. H. Hao and H. G. Cheng

School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875, China. *Corresponding author: winner8lip@163.com.

 

Abstract

The study of spatial variability of nitrogen pollution in soil has significance for field fertilization management and attempts to decrease the loss of nitrogen. After monitoring soil sample data collected from Wulate and Yichang irrigation district in the east of the case study Hetao irrigation area, traditional statistics and ordinary kriging method of geostatistics were used to discuss the spatial distribution of nitrogen in soil (total nitrogen, ammonium nitrogen and nitrate nitrogen) within the depth of 0 to 20cm and the correlation between nitrogen pollution and groundwater level, irrigation amount, and drainage and return water flows. The results indicate that in different irrigation periods the theoretical variogram models of nitrogen in soil are spherical, gaussian and exponential model. The residual sums of squares (RSS) are in the range from 0.009 to 0.1238, showing good fitness to the observed variogram. The nitrogen in soil have strong spatial relativity except the ammonium nitrogen in November; the soil nitrogen content is generally high in northeast and low in southwest in April and July which is closely related to high the elevation in northeast and low in southwest; in the whole area, the total nitrogen and nitrate nitrogen in soil have the highest content in April and the lowest in November, while the ammonium nitrogen in soil keeps the highest content in July, lowest in November. The temporal and spatial variability of nitrogen in soil are greatly controlled by changes of groundwater level, quantity of irrigation, drainage and return water.


Keywords: soil, nitrogen, spatial variability, geostatistics method

 

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