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Infiltration and Salt Leaching Effects due to Sandy Particles Adding on Heavy Saline-Alkali Topsoil, in Hetao Irrigation District
* 1 , 1 , * 2 , 1 , 1
1  College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, China
2  nstituto Politécnico de Coimbra, Escola Superior Agrária, Coimbra; LEAF - Linking Landscape, Environment, Agriculture and Food, Institute of Agronomy, University of Lisbon, Portugal


Introduction: Soil salinization restricts the Hetao Irrigation District (China) agriculture, affecting about 64% of total cultivated land. A common local practice to deal with this problem is to improve the topsoil by adding wind sand.This study deals with this problem, based on laboratory work, analysing its effects on soil infiltration and salt leaching

Material and Methods: Ulat Front Banner site samples of a silty loam saline soil were used, 40cm deep, with 21 g/kg of salinity. Wind sand was use to add in 30cm soil toplayer. The infiltration tests carried out on plastic columns with 9cm diameter and 45cm high, being loaded by soil mixed with aeolian sandy, with 2% to 30% ratio, supplied by a constant hydraulic head. The 30-40cm layer had unchanged soil. To determine the salt leaching in the soil column, soil samples were taken during 15 days to soil salinity measurement.

Results: It was observed an increase of the infiltration rate, from 1.1mm/h to 7.4mm/h (6.6 times more), in responde to the adding of 30% of sandy particles; also that the effect on salt leaching was significant, being observed on top 15 cm layer, after 7 days of infiltration, the salt relative decrease of 25%, 42%, and 55%, relatively to the treatments with 14%, 20% and 30% of sandy particles added, respectively.

Conclusions: The practice of adding sandy particles in the 30cm topsoil has a significant impact on soil infiltration and deep percolation salt leaching. A ratio of 30% of sand allowed an increase of 6.6 times of the infiltration rate, that in turn allowed a decrease about 50% of the soil salinity after one week of infiltration. This results are encouraging and appeal for field studies to assess the impact of field-scale drainage system, and the effects of this soil melioration on agronomical aspects.

Keywords: soil infiltration; salt leaching; soil drainage; heavy saline-alkali soil; sand mixing; water-salt transport; Hetao