The soil–water flow system beneath a cotton field in arid north-west China, serviced by mulched drip irrigation using brackish water | système sol-écoulement d’eau en-dessous d’un champ de coton en milieu aride dans le Nord-Ouest de la Chine, entretenu par une irrigation au goutte à goutte sous bâche utilisant eau eau saumâtre El sistema de flujo agua-suelo debajo de un campo de algodón en el árido noroeste de China, servido por una cobertura de riego por goteo usando agua salobre 中国西北干旱区微咸水膜下滴灌棉田土壤水流系统 Sistema de fluxo da água no solo sob uma plantação de algodão no noroeste árido da China, utilizando rega gota-a-gota com água salobra sob uma tela
2015
Li, Xianwen | Jin, Menggui | Huang, Jinou | Yuan, Jingjing
A field experiment was carried out in southern Xinjiang, China, to reveal soil-water flow pattern beneath a combined plastic-mulch (film) and drip-irrigation system using brackish water. The soil-water flow system (SWFS) was characterized from soil surface to the water table based on observed spatio-temporal distribution of total soil-water potential, water content and electric conductivity. Root suction provided a strong inner sink. The results indicated that SWFS determined the soil salinity and moisture distribution. Drip-irrigation events could leach excess salts from the root zone and provide soil conditions with a tolerable salinity level that supports the growth of cotton. High-salinity strips were formed along the wetting front and at the bare soil surface. Hydrogeology conditions, irrigation regime, climate, plant growth and use of mulch would affect potential sources and sinks, boundary conditions and the size of the SWFS. At depth 0–60 cm, the soil salinity at the end of the irrigation season was 1.9 times that at the beginning. Beneath the mulch cover, the soil-water content in the ‘wide rows’ zone (55 cm between the two rows with no drip line) was higher than that in the ‘narrow rows’ zone (15 cm between the two rows with a drip line) due to the strong root-water uptake. The downward water flow below the divergent curved surface of zero flux before irrigation, and the water-table fluctuation with irrigation events, indicated that excessive irrigation occurred.
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