Characteristics of Channeling Flow in Cultivated Horizon of Saline Rice Soil

1 Introduction The preferential flow tends to result in the loss of irriga- tion water and nutrients. The formation of the preferen- tial flow was caused by various factors, such as soil structure, tillage, worm cavity and root channeling rup- ture (Pot et al., 2005). Besides, frozen rupture can not be ignored in the northeastern China where the lowest tem- perature reaches -40℃ (Wang et al., 1993). There are several types of preferential flow, such as bypass flow, channeling flow and macro…

Characteristics of channeling flow in cultivated horizon of saline rice soil

By applying bromide ion as tracer,the channeling flow has been quantitatively described in saline rice soil and alkaline soil of Da,an City,Jilin Province of China.Breakthrough curves of bromide ion in the saline rice soils after 1-year cultivation and 5-year cultivation and alkaline soil have been attained.Results show that the rice cultivation practice can improve the alkaline soil structure,however,it can accelerate the development of channeling flow pathway.Therefore,the channeling flow pathway has been developed widely in saline rice soil,but rarely in the alkaline soil.Three models of convection-dispersion equation(CDE),transfer functional model(TFM) and Back-Progation Network(BP Network) were used to simulate the transportation process of bromide ion.The peaks of probability density function of saline rice soil are higher with left skewed feature compared with that of the alkaline soil.It shows that the TFM and CDE can simulate the transportation process of the bromide ion in saline rice soil after 5-year cultivation,however,some deviation exists when it was used to simulate transportation process of bromide ion in saline rice soil after 1-year cul-tivation and alkaline soil;BP network can effectively simulate transportation process of bromide ion in both saline rice soil and alkaline soil.