Wang Quanjiu

Chloride Transport in an Aggregated Clay Soil Column

AbstractSoil aggregates as the basic units of soil structure greatly affect soil properties and fertilizer. They have an important theoretical and practical significance in studying the change in solute transport with different aggregate-size soil on the Loess Plateau. Based on a soil column experiment in the laboratory, breakthrough curves (BTCs) of chloride displaced through columns of different aggregate sizes of a clay soil were measured under water-saturated steady-flow conditions. The data were fitted with a convection and dispersion equation (CDE), a mobile-immobile model, and a two-flow-region model. In the CDE, all soil water was assumed to be mobile with a physical equilibrium existing in the system. For the mobile-immobile model, soil water was partitioned into mobile and immobile regions and convective diffusive solute transport was limited to the mobile water region; however, chloride transfer between the two regions was assumed to occur at a rate proportional to the difference in tracer conc...

Logistic model analysis of winter wheat growth on China's Loess Plateau

Xiangxiang, W., Quanjiu, W., Jun, F., Lijun, S. and Xinlei, S. 2014. Logistic model analysis of winter wheat growth on Chinas Loess Plateau. Can. J. Plant Sci. 94: 1471-1479. The leaf area index (LAI) and above-ground biomass are closely related to crop growth status and yields. Therefore, analysis of their variation and development of a mathematical model for their prediction can provide a theoretical basis for further research. This paper presents a new equation for logistic pattern that calculates above-ground biomass and LAI for different irrigation treatments independent of growing degree days (GDD) and plant height. The model root mean square of error (RMSE) for the LAI was from 0.25 to 1.36, and for above-ground biomass it was from 0.49 to 1.34. The r2 values for the models output under the single irrigation, double irrigation, triple irrigation, and quadruple irrigation treatments were 0.98, 0.87, 0.96, 0.98 and 0.99, respectively. For above-ground biomass they were 0.96, 0.97, 0.99, 0.97, and 0.97, respectively. The relative error for LAI ranged from 0.026 to 15.2%. For above-ground biomass, the Re ranged from 5.78 to 8.79%. The results gave good agreement between the estimated values and the measured values. The Logistic model was good at estimating the LAI and the above-ground biomass from the plant height.

Estimation of infiltration parameters and the irrigation coefficients with the surface irrigation advance distance.

A theory based on Manning roughness equation, Philip equation and water balance equation was developed which only employed the advance distance in the calculation of the infiltration parameters and irrigation coefficients in both the border irrigation and the surge irrigation. The improved procedure was validated with both the border irrigation and surge irrigation experiments. The main results are shown as follows. Infiltration parameters of the Philip equation could be calculated accurately only using water advance distance in the irrigation process comparing to the experimental data. With the calculated parameters and the water balance equation, the irrigation coefficients were also estimated. The water advance velocity should be measured at about 0.5 m to 1.0 m far from the water advance in the experimental corn fields.