Author(s): Xueyan Lv; Shiqiang Wu; Sha Shi; Donghui Zhou; Qianqian Yang
Linked Author(s): Wu Shiqiang
Keywords: Irrigation pattern; Paddy-field soil; Phosphorus; Adsorption; Desorption
Abstract: To investigate the affects of irrigation pattern on phosphorus adsorption and desorption on paddy-field soils, some surface soil samples from paddy fields with different irrigation methods, flooding-irrigation (FIR) and intermittent-irrigation (IIR), in the catchment of Lake Taihu were taken for a laboratory experiment. The results show that IIR can increase the soil’s retention capacity of nutrients, especially for nitrogen, which has a 4. 9 times of ammonia and total nitrogen as much as those in FIR soil. The retention capacity of total phosphorus in IIR soil is twenty percent higher than that in FIR soil. Adsorption kinetic experiment indicates that eighty percent phosphorus is adsorbed in the first 3 hours. The fitting results of pseudo-second order adsorption equation provide equilibrium adsorption capacity of the two samples are 333. 3 and 277. 8mg/kg, respectively, and the adsorption rate constants are 0. 123 and 0. 118 g/mg·min, respectively. The isothermal adsorption of phosphorus on the soils can both be described best using Freundlich equation. Although the maximum adsorption capacity of FIR soil (1000. 00 mg/kg) is higher than that of IIR soil (909. 09mg/kg), there is no significant affect of irrigation pattern on the adsorption capacity of phosphorus as the original content is considered. The results of desorption experiment demonstrate that the isothermal desorption of P is significantly correlated with isothermally adsorbed P. Irrigation pattern has not fundamentally changed the adsorption and desorption characters of P on paddy-field soils. However, IIR is able to increase P retention capacity in soil, which represents IIR can reduce not only the discharge of agricultural wastewater but also the risk of P loss.
Year: 2013