Nitrate vertical transport in the main paddy soils of Tai Lake region, China》.pdfVIP

Geoderma 142 (2007) 136 – 141 /locate/geoderma ☆ Nitrate vertical transport in the main paddy soils of Tai Lake region, China Xiaomin Chen ⁎, Huashan Wu, Fei Wo College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, The Peoples Republic of China Received 30 August 2006; received in revised form 17 March 2007; accepted 5 August 2007 Available online 5 September 2007 Abstract The influence of texture, bulk density, and organic matter content on the process of nitrate vertical transport in the three main paddy soils (Bai soil, Huangni soil and Wushan soil) of the Tai Lake region were studied in the soil columns. Breakthrough curves (BTC) were obtained separately for each of thirteen horizons. The results were as follows: vertical transport velocity of nitrate decreased, and the BTCs of nitrate were more dispersed, in each horizon from the surface layer to the bottom in every soil profile. Among the three soils, the average flux of Wushan soil was the least and its nitrate BTC was the most dispersed. Under saturated conditions, nitrate penetrated the soil column quickly. The transport of nitrate was affected by clay content. As the clay content increased, nitrate outflow was retarded, and the peak concentration was reduced. Nitrate BTCs rose and fell gently when the nitrate concentration was lower. All nitrate BTCs were asymmetric, and tailing was more obvious when clay content was high. Soil bulk density and th