Field Studies on³²P Movement and P Leaching from Flooded Paddy Soils in the Region of Taihu Lake, China

Abstract

Field experiments were done in two sites, Yixing and Changshu, Jiangsu province, China, to study P movement and leaching in flooded paddy soils. P movement in soil was investigated by using the KH2 32PO4 tracker method, and the amount of P leached from the soil layer in different depths was estimated by measuring P concentrations in the soil solution and saturated hydraulic conductivities in field. Determination was done about one month after P application. There was 46% and 42% of total 32P retained in the 0-5cm layer of soil in the Yixing site and in the Changshu site respectively. The 32P retained in the 25-30 cm layer was only about 1-2% of the total 32P added. Furthermore, 8.01% of 32P in the soil of Yixing site and 16.8% of 32P in the soil of Changshu site was lost from the layer 0-30 cm soil. The seasonal amounts of P leached from the top soil layer and from bottom layer are about 4.5-5.8% and 1.6-2.1% of the total P application, respectively. Changes of total P concentrations in soil solutions during rice growth showed that the fertilizer P applied before flooding of the paddy fields suffered a flash leaching loss and a slow leaching loss. We concluded that the fertilizer P could quickly move in the flooded paddy rice field and parts of it can enter into surface water and ground water. Unless the P application is well managed the risk of P loss and consequently environmental pollution exist.

Study on Degradation of Fertilizer and Pesticides Using Lysimeter

“…This results considerably in lowering leachate of phosphate and also high phosphate sorption within the subsoil. The current study was also substantiated by the field studies on phosphate leaching carried out by Xie et al, (2004) [8].…”

Methods and tools for integrated assessment of land use policies on sustainable development in developing countries

“…Grontmij (2005) estimated a contribution of 58,200 tons/yr from paddy and dryland fields compared to 5500 tons/yr from livestock and 2600 tons/yr from fish farming. The contribution to phosphorus (P) load was estimated to be small (around 0) compared to livestock (1250 tons/yr) and fish (300 tons/yr), but experiments show that due to long-term high P application and extreme rainfall events, the arable sector also contributes to P losses (Cao and Zhang, 2004;Guo et al, 2004;Xie et al, 2004). To improve water quality, it is essential to reduce emissions of both nutrients.…”

Nitrogen and phosphorus leaching losses from paddy fields with different water and nitrogen managements

“…Thus, P leaching losses from agricultural fields are usually insignificant. However, recently published studies (Zhang et al 2003;Xie et al 2004;Shan et al 2005;Zhao et al 2009a, b) have challenged this assumption. Reports have identified leaching as a significant pathway for P losses from high P status soils.…”