| Abstract |
| The aim of this study is to investigate the ponded water quality of conventional paddy and organic paddy at different fertilization times. Water and soil were sampled and analyzed two times, after basal fertilization (May 2015) and after additional fertilization (August 2015). The statistical significance between groups was determined by Duncan`s multiple range test. The results show that pH, COD, and SS of ponded water were not statistically dependent on fertilization timing and farming methods. EC of ponded water in conventional paddy after additional fertilization was higher than that of organic paddy, and higher BOD was observed after additional fertilization than after basal fertilization. In contrast to T-N, NH₄-N, and NO₂-N, fertilization timing statistically influenced on NO₃-N, T-P and PO₄-P. T-P and PO₄-P concentrations of ponded water in organic and conventional paddy were also different depending on the farming method. Soils in conventional and organic paddy were also sampled and analyzed to compare them with water quality data. pH and EC of paddy soil were not statistically dependent on fertilization timing and farming methods. Higher OM content was observed in conventional paddy than organic paddy. Although T-N, NH₄-N, and NO₃-N of ponded water were not dependent on fertilization timing, their amounts in soils were varied with fertilization timing. T-P in soil was higher after additional fertilization than after basal fertilization and vice versa, P₂O5 was higher after basal fertilization. It can be concluded that fertilization timing influenced on ponded water quality more than farming methods. |
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| Key Words |
| Organic paddy, Conventional paddy, Ponded water, Water quality, Soil properties, Fertilization timing |
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