Influences of Land Use during the Puddling Period on Water Balance and Quality in a Rice Farming Area

• Published in: International Journal of Environmental and Rural Development Vol. 2; no. 1; pp. 13 - 18
• Main Authors: HASAN, MOHAMMED KAMRUL, TADAO, YAMAMOTO, TETUAKI, NAGASAWA
• Format: Journal Article
• Language: Japanese
• Published: Institute of Environmental Rehabilitation and Conservation, Research Center 2011
• Subjects: Hokkaido; land and water use; puddling period; water balance; water quality
• ISSN: 2185-159X; 2433-3700
• DOI: 10.32115/ijerd.2.1_13

The study was carried out on the Shinotsu Canal agricultural watershed of Hokkaido, Japan from 2003 to 2008. This study was conducted to evaluate the nutrients fluxes after using irrigation into the paddy fields and the effectiveness of the paddy fields in removing nutrients load of the Shinotsu Canal watershed. Upper part of the Shinotsu Canal is dominated by paddy field and lower part is dominated by upland field. Water samples were collected with an automatic sampler at pump station (inflow) and end of drainage channel (outflow) of both block, and measured volume of inflow and outflow at puddling period (May). The concentration of suspended solids (SS) was determined by gravimetrically through suction filtration, total nitrogen (TN) and total phosphorus (TP) were determined by UV spectrophotometric methods, respectively. Water balance is higher at lower part of Mihara drainage block (MDB) than upper part of Tsukigata drainage block (TDB) due to high percentage of upland that caused losses of water by leakage and percolation. TN, TP and SS concentrations in drainage water are higher in MDB than that of TDB. The net loads of TN and TP are showed negative and lower values in TDB whereas MDB is positive and higher values, due to a combination of nitrification and denitrification, sedimentation reactions and sorption by soil is more in high percentage of paddy field in TDB. TN, TP and SS concentrations outflow load and net load are decreasing from 2003 to 2008 due to changed of water management by progress of pipe line. From the viewpoint of reducing the outflow of nutrients, it may be stated that the paddy field dominated area showed good performance in purification function for nutrients compounds.