Spatial Distributional of Irrigation Water Quality in Peaty Paddy Field of Paser Regency, East Kalimantan Province, Indonesia

Paddy is one of the main food-crop commodities in Indonesia. The main problem in paddy cultivation in Paser Regency is good water quality for plants. Water is the main requirement for paddy plants to grow and develop. Water quality to meet the needs of paddy plants is a very important factor. pH H2O, TDS (Total Dissolve Solid) and EC (Electrical Conductivity) are some of the water parameters used as a reference in determining land suitability for paddy plants. The purpose of this research is to spatially analyse the water parameters (pH H2O, TDS and EC) for the water needs of paddy plants in Paser Regency. Determination of sample points using stratified random sampling method and parameter measurements are carried out directly in the field in the irrigation area. Interpolation analysis used the IDW (Inverse Distance Weighted) method with a power weight of 2. RMSE values from the interpolation results for pH H2O 0.0001, TDS 0.1695 and EC 0.0003. The results of the interpolation of several parameters are then analysed by overlay to determine the spatial relationship between parameters. The results of the analysis show that the average values in Paser Regency are pH H2O 6.13, TDS 478.64 ppm and EC 0.82 mS/cm. The area of pH H2O (6.5-8.4) suitable for paddy plants is 391447.87 ha, TDS (<2000 ppm) 1067265.23 ha and EC (<3 mS/cm) 1066907.37 ha. Most of the pH H2O suitable for paddy plants is in the northern region, while the TDS and EC are better in the northern region although most of them are still suitable for paddy plants. Each parameter has a spatial relationship, where the value of each parameter influences each other. Overall, the northern area in Paser Regency is more suitable for paddy cultivation according to water parameters, namely pH H2O, TDS and EC. © The Authors, published by EDP Sciences. All Rights Reserved.