ASSESMENT OF RICE MILL WASTE WATER AND ITS IMPACT ON GERMINATION AND SEEDLING GROWTH OF DIFFERENT VEGETABLES

Abstract

An investigation was carried out to assess the suitability for agricultural purpose of 26 rice mill waste water samples collected from different locations of Dinajpur sadar upazila of Dinajpur district. Analyses included pH, EC, TDS (Total dissolved solids), cations (Ca2+, Mg2+, Na+ , K+ , Cu2+, Mn2+, Fe3+) and anions (HCO3 - , SO4 2- , PO4 3- and Cl- ). Several computed variables such as SAR (Sodium adsorption ratio), hardness (HT), permeability index (PI), Kelly‟s ratio, Gibbs ratio and potential salinity to evaluate the suitability of waste water for specific uses. The waste water were found basic (pH varied from 6.38 to 6.90) and suitable for vegetables. Waste water samples contained Ca2+, K+ and Na+ as the dominant cations and HCO3 - and Cl- were the dominant anions. According to EC value, the samples were excellent and good for germination purposes. The SAR value of all water samples under test were excellent classes. Maximum samples were within hard class regarding hardness. Based on, Cland PO4 3- all rice mill waste water samples were within the 'safe' limit for germination. The positive coefficient of correlation among pH, EC, TDS, Mg, K, HT, Ca, Mg, K, Na and HCO3 reproduced that the quality of the free soil solution may indicate the distribution of sodium ion in the absorbed phase. On the other hand the negative coefficient of correlation Na-Mn, Na-Cu, Na-pH, Fe-SO4, Cu-SO4 indicated that the increase of one parameter will result in the decrease of the aforementioned parameters. Germination test, shoot and root length of okra, radish, mustard, cucumber and stem amaranth seeds using different rice mill waste water samples were also performed. The highest germination (96.67%, 97.07% and 70.00%) was found in radish, mustard and stem amaranth, respectively with the treatments of T1 and T2, T4 and T1. It was observed that some waste water effluents could also delay germination and growth of crops such as okra. However, overall view the rice mill waste water was suitable for germination and also effluent from rice mill waste water could be utilized for irrigation purposes after proper treatment.