Department of Agricultural Engineering, Assam Agricultural University (AAU), Jorhat, Assam, 785013.
*Corresponding author: (E-mail: s_haz2002@yahoo.co.in)
†Present address: Department of Soil Science, AAU.
‡Present address: Tocklai Experimental Station, Jorhat, Assam 785008.
Properties of the effluent of Nagaon paper mill at Jagiroad, Assam and typical acid soils receiving either this effluent or shallow tube well (STW) irrigation for 17 years were analyzed. The effluent was alkaline in reaction (pH 7.6, EC 2.5 dS m−1) and contained high levels of dissolved salts, bases and chloride. The pH of the effluent irrigated soil was observed to be 1.3 units higher due to effluent irrigation. Soil salinity (EC) was increased by more than three times. Similarly, CEC, base saturation, total and water soluble basic cations, ESP and SAR were significantly more in the effluent irrigated soil. The chloride concentration of the effluent irrigated soil was 197 mg kg−1 against 43 mg kg−1 observed in the STW irrigated soil. Although, rise in soil pH, CEC and base saturation are desirable for biological activity in acidic soils, the effluent irrigated soils showed rather very low value of microbial biomass carbon content. Overall, the effluent altered the soil characteristics that are not typical of acid soils of this region.
Acidity, CEC, effluent-irrigation, ESP, microbial biomass, salinity, sodicity, soil respiration
