Effects of diluted Kraft pulp mill effluent on hybrid poplar and soil chemical properties

Irrigation with effluents can detrimentally affect soil physical and chemical properties and impact plant growth and development. Excessive irrigation can leach salts from the root zone; which can be accomplished by precipitation in some areas. This study was conducted to examine the effect of applications of Kraft pulp mill effluent (KPME) with and without distilled water (DW) to simulate precipitation would have on soil chemical properties and growth of hybrid poplar (Populus deltoides x P. petrowskyana L. cv. Walker). Distilled water (DW), KPME, and a 50% combination (v/v; COMB) of DW and KPME were applied at rates of 6 and 9 mm day(-1). COMB resulted in heights, biomasses, and leaf areas that were greater than those for KPME and comparable to those for DW. Diluted KPME treatments (i.e., COMB) still significantly increased soil electrical conductivity and sodium adsorption ratio compared to DW. Leachate collected from KPME 9 mm day(-1) had concentrations of HCO3-, SO42-, Cl-, Ca2+, K+, and Mg2+ comparable to those collected from COMB 9 mm day(-1), but Na+ concentrations were three times higher in KPME than COMB 9 mm day(-1). Results indicate that precipitation or additional irrigation water could potentially provide the leaching necessary to prevent salt accumulation within the rooting zone; however, irrigating with saline or sodic effluents requires careful management.