Pulp mill effluent as a supplemental water source for irrigation.

摘要

Agroforestry systems for wastewater irrigation have been underutilized in Canada and could be 'greener' alternatives for allow industries and communities to effluent discharge into water bodies. Effluents are a valuable resource of both water and nutrients. When combined these systems can be advantageous in sub-humid climates at more northern latitudes where research into incorporating effluents as supplemental sources of irrigation water has been limited.;Over five years, three growth chamber studies and one field study were conducted to evaluate the potential use of Kraft pulp mill effluents as sources of irrigation water. These studies evaluated the effects irrigating with water, effluents from a Kraft pulp mill [a final effluent and a waste activated sludge] and a municipality and various combinations of distilled water and Kraft pulp mill effluents would have on selected soil chemical properties and the growth and nutrient uptake of hybrid poplar (Populus deltoides x P. petrowskyana), reed canarygrass (Phalaris arundinacea L.), timothy (Phleum pratense L.), alsike clover (Trifolium hybridum L.), and winter wheat (Triticum aestivum L.).;Pulp mill effluents consistently resulted in significant increases in soluble SO42-, Na+, and Cl- in the soil while diluting the effluents reduced these increases. Electrical conductivity of saturated paste extracts (ECe) and sodium adsorption ratio (SAR) increased with pulp mill effluents compared to tap water (TPW) and municipal effluent (ME) but diluted treatments remained significantly greater than control treatments. Only when soils were amended with gypsum did solution SAR of soils irrigated with effluents decrease, due to additional Ca, compared to control soils. Wheat grown on wood ash-amended soils irrigated with effluents resulted in significant increases in biomass. Increasing the application rate significantly increased biomass for both crops, but the Kraft pulp mill effluent (KPME) treatment significantly decreased leaf area of the hybrid poplar (HYBP). Effluent/distilled water combinations (COMB) resulted in heights, biomasses, and leaf areas that were greater than those for KPME and were comparable to those for DW.;Results indicate dilutions and precipitation reduced ion accumulations within the rooting zone. Soil salt loading must be considered when determining application rates of effluents. However, more research is required for the management and timing of applications as effluent applications are likely required only during dry periods.