Irrigation of intensively cultured plantations with paper mill effluent

Abstract

Two current problems facing forest industries are effluent disposal and wood supply. One possible common solution is to use mill effluent to irrigate intensively culture plantations. It was found that large amounts of effluents could be disposed of and that good growth of Populus could be maintained by flood-irrigating a plantation with the effluent. Irrigation rates averaging 11 inches/week (297 mm) resulted in the equivalent of a 10 foot (3.0 m) depth of effluent applied during each of two growing seasons. Both Populus and Salix had good survival and Populus growth averaged more than 3 foot/year (0.9 metres) with these high irrigation rates. During the third year, application of 36 foot (11 metres) of effluent resulted in Populus growth of 6-7 foot (1.8-2.1 metres). Renovation of the secondary-treated effluent percolating to the groundwater table during the first 2 years (no data was collected the third year) was better than the quality of the tertiary-treated effluent normally discharged to a nearby river. Essentially all N and P were removed. However, most Na, Cl, and SO/sub 4/ reached the water table; this poses a potential for serious aquifer contamination. Nevertheless, by locating such disposal areas near natural aquifer drains, the impact onmore » aquifer contamination may be reduced. In this way the effluent renovation and disposal problem may be at least partially solved, while at the same time substantial tonnages of fiber are produced.« less