Aspen Response to Forest Soils Amended with Municipal and Industrial By-products on Two Northern Minnesota Sites: Experimental Design and Preliminary Results

The utilization of municipal and industrial by-products as forest soil amendments can improve forest soil fertility. In this field study, aspen (Populus tremuloides Michx.) seedlings were planted at two forested sites (Itasca and Carlton counties) amended with treatments of biosolids, boiler ash, and inorganic agricultural fertilizers. Experimental treatments included biosolids at rates equivalent to 70, 140, 210, and 280 kg available N ha-1, two types of boiler ash (application rates based on % Effective Neutralizing Power), boiler ash plus biosolids, and an untreated control. Preliminary results are reported for soil properties, aspen seedling survival, height, and caliper. Soil pH decreased with increased N application from both biosolids and fertilizer sources, but increased through additions of boiler ash and lime. Soil P increased with increased biosolids and ash application rates. Soil K increased with ash and K fertilizer applications. No differences were detected in aspen seedling survival among treatments at the conclusion of the first and second growing seasons at either installation. Height differences among treatments were detected through ANOVA in 2000 and 2001, but were inconclusive. Aspen height and caliper growth in Carlton County was greater than in Itasca County