Biosolids Land Application Project

The Golden Horseshoe Soil and Crop Improvement Association (SCIA) established the Biosolids Project to demonstrate the value of biosolids utilization in a crop fertility program. The project was designed to compare a crop fertility program that used either municipal sewage biosolids (MSB) or pulp and paper mill biosolids (PPMB) to the co-operators normal fertility program that used commercial fertilizer.

Methods

The biosolids application rates were either the approved rate as set out in the Certificate of Approval or the rate that provided the crop nutrient requirements, whichever was lower. The project established 7 co-operator sites and utilized 4 MSB sources and 2 types (liquid or dewatered) and one PPMB source. Each site generally used only 1 biosolids type in a multiple replicated field length plot design.

Soil quality parameters (pH, plant available phosphorus, and the 11 regulated metals) were measured prior to the biosolids application and then 2 years after application. The concentration of the 11 regulated metals was also measured in the crop leaves and the grain. Crop yield measurements were also taken.

Soil Analysis Results

The soil analysis results showed no elevated concentrations of the 11 regulated metals. There were no changes in soil pH in the biosolids treated plots compared to the corresponding control plot that received only commercial fertilizer. At 4 of the 6 MSB sites the biosolids application resulted in higher concentrations of plant available phosphorus measured 2 years after the biosolids application. The PPMB application site had lower plant available phosphorus.

Tissue Analysis Results

Although most sites showed no increases in the concentrations of the regulated metals in the tissue samples, the tissue samples at one site had high concentrations of copper and zinc in the treated compared to the control samples. The higher concentrations were 85% and 75% respectively of what would be considered the normal maximum concentration of these elements in plant tissue.

Crop Yields

At all the MSB application sites the crop yield was comparable to the commercially fertilized control plots. The PPMB plot out-yielded the commercial fertilizer plot. This may have partially been due to the very dry growing season and the moisture holding ability of the PPMB material.

Overall there was very little difference in soil quality, crop quality or crop yield between the biosolids treated plots and the commercial fertilizer plots. The project demonstrates that these biosolids can be safely and effectively utilized in a crop fertility program.

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