Guidelines for the Beneficial Use of Fertilizing Residuals

2 General
2.1 Definition of fertilizing residuals (FRs)
FRs are “residual materials that can be used to maintain or improve, separately or
simultaneously, plant nutrition, as well as the physical and chemical properties and
biological activity of soils.” This definition combines the expression “residual materials,”
as defined in section 1 of the Environment Quality Act (EQA), and the concept of
“fertilizers and soil conditioners,” as defined by the International Organization for
Standardization (ISO, 1984).
Hence FRs are a subgroup of “fertilizing materials” which, according to international
terminology (see Glossary), include both fertilizers and soil amendments. For example, a
FR that is high in organic matter and low in nitrogen and phosphorus would be
considered a “fertilizing material” in the soil amendment subcategory, even though it
does not have any significant fertilizing properties.
By convention, livestock waste (manure) and other “farm residuals” are not considered to
be FRs, even though they are residual materials and have both fertilizing and soil
amendment properties.
Soils, by convention, are not considered to be FRs, either. However, sandy deposits and
soils may be blended with FRs to make commercial soil mixes.
2.2 Types and uses of FRs
FRs come in a variety of solid and liquid forms, determined notably by their dryness (dry
matter content). Some are intended as plant fertilizers, while others are used mainly as
soil amendments. The main types of FRs are “biosolids,” liming materials and composts.
Biosolids, traditionally called “sludges,” result from the primary treatment (primary
biosolids) or secondary treatment (secondary biosolids) of wastewater. They are often
mixed together (mixed biosolids) and come from municipal and industrial wastewater
treatment plants. Biosolids are used as organic soil amendments and as a source of
fertilizing components.
Liming materials include ashes, cement kiln dust, lime mud from paper mills and other
alkaline mineral residuals used mainly for raising soil pH. By convention, composts are
considered to be FRs within the context of this document, since they are made from
residual materials. However, commercially, they are also considered “products,” and are
mainly used as organic soil amendments.
In Québec, FRs are chiefly used for:
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