Organic Soil Fertililzation

The City of Pembroke Pollution Control Centre has a fertilizer that may be advantageous to some local farmers who are looking to improve their organic soil conditioning. The fertilizer is high in nitrogen and phosphorous but very low in heavy metals. The following are some excerpts from a report entitled "Guidelines for Sewage Sludge Utilization on Agriculture Lands" as prepared by the Sludge and Waste Utilization Committee. The development of these guidelines is sponsored by both the Ministry of the Environment and the Ministry of Agriculture and Food.

Through Municipal Sewage Treatment Plants, solids in municipal sewage are removed and the treated water is discharged to our lakes and rivers. A by-product of this process is a nutrient-rich black liquid known as sludge.

Ontario's farmers have been using sludge as a fertilizer for their crops for many years. In 1986 approximately 1.25 million our of a total of 6.5 million cubic meters of sludge produced annually in Ontario was applied to agricultural land.

Farmers and Municipalities Benefit

The application of uncontaminated sewage sludge on land can offer both Ontario's farmers and municipalities uncontaminated municipal sewage sludge providing inexpensive and sometimes even free natural fertilizer to farmers while decreasing their dependence on more expensive and often imported chemical fertilizers. It could be worth as much as $200 per acre to farmers.

Sludge not only contains large amounts of phosphorous, nitrogen and other plant nutrients, but it also includes carbon compounds that can help improve the soil's capacity to retain moisture and remain workable. The sludge is especially beneficial for soil which is low in phosphorous.

Extensive Research Leads to Better Controls

In the 1970's, Ontario and Canada funded research on sludge applied to farmland. Metals, nutrients, pathogen survival, sludge application rates, and impacts on land productivity and the environment were studied. This research enabled the province to develop sludge spreading guidelines that are now contained in Ontario's Guidelines for Sewage Sludge Utilization on Agricultural Lands.

Sludge can become contaminated with a variety of inorganic and organic compounds. Strict control of industrial, municipal and household discharges to the sewer system and a well operating treatment plant are necessary to ensure a high quality of sludge. The Ministry of the Environment only supports the application of sewage sludge to land where a high quality of sludge can be guaranteed.

During the past 15 years, the Ministries of Environment and Agriculture and Food have collaborated with municipalities and farmers to improve sludge quality and land application practices. The metal and nutrient content of all Ontario sludge used on farmland is now regularly checked by government or commercial laboratories to ensure it meets established parameters.

Some of the guidelines listed are:

1. Sludge can only be spread on mineral soil, not on organic soil;
2. The soil must have a pH greater than 6.0;
3. The slope of the land should be less than 9 %:
4. Distance restrictions that apply when spreading sludge near residence, wells, water tables, etc.

The only expense incurred by the recipient is the cost of spreading the dried sludge onto their fields.