Soils are more important to us than we realize, but they are often taken for granted. Around the world, farmers strive for sustainable, productive agricultural soils. In 2015, we celebrated the International Year of Soils as designated by the Food and Agriculture Organization of the United Nations (FAO). In FAO’s "The Status of the World's Soil Resources", it was reported that soils are deteriorating. They attributed this to a number of factors including:
- soil erosion,
- nutrient depletion,
- loss of organic carbon,
- over application of mineral fertilizers and pesticides, and
- declining soil biodiversity.
Further recognition was given by the International Union of Soil Sciences (IUSS) when it declared 2015-2024 the "decade of soils" in an effort to bring more attention to soil's fundamental role in sustaining human life.
Desertification of Soils Trend and the Nutrient Management Act
Desertification of soils has been an ongoing concern in Canada, specifically in Ontario and Quebec, as soils continue to lose organic matter.
In short, we need to do more to build our soils and we need to do it better. In Ontario, we've been working with the Nutrient Management Act (NMA) for over 6 years now. The act and associated regulations ensure that any nutrient rich material (with the exception of fertilizer) is used in a beneficial manner that's protective of the environment. Non-Agricultural Source Material (NASM) which is nutrient rich material includes manures, biosolids, food and beverage waste, and other non-agricultural source materials. The NMA has provided direction and a push in the right direction for sustainability and environmental responsibility.
The Importance of Biosolids as a NASM
Biosolids is one type of NASM that is key to improving our soils. The land application of biosolids has been going strong for over 50 years in Ontario. They provide many of the same macro and micro nutrients as well as organic matter that are found in manure. The importance of biosolids in agricultural nutrient management is well established and supported by government and academia. The quality of biosolids has continually improved with many municipalities further processing their biosolids into sailable fertilizer product.
Over the past couple of years, there has been a renewed interest in using NASM in different ways:
- Renewable natural gas,
- Electricity generation, or
- Biochar production.
In each instance, a portion of the processed material creates a residual that needs to be managed, typically through beneficial use on agricultural land.
Biosolids Land Application Alternative to Landfills
In Canada, over 2.5 million wet tonnes of biosolids are produced each year. Historically about 25% of that material was taken to landfill, with the remainder either used on agricultural land (35%) or incinerated (40%). Additionally, 34 million tonnes of municipal and industrial waste is generated each year of which only 8 million tonnes (25%) is recycled.
As the province moves towards a more sustainable future, biosolids and other organic materials are becoming coveted resources rather than wastes. New legislation is forcing this change in Ontario with the Waste Free Ontario Act. A renewed focus on reuse has come to the forefront. With diversion goals of 30% by 2020 and up to 80% by 2050, biosolids and other organic resources will no longer be permitted in landfills. Other provinces have already banned organics in landfills.
While biosolids land application and other NASM will increase over the coming years, it will remain a viable and desirable option for municipalities. Only 15% of Ontario's land base would be needed to use all the biosolids produced in the province beneficially, leaving 85% of the agricultural land available to receive other soil amendments therefore there is a lot of room for growth.
There are additional benefits as returning organic matter to our soils will reduce our carbon footprint through carbon sequestering while simultaneously increasing yields and improving soil resilience. A 1% increase in soil organic matter is approximated to 5.8 tons/acre of sequestered carbon. A study in Michigan also showed a crop-yield increase of about 12% for every 1% increase in soil organic matter.
Biosolids land application produces positive results with both crop production and environmental sustainability. To see biosolids land application in action, check out the Case Study: Brant County.