GHGMP Project Reports by Region

A surf 'n turf solution to improved crop fertility

Compost may reduce reliance on commercial fertilizers

Using a combination of so-called waste from nearby fish processing and poultry operations appears to be helping a Newfoundland vegetable producer produce high-yielding, high quality product for his provincial market.

Compost made from a blend of poultry manure, crab shells and offal proved to be a valuable nutrient for crops in a demonstration project at David Dwyer's Shearstown-area farm on Conception Bay. Dwyer will be repeating the demonstration on approximately two acres of vegetables in 2004. The demonstration is among a wide-range of projects funded in part by the federal Greenhouse Gas Mitigation Program.

The demonstration shows compost can be a valuable soil nutrient that can reduce reliance on more expensive commercial fertilizers, says Dwyer. With the use of soil testing and compost nutrient analysis he hopes to get a better handle on compost application rates this year. "We need to fine-tune rates so we are better matching the nutrients being applied to crop needs," he says.

Range of benefits

The value of the demonstration ranges from reducing farm input costs to environmental benefits. Reducing commercial fertilizer requirements contributes to a reduction in the amount of fossil fuel needed in the manufacturing process, and better matching nutrients to crop requirements reduces the risk of fertilizer over-application. Both steps help reduce greenhouse gas emissions. As well, using poultry manure and crab processing waste in compost reduces the impact of these materials on the environment.

Dwyer produced about 12 tonnes of composted material in 2002 for use in the 2003 demonstration project. The plot is just part of his 70 acre vegetable farm at Shearstown, a community on Newfoundland's east coast about 80 kilometers from St. John's. Dwyer produces a range of crops including carrots, cabbage, rutabaga and beets, which are sold at the farm gate and through local retailers.

Depending on the crop, commercial fertilizer requirements range from 300 to 1,200 pounds per acre per year. However, waste material from nearby fish processing plants is easy to acquire, he says. "They usually buy permits to dispose of the waste either in a landfill or to dump it in the ocean," says Dwyer. "So they're glad to deliver shells and offal to the farm free of charge, which saves them plant permit fees."

For the composting material, Dwyer used a ratio of approximately 30 percent crab offal with about 70 percent poultry or stable manure. The materials were turned three times over several weeks and then allowed to sit for the winter. The compost assembled last summer will be applied to the land this spring and incorporated into the soil with disc tillage.

Good yield, quality

Rutabaga and cabbage produced in the 2003 demonstration were top quality, says Dwyer. "Plants were larger and had very good colour," he says. "Compost was the only fertilizer used on the plot."

He wants to further evaluate compost on a new variety of rutabaga he has developed. The variety shows improved resistance to root maggot, as well as clubroot, a common and costly disease in cruciferous crops such as rutabaga. "A new variety could not only improve production but also reduce the need for pesticides, which is of value to the kitchen gardener as well as organic growers," says Dwyer.

Over the next couple years the demonstration emphasis will be on fine-tuning application rates and looking at the economics of composting, says Ann Marie Whelan, field co-ordinator for the GHGMP in Newfoundland and Labrador. Assisting with the project are soil and crop specialists from the Agrifoods Division of Newfoundland and Labrador's Department of Natural Resources as well as from Agriculture and Agri-Food Canada.

Testing important

Soil testing, plant tissue testing and compost nutrient analysis will be among the technologies used to determine proper application rates. "It will also be important to evaluate the crop at harvest for yield, quality and how well the produce stores," says Whelan.

Dwyer is confident compost can be a valuable nutrient source for vegetable crop production. Along with producing a quality product, he likes that it benefits the environment.

"Economics are important and it will be interesting to compare the cost of compost with that of commercial fertilizer," he says. "Even if I don't see increased yields, there's an added benefit of increasing organic matter in the soil, which improves soil quality and carbon sequestration in the long term."