GHGMP Project Reports by Region

Compost helps boost NL vegetable yield by nearly 60 percent

Demonstration shows organic nutrients are good for the environment and good for the pocketbook

Compost made from the so-called waste of fish processing and poultry operations appears to make a dramatic difference in vegetable crop yields, while benefiting the environment, Newfoundland vegetable producers are learning.

A second year of field demonstrations, comparing crops produced using compost as the main source of fertility versus chemical fertilizer, nearly doubled the yields of cabbage and rutabaga on David Dwyer's vegetable farm near Shearstown on Newfoundland's Conception Bay.

"Compost appears to produce a range of benefits, not only in the quantity but quality of the crops," says Ann Marie Whelan, an agrologist and Newfoundland and Labrador (NL) field co-ordinator for the Greenhouse Gas Mitigation Program for Canadian Agriculture (GHGMP).

"In a demonstration completed in 2005, rutabaga and cabbage yields in the Dwyer project were up nearly 60 percent, and the produce had better size and appearance over crops produced with chemical fertilizer," says Whelan. "This project is showing farmers there are opportunities to reduce costs, improve yields and also benefit the environment."

National program

The compost project is one of dozens of demonstrations across the country supported in part by the national GHGMP. Launched in 2003, the program is designed to demonstrate and raise awareness of a wide range of practices that not only benefit production but also help reduce greenhouse gas emissions and benefit the environment. The soil sector of the GHGMP program is administered nationally by the Soil Conservation Council of Canada (SCCC).

Blending a combination of crab shells and offal and poultry manure - the by-products of local farming and fishing activities - produces a nutrient-rich soil amendment that reduces reliance on chemical fertilizer. Soil testing, plant tissue testing and compost nutrient analysis were used to determine the proper compost application rates.

"Replacing chemical fertilizer with compost reduces the amount of fossil fuels used in the manufacture of fertilizer. Burning fuel contributes to greenhouse gas emissions," says Whelan. "And better matching nutrients to crop requirements reduces the risk of fertilizer over-application. Using poultry manure and crab processing waste in compost reduces the impact of these materials on the environment."

The compost comparison was carried out on a one-acre plot that was just part of Dwyer's 70-acre vegetable farm on Newfoundland's east coast about 80 kilometres 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.

Dramatic yield increase

The 2005 rutabaga plot, treated with compost, yielded 45,427 pounds of vegetables per acre, compared to 28,717 pounds per acre on adjoining land treated with chemical fertilizer. The provincial average for rutabaga production is about 17,500 pounds per acre.

Similarly, the cabbage plot treated with compost yielded 58,406 pounds of cabbage per acre, compared to 37,315 pounds on the adjoining field treated with chemical fertilizer. The provincial average for cabbage production is about 20,000 pounds per acre.

"These are dramatic yield increases in the 55 to 60 percent range," says Whelan. "The vegetables also appeared to have better size, color and less blight and less potato clubroot, making for a superior product over crops grown with chemical fertilizer."

Whelan also noted in a region where drought, in recent years, has reduce yields and wiped out crops, fields treated with compost had improved moisture retention and were better able to withstand the dry conditions.

The compost was used to replace between 800 and 900 pounds of chemical fertilizer per acre. Depending on the crop, commercial fertilizer requirements range from 300 to 1,200 pounds per acre per year. In Dwyer's area however, waste material from nearby fish processing plants and poultry manure are readily available.

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

While reducing crop input costs and increasing yields are important economic benefits, compost also has a proven track record for increasing soil organic matter, which improves soil quality and carbon sequestration in the long term.

Regional reports will be posted as information becomes available. Please check back regularly for updates.