Organic Vegetable Production Experiments

Phil Warman, Nova Scotia Agricultural College, Truro NS

A long-term study compared crop rotations that used either compost or commercial fertilizer for vegetable production. Vegetable yields in six different rotations using compost (only) were generally similar to those where commercial fertilizers were used. Nutrient content of the vegetables was similar between soil fertility amendments for most nutrients. Phosphorous content of the edible portion of the vegetable, and the phosphorous and potassium content of the leaves were lower in the compost treatment in the last year of the 12 year study.

A number of extractable soil nutrients were present in higher concentrations after 11 years of compost than they were after 11 years of commercial fertilizers. These include carbon, calcium, magnesium, copper, zinc and boron. Nitrogen and phosphorous levels were higher in some years after the compost amendment. The cation exchange capacity of the soils was increased by compost amendment.

Soil nutrient availability in the compost varied from year to year, due to moisture and temperature as much as from the source of the compost as the amount applied. In the last years, the compost provided a higher level of nutrients than expected, possibly because the soil environment was more favourable after several years of organic amendments. Soil biochemical changes are being examined further.

This study suggests that long-term applications of agronomically appropriate levels of quality compost can provide the nutrients needed for most vegetable crops.


Source
1st Canadian Organic Agriculture Research Workshop, University of Guelph, January 2004


Contact Info
Phil Warman, Nova Scotia Agricultural College, Box 550, Truro, Nova Scotia, B2N 5E3 CANADA, Email: pwarman@nsac.ca


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