Soil fertility, yield, and nutrient contents of vegetable crops after twelve years of compost or fertilizer amendments.

Full report by P.R. Warman
Department of Environmental Sciences, Nova Scotia Agricultural College, Truro, N. S., Canada

Research comparing the use of compost versus conventional fertilizer on vegetable plots has been conducted over an 11 year period near Truro, Nova Scotia. It is likely the longest study of its kind in Canada.

Compost and fertilizer applications have been based on the results of soil sampling and the Nova Scotia Soil Test Recommendations, and assuming 50 or 100% availability of the total N in the mature composts or fertilizers, respectively.

The composts consist of animal manure, food waste, yard waste and straw or racetrack manure bedding. Marketable yields have been taken annually since 1990 and the plant tissue samples have been analysed for macro- and micronutrients, while soils have been sampled for pH, organic matter and Mehlich-3 extractable nutrients since 1994.

Highlights of the study's 2001 cropping year, based on fresh weight yields:

• Compost treatment resulted in numerically, but not significantly, higher yields for the carrots, peppers, onions and tomatoes
• Compost treatment resulted in significantly higher yields for green and yellow beans
• Cauliflower and Brussels sprouts yields were higher in the fertilizer-amended plot
• Soils with compost had higher pH, CEC, C, N and Mehlich-3 extractable levels of P, Ca, Mg, Mn, Zn and B compared with the fertilized plots
• Increased nutrients in the compost-amended soil did not increase the nutrients in the leaf tissue or the edible portion of the plant
• Of the 16 elements tested, only P and K were higher in the fertilizer-amended plant leaf tissue, while levels of P were significantly higher in the edible portion of the plant

This study demonstrated that the long-term use of compost can produce similar yields and elemental analysis for most crops in compost-amended and conventionally-fertilized soils.

The full report of this research, entitled "THE LONG-TERM VEGETABLE PRODUCTION EXPERIMENT: PLANT GROWTH AND SOIL FERTILITY COMPARISONS BETWEEN FERTILIZER AND COMPOST-AMENDED SOILS" is available elsewhere on this website.