Nutrient Supply From Organic Soil Amendments

A. M. Hammermeister^1,4, T. Astatkie², P. R. Warman³, E. Jelizkova¹ and R. C. Martin¹

The use of organic amendments is complicated by variability in nutrient content, combination of nutrients provided and variability in the quantity and timing of nutrient release. Ion exchange membranes (PRS™™) were used in a growth room experiment to measure nutrient supply from poultry manure compost (PMC), vermicastings (VC), feather meal (FM), and alfalfa meal (AA) with total N contents of 58, 14, 144, 30 g kg^-1 respectively. The amendments were applied at three rates (0, 200, 400, 800 kg total N ha^-1) to an impoverished sandy soil with no crop, lettuce or orchard grass. The 400 and 800 kg total N ha^-1 rate treatments had low nutrient supply rates, in some cases only 10% higher than the 200 kg total N ha^-1 treatment. Over 88 d, cumulative NO₃^- supply was highest in the PMC and FM; NH4+ supply rate was initially very high but decreased quickly. VC initially were highest in NO₃^- supply but lowest in cumulative NO₃^-. H₂PO₄^- and SO₄^2- supply rate of all amendments was lower than that for unamended soil except SO₄^2- in VC amended soil. Lettuce was sensitive to phytotoxicity resulting from PMC and FM; orchard grass was more tolerant. Lettuce yields were highest in the vermicastings treatment, but differences in orchard grass yields among amendments were small. Nutrient supply rate was influenced significantly by the microbial community's ability to utilize the organic nutrients.


Source
2nd OACC Organic Research Workshop, Presented in association with the Organic Connections: Prairie Wide Organic Conference and Trade Show, November 14-16th, 2004


Author Locations and Affiliations
(1) Organic Agriculture Centre of Canada, NSAC
(2) Department of Engineering, NSAC
(3) Department of Environmental Sciences, NSAC Nova Scotia Agricultural College
P.O. Box 550, Truro, NS B2N 5E3
(4) Corresponding author: ahammermeister@nsac.ca


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