Nutrient supply from organic amendments applied to unvegetated soil, lettuce and orchardgrass
Hammermeister, A.M., T. Astatkie, E. A. Jeliazkova, P. R.Warman and R. C. Martin. 2006. Canadian Journal of Soil Science 86:21-33
Abstract
Organic sources of nutrients
are increasingly being used in horticultural and certified organic production. The nutrient-supplying potentials of poultry manure
compost (PM), feather meal (FM), alfalfa meal (AA) and vermicastings (VC) and an unamended control were measured in a
growth room experiment. The amendments were applied at rates equivalent to 200, 400 and 800 kg total N ha-1 to a soil of low
fertility. Nitrogen supply rates and concentrations were measured over 6 mo in unvegetated pots using PRS™ -probes and KCl
extraction, respectively. Biomass of lettuce (Lactuca sativa L.) and orchardgrass (Dactylis glomerata L.) and N uptake of orchardgrass
were measured. Repeated measures analysis revealed significant amendment x rate x time interaction effects for N supply
rate and concentration. Of total N applied, available N was 50 to 70% in the FM and PM treatments, 10 to 40% in the AA treatments,
and 10% in the VC treatments. High rates of FM and PM were toxic to lettuce but produced good orchardgrass yields. VC
was safe for lettuce but low N availability limited long-term orchardgrass growth. Higher application rates did not result in corresponding
increases in nutrient supply. Consideration should be given to balancing the ratio of available nutrients in amendments
with plant requirements.
Key Words
Apparent nitrogen recovery, plant N uptake, feather meal, alfalfa meal, vermicastings, poultry manure compost
