Nutrient supply from organic amendments applied to unvegetated soil, lettuce and orchardgrass

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 × rate × 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

Effect of organic amendments on half-highbush blueberry production and soil fertility

Five treatments were compared using two half-highbush blueberry cultivars (cv Chippewa and Polaris) transplanted and grown for their first three growing seasons at a site in Boutiliers Point, N.S., a Gibraltar brown sandy loam (Ferro-Humic Podzol). The five treatments were as follows: Alfalfa meal + rock P + wood ash; NPK fertilizer; Municipal Solid Waste (MSWC) compost; Ruminant compost; food waste, manure and yardwaste compost (FMYC). All amendments were weighed and applied in an amount equivalent to the total N of the recommended NPK fertilizer for blueberries, assuming 25% N availability from each of the organic amendments. Soil extractable nutrients, leaf nutrients and fruit yields were measured and compared. The fertility treatments produced few effects on extractable levels of nutrients in the soil and leaf. ‘Chippewa’ responded more than ‘Polaris’ to the fertility treatments. The K fertilizing ability of the Ruminant compost was evident in all three growing seasons. ‘Chippewa’ showed consistent soil and leaf P response to Ruminant compost throughout the growing season; however, it failed to produce a comparative increase in the fruit yield. The NPK fertilizer treatment reduced the soil pH compared to other soil amendments while the MSW treatment increased the soil pH each year. The yield results showed that there were no statistical differences between the treatments for either cultivar (one year of data). Thus, the composts provided equivalent amounts of plant essential nutrients without increasing the trace element concentration in soil and tissue