ARS | Publication request: CHANGES IN PLANT GROWTH AND N UPTAKE WITH COMPOST MATURITY

Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 7, 2005
Publication Date: November 7, 2005
Citation: Hutchinson, M., Griffin, T.S. 2005. Changes in plant growth and n uptake with compost maturity. American Society of Agronomy Abstracts. ON CD

Technical Abstract: Improving the prediction of plant available nitrogen (PAN) from compost at different maturity stages will allow growers to better utilize this N source. Thirteen compost samples were collected from a single windrow over a 100 d period. The compost feedstock included fish waste, sea urchins, spoiled haylage, heifer manure and dry softwood shavings. A greenhouse experiment was conducted with a sandy loam soil amended with each compost, at an application rate equivalent to 400 kg of total N/ha. Two non-compost controls were also included: minus N and plus N (15 mg of N/kg of soil/week). All pots received similar amounts of potassium and phosphorous. Annual ryegrass was planted to a depth of 1.5 cm in each pot. Pots were weighed and watered daily to maintain soil water at estimated field capacity. Ryegrass was harvested at 30 and 60 d after planting. Barley was then planted in the pots and harvested after 30 d of growth. Total above-ground plant biomass, N concentration, and N removal were estimated. Plant biomass for compost-amended soil was significantly higher than the minus N control and less than the plus N control. There were significant differences in plant biomass between compost treatments, although the relationship between compost maturity and plant biomass was more variable for early plant growth (ryegrass harvests) than for later plant growth (barley). This may have been due to phytotoxicity of the most immature composts. Nitrogen availability was strongly correlated with compost maturity for the last plant harvest. This research helps refine the relationship between compost maturity and N availability.