|Angle, J scott|
Submitted to: International Conference on Serpentine Ecology
Publication Type: Abstract only
Publication Acceptance Date: 2/24/2006
Publication Date: 5/16/2006
Citation: Angle, J., Zhang, L., Chaney, R.L. 2006. Degradation of alyssum biomass in soil. International Conference on Serpentine Ecology. Sienna, Italy, May 2006. p. 6. Interpretive Summary: .
Technical Abstract: The reasons for Ni hyperaccumulation remain unproven; however, elemental allelopathy has been suggested as a possible reason for this unusual trait. It has been suggested that continual transport of Ni from soil to leaves, then shedding of leaves to fall on the soil surface, may create a Ni toxic zone that could inhibit germination and growth of competing plants. This theory was tested by adding high and low Ni biomass to both high and low Ni soils. High and low Ni biomass was created by growing Alyssum murale in high (serpentine) and low Ni (silt loam) soil. High and low Ni leaves contained 12.2 and 0.45 g Ni / kg, respectively. For both soils, soluble Ni was released rapidly from leaves upon introduction into the soil. Release and solubilization was nearly complete within two or three days. However, resorption to soil constituents and subsequent reduction in Ni availability occurred soon after the initial release from biomass. Within seven days, sorption resulting in near background levels was observed. Ni was sorbed more quickly in the high Ni serpentine soil than the non serpentine soil which was most likely related to the high iron content in the former. When eight plant species were seeded into high Ni biomass amended soil, few Ni related effects were observed. When inorganic Ni was added at an equivalent rate, significant inhibition of seed germination was found. These data indicate that a single application of high Ni biomass to soil did not create allelopathic effects as theorized. However, with repeated application of high Ni biomass to the soil surface following yearly leaf fall, it may still be possible for a Ni toxic zone to develop around the base of the plant.