Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2014
Publication Date: 11/11/2015
Citation: Han, Y., Douds, D.D., Boateng, A.A. 2015. Effect of biochar soil-amendments on Allium porrum growth, arbuscular mycorrhizal fungus colonization. Journal of Plant Nutrition. DOI:org/10.1080/01904167.2015.1089903.
Interpretive Summary: Biochars are charcoal-like materials produced by burning plant material in conditions of low oxygen availability. Addition of biochar to soil has been shown to be beneficial to both the soil and to growth of plants. Arbuscular mycorrhizal [AM] fungi are soil fungi that form a symbiosis with plants, imparting to the plant a variety of benefits including enhanced nutrient and water uptake. “Heavy metals,” such as zinc and copper, are significant pollutants in soil due to man’s application of industrial wastes and pesticides to the soil. One common beneficial characteristic of biochar and AM fungi is a certain amount of protection of plants from the toxic effects of too much heavy metal in the soil. We conducted an experiment in which biochars and AM fungi were examined for their protective effects on leek plants grown in the presence of zinc and copper. Biochar and AM fungi protected the plants from heavy metal toxicity, as evidenced by maintenance of plant growth. Certain types of biochar, however, severely impacted the colonization of roots by AM fungi. These findings are significant because they supply information on selecting biochars for application to agricultural soils while being mindful of potential negative impacts upon AM fungi.
Technical Abstract: Aims: Examine the interaction of biochar addition and arbuscular mycorrhizal [AM] fungus inoculation upon growth and Zn and Cu uptake by Allium porrum L. in heavy metal amended soil mix, and relate these responses to physicochemical properties of the biochars. Methods: The experiment was a complete factorial with three factors. A. porrum seedlings were grown in a controlled environment chamber in media with or without Zn and Cu addition, with and without the AM fungus Glomus intraradices Schenck & Smith, and either without biochar or in the presence of one of 12 different biochars. Biochars were created by pyrolysis of three biomass feedstocks subjected to various process conditions including fast pyrolysis and steam activation. Results: Fast pyrolysis biochars from all feedstocks greatly reduced colonization of roots by the AM fungus. Among biochars produced by a given pyrolysis method, higher surface areas were accompanied by higher AM fungus colonization. Biochar addition had various effects on plant P content, which was correlated well with reduced AM fungus colonization. Addition of heavy metals reduced root weight by 22% in the absence of biochar relative to plants grown without heavy metals. Root weight increased 15% with heavy metals in the presence of biochar relative to plants grown without biochar. Cu and Zn uptake by A. porrum was affected by biochar, but results contrasted with previous studies of heavy metal adsorption conducted in aqueous solution. Conclusion: These findings are pertinent in selecting biochars for application to agricultural soils for heavy metal adsorption while being mindful of potential impacts upon the AM symbiosis.