Please use this identifier to cite or link to this item: http://hdl.handle.net/10125/61644

Biochar Increasing Internal Tolerance to Manganese Toxicity in a Manganese-Rich Acid Soil

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Title:Biochar Increasing Internal Tolerance to Manganese Toxicity in a Manganese-Rich Acid Soil
Authors:Marquez, Josiah M. K.
Contributors:Deenik, Jonathan L. (advisor)
Tropical Plant and Soil Science (department)
Keywords:Biochar
Mn toxicity
soybean growth
Date Issued:2014
Publisher:University of Hawaii at Manoa
Abstract:Manganese (Mn) toxicity is a serious constraint on crop productivity in prime
agricultural land in central Oahu. Liming alleviates Mn toxicity by raising soil pH and supplying
calcium (Ca), reducing plant available Mn. Biochar shows promise as a sustainable alternative
to lime in remediating Mn toxicity. We implemented a series of soybean greenhouse
experiments to test the potential of five biochars with differing physico-chemical properties to
remediate Mn toxicity. Additionally, to compare the effects of calcium nutrition and pH, we
conducted another experiment with 4 increasing rates of two different Ca sources, lime (CaCO3)
and a neutral Ca salt (CaSO4). Our results showed that pH increase was effective in alleviating
Mn toxicity from the soil; however, Ca nutrition independent of pH also contributed to
alleviation. Biochar treatments maintained soybean growth similar to the limed control, despite
having toxic levels of Mn in tissue and soil, suggesting alleviation by increasing plant Mn
tolerance. A second planting in the same biochar treatments resulted in Mn toxicity in almost
all biochars, suggesting that biochars’ alleviating properties lack persistence in the soil, except
for the anaerobic digest biochar, which continued to detoxify Mn. A follow-up bioassay grow-
out was conducted, which gave results suggesting that alleviation from anaerobic digest biochar
was from biochar-derived compounds absorbed into the plant. We propose that alleviation of
Mn toxicity from biochar involves Mn tolerance through organic chelates, specifically phenolic
compounds. Increasing internal tolerance with biochar can have implications not only in
agriculture, but also in phytoremediation of heavy metals.
Pages/Duration:48 pages
URI:http://hdl.handle.net/10125/61644
Rights:All UHM Honors Projects are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Honors Projects for Tropical Plant and Soil Sciences


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