The Concept of Phytoextraction of Soil Trace Elements


In 1978 I began working on the concept of phytoextraction and phytomining as part of a project on remediation of metal contaminated soils. I did my Ph.D. on Ni in soybeans. And was studying the potential for phytotoxicity or food-chain risks from metals in land-applied biosolids. To an agronomist who read the Brooks et al. early papers on hyperaccumulation with a botanical prospecting focus, the potential use for phytoremediation/phytoextraction and even phytomining seemed obvious. I summarized the concept in a 1980 paper for an US-EPA Conference, and a report on our research to US-EPA, and then a book chapter which has been cited 643 times. In later review papers I looked at the overall potential for phytoextraction where someone would pay to have metals removed from a contaminated soil. And for the potential for $ value of a metal crop for different elements for which known hyperaccumulators existed. Hyperaccumulation of most elements will not pay for the cost of growing and harvesting the crop, but for Ni the potential value of a high Ni crop was clear. We obtained funding, collected germplasm, tested agronomy (fertilizers; soil pH; density; harvest schedule) and genetics, and developed improved cultivars for commercial use in temperate zones of Alyssum murale (Odontarrhena chalcidica) and Alyssum corsicum (Odontarrhena corsica). The overall theoretical framework for economic phytomining of a number of elements will be summarized. Progress of the Univ. Queensland team in Sabah with Phyllanthus rufuschaneyi has been remarkable and is expected to become an economic Ni farming operation.


Dr. Rufus L. Chaney retired from his position as a Senior Research Agronomist in the Adaptive Cropping Systems Laboratory of the USDA-Agricultural Research Service at Beltsville, MD, after 47 years of soil-plant environmental research. He conducted research on the fate, food-chain transfer, and potential effects of soil microelements. The research includes studies on 1) plant uptake of metals and translocation to edible plant tissues; considered plant-soil interactions in microelement phytoavailability; 2) speciation of metals in plants and bioavailability to animals; 3) development of hyperaccumulator crops to phytoextract and recycle metals from contaminated or mineralized soils; 4) bioavailability of lead and other metals in soils, biosolids, and composts directly ingested by animals; 5) development of "Tailor-Made Composts and Biosolids" to remediate Pb, Zn, Cd, Ni and other element contaminated soils including urban gardens; and 6) potential methods to reduce food-chain transfer or toxicity of metals in organic resources and potential regulatory approaches to protect food safety and soil fertility.

During his research he has mentored 45 MSC and PhD students, and 34 visiting scientists and postdoctoral scientists from 23 countries. Awards received during his career included being elected as Fellow of the American Society of Agronomy (1992), the Soil Science Society of America (1992), the American Association for the Advancement of Science (2001), the American Society of Agronomy Environmental Quality Research Award in 2000, Beltsville Area Senior Research Scientist of the Year in 1995, the USDA Secretary’s Honour Award for Environmental Protection in 1997, the USDA Presidential Rank Meritorious Senior Professional Award in 2003, and was promoted to the Senior Scientific Research Service in 2004. With all these achievements, he was elected to the “ARS Science Hall of Fame” in 2013.

Since beginning his career in 1969, Dr. Chaney has 493 published papers (348 Peer Reviewed) and 320 published abstracts on these topics. He has cooperated with the US-Environmental Protection Agency, the US-Food and Drug Administration, the Office of Management and Budget, and many States in preparing advice and regulations for utilization of biosolids and other beneficial soil amendments in and remediation of metal contaminated soils. His H-Index=96 (Feb., 2019).


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