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| Rural Industries |
Objective
To investigate the role of rare earth elements (REE) in the nutrition and productivity of agricultural plants.
Background
Over the past fifteen years Chinese scientists have
established that trace amounts of rare earth elements (seventeen
chemically similar trivalent cations) can increase crop and livestock
production. This has resulted in a large extension program to
promote the use of rare earth elements in Chinese agricultural
systems. In 1993, 3.73 million ha of crop, horticultural and pasture
land was treated with REE. Yield responses in the order of 8%
to 15% are typical and claims for improved quality of produce
have been made.
Australia has considerable reserves of REE. To date, exploitation of these resources has been confined to the manufacturing and processing industries. Experience in China raises the prospects that these resources might also play a role in Australia's agricultural industries.
Research
Rare earth elements were applied, either as additions to the nutrient solutions in which corn and mungbean (Vigna radiata) were grown, or as foliar sprays.
Outcome
When added to nutrient solutions, the REE lanthanum
(La) or cerium (Ce) were toxic to the root elongation of corn
and mungbean seedlings at concentrations ranging from 1 to 20
mM (0.1 to 3 parts per million). When exposed to concentrations
of La or Ce from 0 to 1.4 mM, the total dry matter production
of corn was unaffected, although root growth was increased by
36% in the presence of 0.19 mM La. The root growth of mungbean
was increased 21% in the presence of 0.19 mM La, although the
total dry matter yield of mungbean was unaffected at this La concentration
and was severely depressed by higher concentrations of La or Ce.
Corn and mungbean plants were sprayed with the REE-containing fertiliser obtained from China (called 'Nongle' = happy farmer). The rates of foliar application were those recommended in China and included 0, 0.025, 0.05, 0.1, 0.5 and 1.0%. There was a trend for 0.1% 'Nongle' to increase the total dry matter production of mungbean, but concentrations of 'Nongle' above 0.1% were toxic to corn and mungbean.
Implications
Rare earth elements are toxic to plants in most situations
that were studied. Corn is more tolerant to the application of
REE than is mungbean. If beneficial effects of La or Ce are to
be found in a species such as mungbean, they are likely to occur
at external La or Ce concentrations less than 0.2 mM. If the foliar
application of REE is beneficial to plants then the effects are
likely to be small and concentrations less than 0.1% need to be
evaluated further.
RIRDC Project No: CSC-47A
RESEARCHER: Dr F W Smith & Mr E Diatloff Prof C J Asher
ORGANISATION: CSIRO Div of Tropical Crops Dept of Crops
Cunningham Laboratory and Pastures
ST LUCIA QLD 4067 University of Qld ST LUCIA QLD 4067PHONE: 07 377 0233 07 365 2067
FAX: 07 371 3946
Last updated: 10 October 1996
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