Zinc Fertilization Plus Liming to Reduce Cadmium Uptake by Romaine Lettuce on Cd-Mineralized Lockwood Soil (2009)
"Lockwood shaly loam (Pachic Argixerolls) and similar Cd mineralized soils derived from marine shale in California contain higher Cd levels and higher Cd:Zn ratios than uncontaminated US soils, and produce leafy vegetables with considerably higher Cd than is normal for US lettuce. Previous work by Burau et al. suggested that, in contrast with geogenic Zn+Cd enriched soils, liming the Cd-mineralized soils did not effectively reduce crop Cd concentration. Our previous studies found for high Cd:Zn soils, liming may not reduce crop Cd but liming plus Zn fertilizer can strongly reduce crop Cd. Greenhouse pot trials were undertaken with addition of 0-500 mg Zn kg-1 to Lockwood soil (5.3 mg Cd and 54 mg Zn kg-1). All pots were made calcareous with reagent CaCO3 (harvest pHW 7.8 ), or adjusted to a range of pH without Zn fertilizer. The zero Zn calcareous treatment produced lettuce with 13.2 mg Cd kg-1 DW and only 10.5 mg Zn kg 1 DW; adding 100 mg Zn kg-1 soil produced lettuce containing 2.53 mg Cd kg-1 and 35 mg Zn kg-1; adding 250 mg Zn kg-1, 6.3 mg Cd kg-1 lettuce; and 500 mg Zn kg-1, 3.9 mg Cd kg-1 lettuce. For the 0 Zn treatment, acidification or liming increased lettuce Cd. The key finding is that if Zn is added to raise Cd:Zn ratio, liming these soils can be highly effective in reducing lettuce Cd, much like found for other Cd+Zn enriched soils."
not news to me re the cd uptake in nutrient depleted soil conditions, but i think it was magnesium i had on the radar not zn. (though i have read about soil zinc depletion issues in other crop contexts before). i am trying to work through the challenges where organic produce is concerned, since i know there's less cadmium uptake there as well.
i already gave up california produce to a large extent after seeing the aquifer depletion maps and absorbing some thinking about vegetable shipments around the continent amounting to exporting already scarce water all over the place. the particular cadmium dynamic is worth knowing.
pursue optimal self care at least as actively as a diagnosis
ask for referrals to preventive health care specialists eg dietitians
don't let suboptimal self care muddy any underlying diagnostic picture!
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