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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Adaptive Cropping Systems Laboratory » Research » Publications at this Location » Publication #331889
Title: Effect of Soil Amendments on Cd accumulation by Spinach from a Cd-Mineralized Soil

Author
item PAUL, ADRIAN - Universite Catholique De Lille
item Chaney, Rufus

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Certain cadmium mineralized, marine shale-derived, California soils contain high levels of natural cadmium which cause increase in the cadmium levels in leafy vegetables (spinach, Romaine lettuce) grown on these soils. In some cases, cadmium concentration in spinach have led to Food and Drug Administration crop recalls due to excessive cadmium. Our previous research showed that if one added zinc and limestone together to the soil it could achieve lowering of crop cadmium to approved levels. In addition, our previous research showed that the combination of cadmium adsorption capacity and zinc in modern biosolids composts produced in California could reduce metal uptake. So we tested combinations of zinc, limestone, manganese, and biosolids compost additions to a Lockwood shaly loam soil with 5.9 mg Cd/kg (much higher than median US soil of 0.20 mg/kg), and grew ‘Seaside’ spinach. The results showed that addition of manganese to increase soil adsorption of cadmium caused soil acidification and promoted cadmium uptake. Addition of zinc strongly reduced cadmium accumulation by spinach, but when combined with limestone drove spinach cadmium below approved limits. Biosolids compost amendment strongly reduced crop cadmium even though this acidic compost lowered the pH of the amended soil. Combining biosolids compost with limestone, and with zinc, achieved spinach cadmium lower than limits. Thus both cadmium adsorption amendments and zinc fertilizers or byproducts can significantly reduce cadmium accumulation in spinach and assist the leafy vegetable producers grow marketable products.

Technical Abstract: Cadmium mineralized soils occur in many nations. When these soils are non-calcareous, crops and especially leafy vegetables such as lettuce and spinach accumulate levels of Cd which exceed international standards. Lockwood loam from Monterey Co., CA, has been found to cause excessive Cd in leafy vegetable crops. Agronomic or genetic management alternatives are needed to allow use of these highly productive soils. Previous research has shown that Zn fertilizer plus limestone incorporation or biosolids compost and sorbent oxide amendments can reduce crop Cd accumulation. We tested incorporation of combinations of biosolids compost (10%), of Mn, Zn and limestone (5%) to limit Cd phytoavailability. Added Mn2+ caused acidification which increased spinach Cd. Added Zn inhibited Cd accumulation as did biosolids compost, but much greater reductions were achieved if the soil was made calcareous to prevent the acidification from addition of compost or Zn salts. With Zn fertilizer + limestone or biosolids compost plus Zn fertilizer plus limestone, spinach Cd levels were below international Cd limits.