Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2003
Publication Date: 4/1/2004
Citation: Kukier, U., Chaney, R.L. 2004. In situ remediation of ni-phytotoxicity for different plant species. Journal of Plant Nutrition. 27(3):465-495. Interpretive Summary: Smelters have emitted metals and caused contamination of surrounding soils at many locations. In locations where soils were or became strongly acidic, Ni smelters caused severe Ni phytotoxicity to oats and other plant species. Previous research had shown that if such soils are made alkaline (calcareous) and any fertilizers needed for calcareous soils are applied, that Ni phytotoxicity was readily remediated. These studies were limited t oat, wheat and redbeet. Because the removal and replace of contaminated soils costs about 100-1000 times more that in situ remediation with limestone and fertilizers, it was important to determine if liming would prevent Ni phytotoxicity in a range of crop and garden species commonly grown in the region where the smelter contamination occurred. Soil with 2900 mg Ni/kg was collected from a tilled farm field near the smelter. Eleven crops were grown on the soil at the pH collected (near pH 5.0 after addition of fertilizers), limed to pH about 6.0, and limed to make the soi calcareous (pH 7.7). Liming the soil greatly reduced the solubility of Ni in the soil. For sensitive crops, liming to pH 6 did not improve growth, while for relatively resistant crops, liming to pH 6 gave near maximal yields. For all crops tested, liming to calcareous pH gave full prevention of Ni phytotoxicity. Crops differed in relative uptake of Ni at the same soil pH, and in susceptibility to foliar Ni (perennial ryegrass tolerated higher leaf Ni than other species). Swiss chard, redbeet and tomato were very sensitive; oat and radish were sensitive, bean and soybean were somewhat resistant; barley, wheat, ryegrass and corn were relatively resistant to Ni phytotoxicity based on improvement in yield upon making the soil calcareous. In situ remediation was very successful for all species.
Technical Abstract: Soils surrounding a nickel refinery in Port Colborne, Ontario, Canada were contaminated with Ni by particulate emissions. Ni phytotoxicity had occurred in sensitive crops grown on strongly acidic soils. Phytotoxicity could be alleviated by addition of fertilizers and raising soil pH. This previous research examined toxicity to oat, wheat, and redbeet, but whether making soils calcareous could provide full remediation of Ni phytotoxicity for other crops was unknown. Thus, a greenhouse study with 11 agricultural crop and garden species was conducted to test if Ni phytotoxicity could be ameliorated by a high rate of limestone plus nutrients (Mn, P) needed for calcareous soil conditions. The selected species represented a wide range of susceptibility to Ni toxicity. Welland clay loam soil (Typic Epiaquoll; 2900 mg kg-1 Ni) used in the study was collected in the vicinity of a refinery. At the original pH of 5.2, this soil was moderately to extremely phytotoxic to all plant species. Toxicity symptoms in dicots included interveinal chlorosis and necrosis of leaves. In grasses, a banded chlorosis was present, except for corn (Zea mays L.), which exhibited a interveinal chlorosis. Two limestone rates, 2.5 and 50 Mg ha-1, were included in the test. Both liming and plant species significantly affected soil pH, Sr(NO3)2-extractable soil Ni, and Ni phytotoxicity. The increase in pH decreased Sr(NO3)2-extractable soil Ni in an exponential manner. Grass species were more resistant to Ni toxicity than dicots. Liming soil to pH of 5.9-6.3 enabled good growth of several grass species, but dicot species were still stunted or died. Making the soil calcareous (pH 7.7-7.8) ameliorated Ni toxicity in all species tested.