Influence of Trace Metals on Some Soil Nitrogen Transformations

Abstract

An investigation to evaluate the influence of trace metals on N immobilization, N mineralization, and nitrification was conducted. Samples of Yolo silt loam amended with 100 ppm NH4‐N, 1% sewage sludge, and 1% ground alfalfa (Medicago sativa L.) were treated with solutions to provide 100, 200, and 400 ppm of Cd(II), Cr(III), Cu(II), Mn(II), Pb(II) and Zn(II), and incubated for 2, 4, 8, and 12‐week periods. Metals were determined by extracting with water, KNO3, DTPA (diethylenetriaminepentaacetic acid), and HNO, at the end of each incubation period. All metals reverted quickly to more insoluble forms. Quantities of metals extractable with water + KNO3 + DTPA decreased with time, while corresponding increases in HNO3‐soluble forms occurred. Nitrogen immobilization was measured during the 2‐ to 4‐week period, and N mineralization and nitrification during the 4‐ to 12‐week period. At low levels of metal addition Mn and Pb stimulated N immobilization, but at 400 ppm all metals were inhibitory to all N transformations. Among the six metals studied the sequence in order of decreasing inhibition was Cr > Cd > Cu > Zn > Mn > Pb. it was concluded that N transformation rates may be affected by trace metals in soils receiving heavy sludge applications.

Developments in Bioremediation of Soils and Sediments Polluted with Metals and Radionuclides: 2. Field Research on Bioremediation of Metals and Radionuclides

“…Techniques have been developed to assess the health of the soil microbial population, including measure of soil function through respiration, N cycling, and ability to utilize added substrates (CELA and SUMNER 2002;CHANG and BROADBENT 1982;MCGRATH 2002;SAUVE 2002). One example is the Biolog extraction (KELLY and TATE 1998), which attempts to evaluate the functionality of the soil microbial population through its ability to utilize a range of carbon sources.…”

Effects Of Pb, Cu, Sb, In and Ag Contamination on the Proliferation of Soil Bacterial Colonies, Soil Dehydrogenase Activity, and Phospholipid Fatty Acid Profiles of Soil Microbial Communities

“…The addition of Cd, Cr, Cu, Ni, Pb and Zn to soil inhibits soil respiration (Chang and Broadbent, 1981;Ohya et al, 1986;Hattori, 1992), nitrogen mineralization (Liang and Tabatabai, 1977;Chang and Broadbent, 1982), and nitrification (Liang and Tabatabai, 1978;Cela and Sumner, 2002a,b). Aoyama and Nagumo (1997) also found that in heavy metal contaminated apple orchard soils in field experiments, dehydrogenase activity/soil organic C was negatively correlated with the amount of 0.1 M CaCl 2 -extractable Cu, which represented the readily-soluble Cu.…”

Effects of Cr3+, Cr6+ and tannery sludge on C and N mineralization and microbial activity in semi-arid soils

“…James and Bartlett [3] found that nitrification was inhibited by Cr 6+ at a concentration of 10 g g −1 in soil suspensions, but no inhibition was observed in treatments containing Cr 3+ in sewage sludge or tannery effluent. Chang and Broadbent [4] observed that nitrogen immobilization, mineralization and nitrification were inhibited to a great extent by Cr 3+ added to a neutral soil, but Cr 6+ was not measured in the extracting solutions used to characterize soil Cr during the experiment. Barajas-Aceves and Dendooven [5] reported that tannery sludge added to semi-arid soils had no inhibitory effect on N mineralization.…”