Effect of Manure Application on Net Nitrification Rates, Heavy Metal Concentrations and Nitrifying Archaea/Bacteria in Soils

In this study, we determined the effect of manure application on net nitrification rates (NNRs), heavy metal concentrations (HMCs), and abundance of ammonia-oxidizing archaea (AOA)/bacteria (AOB), and nitrite-oxidizing bacteria (NOB) in soil. HMCs were measured by atomic absorption spectroscopy. Abundance of AOA, AOB, and NOB was enumerated by q-PCR. NNRs ranged from 2.8 to 14.7 mg kg(-1) h(-1) and were significantly (p < 0.05) increased in manure soils as compared to control soils. NNRs were affected by pH 7 and temperature 30 degrees C. Cd, Fe and Pb concentrations were classified as excessively polluted, moderate contamination and slight pollution, respectively, in the manure soils. NNRs and concentrations of Fe and Pb were significantly (p < 0.00) positive correlated, but Cu and Cd were significantly (p < 0.00) negative correlated with NNRs. Application of manure significantly (p < 0.05) increased HMCs (Fe, Cu, and Pb), which have indirect and direct effects on NNRs and nitrifying bacteria.

Automated summary

Manure application significantly increased net nitrification rates (NNRs) in soil and had effects on heavy metal concentrations, abundance of ammonia-oxidizing archaea/bacteria and nitrite-oxidizing bacteria. The concentrations of Fe and Pb were positively correlated with NNRs, while Cu and Cd were negatively correlated with NNRs.