Redox potential, nitrate content and pH in flooded Eutric Cambisol during nitrate reduction.

摘要

Topsoils (0-30 cm) from 16 arable Cambisols from Poland developed from sand, loam and silt were used to study soil ability to reduce nitrates under flooding conditions. The highest drop of redox potential (Eh) was observed during the first day of soil flooding. Decreasing tendency in pH values was observed of alkaline and neutral soils, and an increase in pH of acid and strongly acid soils, accompanied by a decrease in Eh values. Redox potential was negatively correlated with the pH values (R2=0.3041; p<0.001). The reduction of NO3- varied from 20 to 100% depending on the type of soil and on the time of incubation. With a decrease of nitrate content within the range from 100 to 10 mg NO3--N/kg, the value of redox potential decreased from 250 to 190 mV. The highest reduction of nitrates coincided with Eh values within a narrow range between 200 and 210 mV. Statistical analysis of redox potential in the function of the content of nitrates showed a curvilinear relation (R2=0.3823; p<0.001)..