Nitrate reduction in deep soil horizons

Abstract

In seven days of the continuous incubation experiment at T=18°C with undisturbed soil samples of brown soils from the Apače Valley different dose of nitrate and additional glucose in some soil depth have statistically different impact on nitrate reduction rate (p=0.1, p=0.05 or p=0.01). This was in soil depths of 10-20 cm, 30-40 cm, 50-60 cm, and 90+ cm which correspond to soil horizons A_p, A_1,2, A_pog and C from 0.23±0.005 to 3.23±0.7, from 0.042±0.003 to 1.63±0.20, from 0.15±0.04 to 1.7±0.1 and from 0.004±0.001 to 1.05±0.09 mg N-NO₃/kg of dry soil/day respectively. Linear models of added nitrate concentration impact on nitrate reduction rate vary statistically distinguishing among soil depths (p=0.01). With additional glucose, the nitrate reduction was 5.5 times faster in the gravel parent material and 2.3 times faster in the uppermost soil layer.