Soil Mixing Effects on Inorganic Nitrogen Production and Consumption in Forest and Shrubland Soils
Plant & Soil
Soils that are physically disturbed are often reported to show net nitrification and NO−3 loss. To investigate the response of soil N cycling rates to soil mixing, we assayed gross rates of mineralization, nitrification, NH+4 consumption, and NO−3 consumption in a suite of soils from eleven woody plant communities in Oregon, New Mexico, and Utah. Results suggest that the common response of net NO−3 flux from disturbed soils is not a straightforward response of increased gross nitrification, but instead may be due to the balance of several factors. While mineralization and NH+4 assimilation were higher in mixed than intact cores, NO−3 consumption declined. Mean net nitrification was 0.12 mg N kg−1 d−1 in disturbed cores, which was significantly higher than in intact cores (−0.19 mg N kg−1 d−1). However, higher net nitrification rates in disturbed soils were due to the suppression of NO−3 consumption, rather than an increase in nitrification. Our results suggest that at least in the short term, disturbance may significantly increase NO−3 flux at the ecosystem level, and that N cycling rates measured in core studies employing mixed soils may not be representative of rates in undisturbed soils.
Booth, M.S., J.M. Stark, and S.C. Hart. 2006. Soil mixing effects on inorganic nitrogen production and consumption in forest and shrubland soils. Plant & Soil 289:5-15.