Denitrification in No-Till and Plowed Soils
1982
Rice, Charles W. | Smith, M Scott
No-till and plowed soils were compared with regard to denitrifying activity. To assay denitrification with minimal physical disruption of the soil, an important consideration in the study of tillage effects, a procedure was developed employing acetylene (C₂H₂) inhibition of nitrous oxide (N₂O) reduction in intact soil cores. This approach and a short-term, anaerobic soil slurry assay were consistent in indicating greater denitrifying activity in no-till than in plowed Maury silt loam soil. In the intact core assay, ratios of no-till to plowed soil activity were >1 on all sampling dates, and were as high as 77. Intact cores from a Crider (Typic Paleudalfs) soil showed a similar tillage effect, but tillage had inconsistent effects on both soil water content and denitrifying activity in a Tilsit (Typic Fragiudults) soil. It is suggested that the generally higher soil moisture contents observed in no-till soils, rather than tillage per se, are primarily responsible for higher denitrifying activity. Enhanced denitrification may account, in part, for the lower soil NO⁻₃ concentrations and higher N fertilizer requirements sometimes reported for no-till soils.
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