Tillage effects on gaseous emissions from an intensively farmed organic soil in North Central Ohio

As in other drained, intensively cultivated Histosols of the world, soil subsidence is a growing concern of vegetable farmers in the muck crops region of North Central, Ohio. Subsidence in organic soils is caused primarily by aerobic degradation of soil organic matter (SOM), which in turn makes available large quantities of once bound C and N. Upon drainage and cultivation, soil C and N dynamics shift drastically. Organic soils transition from CO2 and organic N sinks, to persistent sources, whereas CH4 uptake capacity increases. Therefore, this study was conducted to assess the short-term (within the first year) impact of conversion of intensively tilled organic soils to no-till management. The specific objectives of this study were to: (i) compare soil moisture content, soil temperature, and greenhouse gas (GHG) emission rates from moldboard/disking (MB), no-till (NT), and bare (B) treatments in cultivated organic soils, and (ii) estimate the rate of subsidence associated with these tillage practices. Over the year, soil moisture content (SMC) was significantly higher in MB (0.90 kg kg(-1)) than B (0.84 kg kg(-1)) treatments; however NT (0.87 kg kg(-1)) was not significantly different from either MB or B treatments. Mean annual temperatures at 5 cm depth were significantly higher in B (16.9 degrees C) compared to MB (16.2 degrees C) and NT (15.9 degrees C) treatments The CO2 emissions were not significantly different among treatments, while N2O emissions were significantly higher from MB (96.9 kg N2O-N ha(-1) yr(-1)) than NT (35.8 kg N2O-N ha(-1) yr(-1)) plots. Both CH4 uptake and CH4 emission exhibited low annual flux in all treatments. (c) 2007 Elsevier B.V. All rights reserved.