【作物种植顺序和氮肥施用影响旱地土壤温室气体排放】Upendra M. Sainju Thecan Caesar-TonThat Andrew W. Lenssen and Joy L. Barsotti. Dryland Soil Greenhouse Gas Emissions Affected by Cropping Sequence and Nitrogen Fertilization. SSSAJ Vol. 76 No. 5 p. 1741-1757

Abstract

Information is needed to mitigate dryland soil greenhouse gas (GHG) emissions by using novel management practices. We evaluated the effects of cropping sequence and N fertilization on dryland soil temperature and water content at the 0- to 15-cm depth and surface CO₂ N₂O and CH₄ fluxes in a Williams loam (fine-loamy mixed superactive frigid Typic Argiustolls) in eastern Montana. Treatments were no-tilled continuous malt barley (Hordeum vulgaris L.) (NTCB) no-tilled malt barley–pea (Pisum sativum L.) (NTB–P) and conventional-tilled malt barley–fallow (CTB–F) (control) each with 0 and 80 kg N ha⁻¹. Gas fluxes were measured at 3 to 14 d intervals using static vented chambers from March to November 2008 to 2011. Soil temperature varied but water content was greater in CTB–F than in other treatments. The GHG fluxes varied with date of sampling peaking immediately after substantial precipitation (>15 mm) and N fertilization during increased soil temperature. Total CO₂ flux from March to November was greater in NTCB and NTB–P with 80 kg N ha⁻¹ than in other treatments from 2008 to 2010. Total N₂O flux was greater in NTCB with 0 kg N ha⁻¹ and in NTB–P with 80 kg N ha⁻¹ than in other treatments in 2008 and 2011. Total CH₄ uptake was greater with 80 than with 0 kg N ha⁻¹ in NTCB in 2009 and 2011. Because of intermediate level of CO₂ equivalent of GHG emissions and known favorable effect on malt barley yield NTB–P with 0 kg N ha⁻¹ might mitigate GHG emissions and sustain crop yields compared to other treatments in eastern Montana. For accounting global warming potential of management practices however additional information on soil C dynamics and CO₂ associated with production inputs and machinery use are needed.

【常规和免耕小麦土壤水动态】A. Patrignani C. B. Godsey T. E. Ochsner and J. T. Edwards. Soil Water Dynamics of Conventional and No-Till Wheat in the Southern Great Plains. SSSAJ Vol. 76 No. 5 p. 1768-1775

Abstract

Continuous winter wheat (Triticum aestivum L.) represents ~75% of the total grain cropland acreage in Oklahoma. Wheat is mainly sown using conventional tillage (CT) which is linked with low precipitation storage efficiency (PSE) and contributes to water and wind erosion. The objectives of this study were to compare PSE of fallow periods and water content dynamics of the soil profile during the growing season of winter wheat monoculture under both CT and no-till (NT) systems. Soil moisture was measured weekly from April to November and every 20 d during the winter period using a neutron probe moisture meter in field experiments at two locations from 2009 to 2