Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, Ontario, Canada K1A 0C6; International Centre for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syrian Arab Republic.
J Environ Manage. 2013 Nov 15;129:652-64. doi: 10.1016/j.jenvman.2013.05.040. Epub 2013 Jul 30.
Controlled tile drainage can boost crop yields and improve water quality, but it also has the potential to increase GHG emissions. This study compared in-situ chamber-based measures of soil CH4, N2O, and CO2 fluxes for silt loam soil under corn and soybean cropping with conventional tile drainage (UTD) and controlled tile drainage (CTD). A semi-empirical model (NEMIS-NOE) was also used to predict soil N2O fluxes from soils using observed soil data. Observed N2O and CH4 fluxes between UTD and CTD fields during the farming season were not significantly different at 0.05 level. Soils were primarily a sink for CH4 but in some cases a source (sources were associated exclusively with CTD). The average N2O fluxes measured ranged between 0.003 and 0.028 kg N ha(-1) day(-1). There were some significantly higher (p ≤ 0.05) CO2 fluxes associated with CTD relative to UTD during some years of study. Correlation analyses indicated that the shallower the water table, the greater the CO2 fluxes. Higher corn plant C for CTD tended to offset estimated higher CTD CO2 C losses via soil respiration by ∼100-300 kg C ha(-1). There were good fits between observed and predicted (NEMIS-NOE) N2O fluxes for corn (R(2) = 0.70) and soybean (R(2) = 0.53). Predicted N2O fluxes were higher for CTD for approximately 70% of the paired-field study periods suggesting that soil physical factors, such as water-filled pore space, imposed by CTD have potentially strong impacts on net N fluxes. Model predictions of daily cumulative N2O fluxes for the agronomically-active study period for corn-CTD and corn-UTD, as a percentage of total N fertilizer applied, were 3.1% and 2.6%, respectively. For predicted N2O fluxes on basis of yield units, indices were 0.0005 and 0.0004 (kg N kg(-1) crop grain yield) for CTD and UTD corn fields, respectively, and 0.0011 and 0.0005 for CTD and UTD soybean fields, respectively.
控制型暗管排水可以提高作物产量并改善水质，但它也有可能增加温室气体排放。本研究比较了在玉米和大豆种植下，常规暗管排水（UTD）和控制型暗管排水（CTD）条件下粉壤土的原位室测土壤 CH4、N2O 和 CO2 通量。还使用了半经验模型（NEMIS-NOE）来根据观测到的土壤数据预测土壤 N2O 通量。在耕作季节，UTD 和 CTD 田间之间的观测到的 N2O 和 CH4 通量在 0.05 水平上没有显著差异。土壤主要是 CH4 的汇，但在某些情况下是源（源仅与 CTD 相关）。测量的平均 N2O 通量在 0.003 至 0.028 kg N ha(-1) d(-1) 之间。在研究的某些年份中，与 UTD 相比，与 CTD 相关的 CO2 通量有些显著更高（p ≤ 0.05）。相关分析表明，地下水位越浅，CO2 通量越大。CTD 下玉米植物 C 较高，通过土壤呼吸估计的 CTD CO2 C 损失量约为 100-300 kg C ha(-1)。观测到的和预测的（NEMIS-NOE）N2O 通量与玉米（R(2) = 0.70）和大豆（R(2) = 0.53）之间具有良好的拟合度。在大约 70%的配对田间研究期间，CTD 的预测 N2O 通量较高，这表明 CTD 施加的土壤物理因素（如充水孔隙空间）可能对净 N 通量产生强烈影响。根据玉米-CTD 和玉米-UTD 的农艺活跃研究期间的日累积 N2O 通量进行模型预测，作为施入总氮肥的百分比，分别为 3.1%和 2.6%。对于基于产量单位的预测 N2O 通量，CTD 和 UTD 玉米田的指数分别为 0.0005 和 0.0004（kg N kg(-1) 作物籽粒产量），而 CTD 和 UTD 大豆田的指数分别为 0.0011 和 0.0005。
