Non‐Legume Cover Crops Can Increase Non‐Growing Season Nitrous Oxide Emissions
Non‐Legume Cover Crops Can Increase Non‐Growing Season Nitrous Oxide Emissions
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DOI：
10.2136/sssaj2016.08.0269
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发表时间：
2017
影响因子：
2.9
通讯作者：
B. Thomas;X. Hao;F. Larney;C. Goyer;M. Chantigny;A. Charles
中科院分区：
文献类型：
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作者：
B. Thomas;X. Hao;F. Larney;C. Goyer;M. Chantigny;A. Charles
覆盖作物保留收获后的营养，但它们如何影响非生长季节的一氧化二氮（NH 4 O）排放尚不清楚。因此，我们量化了覆盖作物类型（秋黑麦[Secale cereale L.]或油籽萝卜[Raphanus sativus L.]）肥料源（堆肥或无机肥）对两个非生长季的NH_2O排放、土壤水溶性有机碳（WEOC）和硝态氮（NO_3）的动态变化有影响。也包括不施肥或覆盖作物的处理。每周，使用通风静态箱测定NH 4 O通量;每月测量土壤WEOC和NO-N浓度。每个非生长季节，平均NH 4 O通量在冬季（12月21日至3月20日）比春季（3月21日至6月20日）或秋季（9月22日至12月20日）大74至450%。在2014-2015年冬季，与秋黑麦和无覆盖作物相比，油籽萝卜的平均NH_4 O通量分别增加了39%和323%，而平均NH_4 O通量与冬前（2014年12月16日）NO_3浓度密切相关（r = 0.96; P < 0.001），表明NO_3浓度< 6 mg NO_3-N kg-1限制了NH_4 O通量。在2014-2015年，秋季黑麦和油菜萝卜的累积氧化亚氮排放量分别比没有覆盖作物的改良土壤高76%和154%。在两个冬季，指数模型解释了冬前WEOC与NO之比和N 2 O通量之间67%的变异性，表明有机C和NO控制了冬季N 2 O通量。非豆科覆盖作物增加了非生长季N 2 O的排放，这表明覆盖作物将反硝化基质集中在根相关土壤中，以增强N 2 O通量。
Cover crops retain post-harvest nutrients but how they impact non-growing season nitrous oxide (N₂O) emissions is unclear. Therefore, we quantified how cover crop type (fall rye [Secale cereale L.] or oilseed radish [Raphanus sativus L.]) and fertilizer source (compost or inorganic fertilizer) affected N₂O emissions, soil water-extractable organic C (WEOC) and nitrate (NO₃) dynamics over two non-growing seasons. A treatment with no fertilizer or cover crop was also included. Weekly, N₂O fluxes were determined using vented static chambers; soil WEOC and NO₃–N concentrations were measured monthly. Each non-growing season, mean N₂O fluxes were 74 to 450% greater in the winter (21 December–20 March) than spring (21 March–20 June) or fall (22 September–20 December). In winter 2014–2015, oilseed radish increased the mean N₂O flux by 39 and 323% compared with fall rye and no cover crop, respectively, while the mean N₂O fluxes were strongly correlated to the pre-winter (16 Dec. 2014) NO₃ concentrations (r = 0.96; P < 0.001), indicating NO₃ levels < 6 mg NO₃–N kg–¹ limited N₂O fluxes. In 2014–2015, fall rye and oilseed radish had 76 and 154% greater cumulative N₂O emissions than amended soils with no cover crop, respectively. Across both winters, an exponential model explained 67% of variability between the pre-winter WEOC to NO₃ ratio and N₂O fluxes, indicating that organic C and NO₃ controlled over-winter N₂O fluxes. Non-legume cover crops increased non-growing season N₂O emissions, suggesting that cover crops concentrate denitrification substrates in root-associated soil to enhance N₂O fluxes.