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Greenhouse Gas Fluxes following Tillage and Wetting in a Wheat‐Fallow Cropping System
Author(s) -
Kessavalou Anabayan,
Doran John W.,
Mosier Arvin R.,
Drijber Rhae A.
Publication year - 1998
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1998.00472425002700050016x
Subject(s) - tillage , environmental science , agronomy , plough , summer fallow , conventional tillage , soil water , greenhouse gas , nitrous oxide , carbon dioxide , chemistry , soil science , cropping , ecology , organic chemistry , biology , agriculture
Little is known about the relative contributions of episodic tillage and precipitation events to annual greenhouse gas emissions from soil. Consequently, we measured carbon dioxide (CO 2 ), nitrous oxide (N 2 O), and methane (CH 4 ) fluxes from soil in wheat‐fallow cropping system in western Nebraska using vented surface chambers, before and immediately after tillage and wetting with 5.1 cm of water, during the fallow period in 1995/1996. Replicated fallow management treatments included no‐tillage, subtillage, and plow representing a wide range in degree of soil disturbance. Soil bulk density, water‐filled pore space, electrical conductivity (EC 1:1 ), nitrate (NO 3 ), and pH within the top 30.5 cm soil, and soil temperature at 0 to 7.6 cm were measured to assess their correlation with variations in gas flux and tillage and wetting. Atmospheric concentrations above the soil (at ~40 cm) increased by 15% for CO 2 and 9 to 31% for N 2 O and 6 to 16% for CH 4 within 1 min after tillage and returned to background concentrations within 2 h. Except immediately after tillage, net CH 4 flux was negative, from the atmosphere into soil, and is referred to as CH 4 uptake. Overall, increases (1.5–4‐fold) in CO 2 and N 2 O losses from soil, and CH 4 uptake by soil were short lived and returned to background levels within 8 to 24 h after tillage. Losses of CO 2 and N 2 O increased to 1.7 and 5 times background emissions, respectively, for 24 h following wetting, while CH 4 uptake declined by about 60% for 3 to 14 d after wetting. Water‐filled pore space in the surface soil fell below 60% within 24 h after saturation and exhibited an inverse relationship ( R 2 = 0.66) with CH 4 uptake. A significant decline in soil NO 3 and EC 1:1 in the top 7.6 cm occurred following wetting. Under our experimental conditions, and the expected frequency of tillage and wetting events, failure to include these short‐lived episodic gas pulses in annual flux estimations may underestimate annual CO 2 and N 2 O loss up to 13 and 24%, respectively, and overestimate CH 4 uptake by up to 18% in this cropping system.