Greenhouse gas budget and methane dynamics in a no tillage chronosequence Research Project Indiana University and Ohio State University United States Department Of Agriculture Cooperative State Research Education And Extension Service USA OMB Approved No 0524 0039 Research Assistant 2009 2012 3 years Bu projede gorev almak icin 6 ay sure ile TUBITAK tarafindan USA da 6 ay sure ile gorevlendirildim

Abstract<o:p></o:p>

Nearly a quarter of all

cropland in the US is under no-till (NT) - a management practice with

well-documented positive effects on soil C sequestration, and soil quality

maintenance. Although widespread adoption of no-tillage farming can help

mitigate the global warming effect, there is a paucity of field-based data

regarding the long-term impact of NT on greenhouse gas (GHG) fluxes.

Accumulation of crop residue on soil surface increased soil moisture and

availability of labile organic substrates could stimulate the emission of

carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4)

from NT systems. Conversely, long-term adoption of no-tillage could lead to the

evolution of a more active population of methanotrophs, increase soil

macroporosity and ultimately improve the CH4 sink strength of

croplands. Our primary hypothesis in this study is that the longer no-tillage is

continuously applied to soil, the greater becomes the soil’s ability and

potential to oxidize CH4. We also recognize that expression

of the CH4 oxidation potential of NT soils could be hindered by other

soil factors. Thus, there is a need to examine discrepancies between biological

potential and actual CH4 fluxes in NT soils. Based on these

considerations, the proposed research will address the following three

objectives: <o:p></o:p>

(1) Assess the impact of long-term

no-tillage on GHG fluxes, and examine relationships between gas fluxes and

biophysical properties of NT soils.<o:p></o:p>

(2)

Evaluate the link between soil drainage characteristics and the impact

of long-term no-till on GHG fluxes. <o:p></o:p>

(3) Characterize the CH4

oxidation potential of NT soils, and identify factors limiting expression of

that potential. <o:p></o:p>

Although CH4 is a major focus, the proposed research is a comprehensive assessment encompassing all three major

soil-derived GHG (CO2, N2O, and CH4) in order

to fully appraise the global warming mitigation potential (GWMP) of no-tillage

farming. We will monitor GHG fluxes (2 full years) at research stations and

farmers’ fields in similar soil types and under no-tillage for up to 46 years.

Detailed studies using the kinetic approach, stable C isotope, and selective

inhibition techniques will be conducted in order to characterize the community

of CH4-oxidizers in NT soils and assess the effect of no-tillage

duration and soil drainage characteristics on GHG dynamics. These experiments

will be conducted to determine the potential for no-tillage soils to oxidize CH4

and to provide guidance as to management options that can be used to achieve

this potential. Our goal is to provide a basis to enhance and project the

contribution of no-till farming to regional GHG inventory under various

scenarios of conservation tillage adoption in US agriculture. The proposed

research addresses several priorities of the Air Quality program and most

specifically priority #2 “increase adoption of best management practices to

reduce agricultural emissions”.