Author
|
Submitted to: Intech
Publication Type: Book / Chapter Publication Acceptance Date: 11/17/2017 Publication Date: 3/14/2018 Citation: Sainju, U.M. 2018. Agricultural management impact on greenhouse gas emissions. In: Rao, C.S., Shankar, A.K., and Shanker, C., editors. Climate Resilient Agriculture - Strategies and Perspectives. Rijeka, Croatia: InTech Publication. p. 89-103. http://dx.doi.org/10.5772/intechopen.72368. DOI: https://doi.org/10.5772/intechopen.72368 Interpretive Summary: Producers use various soil and crop management practices, such as tillage, cropping systems, N fertilization, organic fertilizer application, cover cropping, fallowing, liming, etc. to enhance crop yield and quality from croplands. These practices can also lead to greenhouse gas (GHGs: carbon dioxide, nitrous oxide, and methane) emissions that contribute to global warming. In general, management practices in croplands can contribute 10 to 20% of global greenhouse gases. The impact of such practices on net GHG emissions from croplands is still evolving. Net GHG emissions from a management practice is measured by calculating net global warming potential (GWP) which accounts for all sources and sinks of carbon dioxide equivalents from farm operations, chemical inputs, soil carbon sequestration rate, and nitrous oxide and methane emissions. Soil carbon sequestration rate and methane emissions can either be source or sink, but other factors are usually sources of GHGs, depending on cropping systems, crop types, management practices, and soil and climatic conditions. Another term used for measuring net GHG emissions is net greenhouse gas intensity (GHGI) or yield-scaled global warming potential which is calculated by dividing net GWP by crop yield. Both of these terms can measure net GHG emissions in various ways and expressed as carbon dioxide equivalents (kg CO2 eq. ha-1 yr-1 for GWP and kg CO2 eq. kg-1 grain or biomass yield for GHGI). An agricultural practice may be a source of net GHG emissions using GWP, but a sink using GHGI. In other instances, both may be simultaneously source or sink of net GHGs. This paper discusses a literature review of various management practices on net GWP and GHGI and ways to mitigate net GHG emissions using novel management techniques from croplands. This information is needed to evaluate the state of carbon cycle in the terrestrial ecosystem in North America for the US Carbon Cycle Science Program (SOCCR-2). Technical Abstract: Management practices used on croplands to enhance crop yields and quality can contribute about 10 to 20% of global greenhouse gases (GHGs: carbon dioxide [CO2], nitrous oxide [N2O], and methane [CH4]). Some of these practices are tillage, cropping systems, N fertilization, organic fertilizer application, cover cropping, fallowing, liming, etc. The impact of these practices on GHGs in radiative forcing in the earth’s atmosphere is quantitatively estimated by calculating net global warming potential (GWP) which accounts for all sources and sinks of CO2 equivalents from farm operations, chemical inputs, soil carbon sequestration, and N2O and CH4 emissions. Net GWP for a crop production system is expressed as kg CO2 eq. ha-1 yr-1. Net GWP can also be expressed in terms of crop yield (kg CO2 eq. kg-1 grain or biomass yield) which is referred to as net greenhouse gas intensity (GHGI) or yield-scaled GWP and is calculated by dividing net GWP by crop yield. This article discusses the literature review of the effects of various management practices on GWP and GHGI from croplands as well as different methods used to calculate net GWP and GHGI. The paper also discusses novel management techniques to mitigate net CO2 emissions from croplands to the atmosphere. This information will be used to address the state of carbon cycle for the US Carbon Cycle Science Program (SOCCR-2). |
