Part of the book: CO2 Sequestration and Valorization
Flooded rice (Oryza sativa L.) cultivation has been identified as one of the leading global agricultural sources of anthropogenic methane (CH4) emissions. Furthermore, it has been estimated that global rice production is responsible for 11% of total anthropogenic CH4 emissions. Considering that CH4 has a global warming potential that is approximately 25 times more potent, on a mass basis, than carbon dioxide (CO2) and rice production is globally extensive and concentrated in several mid-southern and southern states and California, the purpose of this review is two-fold: (i) discuss the factors known to control CH4 production in the soil and transport to the atmosphere from rice cultivation and (ii) summarize the historic and recent research conducted on CH4 emissions from rice production in the temperate United States. Though some knowledge has been gained, there is much more that still needs to be learned and understood regarding CH4 emissions from rice production in the United States, its contribution to climate change, and potential mitigation strategies. Extending the current knowledge base surrounding CH4 emissions from rice cultivation will help regulatory bodies, such as the Environmental Protection Agency, refine greenhouse gas emissions factors to combat the potential negative effects of climate change.
Part of the book: Greenhouse Gases
Increasing understanding of soil carbon (C) sequestration dynamics and general functioning in disappearing native grassland ecosystems, has the potential to enhance soil rehabilitation and ecosystem restoration. The objective of this study was to evaluate the effects of landuse (native tallgrass prairie and managed agriculture) and physiographic region (northwest Arkansas and east-central Arkansas) on the change in soil C and nitrogen (N) storage and other soil properties over a 15-year period. Despite the native prairie losing soil C at a rate of 4.7 Mg ha−1 year−1 over the 15-year duration of this study, soil C storage in 2016 was more than 2.5 times greater in the native prairie than in the cultivated agroecosystems in the Grand Prairie. Averaged across landuse, TC concentration (P < 0.01) and content (P < 0.01) changed more over time in the Ozark Highlands region of northwest Arkansas (0.02% year−1 and 0.28 Mg ha−1 year−1, respectively), than in the Grand Prairie region of east-central Arkansas. This study demonstrates the value of direct measurements over time for assessing temporal changes in soil properties and results can potentially direct future restoration activities to be as successful as possible.
Part of the book: CO2 Sequestration
Prairie mounds are unique soil surface features that will become increasingly scarce as native tallgrass prairies are continually lost. This study aimed to evaluate (i) whether the soil moisture regime (SMR), mound position, and soil depth affect soil volumetric water content (VWC) and (ii) whether the SMR and mound position affect vegetation over time. Soil VWC was measured continuously from April 2017 to June 2018, and vegetation was sampled in June and August 2017 and in May and August 2018. Maximum VWC for selected rainfall events was ~ 2.5 times greater at 10 cm in the aquic inter-mound than the udic mound position at 30 cm. Soil dry-down rates were four times greater in the udic soil at 10 cm than the aquic soil at 30 cm. Aboveground plant biomass was numerically largest (8489 kg ha−1) at the aquic summit in August 2018 and smallest (1280 kg ha−1) at the aquic inter-mound in May 2018. Results clearly demonstrate the effects that prairie mound topography and differing SMRs have on soil water dynamics and prairie vegetation and suggest that management efforts need to account for mound topography and SMR in order to be most successful.
Part of the book: Grasses and Grassland Aspects