Landscape control of nitrous oxide emissions during the transition from conservation reserve program to perennial grasses for bioenergy
TLDR
In this paper, the authors measured N2O emissions and associated environmental drivers during the transition of perennial grassland in a Conservation Reserve Program (CRP) to switchgrass (Panicum virgatum L.) and Miscanthus x giganteus in the bottom 3-ha of a watershed in the Ridge and Valley ecoregion of the northeastern United States.Abstract:
Future liquid fuel demand from renewable sources may, in part, be met by converting the seasonally wet portions of the landscape currently managed for soil and water conservation to perennial energy crops. However, this shift may increase nitrous oxide (N2O) emissions, thus limiting the carbon (C) benefits of energy crops. Particularly high emissions may occur during the transition period when the soil is disturbed, plants are establishing, and nitrate and water accumulation may favor emissions. We measured N2O emissions and associated environmental drivers during the transition of perennial grassland in a Conservation Reserve Program (CRP) to switchgrass (Panicum virgatum L.) and Miscanthus x giganteus in the bottom 3-ha of a watershed in the Ridge and Valley ecoregion of the northeastern United States. Replicated treatments of CRP (unconverted), unfertilized switchgrass (switchgrass), nitrogen (N) fertilized switchgrass (switchgrass-N), and Miscanthus were randomized in four blocks. Each plot was divided into shoulder, backslope, and footslope positions based on the slope and moisture gradient. Soil N2O flux, soil moisture, and soil mineral nitrogen availability were monitored during the growing season of 2013, the year after the land conversion. Growing season N2O flux showed a significant vegetation-by-landscape position interaction (P < 0.009). Switchgrass-N and Miscanthus treatments had 3 and 6-times higher cumulative flux respectively than the CRP in the footslope, but at other landscape positions fluxes were similar among land uses. A peak N2O emission event, contributing 26% of the cumulative flux, occurred after a 10.8-cm of rain during early June. Prolonged subsoil saturation coinciding with high mineral N concentration fueled N2O emission hot spots in the footslopes under energy crops. Our results suggest that mitigating N2O emissions during the transition of CRP to energy crops would mostly require a site-specific management of the footslopes.read more
Citations
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Coupling soil water processes and the nitrogen cycle across spatial scales: Potentials, bottlenecks and solutions
TL;DR: In this paper, the authors proposed a comprehensive coupling of the soil water-N-cycle across time and space, using hydrogeophysical tools to detect soil water processes and then linked to electrochemical N sensors to reveal the soil N cycle, upscaling small-scale observations and simulations by constructing functions between soil water and ancillary soil, topography and vegetation variables in the hydropedological functional units.
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The Effect of Land-Use Change on Soil CH4 and N2O Fluxes: A Global Meta-Analysis
Marshall D. McDaniel,Marshall D. McDaniel,D. Saha,Marc G. Dumont,Marcela Hernández,Mark A. Adams,Mark A. Adams +6 more
TL;DR: In this article, the authors used a global meta-analysis (62 studies, 1670 paired comparisons) to examine effects of land conversion on soil-atmosphere fluxes of methane (CH4) and nitrous oxide (N2O) from upland soils, and determine soil and environmental factors driving these effects.
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The response of maize, sorghum, and soybean yield to growing-phase climate revealed with machine learning
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Machine learning improves predictions of agricultural nitrous oxide (N 2 O) emissions from intensively managed cropping systems
TL;DR: In this paper, a machine learning approach was used to predict field-level N2O fluxes in a continuous corn rotation at a site in the upper US Midwest (∼3000 sub-daily flux observations), supplemented with weekly to biweekly manual chamber measurements.
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