Publications by authors named "Marta A Alfaro"

Livestock manure management systems can be significant sources of nitrous oxide (N O), methane (CH ), and ammonia (NH ) emissions. Many studies have been conducted to improve our understanding of the emission processes and to identify influential variables in order to develop mitigation techniques adapted to each manure management step (animal housing, outdoor storage, and manure spreading to land). The international project DATAMAN (http://www.

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Manure application to land and deposition of urine and dung by grazing animals are major sources of ammonia (NH ) and nitrous oxide (N O) emissions. Using data on NH and N O emissions following land-applied manures and excreta deposited during grazing, emission factors (EFs) disaggregated by climate zone were developed, and the effects of mitigation strategies were evaluated. The NH data represent emissions from cattle and swine manures in temperate wet climates, and the N O data include cattle, sheep, and swine manure emissions in temperate wet/dry and tropical wet/dry climates.

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Nitrous oxide (N O), ammonia (NH ), and methane (CH ) emissions from the manure management chain of livestock production systems are important contributors to greenhouse gases (GHGs) and NH emitted by human activities. Several studies have evaluated manure-related emissions and associated key variables at regional, national, or continental scales. However, there have been few studies focusing on the drivers of these emissions using a global dataset.

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Static chambers are often used for measuring nitrous oxide (N O) fluxes from soils, but statistical analysis of chamber data is challenged by the inherently heterogeneous nature of N O fluxes. Because N O chamber measurements are commonly used to assess N O mitigation strategies or to determine country-specific emission factors (EFs) for calculating national greenhouse gas inventories, it is important that statistical analysis of the data is sound and that EFs are robustly estimated. This paper is one of a series of articles that provide guidance on different aspects of N O chamber methodologies.

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There have been only a few studies of potassium (K) losses from grassland systems, and little is known about their dynamics, especially in relation to nitrogen (N) management. A study was performed during the autumn and winter of 1999 and 2000 to understand the effects of N and drainage on the dynamics of K leaching on a hillslope grassland soil in southwestern England. Two N application rates were studied (0 and 280 kg N ha(-1) yr(-1)), both with and without tile drainage.

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