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<!DOCTYPE html>
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<head>
<title>Spring Nitrous Oxide Emissions</title>
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<h1>Spring Nitrous Oxide Emissions</h1>
<p>Ranae Dietzel</p>
</header>
<section id="working-towards-a-global-estimate-of-n2o-emissions" class="titleslide slide level1"><h2 class="shout">Working towards a global estimate of N<sub>2</sub>O emissions</h2></section><section id="why-is-n2o-important" class="slide level2">
<h2>Why is N<sub>2</sub>O important?</h2>
<ul>
<li>N<sub>2</sub>O has 300 times the global warming potential of CO<sub>2</sub><br />
</li>
<li>Acts as both a greenhouse gas and contributes to ozone depletion<br />
</li>
<li>N<sub>2</sub>O is difficult to measure, leading to low confidence in budgets and poor understanding of feedbacks</li>
</ul>
</section>
<section id="problems" class="titleslide slide level1"><h2 class="shout">Problems:</h2></section></section>
<section id="dont-know-how-much-n2o-we-produce" class="titleslide slide level1"><h2 class="shout">Don’t know how much N<sub>2</sub>O we produce</h2></section></section>
<section id="dont-know-how-to-control-n2o" class="titleslide slide level1"><h2 class="shout">Don’t know how to control N<sub>2</sub>O</h2></section><section id="what-is-n2o-to-an-agronomist" class="slide level2">
<h2>What is N<sub>2</sub>O to an agronomist?</h2>
By-product of microbially mediated nitrogen transformations<br />
<center>
<img src="images/nitrogen_pathways.png", width = 800>
</center>
</section>
<section id="background" class="titleslide slide level1"><h2 class="shout">Background</h2></section><section id="worked-on-n2o-during-masters" class="slide level2 cover white">
<h2>Worked on N<sub>2</sub>O during Masters</h2>
<p><img src="images/harford.jpg" class="cover height"></p>
</section><section id="before-that-worked-at-usda-ars-north-central-soil-conservation-research-lab-in-morris-mn" class="slide level2">
<h2>Before that worked at USDA-ARS North Central Soil Conservation Research Lab in Morris, MN</h2>
<center>
<img src="images/musky.jpg", width = 300>
</center>
</section><section id="worked-on-4-n2o-experiments-may-december" class="slide level2">
<h2>Worked on 4 N<sub>2</sub>O experiments May-December</h2>
<center>
<img src="images/SwanLake.jpg", width = 800>
</center>
</section><section id="greenhouse-gas-emission-from-contrasting-management-scenarios-in-the-northern-corn-belt" class="slide level2">
<h2>Greenhouse Gas Emission from Contrasting Management Scenarios in the Northern Corn Belt</h2>
<center>
<img src="images/johnson_table.png", width = 850>
</center>
<div style="font-size: 60%; position: absolute; right: 5%; width: fit-content; height: fit-content; top:90%; z-index:10">
Johnson et al., 2010, SSSAJ 74:396-406
</div>
</section><section id="freeze-thaw-n2o-peaks" class="slide level2 cover white">
<h2>Freeze-Thaw N<sub>2</sub>O Peaks</h2>
<img src="images/white_whale.jpg" class="cover height"><br />
<p style="color:white">
Great White Whale of Greenhouse Gases
</p>
</section><section id="emissions-of-nitrous-oxide-from-soils---nature-1982-duxbury-et-al." class="slide level2">
<h2>Emissions of nitrous oxide from soils - <em>Nature</em> 1982, Duxbury et al.</h2>
<ul>
<li>In alfalfa, 66% of annual emissions in 2 week period during spring<br />
</li>
<li>27% of annual emissions during 2 days of spring
<center>
<img src="images/duxbury_figure.png", width = 500>
</center>
<div style="font-size: 60%; position: absolute; right: 5%; width: fit-content; height: fit-content; top:90%; z-index:10">
Duxbury et al., 1982, Nature 298:462-464
</div></li>
</ul>
</section><section id="seasonal-variability-in-emission-of-nitrous-oxide-from-soil-geophysical-research-letters-1980-bremner-et-al." class="slide level2">
<h2>Seasonal variability in emission of nitrous oxide from soil, <em>Geophysical Research Letters</em>, 1980, Bremner et al.</h2>
<img src="images/iowa_figure.png", width = 455>
<div style="font-size: 60%; position: absolute; right: 5%; width: fit-content; height: fit-content; top:90%; z-index:10">
Bremner et al., 1980, Geophysical Research Letters 7:641-644
</div>
</section><section id="what-causes-peaks-in-the-spring" class="slide level2 cover white">
<h2>What causes peaks in the spring?</h2>
<img src="images/needle_ice.jpg" class="cover height"><br />
<p style="color:white">
Wet conditions leading to anaerobic respiration (denitrification)
</p>
</section><section id="what-causes-peaks-in-the-spring-1" class="slide level2">
<h2>What causes peaks in the spring?</h2>
<ul>
<li>Big flush of labile carbon and nitrogen as frozen microbes and plant cells thaw and burst<br />
</li>
<li>Drop in pH as soil solution is flooded with new solutes<br />
</li>
<li>Trapped gases not a big contributer to spring peaks</li>
</ul>
</section><section id="what-causes-peaks-in-the-spring-2" class="slide level2">
<h2>What causes peaks in the spring?</h2>
Nitrate reduction efficiency plays a huge role in spring peaks<br />
<center>
<img src="images/denitrification_pathway.png", width = 485>
</center>
</section>
<section id="what-causes-inefficiency" class="titleslide slide level1"><h2 class="shout">What causes inefficiency?</h2></section></section>
<section id="cold" class="titleslide slide level1"><h2 class="shout">Cold?</h2></section><section id="section" class="slide level2">
<h2></h2>
<center>
<img src="images/SBandB.png", width = 400>
</center>
<div style="font-size: 60%; position: absolute; right: 5%; width: fit-content; height: fit-content; top:90%; z-index:10">
Dietzel et al., 2011, Soil Biology & Biochemistry 43:1989-1991
</div>
</section><section id="more-evidence-from-canada" class="slide level2">
<h2>More evidence from Canada</h2>
<center>
<img src="images/wagner2004.png", width = 500>
</center>
<div style="font-size: 60%; position: absolute; right: 5%; width: fit-content; height: fit-content; top:90%; z-index:10">
Wagner-Riddle et al., 2007, Global Change Biology 13:1722-1736
</div>
</section>
<section id="colder-winters---more-n2o" class="titleslide slide level1"><h2 class="shout">Colder winters -> more N<sub>2</sub>O</h2></section><section id="section-1" class="slide level2">
<h2></h2>
<center>
<img src="images/wagner-riddle_cover.png", width = 700>
</center>
</section><section id="modeled-spring-emissions-from-freezing-degree-days" class="slide level2">
<h2>Modeled spring emissions from freezing degree days</h2>
<center>
<img src="images/nature_curve.png", width = 750>
</center>
</section><section id="scaled-model-up-to-find-current-estimates-miss-28-of-annual-emissions" class="slide level2">
<h2>Scaled model up to find current estimates miss ~ 28% of annual emissions</h2>
<center>
<img src="images/wagner-riddle_map.png", width = 750>
</center>
</section><section id="but-acknowledged-parameters-beyond-freezing-degrees-days-are-needed" class="slide level2">
<h2>But acknowledged parameters beyond freezing degrees days are needed</h2>
<center>
<img src="images/wagner-riddle_text.png", width = 700>
</center>
</section>
<section id="lets-do-this" class="titleslide slide level1"><h2 class="shout">Let’s do this</h2></section><section id="usda-ars-gracenet" class="slide level2">
<h2>USDA-ARS-GRACEnet</h2>
<strong>G</strong>reenhouse gas <strong>R</strong>eduction through <strong>A</strong>gricultural <strong>C</strong>arbon <strong>E</strong>nhancement network<br />
<center>
<img src="images/GRACEnet_people.png", width = 225>
</center>
</section><section id="gracenet-collection-and-sites" class="slide level2">
<h2>GRACEnet collection and sites</h2>
<center>
<img src="images/gracenet_map.png", width = 750>
</center>
</section><section id="gracenet-pubs-up-to-2012" class="slide level2">
<h2>GRACEnet Pubs up to 2012</h2>
<p><img src="images/pubs.gif", width = 700></p>
</section><section id="gracenet-data-iswas-available-in-easily-accessible-public-database" class="slide level2">
<h2>GRACEnet data is/was available in easily accessible public database</h2>
</section><section id="all-available-sites" class="slide level2">
<h2>All available sites</h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-2-1.png" width="768" /></p>
</section><section id="sites-that-experience-freezing" class="slide level2">
<h2>Sites that experience freezing</h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-3-1.png" width="768" /></p>
</section><section id="section-2" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-4-1.png" width="768" /></p>
</section><section id="section-3" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-5-1.png" width="768" /></p>
</section><section id="section-4" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-6-1.png" width="768" /></p>
</section><section id="section-5" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-7-1.png" width="768" /></p>
</section><section id="soil-hydrological-properties" class="slide level2">
<h2>Soil Hydrological Properties</h2>
<p>Clay (%)<br />
Sand (%)<br />
Silt (%)<br />
Fine Silt (%)<br />
Coarse Silt (%)<br />
Ks<br />
<span class="math inline">\(\theta\)</span><sub>s</sub> (L L<sup>1</sup>)<br />
<span class="math inline">\(\theta\)</span><sub>r</sub> (L L<sup>1</sup>)</p>
</section><section id="substrate-properties" class="slide level2">
<h2>Substrate Properties</h2>
<p>Organic Carbon<br />
Organic Matter<br />
Total Nitrogen<br />
C:N Ratio</p>
</section><section id="soil-chemical-properties" class="slide level2">
<h2>Soil Chemical Properties</h2>
<p>pH<br />
Cation Exchange Capacity<br />
Exchangeable Mg<br />
Exchangeable K<br />
Exchangeable K Saturation<br />
Excahgeable Ca<br />
Base Saturation</p>
</section><section id="antecedant-weather-conditions" class="slide level2">
<h2>Antecedant Weather Conditions</h2>
<p>How cold - sum of daily minimum temperatures below 0<br />
How warm - sum of daily maximum temperatures<br />
How sunny - sum of daily total radiation<br />
How wet - sum of daily precipitation<br />
How snowy - sum of daily snowfall</p>
</section><section id="how-do-these-contribute-to-magnitude-of-spring-n2o-emissions" class="slide level2">
<h2>How do these contribute to magnitude of spring N<sub>2</sub>O emissions?</h2>
<center>
<img src="images/source.gif", width = 500>
</center>
</section><section id="partial-least-squares-pls-regression" class="slide level2">
<h2>Partial Least Squares (PLS) Regression</h2>
<ul>
<li>Has some similarities to Principal Components Analysis (PCA)<br />
</li>
<li>Good to use if predictors are correlated and contain similar predictive information<br />
</li>
<li>Can produce a predictive model</li>
</ul>
<div style="font-size: 60%; position: absolute; right: 5%; width: fit-content; height: fit-content; top:90%; z-index:10">
Bjørn-Helge Mevik, Ron Wehrens and Kristian Hovde Liland (2016). pls: Partial Least Squares and Principal Component Regression.
</div>
</section><section id="partial-least-squares-pls-regression-1" class="slide level2">
<h2>Partial Least Squares (PLS) Regression</h2>
<center>
<img src="images/pls_diagram.png", width = 550>
</center>
<div style="font-size: 60%; position: absolute; right: 5%; width: fit-content; height: fit-content; top:90%; z-index:10">
Kuhn and Johnson, 2013, Applied Predictive Modeling <a href="DOI:10.1007/978-1-4614-6849-3" class="uri">DOI:10.1007/978-1-4614-6849-3</a>
</div>
</section><section id="section-6" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-8-1.png" width="768" /></p>
</section><section id="section-7" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-9-1.png" width="768" /></p>
</section><section id="section-8" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-10-1.png" width="768" /></p>
</section><section id="section-9" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-11-1.png" width="768" /></p>
</section><section id="section-10" class="slide level2">
<h2></h2>
<center>
<img src="images/canada_sites.png", width = 600>
</center>
</section><section id="section-11" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-12-1.png" width="768" /></p>
</section><section id="section-12" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-13-1.png" width="768" /></p>
</section><section id="section-13" class="slide level2">
<h2></h2>
<center>
<img src="images/validation_sites.png", width = 600>
</center>
</section><section id="section-14" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-14-1.png" width="768" /></p>
</section><section id="section-15" class="slide level2">
<h2></h2>
<p><img src="agron_dept_seminar_files/figure-revealjs/unnamed-chunk-15-1.png" width="768" /></p>
</section>
<section id="what-does-this-mean" class="titleslide slide level1"><h2 class="shout">What does this mean?</h2></section><section id="what-does-this-mean-1" class="slide level2">
<h2>What does this mean?</h2>
<ul>
<li>Across large spatial scales, freezing degree days is not a good predictor of spring N<sub>2</sub>O fluxes<br />
</li>
<li>Within a specific soil type, we currently don’t have enough data to quantify the effect of winter weather conditions on spring N<sub>2</sub>O emissions</li>
<li><strong>Soil characteristics drive spatial variability of N<sub>2</sub>O emissions.</strong><br />
</li>
<li>Organic Matter<br />
</li>
<li><span class="math inline">\(\theta\)</span><sub>s</sub><br />
</li>
<li>Clay<br />
</li>
<li>Exchangeable Mg</li>
</ul>
</section><section id="early-spring-emissions-are-still-important-neglected-and-probably-underestimated" class="slide level2">
<h2>Early spring emissions are still important, neglected, and probably underestimated</h2>
<ul>
<li>Need better (continuous) and more measurements</li>
</ul>
<center>
<img src="images/laser.gif", width = 350>
</center>
</section><section id="need-better-modeling-of-this-phenomenon" class="slide level2">
<h2>Need better modeling of this phenomenon</h2>
<ul>
<li>Relationships are too complex for large-scale modeling<br />
</li>
<li>N<sub>2</sub>O timing is very dynamic<br />
</li>
<li>Cold winters manifest in soil conditions<br />
</li>
<li>Daily time step, mechanistic model would make best predictions<br />
</li>
<li><strong>I am bringing spring N<sub>2</sub>O emissions to APSIM</strong><br />
</li>
<li>Then we can scale up (still dependent on good soils maps)</li>
</ul>
</section><section id="nitrous-oxide-reduction-efficiency-drivers-still-in-question" class="slide level2">
<h2>Nitrous oxide reduction efficiency drivers still in question</h2>
<p>Variables listed should lead to more denitrification, but what controls <em>nosZ</em>?</p>
<center>
<img src="images/denitrification_pathway.png", width = 350>
</center>
</section><section id="thank-you" class="slide level2">
<h2>Thank You!</h2>
<ul>
<li>Agriculture and Food Research Initiative competitive grant number 2016-67012-25170 for the money<br />
</li>
<li>USDA-ARS for all the data<br />
</li>
<li>R Community for all the tools</li>
<li>Integrated Cropping Systems lab (Archontoulis) for all the support</li>
</ul>
</section>
<section id="questions" class="titleslide slide level1"><h2 class="shout">Questions?</h2></section></section>
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