drivers of soil respiration of root and microbial ... - Unitus DSpace
drivers of soil respiration of root and microbial ... - Unitus DSpace
drivers of soil respiration of root and microbial ... - Unitus DSpace
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5.2.4. Sampling <strong>and</strong> analyses……………………………………….….…….........126<br />
5.2.5. Statistics..........................................................................................................126<br />
5.3. Results ……………………………………………………………………….….…...127<br />
5.3.1. Aboveground <strong>and</strong> belowground plant biomass……………………….…….127<br />
5.3.2. Dynamics <strong>of</strong> 14 CO2 efflux from a <strong>soil</strong> compartment with Lupinus albus<br />
<strong>and</strong> Zea mays……………………………………………………….……….……..127<br />
5.3.3. 15 N uptake by plants………………………………………………….……...132<br />
5.3.4. Total CO2 efflux from planted <strong>soil</strong> with Lupinus albus <strong>and</strong> Zea<br />
mays (V6)…..............................................................................................................133<br />
5.4. Discussion…………………………………………………………………….………136<br />
5.4.1. Root-derived CO2 – comparison <strong>of</strong> two methods…………………..…….…136<br />
5.4.2. 14 C-CO2 efflux from <strong>soil</strong> ………………………………………………….....137<br />
5.4.3. NH4 + versus NO3 - supply – effect on the <strong>root</strong> <strong>respiration</strong> …………….……138<br />
5.4.4. Carbon costs <strong>of</strong> nitrate reduction – comparison between species <strong>and</strong> different<br />
N supplies………………………………………………………………………….140<br />
5.4.5. Effect <strong>of</strong> growing stage on <strong>root</strong> <strong>respiration</strong>………………………………..141<br />
5.4.6. Conclusions………………………………………………..………………..142<br />
6. CONTRIBUTION OF ROOT RESPIRATION TO CO2 EMISSION FROM SOIL IN<br />
GRASSLANDS: COMPARISON OF PARTITIONING METHODS………..........................147<br />
6.1. Introduction……………………………………………………………………….…148<br />
6.2. Materials <strong>and</strong> Methods…………………………………………………………..….150<br />
6.2.1. Mesh- exclusion technique…………………………………………….……150<br />
6.2.2. Combined method: SIR+component integration…………………………..151<br />
6.2.3. Regression analyses technique…………………………………………...…152<br />
6.3. Results………………………………………………………………….…………….152<br />
6.3.1. 2007: Mesh- exclusion vs. combined SIR………………………………….152<br />
6.3.2. 2008: Mesh- exclusion vs. regression technique…………………………...156<br />
6.4. Discussion……………………………………………………………………………158<br />
6.4.1. Mesh-exclusion……………………………………………………….…….158<br />
6.4.2. Combined SIR………………………………………………………..……..159<br />
6.4.3. Regression analyses technique……………………………………………..160<br />
6.4.4. General comparison <strong>of</strong> three partitioning methods………………….…….162<br />
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