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Monitoring of CO2 Flux and Contribution for Components in the Soil-Plant System in a Grassland from Northeastern Mexico
1 López-Santos Armando, 2 Cadena-Zapata Martín, 2 Zermeño-González Alejandro, 3 González-Cervantes Guillermo., 2 Gil-Marín José Alexander, 3 Sánchez-Cohen Ignacio
1 Unidad Regional Universitaria de Zonas Áridas de la UACh ([email protected]), 2 División de Ingeniería UAAAN, Buenavista, Saltillo, Coah. Méx., 3 Centro Nacional de Investigación Interdisciplinario en Relaciones Agua Suelo Planta Atmósfera del INIFAP, Gómez Palacio, Dgo, Mex.
Abstract The monitoring and quantification of CO2 released to the atmosphere by the rural production systems is an uprising need when facing the actual challenge of global warming. It is known, that in the last decade the change of land use and silviculture have contributed in a significant manner in the net emissions of CO2 to the atmosphere. However, is not quite clear the magnitude of the contribution of each individual ecosystem, and even it is least known the contribution of the separate action of the soil-plant system components. There are three methods for monitoring and quantifying the CO2 flux in an extensive open area condition: i) Open or close use of interchange gas chambers; ii) Using the technique of the Bowen Relation Method; and iii) Using the Eddy Covariance Method. In this experiment, the last mentioned was used for its high reliability in the measurements of mass and energy flux in extensive land conditions. The experiment was carried out at Rancho Los Angeles Municipality of Saltillo, Coahuila, México (25º 6.650’ N and 100º 59.413’ W). It was measured the CO2 flux, in plots of 2.4 ha after removing the native vegetation, dominated by three families (Chenopodacea, Euphorbacea y Asteraceae), using two tillage treatments: vertical tillage by chiseling (VT) and conventional tillage by disc ploughing (CT), the flux was measured as well in a reference plot without tillage treatment (NT). In all plots it was determined the magnitude of flux for each component at the soil-plant system. The results showed that under the predominant climatic conditions at Autumn 2006, when separating the components of the soil-plant system from the CO2 total flux monitored (FCO2tm), the more important contribution came from the soil in both tillage methods used (FCO2sLV=66 % and FCO2sLC=74 %). Key words: Eddy Covariance, Rural Production Systems, CO2 flux.
Introduction
Mexico ranks second among the Latin-Americans countries as CO2 emitter, with net emissions of 444.5 millions of metric tons for 1990, from this amount, it is estimated that the change in land use and silviculture contribute with 30.6 % (PNUMA-SEMARNAT, 2004). Considering the need to reduce release of CO2 and maintain the quality of the soil to support food production, the role and importance of the tillage practices and its impact in the organic matter should be reexamined (So et al, 2001; Lokupitiya et al, 2006), this is also important because of the raise of carbon bonus market among the countries that signed the Kyoto protocol (Inclán, 2007; Cervantes, 2007).
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The CO2 emissions from the surface on bare soil give a direct assessment in the short time about the carbon dynamic in the soil, but when vegetation is present, the interpretation of the total soil respiration is difficult due to the root contribution in the CO2 release (Rochete, 1999). It has been estimated that the rizosfera contributes with 40-50 % of the total soil respiration, and the 50-60 % remaining includes the decomposed microbial root exudates and other rhizodepotitions (Kuzyakov, 2002). Some authors (Rochete, 1999) have utilized values of isotopic carbon (13C) in order to measure CO2 separating from the total soil respiration that which comes from the rhizosphere in a maize crop (Zea mays L.) by using a portable chamber for gas exchange (LI-Cor), from those experiments, and they found that the rhizosphere contributes with 45% of the total respiration, this value agrees also with that reported by Kuzyakov (2002). Also they observed as well that the values of the soil respiration decreased from 3.3 to 1.4 g m-2d-1. Similarly, other authors (Qi et al, 2007) used a dark gas exchange fix chamber to measure total respiration, also the microbial and radicular from a grassland dominated by S. balcalensis and from bare soil, condition obtained by cutting the aerial part of the plants the day before the sampling, it was found that maximum spoil respiration occurred in July with a value of 6 g CO2 m-2d-1. In terrestrial ecosystems, the CO2 movements, as well as, other energy flux energetic, can be measured basically by three methods: 1) Eddy Covariance, (EC); 2) Bowen Relation, (BR); and 3) Open or Close, exchange gas chamber (CIG). Every method have advantages and disadvantages in relation to the measurements to characterize the flux behavior, because they are affected by variability in the local and surrounding conditions during day and night, such as humidity, temperature, barometric pressure, wind direction, etc. (Peters et al, 2001; Clark , 2001). In the present work, the total measure of CO2 flux, is part of an investigation based in the Eddy Covariance method, which have the follow characteristics: i) Direct measurements of the heat flux, water vapor and carbon dioxide; ii) Not assumption is made of coefficient values; iii) measurements are independent; iv) Allow to evaluate the precision of energy balance (Rn=H+LE+G); and v) Is considered the most precise method to measure superficial fluxes (Peters et al, 2001; Clark , 2001). Based on the above, the objectives of this work were: i) Monitoring CO2 flux in extensive outdoor conditions and ii) To asses the contribution of native vegetation in the CO2 sequestration by the separation of the soil-plant components system.
Materials and Methods
This investigation was carried out in the autumn 2006, at Rancho “Los Angeles”, municipality of Saltillo, Coah., México. This is a farm dedicated to the Charolais breed production, in a total surface around 6700 has. The site location is 25º 6.650’ N and
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100º 59.413 W, in the sub province called Gran Sierra Plegada, located at north of the Physiographic Region Sierra Madre Oriental, as could be seen in the Figure 1.
Figure 1. Field where was put the monitoring system (UTM coordinates system)
Two factors influence the cattle management in this place: One is the climate [BWhw(x´)(e)] which is semiarid (Garcia, 1975), having a precipitation of 350 mm per year, with a rainy season from May to September when falls 80 to 90 percent of total rain; the other factor is the landform; having to the north mountains like the Sierra Leona with a maxim altitude above sea level of 2850 m and to the south the Sierra Los Angeles with 2400 m above sea level, this condition have produced small valleys used as grazing lots, which have an average altitude of 2100 m. The soil type, is mainly Luvisol in a 40 % of total surface, the soils are deep with superficial horizons of dark color and high organic matter content (INEGI, 1976). The vegetation have a distribution in relation to the topographic, edaphic, and microclimatic characteristics in this place, in the hillslope prevail the shrub and in the hilltop prevail the pine trees (Pinus sp.) combined with shrubs; In the valleys is well established the grasses which are a compound that includes the following gramineae: Asistida, Buchloe, Boteloua, Mulenbergia, Steria e Stipia (Mellado, 2007), that are sharing spaces with other plants from families like Laminaceas, Chenopodaceas, Euphobaceas and Asteraceas.
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Selection, location and characteristics of the monitoring plot The monitoring of CO2 flux was made in an area of 35 has of the grazing lot number four located at the central part of the Ranch (rectangle at the Figure1 centre). Three plots of 2.4 ha each, with similar characteristics in soil type and vegetation were established. The dimensions of each plot were: a width of 120 m to N-S direction and a length of 200 m to E-W direction. The soil horizons from 0-0.30 and 0.30-0.60 m depth were studied, the resulting data showed texture with clay content greater than 40% (Boyoucos Hydrometer), PH with more than 8 (potentiometer), color in the soil surface layer (Munsell tables: 10YR 5/2), and total carbonates content grater than 37% (neutralization volume), from this data and based on the INEGI (2001) methodology, it is deduced that the soil characteristics match with a Feozem luvic (Hl) (INEGI 1976; FAO-ISRIC-ISSS-AISS-IBG, 1994). On the other hand, the native vegetation found in this season of the year and its relative importance value (RIV) was determined using line interception method and the more important species are shown in Table 1. Table 1. Floristic list and RIV in the monitoring plots Family Technical name RIV
Asteraceae Brickellia laciniata Gray 7
Asteraceae Zinnia acerosa (DC.) Gray 5
Asteraceae Aphanostephus ramosissimus DC. 5
Acanthaceae Dischoryste linearis (T.&G.)O. Ktze 7
Onagraceae Calylophus belandieri (Spach) Towner 10
Euphorbiaceae Euphorbia furcillata H.B.K. 2
Boraginaceae Tiquila canescens (DC.) Richardson 8
Laminacea Marrubium vulgare L. 50 It was noticed that in the grazing lot were experimental plots were established, the gramineae were not dominant spices due to this lot had been also used to establish winter forage crops like oats (Avena sativa) and barley (Hordeum vulgare L.), so other families as listed in table 1 were dominants. Monitoring duration of FCO2 and separation of components In the first plot the monitoring of FCO2 was made during space of 21 days (from October 20th to November 10th) under not disturbed soil-plant system, this condition was defined as total flux monitored or FCO2NT, in a second plot, the measurements of
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FCO2 was made during 18 days (from November 10th to November 28th) the condition of the plot was that the present vegetation was eliminated, with a chisel plough with delta wings at 25 cm depth. This condition of the system where vegetation were removed by vertical tillage was defined as FCO2SVT the flux was monitored directly from the tilled soil. In a third plot the native vegetation was removed using a disc plough, to a depth of 25 cm. The measurements of CO2 flux in this condition of bare soil defined as FCO2SCT was made for 27 days (until December 8th) Figure 2, illustrates the condition of the second and third plot where the two types of tillage were carried out.
Figure 2. Exclusion vegetal cover by VT (left) and CT (right)
Instrumentation for monitoring the systems The instruments used, were integrated in an automatic meteorological station (Eddy Station), which has the following components: (1) net radiometer Nr (model NR-LITE, Keep and Zonen Inc.) to measure the difference between short and long wave radiation, (2) a sensor to measure air temperature and water vapor, respectively (model HMP45C, Vaisala, Inc.) (3) two plates to measure heat flux soil (model HFT3, REBS Inc.), attached with two thermocouples of four tips (model TCAV, Campbell, Sci. Inc) for measuring the energetic gradient in the soil, G. The Eddy Station had other instruments like a sensor to measure wind speed and wind direction (model 03001-5, RM Young Inc.), an electronic pluviograph to measure the rain events (model TE525, Texas Instruments, Inc.). Also, were used two [datalogers] (models 23X and CR7, both of Campbell, Sci Inc.), and two solar panel one of 64 W and other of 20 W, which provided the energy required for the monitoring system.
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Results and Discussion
The results that will be discussed correspond to the first step of an investigation about the measure and evaluation of energy and mass flux under different conditions of soil management and season of the year. The purpose of this is to asses the role of the agroproductive systems from semiarid condition in the FCO2 dynamics. Figure 3, shows a flow chart for the analysis for the energy and mass flux from the data collected at the experimental plots.
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Figure 3. Diagram to analysis for the energy and mass flux
As a first step, the data of the experiment was arranged in two sets, the data from the eddy station was tabulated for analysis in excel files. Other data from laboratory, and field properties of soil and characteristics of the vegetation was arranged in another set for analysis. In a second step, the analysis of G and the wind direction (WD) was used as a criterion to correct every one of the flux variables. According to the experimental site prevailing wind direction, the acceptable range of WD were from 0 to 90o NE and from 270 to 360o NW. As a third step, energetic fluxes were determined, with the exception of Rn under soil surface and in soil surface with W m-2. The first is represented by the heat flux at the edaphic layer (G) at 0.08 m depth. The second is represented by the sensible heath (H) and latent heath or water vapor (LE) which were measured at 1.4 m above the soil surface.
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The correction of G was made using the formula:
[(Cds+θw•Cw) ρd •∆T•∆z] G = GD8 + ∆t (1)
Were GD8 is the heath flux, measured at 8 cm depth from the soil surface; Cds is caloric capacity of the minerals (840 J•Kg-1K-1); θw is the volumetric water content, Cw is the caloric capacity of the water (4190 J•Kg-1K-1); ∆T is the average change in temperature (oC) by the sensors placed from 2 to 6 cm depth. ∆z is the depth at which the plate for sensing the heath flux is placed (0.08m); and ∆t is the variation of time in seconds. For H and L, there were utilized the following equations (2) and (3):
H = ρa•Cp • w’ Ts’ -0.51•Ta [ ρa•Cp ] λE λ
(2)
LE = λw’ ρwv’ (3)
Were, ρa is the air density (kg m-3); Cp is the caloric capacity of the air (J kg-1 K-1); Ts is the sonic temperature measured whit the anemometer; Ta is the air temperature; w’ is the vertical win speed (m s-1); λ is the heat water vapor (J kg-1). w’Ts’, w’ρwv’ represents the covariance among the variables and the top bar means the average in a time interval that was established as 20 minutes. The frequency of data gathering for w’, Ts, and ρwv, and Ta were of 10 Hz. A fourth step was the correction of FCO2 according to the next formula (4).
FCO2 = ρCO2’• w’ (4)
Where ρCO2 is the density of carbon dioxide (μmol CO2 m-3) and ρwv is the density of the water vapor (kg m-3). The frequency on the measurements was the same as indicated before for the other variables. As a fifth step for the data from the accepted ranges of WD, the CR is determined according to the following equation:
[Rn-G] CR = [H + LE] (5)
In this case it is important to mention the instantaneous values measured with the carbon dioxide analyzer and the air water content from the 3D sonic anemometer.
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Those data are valid when corrected according to the local air density and correspond to values between 0.7 and 1 (Zermeño-Gonzalez, 2001; Ham, 2003). The sixth and last part of the process was to make the numerical and graphic analysis of FCO2 considering that as mass flux μmol m-2s-1 is independent from the calculations in equation (5). However, it is used as a reference, the data series that fall in the ranges that meet the criteria indicated for CR.
FCO2 measured above the soil-plant system In the first plot (reference plot) not disturbed by the tillage was made the total measuring of FCO2. In this phase of monitoring as can be seen in the Figure 4 for the day number 294, had a typical behavior represented for diurnal assimilation and nocturnal release. The first, due to the photosynthetic process from the phototropic organisms, with a rate maxim of assimilation close to 3 μmol de CO2 m-2s-1, which occurred around 13:00 hs; and the second like product from breakdown organic matter by macro and microorganism whit a maxim releaser of -3 μmol de CO2 m-2s-1, occurred between the 19:00 and the 20:00 hs. These results are similar to other reported (Scow, 1999; Pumpanen et al 2003; Qi et al, 2007). These allow to found the general characteristics in the FCO2 dynamic, for the release as well as assimilation, and whit this was estimated the proportion of the contribution from every component of the soil-plant system.
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Figure 4. CO2 flux from the soil with native vegetation (FCO2NT), observed at day 294
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FCO2 monitored whit native vegetation excluded by tillage The temporal elimination of the vegetation at the soil surface and the exposition of the root system to the action of environmental factors, allowed to have an exclusion of the vegetal cover and its root system, like can see in the Figure 5. From that, it was established that the flux measured under those soil management conditions correspond to the FCO2 produced or released under the soil condition left by both tillage system used VT and CT. This is FCO2SVT and FCO2SCT, respectively.
Figure 5. Exclusion vegetation effect. Aboveground (left) and root in the profile
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As a result of the use of both tillage method it could be observed a significant change in the FCO2 typical behavior, because it changed from capture source to release source; in both management systems the assimilation was negligible, and this situation was maintained for eight and nine continuing days. The release, although with a decrement trend on time was observed day and night in both cases, from 1.14 to 0.99 μmol CO2 m-2 s-1 and for 1.3 to 0.87 μmol CO2 m-2 s-1 for VT y CT, respectively. For VT, as it can be seen in the Figure 6, that a maximum value of 2 μmol CO2 m-2 s-1, occurred at the 14:00 h, it could be observed that the curve that represent the release, was maintained day and night being more pronounced for the last case, similar condition was present for CT as it can be seen en the Figure 7, also, in this tillage system can see a frequent variation in the releases of CO2 from the soil, the maximum value registered was almost same at 2 μmol CO2 m-2 s-1 and values of assimilation of less than 0.5 μmol CO2 m-2 s-1.
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Figure 6. CO2 flux from the soil without vegetation observed at day 316, two days after VT
The data gathered in the different treatments allow to separate and to quantify the participation of each component of the soil-plant studied, it also make the possibility to determine the impact of tillage in the flux dynamics of this production system.
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Figure 7. CO2 flux observed days from 333 to 335, between two and fourth days after CT
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FCO2 estimated for components fro the soil-plant system The net contribution for each component of the soil-plant system, to the release and assimilation of CO2 was estimated taking as a reference the average of four events of the instantaneous rates recorded by the sensor in the undisturbed plot, representing as FCO2mt. The difference resulting from the fluxes in the reference plot (undisturbed condition) and those rates measured in the plots disturbed for each type of tillage are the contribution of each condition to the CO2 released as it is presented in table 2. It should be also stated that under certain environmental condition some abiotic processes such as the dissolution of carbonates and chemical oxidation could be contributing also to the total CO2 flux (Hashimoto and Suzuki, 2002).
Table 2. Average of rate release of CO2 measured and estimated for components from the soil-plant system
LV LC
Events FCO2mt
(†)
FCO2 from the soil-plant system
(FCO2SPVT)‡
FCO2 from the
soil (FCO2sVT)
§
FCO2 from the soil-plant system
(FCO2SPCT)¶
FCO2 from the
soil (FCO2SCT)#
μmol CO2m-2s-1 1 1.600 0.200 1.400 0.730 0.870
2 1.270 0.295 0.975 0.020 1.250
3 1.710 1.030 0.680 0.170 1.540
4 1.618 0.628 0.990 0.741 0.877
Averages 1.527 0.508 1.011 0.415 1.134 Percents 100 34% 66% 26% 74%
† FCO2mt total instant rate measured in the NT plot. ‡ FCO2SPVT, estimated rate for difference among FCO2mt and FCO2sVT. § FCO2sVT, Instant rate measured in the plot with VT. ¶ FCO2SPCT, estimated rate for difference among FCO2tm and FCO2sCT # FCO2sCT, Instant rate measured in the plot with CT.
Conclusions
It was possible to establish the importance that vegetation has (where not gramineae are dominant) in the sequestration of carbon. The rhizosphere in the described soil condition for the experiment contributes with 26 to 34 % of the total flux of CO2.
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Both soil tillage methods used promotes the liberation of CO2 to the atmosphere, this is particularly important when land use have to be changed or when tillage is performed early in the season 4 or 6 months before the rainy season as it is the case in the region.
Recommendations
It should be further investigations on the natural soil capacity to return to the inicial condition after the tillage impact because this could be occur at different time scales for some morphologic and biologic properties. It is important to give a value to the roll played by grassland in the sequestration of carbon, given the importance that in the present and future will have the environmental services and the market of green bonus of carbon.
Thankfulness The work described here has been possible, thanks to the help giving from the UAAAN and CONACYT, particularly the Ingenieria Division, where are the follow Faculties: Ingenieria Mecanica Agrícola, Riego y Drenaje and Soils. Also, thanks for the staff of the Rancho “Los Anegels”, whos gave all kind of help.
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and Soil Components Using Analyses of the natural Abundance of Carbón-13.
Soil Sci. Soc. Am. J. 63: 1207-1213
Scow MK. 1999. Soil Microbial Communities and Carbon Flow in Agroecosistems.
Ed. Academic Press, Editado por Jakson, L. E. Carolina University, USA. Pp
367-413.
So HB, Dalal RC, Chan KY, Menzies NM, Freebarm DM. 2001. Potential of
conservation tillage to reduce carbon dioxide emission in Australian soils. In D.E
Sttot, RH Mothar and GC Steinhardt (eds). Sustaining the global farm. Selected
papers from the 10Th International Soil Conservation Organization meeting.
Zermeño-González A. 2001. Métodos Micrometeorológicos para medir flujos de
calor y vapor de agua entre los cultivos y la atmósfera. XIII Semana
Internacional de Agronomía, 2001
14
http://www.pnuma.org/Cambioclimatico/CAMBIO%20CLIMATICO-web.pdf
López-Santos et al XIIIth World Water Congress, 2008
Montpellier, Fr.
Monitoring of CO2 Flux and Contribution for Components in the Soil-Plant System in a Grassland from Northeastern Mexico
1 López-Santos Armando, 2 Cadena-Zapata Martín, 2 Zermeño-González Alejandro, 3 González-Cervantes Guillermo., 2 Gil-Marín José Alexander, 3 Sánchez-Cohen Ignacio
1 Unidad Regional Universitaria de Zonas Áridas de la UACh ([email protected]), 2 División de Ingeniería UAAAN, Buenavista, Saltillo, Coah. Méx., 3 Centro Nacional de Investigación Interdisciplinario en Relaciones Agua Suelo Planta Atmósfera del INIFAP, Gómez Palacio, Dgo, Mex.
Abstract
The monitoring and quantification of CO2 released to the atmosphere by the rural production systems is an uprising need when facing the actual challenge of global warming. It is known, that in the last decade the change of land use and silviculture have contributed in a significant manner in the net emissions of CO2 to the atmosphere. However, is not quite clear the magnitude of the contribution of each individual ecosystem, and even it is least known the contribution of the separate action of the soil-plant system components. There are three methods for monitoring and quantifying the CO2 flux in an extensive open area condition: i) Open or close use of interchange gas chambers; ii) Using the technique of the Bowen Relation Method; and iii) Using the Eddy Covariance Method. In this experiment, the last mentioned was used for its high reliability in the measurements of mass and energy flux in extensive land conditions. The experiment was carried out at Rancho Los Angeles Municipality of Saltillo, Coahuila, México (25º 6.650’ N and 100º 59.413’ W). It was measured the CO2 flux, in plots of 2.4 ha after removing the native vegetation, dominated by three families (Chenopodacea, Euphorbacea y Asteraceae), using two tillage treatments: vertical tillage by chiseling (VT) and conventional tillage by disc ploughing (CT), the flux was measured as well in a reference plot without tillage treatment (NT). In all plots it was determined the magnitude of flux for each component at the soil-plant system. The results showed that under the predominant climatic conditions at Autumn 2006, when separating the components of the soil-plant system from the CO2 total flux monitored (FCO2tm), the more important contribution came from the soil in both tillage methods used (FCO2sLV=66 % and FCO2sLC=74 %).
Key words: Eddy Covariance, Rural Production Systems, CO2 flux.
Introduction
Mexico ranks second among the Latin-Americans countries as CO2 emitter, with net emissions of 444.5 millions of metric tons for 1990, from this amount, it is estimated that the change in land use and silviculture contribute with 30.6 % (PNUMA-SEMARNAT, 2004). Considering the need to reduce release of CO2 and maintain the quality of the soil to support food production, the role and importance of the tillage practices and its impact in the organic matter should be reexamined (So et al, 2001; Lokupitiya et al, 2006), this is also important because of the raise of carbon bonus market among the countries that signed the Kyoto protocol (Inclán, 2007; Cervantes, 2007).
The CO2 emissions from the surface on bare soil give a direct assessment in the short time about the carbon dynamic in the soil, but when vegetation is present, the interpretation of the total soil respiration is difficult due to the root contribution in the CO2 release (Rochete, 1999). It has been estimated that the rizosfera contributes with 40-50 % of the total soil respiration, and the 50-60 % remaining includes the decomposed microbial root exudates and other rhizodepotitions (Kuzyakov, 2002).
Some authors (Rochete, 1999) have utilized values of isotopic carbon (13C) in order to measure CO2 separating from the total soil respiration that which comes from the rhizosphere in a maize crop (Zea mays L.) by using a portable chamber for gas exchange (LI-Cor), from those experiments, and they found that the rhizosphere contributes with 45% of the total respiration, this value agrees also with that reported by Kuzyakov (2002). Also they observed as well that the values of the soil respiration decreased from 3.3 to 1.4 g m-2d-1.
Similarly, other authors (Qi et al, 2007) used a dark gas exchange fix chamber to measure total respiration, also the microbial and radicular from a grassland dominated by S. balcalensis and from bare soil, condition obtained by cutting the aerial part of the plants the day before the sampling, it was found that maximum spoil respiration occurred in July with a value of 6 g CO2 m-2d-1.
In terrestrial ecosystems, the CO2 movements, as well as, other energy flux energetic, can be measured basically by three methods: 1) Eddy Covariance, (EC); 2) Bowen Relation, (BR); and 3) Open or Close, exchange gas chamber (CIG). Every method have advantages and disadvantages in relation to the measurements to characterize the flux behavior, because they are affected by variability in the local and surrounding conditions during day and night, such as humidity, temperature, barometric pressure, wind direction, etc. (Peters et al, 2001; Clark , 2001).
In the present work, the total measure of CO2 flux, is part of an investigation based in the Eddy Covariance method, which have the follow characteristics: i) Direct measurements of the heat flux, water vapor and carbon dioxide; ii) Not assumption is made of coefficient values; iii) measurements are independent; iv) Allow to evaluate the precision of energy balance (Rn=H+LE+G); and v) Is considered the most precise method to measure superficial fluxes (Peters et al, 2001; Clark , 2001).
Based on the above, the objectives of this work were: i) Monitoring CO2 flux in extensive outdoor conditions and ii) To asses the contribution of native vegetation in the CO2 sequestration by the separation of the soil-plant components system.
Materials and Methods
This investigation was carried out in the autumn 2006, at Rancho “Los Angeles”, municipality of Saltillo, Coah., México. This is a farm dedicated to the Charolais breed production, in a total surface around 6700 has. The site location is 25º 6.650’ N and 100º 59.413 W, in the sub province called Gran Sierra Plegada, located at north of the Physiographic Region Sierra Madre Oriental, as could be seen in the Figure 1.
Figure 1. Field where was put the monitoring system (UTM coordinates system)
Two factors influence the cattle management in this place: One is the climate [BWhw(x´)(e)] which is semiarid (Garcia, 1975), having a precipitation of 350 mm per year, with a rainy season from May to September when falls 80 to 90 percent of total rain; the other factor is the landform; having to the north mountains like the Sierra Leona with a maxim altitude above sea level of 2850 m and to the south the Sierra Los Angeles with 2400 m above sea level, this condition have produced small valleys used as grazing lots, which have an average altitude of 2100 m. The soil type, is mainly Luvisol in a 40 % of total surface, the soils are deep with superficial horizons of dark color and high organic matter content (INEGI, 1976).
The vegetation have a distribution in relation to the topographic, edaphic, and microclimatic characteristics in this place, in the hillslope prevail the shrub and in the hilltop prevail the pine trees (Pinus sp.) combined with shrubs; In the valleys is well established the grasses which are a compound that includes the following gramineae: Asistida, Buchloe, Boteloua, Mulenbergia, Steria e Stipia (Mellado, 2007), that are sharing spaces with other plants from families like Laminaceas, Chenopodaceas, Euphobaceas and Asteraceas.
Selection, location and characteristics of the monitoring plot
The monitoring of CO2 flux was made in an area of 35 has of the grazing lot number four located at the central part of the Ranch (rectangle at the Figure1 centre). Three plots of 2.4 ha each, with similar characteristics in soil type and vegetation were established. The dimensions of each plot were: a width of 120 m to N-S direction and a length of 200 m to E-W direction.
The soil horizons from 0-0.30 and 0.30-0.60 m depth were studied, the resulting data showed texture with clay content greater than 40% (Boyoucos Hydrometer), PH with more than 8 (potentiometer), color in the soil surface layer (Munsell tables: 10YR 5/2), and total carbonates content grater than 37% (neutralization volume), from this data and based on the INEGI (2001) methodology, it is deduced that the soil characteristics match with a Feozem luvic (Hl) (INEGI 1976; FAO-ISRIC-ISSS-AISS-IBG, 1994).
On the other hand, the native vegetation found in this season of the year and its relative importance value (RIV) was determined using line interception method and the more important species are shown in Table 1.
Table 1. Floristic list and RIV in the monitoring plots
Family
Technical name
RIV
Asteraceae
Brickellia laciniata Gray
7
Asteraceae
Zinnia acerosa (DC.) Gray
5
Asteraceae
Aphanostephus ramosissimus DC.
5
Acanthaceae
Dischoryste linearis (T.&G.)O. Ktze
7
Onagraceae
Calylophus belandieri (Spach) Towner
10
Euphorbiaceae
Euphorbia furcillata H.B.K.
2
Boraginaceae
Tiquila canescens (DC.) Richardson
8
Laminacea
Marrubium vulgare L.
50
It was noticed that in the grazing lot were experimental plots were established, the gramineae were not dominant spices due to this lot had been also used to establish winter forage crops like oats (Avena sativa) and barley (Hordeum vulgare L.), so other families as listed in table 1 were dominants.
Monitoring duration of FCO2 and separation of components
In the first plot the monitoring of FCO2 was made during space of 21 days (from October 20th to November 10th) under not disturbed soil-plant system, this condition was defined as total flux monitored or FCO2NT, in a second plot, the measurements of FCO2 was made during 18 days (from November 10th to November 28th) the condition of the plot was that the present vegetation was eliminated, with a chisel plough with delta wings at 25 cm depth. This condition of the system where vegetation were removed by vertical tillage was defined as FCO2SVT the flux was monitored directly from the tilled soil. In a third plot the native vegetation was removed using a disc plough, to a depth of 25 cm. The measurements of CO2 flux in this condition of bare soil defined as FCO2SCT was made for 27 days (until December 8th) Figure 2, illustrates the condition of the second and third plot where the two types of tillage were carried out.
Figure 2. Exclusion vegetal cover by VT (left) and CT (right)
Instrumentation for monitoring the systems
The instruments used, were integrated in an automatic meteorological station (Eddy Station), which has the following components: (1) net radiometer Nr (model NR-LITE, Keep and Zonen Inc.) to measure the difference between short and long wave radiation, (2) a sensor to measure air temperature and water vapor, respectively (model HMP45C, Vaisala, Inc.) (3) two plates to measure heat flux soil (model HFT3, REBS Inc.), attached with two thermocouples of four tips (model TCAV, Campbell, Sci. Inc) for measuring the energetic gradient in the soil, G. The Eddy Station had other instruments like a sensor to measure wind speed and wind direction (model 03001-5, RM Young Inc.), an electronic pluviograph to measure the rain events (model TE525, Texas Instruments, Inc.). Also, were used two [datalogers] (models 23X and CR7, both of Campbell, Sci Inc.), and two solar panel one of 64 W and other of 20 W, which provided the energy required for the monitoring system.
Results and Discussion
The results that will be discussed correspond to the first step of an investigation about the measure and evaluation of energy and mass flux under different conditions of soil management and season of the year. The purpose of this is to asses the role of the agroproductive systems from semiarid condition in the FCO2 dynamics. Figure 3, shows a flow chart for the analysis for the energy and mass flux from the data collected at the experimental plots.
Start
Reviewing and
organization
of
electronic
files
wy Da
assessing
Resumes
Analysisway
to
G y WD
WD
analysis
H y LE
correction
(airdensity)
CR
evaluation
Ouput
acceptable
Series
to
flux variables
Numeric
analysis
and
graphics
to
FCO2
RnandG
correction
FCO2
correction
(airdensity)
Start
Reviewing and
organization
of
electronic
files
wy Da
assessing
Resumes
Analysisway
to
G y WD
WD
analysis
H y LE
correction
(airdensity)
CR
evaluation
Ouput
acceptable
Series
to
flux variables
Numeric
analysis
and
graphics
to
FCO2
RnandG
correction
FCO2
correction
(airdensity)
Figure 3. Diagram to analysis for the energy and mass flux
As a first step, the data of the experiment was arranged in two sets, the data from the eddy station was tabulated for analysis in excel files. Other data from laboratory, and field properties of soil and characteristics of the vegetation was arranged in another set for analysis.
In a second step, the analysis of G and the wind direction (WD) was used as a criterion to correct every one of the flux variables. According to the experimental site prevailing wind direction, the acceptable range of WD were from 0 to 90o NE and from 270 to 360o NW.
As a third step, energetic fluxes were determined, with the exception of Rn under soil surface and in soil surface with W m-2. The first is represented by the heat flux at the edaphic layer (G) at 0.08 m depth. The second is represented by the sensible heath (H) and latent heath or water vapor (LE) which were measured at 1.4 m above the soil surface.
The correction of G was made using the formula:
G =
GD8 +
[(Cds+(w•Cw) (d •∆T•∆z]
(1)
∆t
Were GD8 is the heath flux, measured at 8 cm depth from the soil surface; Cds is caloric capacity of the minerals (840 J•Kg-1K-1); (w is the volumetric water content, Cw is the caloric capacity of the water (4190 J•Kg-1K-1); ∆T is the average change in temperature (oC) by the sensors placed from 2 to 6 cm depth. ∆z is the depth at which the plate for sensing the heath flux is placed (0.08m); and ∆t is the variation of time in seconds.
For H and L, there were utilized the following equations (2) and (3):
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
08:0009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00
Hora del día
FCO
2
(µmol CO
2
m
-2
s
-1
)
Día 316
Houroftheday
CO
2
releasing
(Day)
CO
2
releasing
(Nigth)
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
08:0009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00
Hora del día
FCO
2
(µmol CO
2
m
-2
s
-1
)
Día 316
Houroftheday
CO
2
releasing
(Day)
CO
2
releasing
(Nigth)
H = ρa•Cp • w’ Ts’ -0.51•Ta [ ρa•Cp ] λE
λ
(2)
LE = λw’ ρwv’
(3)
Were, (a is the air density (kg m-3); Cp is the caloric capacity of the air (J kg-1 K-1); Ts is the sonic temperature measured whit the anemometer; Ta is the air temperature; w’ is the vertical win speed (m s-1); ( is the heat water vapor (J kg-1). w’Ts’, w’(wv’ represents the covariance among the variables and the top bar means the average in a time interval that was established as 20 minutes. The frequency of data gathering for w’, Ts, and (wv, and Ta were of 10 Hz.
A fourth step was the correction of FCO2 according to the next formula (4).
FCO2 = ρCO2’• w’
(4)
Where (CO2 is the density of carbon dioxide ((mol CO2 m-3) and (wv is the density of the water vapor (kg m-3). The frequency on the measurements was the same as indicated before for the other variables.
As a fifth step for the data from the accepted ranges of WD, the CR is determined according to the following equation:
CR =
[Rn-G]
(5)
[H + LE]
In this case it is important to mention the instantaneous values measured with the carbon dioxide analyzer and the air water content from the 3D sonic anemometer. Those data are valid when corrected according to the local air density and correspond to values between 0.7 and 1 (Zermeño-Gonzalez, 2001; Ham, 2003).
The sixth and last part of the process was to make the numerical and graphic analysis of FCO2 considering that as mass flux (mol m-2s-1 is independent from the calculations in equation (5). However, it is used as a reference, the data series that fall in the ranges that meet the criteria indicated for CR.
FCO2 measured above the soil-plant system
In the first plot (reference plot) not disturbed by the tillage was made the total measuring of FCO2. In this phase of monitoring as can be seen in the Figure 4 for the day number 294, had a typical behavior represented for diurnal assimilation and nocturnal release. The first, due to the photosynthetic process from the phototropic organisms, with a rate maxim of assimilation close to 3 (mol de CO2 m-2s-1, which occurred around 13:00 hs; and the second like product from breakdown organic matter by macro and microorganism whit a maxim releaser of -3 (mol de CO2 m-2s-1, occurred between the 19:00 and the 20:00 hs. These results are similar to other reported (Scow, 1999; Pumpanen et al 2003; Qi et al, 2007).
These allow to found the general characteristics in the FCO2 dynamic, for the release as well as assimilation, and whit this was estimated the proportion of the contribution from every component of the soil-plant system.
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
10:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:00
Hour fo the day
FCO
2
(µmolCO
2
m
-2
s
-1
)
Figure 4. CO2 flux from the soil with native vegetation (FCO2NT), observed at day 294
FCO2 monitored whit native vegetation excluded by tillage
The temporal elimination of the vegetation at the soil surface and the exposition of the root system to the action of environmental factors, allowed to have an exclusion of the vegetal cover and its root system, like can see in the Figure 5. From that, it was established that the flux measured under those soil management conditions correspond to the FCO2 produced or released under the soil condition left by both tillage system used VT and CT. This is FCO2SVT and FCO2SCT, respectively.
Figure 5. Exclusion vegetation effect. Aboveground (left) and root in the profile view (right)
As a result of the use of both tillage method it could be observed a significant change in the FCO2 typical behavior, because it changed from capture source to release source; in both management systems the assimilation was negligible, and this situation was maintained for eight and nine continuing days. The release, although with a decrement trend on time was observed day and night in both cases, from 1.14 to 0.99 (mol CO2 m-2 s-1 and for 1.3 to 0.87 (mol CO2 m-2 s-1 for VT y CT, respectively.
For VT, as it can be seen in the Figure 6, that a maximum value of 2 (mol CO2 m-2 s-1, occurred at the 14:00 h, it could be observed that the curve that represent the release, was maintained day and night being more pronounced for the last case, similar condition was present for CT as it can be seen en the Figure 7, also, in this tillage system can see a frequent variation in the releases of CO2 from the soil, the maximum value registered was almost same at 2 (mol CO2 m-2 s-1 and values of assimilation of less than 0.5 (mol CO2 m-2 s-1.
Figure 6. CO2 flux from the soil without vegetation observed at day 316, two days after VT
The data gathered in the different treatments allow to separate and to quantify the participation of each component of the soil-plant studied, it also make the possibility to determine the impact of tillage in the flux dynamics of this production system.
EMBED Excel.Chart.8 \s
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
11/29/06 18:0011/29/06 20:0011/29/06 22:00
11/30/06 0:0011/30/06 2:0011/30/06 4:0011/30/06 6:0011/30/06 8:00
11/30/06 10:0011/30/06 12:0011/30/06 14:0011/30/06 16:0011/30/06 18:0011/30/06 20:0011/30/06 22:00
12/1/06 0:0012/1/06 2:0012/1/06 4:0012/1/06 6:00
Time, day and hour
FCO
2
(µmol CO
2
m
-2
s
-1
)
Figure 7. CO2 flux observed days from 333 to 335, between two and fourth days after CT
FCO2 estimated for components fro the soil-plant system
The net contribution for each component of the soil-plant system, to the release and assimilation of CO2 was estimated taking as a reference the average of four events of the instantaneous rates recorded by the sensor in the undisturbed plot, representing as FCO2mt. The difference resulting from the fluxes in the reference plot (undisturbed condition) and those rates measured in the plots disturbed for each type of tillage are the contribution of each condition to the CO2 released as it is presented in table 2.
It should be also stated that under certain environmental condition some abiotic processes such as the dissolution of carbonates and chemical oxidation could be contributing also to the total CO2 flux (Hashimoto and Suzuki, 2002).
Table 2. Average of rate release of CO2 measured and estimated for components from the soil-plant system
Events
FCO2mt
(†)
LV
LC
FCO2
from the soil-plant system (FCO2SPVT)‡
FCO2 from the
soil (FCO2sVT) §
FCO2
from the soil-plant system (FCO2SPCT)¶
FCO2
from the soil (FCO2SCT)#
(mol CO2m-2s-1
1
1.600
0.200
1.400
0.730
0.870
2
1.270
0.295
0.975
0.020
1.250
3
1.710
1.030
0.680
0.170
1.540
4
1.618
0.628
0.990
0.741
0.877
Averages
1.527
0.508
1.011
0.415
1.134
Percents
100
34%
66%
26%
74%
† FCO2mt total instant rate measured in the NT plot.
‡ FCO2SPVT, estimated rate for difference among FCO2mt and FCO2sVT.
§ FCO2sVT, Instant rate measured in the plot with VT.
¶ FCO2SPCT, estimated rate for difference among FCO2tm and FCO2sCT
# FCO2sCT, Instant rate measured in the plot with CT.
Conclusions
It was possible to establish the importance that vegetation has (where not gramineae are dominant) in the sequestration of carbon. The rhizosphere in the described soil condition for the experiment contributes with 26 to 34 % of the total flux of CO2.
Both soil tillage methods used promotes the liberation of CO2 to the atmosphere, this is particularly important when land use have to be changed or when tillage is performed early in the season 4 or 6 months before the rainy season as it is the case in the region.
Recommendations
It should be further investigations on the natural soil capacity to return to the inicial condition after the tillage impact because this could be occur at different time scales for some morphologic and biologic properties. It is important to give a value to the roll played by grassland in the sequestration of carbon, given the importance that in the present and future will have the environmental services and the market of green bonus of carbon.
Thankfulness
The work described here has been possible, thanks to the help giving from the UAAAN and CONACYT, particularly the Ingenieria Division, where are the follow Faculties: Ingenieria Mecanica Agrícola, Riego y Drenaje and Soils. Also, thanks for the staff of the Rancho “Los Anegels”, whos gave all kind of help.
Cited references
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Clark DA, Brown S, Kiclighter WD, Chambers QJ, Thomlinson RJ, Ni J. 2001. Measuring Net Primary Production in Forest: Concepts and Field Methods. Ecological Society of America. Ecological Applications 11(2): 356-370
FAO-ISRIC-ISSS-AISS-IBG, 1994. World Reference Base for Soil Resources. Wagening, Rome. P 56.
García E. 1975. Climas Coahuila y Nuevo León, precipitación y probabilidad de lluvia en la República Mexicana y su evolución. CETENAL, México, D.F.
Ham JM, Heilman JL. Experimental Test of Density and Energy-Balance Corrections on Carbon Dioxide Flux as Measured Using Open-Path Eddy covariance. American Society of Agronomy, 2003; 95: 1393 – 1403.
Hashimoto S, Suzuki M. 2002. Vertical Distribution of Carbon Dioxide Diffusion Coefficients and Production Rates in Forest Soil. Soil Sci. Soc. Am. J. 66: 1151-1158
Inclán GU. 2007. Mercado de Bonos de Carbono y sus beneficios potenciales para proyectos en México. Dirección de Cambio Climático-SENER. Consulted (07/19/07), in http://www.conae.gob.mx/work/sites/CONAE/resources/LocalContent/2962/1/images/22_sener.pdf.
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Kuzyakov Y. 2002. Separating Microbial Respiration of Exudates from Root Respiration in non-sterile soils: a comparison of four Methods. Soil Biology & Biochemistry, 34: 1621-1631
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Mellado M. 2007. Traslape de Dietas entre el Perrito de la Pradera (Cynomys mexicanus) y Bovinos en un Pastizal. Mediano Abierto. Consulated (08/19/08) in http://www.uaaan.mx/DirInv/Rdos2003/Zaridas/dietas.pdf s/f.
Peters G, Fischer B, Munser H. 2001. Eddy Covariance Measurements with Closed-Path Optical Humidity Sensors: A feasible Concepts? Journal of Atmospheric and Oceanic Technology, American Meteorological Society..
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Pumpanen J, Ilvesniemi H, Hari P. 2003. A process Based Model Predicting Soil Carbon Dioxide Efflux and Concentrations. Soil Sci. Soc. Am. J. 67: 402-413
Qi YCh, Dong Y, Liu J, Domroes M, Geng Y, Liu L, et al. 2007. Effect of the Conversion of Grassland to Spring Wheat Field on the CO2 Emission Characteristics in Inner Mongolia, China. Soil and Tillage Research. 94: 310-320
Rochete P, Flanagan LB, Grgorich EG. 1999. Separating Soil Respiration into Plant and Soil Components Using Analyses of the natural Abundance of Carbón-13. Soil Sci. Soc. Am. J. 63: 1207-1213
Scow MK. 1999. Soil Microbial Communities and Carbon Flow in Agroecosistems. Ed. Academic Press, Editado por Jakson, L. E. Carolina University, USA. Pp 367-413.
So HB, Dalal RC, Chan KY, Menzies NM, Freebarm DM. 2001. Potential of conservation tillage to reduce carbon dioxide emission in Australian soils. In D.E Sttot, RH Mothar and GC Steinhardt (eds). Sustaining the global farm. Selected papers from the 10Th International Soil Conservation Organization meeting.
Zermeño-González A. 2001. Métodos Micrometeorológicos para medir flujos de calor y vapor de agua entre los cultivos y la atmósfera. XIII Semana Internacional de Agronomía, 2001
CO2 releasing
(Night)
CO2 assimilation
(Day)
CO2 releasing-assimilation
(Day and Night)
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_1235738914.xls
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0.56944444440.5694444444
0.58333333330.5833333333
0.59722222220.5972222222
0.61111111110.6111111111
0.6250.625
0.63888888890.6388888889
0.65277777780.6527777778
0.66666666670.6666666667
0.68055555560.6805555556
0.69444444440.6944444444
0.70833333330.7083333333
0.72222222220.7222222222
0.73611111110.7361111111
0.750.75
0.76388888890.7638888889
0.77777777780.7777777778
0.79166666670.7916666667
0.80555555560.8055555556
0.81944444440.8194444444
0.83333333330.8333333333
0.84722222220.8472222222
0.86111111110.8611111111
0.8750.875
0.88888888890.8888888889
0.90277777780.9027777778
0.91666666670.9166666667
FCO2 ()
Linea
Hour fo the day
FCO2 (µmolCO2 m-2s-1)
-2.2991438417
0
-2.1891799098
0
-1.9524208319
0
-2.0792159779
0
-2.0175015263
0
-2.0522860354
0
-2.239673552
0
-2.0870705444
0
-2.5796640762
0
-1.4003570105
0
-1.8850959756
0
-1.8402127381
0
-1.9793507744
0
-2.0186236072
0
-1.9468104272
0
-1.4340194386
0
-1.624773198
0
-1.607941984
0
-1.5967211746
0
-1.4923676474
0
-1.8705089234
0
-1.3016138879
0
-1.2544864885
0
-0.1582134122
0
0.2782760726
0
0.8819556172
0
1.8839738947
0
2.8276439634
0
2.6803708403
0
2.5330977172
0
2.2385514711
0
1.5523989775
0
1.2093227308
0
0.866246484
0
1.0377846074
0
1.1521433563
0
DIA 294
DiaHoras del diaFCO2ValorTiempoSum_RnSum_LESum_FCO2LE/RnFCO2/Rnasimilación
µmolCO2/m2sLineaa corregirSegmento(MJ/m2)(MJ/m2)(mmolCO2/m2)promedio
29410:20-2.2990-1.859
29410:40-2.1890-3.184Asimilación10:20 a 18:0011.4754.022-50.0140.351-4.359
29411:00-1.9520Liberacion
29411:20-2.0790Liberación18:20 a 22:00-0.46922.112-47.135promedio
29411:40-2.01801.715
29412:00-2.0520-0.382mm H2O
29412:20-2.2400-3.296L=2.421.662
29412:40-2.0870
29413:00-2.5800
29413:20-1.4000
29413:40-1.8850
29414:00-1.8400
29414:20-1.9790
29414:40-2.0190
29415:00-1.9470
29415:20-1.4340
29415:40-1.6250
29416:00-1.6080
29416:20-1.5970
29416:40-1.4920
29417:00-1.8710
29417:20-1.3020
29417:40-1.2540
29418:00-0.1580
29418:200.2780
29418:400.8820
29419:001.8840
29419:202.8280
29419:402.6800
29420:002.53300.213
29420:202.2390
29420:401.55205.857
29421:001.20900.353
29421:200.8660
29421:401.0380-3.178
29422:001.15204.417
Integrar: Rn, LE, FCO2 de las 10:20 a las 18:00
DiaHoras del diaLERnIntegrar: FCO2 de las 18:20 a las 22:00
W/m2W/m2
29410:20109270
29410:40136330
29411:00144370
29411:20140380
29411:40141410
29412:00136438
29412:20145490
29412:40186545
29413:00177545
29413:20171554
29413:40194572
29414:00199567
29414:20199560
29414:40191538
29415:00182516
29415:20172485
29415:40148444
29416:00131405
29416:20128366
29416:40106308
29417:0099257
29417:2079191
29417:4073142
29418:004031
DiaHoras del diaRn
W/m2
29418:20-1
29418:40-10
29419:00-30
29419:20-32
29419:40-37
29420:00-33
29420:20-36
29420:40-44
29421:00-43
29421:20-52
29421:40-51
29422:00-47
DIA 294
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
FCO2 ()
Linea
Hora del dia
FCO2 (µmolCO2/m-2s-1)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
DIA 295 Y 296
DiaHoras del diaFCO2ValorTiempoSum_RnSum_LESum_FCO2LE/RnFCO2/Rnasimilación
µmolCO2/m2sLineaa corregirSegmento(MJ/m2)(MJ/m2)(mmolCO2/m2)promedio
10/22/06 9:00295900-0.5570-1.562
10/22/06 9:20295920-0.40600.145Asimilación09:00 a 14:404.2181.597-31.6230.379-7.497
10/22/06 9:40295940-0.38300.196Liberacion
10/22/06 10:002951000-0.2780Liberación22:00 a 03:40-0.79226.620-33.601promedio
10/22/06 10:202951020-0.31501.273
10/22/06 10:402951040-0.4850mm H2O
10/22/06 11:002951100-1.0360L=2.420.660
10/22/06 11:202951120-2.0850
10/22/06 11:402951140-2.6410
10/22/06 12:002951200-2.5210
10/22/06 12:202951220-1.8750
10/22/06 12:402951240-1.6170
10/22/06 13:002951300-2.2320
10/22/06 13:202951320-1.7770
10/22/06 13:402951340-1.5240
10/22/06 14:002951400-2.8550
10/22/06 14:202951420-2.5530
10/22/06 14:402951440-2.9820
10/22/06 15:0029515000
10/22/06 15:2029515200
10/22/06 15:4029515400
10/22/06 16:0029516000
10/22/06 16:2029516200
10/22/06 16:4029516400
10/22/06 17:0029517000
10/22/06 17:2029517200
10/22/06 17:4029517400
10/22/06 18:0029518000
10/22/06 18:2029518200
10/22/06 18:4029518400
10/22/06 19:0029519000
10/22/06 19:2029519200
10/22/06 19:4029519400
10/22/06 20:0029520000
10/22/06 20:2029520200
10/22/06 20:4029520400
10/22/06 21:0029521000
10/22/06 21:2029521200
10/22/06 21:4029521400
10/22/06 22:0029522000.1140-1.128
10/22/06 22:2029522200.6470
10/22/06 22:4029522400.4170
10/22/06 23:0029523001.4930
10/22/06 23:2029523201.67802.015Integrar: de las 9:00 a las 14:40 Rn, LE, FCO2
10/22/06 23:4029523401.8620Integrar: FCO2 de las 22:00 a las 3:40
10/23/06 0:0029601.68602.630
10/23/06 0:20296201.51003.953
10/23/06 0:40296401.1580
10/23/06 1:002961001.3450
10/23/06 1:202961201.7870
10/23/06 1:402961402.2760
10/23/06 2:002962002.0000
10/23/06 2:202962201.0810
10/23/06 2:402962401.4070
10/23/06 3:002963000.6180
10/23/06 3:202963200.4790
10/23/06 3:402963401.3640
DiaHoras del diaLERn
W/m2W/m2
2959:001531
2959:201531
2959:401428
29510:001230
29510:202145
29510:404281
29511:004495
29511:2049117
29511:4068168
29512:0068169
29512:2067178
29512:40156372
29513:00124380
29513:20161458
29513:40139440
29514:00112307
29514:20157389
29514:40152421
DiaHoras del diaRn
W/m2
2952200-48
2952220-39
2952240-47
2952300-50
2952320-60
2952340-61
2960-60
29620-55
29640-59
296100-46
296120-45
296140-38
296200-42
296220-10
296240-7
296300-7
296320-8
296340-8
Día 294
Rn
LE
Hora del dia
Flujos (W/m2)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Día 294
DIA 295 Y 296
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
Del día 295 al 296
FCO2
Linea
Fecha y hora del dia
FCO2 (µmolCO2/m-2s-1)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
DIA 296 Y 297
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
Día 295
Rn
LE
Hora del dia
Flujos (W/m2)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
DIA 297 Y 298
DiaHoras del diaFCO2Valor aTiempoSum_RnSum_LESum_FCO2LE/RnFCO2/Rn
µmolCO2/m2sLineacorregirSegmento(MJ/m2)(MJ/m2)(mmolCO2/m2)
10/23/06 9:002969001.0310
10/23/06 9:202969200.1990Asimilación09:40 a 18:004.2512.080-61.4870.489-14.465
10/23/06 9:40296940-0.2380
10/23/06 10:002961000-0.8090Asimilación09:40 a 14:002.5791.071-32.9250.415-12.766
10/23/06 10:202961020-2.2030-0.109
10/23/06 10:402961040-3.3160Liberación18:20 a 9:00-1.00977.708-77.021
10/23/06 11:002961100-2.4850
10/23/06 11:202961120-3.3770mm H2O
10/23/06 11:402961140-3.0220L=1.421.465
10/23/06 12:002961200-3.1510L=2.420.443
10/23/06 12:202961220-2.8900
10/23/06 12:402961240-2.6940
10/23/06 13:002961300-3.4590
10/23/06 13:202961320-2.5800
10/23/06 13:402961340-3.1860
10/23/06 14:002961400-2.3460
10/23/06 14:202961420-2.5560-0.748
10/23/06 14:402961440-2.7660-5.498
10/23/06 15:002961500-1.96000.721
10/23/06 15:202961520-1.57904.484
10/23/06 15:402961540-1.1990-6.724
10/23/06 16:002961600-1.1530
10/23/06 16:202961620-1.2440
10/23/06 16:402961640-1.0510
10/23/06 17:002961700-0.3840
10/23/06 17:202961720-1.2870
10/23/06 17:402961740-0.4520
10/23/06 18:0029618000.0620
10/23/06 18:2029618200.3460
10/23/06 18:4029618401.1180
10/23/06 19:0029619001.5010
10/23/06 19:2029619201.3810
10/23/06 19:4029619401.6030
10/23/06 20:0029620001.97008.082
10/23/06 20:2029620202.2640-0.313
10/23/06 20:4029620402.9250
10/23/06 21:0029621003.33501.292
10/23/06 21:2029621203.7440
10/23/06 21:4029621402.2870
10/23/06 22:0029622002.45204.886
10/23/06 22:2029622201.5910-0.018
10/23/06 22:4029622401.3240
10/23/06 23:0029623001.16200.618
10/23/06 23:2029623200.7910
10/23/06 23:4029623401.0010
10/24/06 0:0029701.3840
10/24/06 0:20297201.2050
10/24/06 0:40297401.2740
10/24/06 1:002971001.2890
10/24/06 1:202971201.2070
10/24/06 1:402971400.9480
10/24/06 2:002972000.9920
10/24/06 2:202972200.7440
10/24/06 2:402972401.0170
10/24/06 3:002973001.5090Integrar: Rn, LE y FCO2 de las 9:40 a las 18:00 hrs
10/24/06 3:202973201.35300.310Integrar: FCO2 de las 18:20 a las 9:00 hrs
10/24/06 3:402973401.1960
10/24/06 4:002974001.1050Integrar: Rn, LE y FCO2 de las 9:40 a las 14:00 hrs
10/24/06 4:202974201.35800.187
10/24/06 4:402974401.6110
10/24/06 5:002975001.72900.675
10/24/06 5:202975201.8460
10/24/06 5:402975401.3950
10/24/06 6:002976001.1160-0.056
10/24/06 6:202976200.8380
10/24/06 6:402976401.2050
10/24/06 7:002977000.8880
10/24/06 7:202977201.1160
10/24/06 7:402977401.23500.536
10/24/06 8:002978001.3530
10/24/06 8:202978201.8620
10/24/06 8:402978401.1120
10/24/06 9:002979000.4920-1.349
10/24/06 9:202979200.1820-19.585
10/24/06 9:40297940-0.1280
10/24/06 10:002971000-0.62000.204
10/24/06 10:202971020-1.66001.246
10/24/06 10:402971040-2.7010
10/24/06 11:002971100-1.9130
10/24/06 11:202971120-1.9150
10/24/06 11:402971140-2.5090
10/24/06 12:002971200-2.9840
10/24/06 12:202971220-2.3530
10/24/06 12:402971240-1.7130
10/24/06 13:002971300-1.8790
10/24/06 13:202971320-2.7560
10/24/06 13:402971340-2.5110
10/24/06 14:002971400-3.7170
DiaHoras del diaLERn
W/m2W/m2
2969:00139
2969:201626
2969:403051
29610:003054
29610:202959
29610:4036100
29611:0044120
29611:2077212
29611:4098287
29612:0079239
29612:2090262
29612:4051171
29613:0088251
29613:2065192
29613:4080211
29614:0073190
29614:2070150
29614:40103140
29615:0099130
29615:2077110
29615:4070100
29616:00105136
29616:2075110
29616:4074109
29617:005059
29617:208484
29617:405337
29618:003212
DiaHoras del diaLERnLinea
W/m2W/m2
2979:00-2-50
2979:20120
2979:4015220
29710:0017330
29710:2010330
29710:4025800
29711:00501220
29711:20611450
29711:40932000
29712:001022250
29712:20841870
29712:40662020
29713:00832120
29713:201002500
29713:401052840
29714:001793300
DiaHoras del diaLERn
W/m2W/m2
296182026
29618401
2961900-13
2961920-18
2961940-22
2962000-42
2962020-36
2962040-33
2962100-32
2962120-34
2962140-31
2962200-35
2962220-34
2962240-29
2962300-29
2962320-28
2962340-18
2970-20
29720-18
29740-29
297100-11
297120-9
297140-22
297200-27
297220-21
297240-7
297300-7
297320-8
297340-7
297400-9
297420-7
297440-7
297500-8
297520-21
297540-18
297600-20
297620-23
297640-23
297700-24
297720-21
297740-18
297800-12
297820-11
297840-9
297900-5
DIA 297 Y 298
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
Día 296
Rn
LE
Hora del dia
Flujos (W/m2)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
FCO2
Linea
Fecha y hora del dia
FCO2 (µmolCO2/m-2s-1)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
DiaHoras del diaFCO2Valor aTiempoSum_RnSum_LESum_FCO2LE/RnFCO2/Rn
µmolCO2/m2sLineacorregirSegmento(MJ/m2)(MJ/m2)(mmolCO2/m2)
10/24/06 21:0029721001.4980
10/24/06 21:2029721202.2610Asimilación09:00 a 14:404.4721.472-52.5980.329-11.762
10/24/06 21:4029721402.45201.056
10/24/06 22:0029722002.6430Liberación21:00 a 8:40-1.30672.221-55.284
10/24/06 22:2029722202.52901.380
10/24/06 22:4029722402.34701.370mm H2O
10/24/06 23:0029723002.4160L=2.420.608
10/24/06 23:2029723202.27800.977
10/24/06 23:4029723402.12500.805Integrar: FCO2 de las 21:00 a las 8:40
10/25/06 0:0029802.1400Integrar: Rn, LE, FCO2 de las 9:00 a las 14:40
10/25/06 0:20298201.82000.992
10/25/06 0:40298401.5000
10/25/06 1:002981001.81303.465
10/25/06 1:202981202.0350
10/25/06 1:402981401.9030
10/25/06 2:002982001.4860
10/25/06 2:202982201.7180
10/25/06 2:402982402.1730
10/25/06 3:002983001.94900.239
10/25/06 3:202983201.8570
10/25/06 3:402983401.8170
10/25/06 4:002984001.8840
10/25/06 4:202984201.6180
10/25/06 4:402984401.53800.246
10/25/06 5:002985001.4590
10/25/06 5:202985201.22500.621
10/25/06 5:402985400.9920
10/25/06 6:002986001.225011.609
10/25/06 6:202986201.045010.553
10/25/06 6:402986401.09105.885
10/25/06 7:002987001.0990
10/25/06 7:202987201.1300
10/25/06 7:402987401.4090
10/25/06 8:002988000.9000
10/25/06 8:202988200.9950
10/25/06 8:402988401.1250
10/25/06 9:002989000.0770
10/25/06 9:20298920-1.2370
10/25/06 9:40298940-1.3790
10/25/06 10:002981000-1.8810
10/25/06 10:202981020-2.5020
10/25/06 10:402981040-3.1010
10/25/06 11:002981100-3.1800
10/25/06 11:202981120-3.4670
10/25/06 11:402981140-3.6570
10/25/06 12:002981200-3.6250
10/25/06 12:202981220-2.9200
10/25/06 12:402981240-3.0080Integrar: FCO2 de las 21:00 a las 8:40
10/25/06 13:002981300-3.0330Integrar: Rn, LE, FCO2 de las 9:00 a las 14:40
10/25/06 13:202981320-1.9240
10/25/06 13:402981340-2.1490
10/25/06 14:002981400-2.4320
10/25/06 14:202981420-3.0830
10/25/06 14:402981440-2.5830
DiaHoras del diaLERn
W/m2W/m2
2989:001832
2989:203875
2989:404191
29810:004197
29810:2059142
29810:4078205
29811:0074230
29811:2079255
29811:4084276
29812:0098299
29812:2077250
29812:4083312
29813:00132390
29813:2056211
29813:4069220
29814:0075247
29814:2082260
29814:40101300
DiaHoras del diaRn
W/m2
2972100-31
2972120-31
2972140-35
2972200-58
2972220-61
2972240-57
2972300-57
2972320-49
2972340-41
2980-35
29820-35
29840-58
298100-46
298120-35
298140-26
298200-27
298220-27
298240-32
298300-21
298320-12
298340-12
298400-19
298420-32
298440-38
298500-34
298520-33
298540-32
298600-35
298620-36
298640-30
298700-30
298720-19
298740-6
2988005
29882010
29884022
Del día 296 al 297
Rn
LE
Linea C
Horas del dia
Flujos (W/m2)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Día 297
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
FCO2
Linea
Hora del dia
FCO2 (µmolCO2 m-2s-1)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Del día 297 al 298
Rn
LE
Hora del dia
Flujos (W/m2)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Día 298
_1267379234.xls
Gráfico2
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