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Effect of beef cattle manure application rate on CH4 and CO2 emissions
Atmospheric Environment 63 (2012) 327e336
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Effect of beef cattle manure application rate on CH4 and CO2 emissions Nhu-Thuc Phan a, Ki-Hyun Kim a, *, David Parker b, Eui-Chan Jeon a, Jae-Hwan Sa a, Chang-Sang Cho a a b
Department of Environment and Energy, Sejong University, Seoul 143-747, Republic of Korea Palo Duro Research Center, West Texas A&M University, Canyon, TX 79016, USA
h i g h l i g h t s < The application of solid manure can release large quantities of greenhouse gases (GHG). < Its implication has scarcely been evaluated with respect to solid beef cattle manure. < The behavior of CH4 and CO2 was examined in relation to manure treatment conditions. < This study will help establish a management scheme for the GHGs from manure treatment.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 26 May 2012 Received in revised form 2 September 2012 Accepted 10 September 2012
In a series of field experiments, emissions of two major greenhouse gases (GHGs), methane (CH4) and carbon dioxide (CO2) were measured using a closed chamber technique in summer 2010 to evaluate the effects of solid beef cattle manure land application techniques. The treatments included a control (C: no manure), two manure application rates (40 and 80 T ha1), and two injection layers (surface vs. subsurface (5 cm)): (1) 40 T ha1 on surface (S40), (2) 80 T ha1 on surface (S80), (3) 40 T ha1 at subsurface (D40), and (4) 80 T ha1 at subsurface (D80)). The exchange patterns of CH4 and CO2 in the control were variable and showed both emission and deposition. However, only emissions were seen in the manure treatments. Emissions of CH4 were seen systematically on the ascending order of 5.35 (C), 59.3 (S40), 68.7 (D40), 188 (S80), and 208 mg m2 h1 (D80), while those of CO2 also showed a similar trend: 12.9 (C), 37.6 (S40), 55.8 (D40), 82.4 (S80), and 95.4 mg m2 h1 (D80). The overall results of our study suggest that the emissions of CH4 and CO2 are affected most noticeably by the differences in the amount of manure application. Ó 2012 Elsevier Ltd. All rights reserved.
Keywords: Beef cattle manure Greenhouse gas (GHG) Emission Flux CH4 CO2
1. Introduction Agricultural activities are estimated to account for about 13.5% of the total greenhouse gas (GHG) emissions (Intergovernmental Panel on Climate Change (IPCC), 2007a). It is estimated that total anthropogenic emissions from agricultural sources can represent 50%, 60%, and 20% of methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2), respectively (IPCC, 2007b). Application of animal manure or slurries may lead to gaseous emissions of CH4, N2O, and CO2 and ground water contamination by nitrate ðNO3 Þ via nitrification of ammonium nitrogen ðNH4 þ eNÞ (Bertora et al., 2008; Fangueiro et al., 2008; Jarecki et al., 2008; Sherlock et al., 2002). As one of the reasonable choices to sequester carbon and nutrient and to promote GHG mitigation, one can consider the use * Corresponding author. Tel.: þ82 2 499 9151; fax: þ82 2 499 2354. E-mail addresses: [email protected], [email protected] (K.-H. Kim). 1352-2310/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.atmosenv.2012.09.028
of appropriate manure management techniques (Duchateau and Vidal, 2003). In fact, runoff transport of nutrients can be reduced efficiently by injection of liquid manure; for example, runoff losses of phosphorous were reduced by more than 94e99% through direct injection of liquid swine effluent as compared to surface application (Daverede et al., 2004). Misselbrook et al. (2002) found that cattle slurry applied by shallow injection on arable land and grass land led to reductions in NH3 emission by 23 and 73%, respectively, as compared with surface broadcast. Parker et al. (in press) reported an 80e95 percent reduction in VOC emissions for injected as opposed to surface applied swine slurry. Likewise, numerous efforts have been made to assess the relationship between slurry/manure application and GHG emissions and to identify the key control factors of such exchange processes. In order to reduce GHG emissions arising from agricultural activities, it is desirable to gain a better understanding of the production, emission, and consumption of these gases in relation to such sources as manure application. The effect of liquid manure
71 7/29 210 64 7/22 203 57 7/15 196
Fig. 1. Location of the study site: Naju, Jeonnam province, South Korea.
CO2 flux measurement
c
6 5/25 145 5 5/24 144 4 5/23 143 3 5/22 142 2 5/21 141 1 5/20 140 0 5/19 139 Elapsed time (days)c Actual date (month/day) Julian day CH4 flux measurement
C. Time and frequency of flux measurements
B. Grouping of treatment and related acronyms
b
20 6/8 159 10 5/29 149 8 5/27 147
Surface Surface Subsurface Subsurface C S40 S80 D40 D80
7 5/26 146
Soil layerb Samplea
12 5/31 151
14 6/2 153
16 6/4 155
18 6/6 157
0.63 72.8
Moisture % pH
6.9 Fermented beef cattle manure
A. Chemical properties of fermented beef cattle manure used in this experiment
Table 1 Basic information of fermented beef cattle manure and experimental scheme for the field analysis of CH4 and CO2 fluxes.
The experiments were conducted on a small farm near the campus of Dongshin University, Naju city (35 020 N 126 430 E), Jeonnam province, South Korea (Fig. 1). Naju is located 350 km south of Seoul, South Korea. The measurements of CH4 and CO2 fluxes at the field started simultaneously on 19 May 2010 but lasted up to 30 days (17 June 2010) and 70 days (29 July, 2010), respectively (Table 1). Although we intended to measure N2O at the same time, we were unable to do so due to the failure of the GC-ECD setup built for that purpose. The measurements of CH4 and CO2 fluxes were not made beyond those durations, as the fluxes from all
Total N %
2.1. Site characteristics and environmental parameters
a
29 6/17 168 26 6/14 165 22 6/10 161
2. Materials and methods
C sample denotes control unit. Surface (0) vs. subsurface (5 cm). Flux measurements were made one time a day basis at 2 PM since 19 May 2010. However, 2 more measurements (9 AM and 5 PM) were made additionally on 20 and 21 May 2010.
50 7/8 189 33 6/21 172
36 6/24 175
0 40 80 40 80
TOC % Total P %
23.1
application has been studied frequently with respect to GHG emissions (Flessa and Beese, 2000; Lovanh et al., 2010; Perälä et al., 2006; Sistani et al., 2010; Wulf et al., 2002). The implication of solid manure application has however scarcely been evaluated in that respect. It is reasonable to infer that there are some chemical, physical, and biological differences in GHG emission potential between liquid and solid manure. Hence, in this study, we aimed to investigate the effect of different land application techniques for solid manure (fermented solid beef cattle manure) on CH4 and CO2 emissions. To this end, a series of field studies were conducted to measure their fluxes after the solid manure application by combining the two different criteria: (1) the rate of application between 40 and 80 T ha1 and (2) the depth of manure injection between surface and 5 cm. By conducting experiments based on these criteria, we attempted to assess the effects of such treatment conditions with solid beef cattle manure on the emission properties of the two major GHGs, CH4 and CO2.
Manure application rate (T ha1)
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0.57
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manure treatments were low and were not different from those of the control unit. During the study period, ambient (and soil) temperature and volumetric soil moisture were measured by a WatchDog Weather Station (model 2800, Spectrum Technologies, USA) equipped with an external temperature sensor (Catalog # 3667) and a WaterScout SM100 Sensor (Catalog # 6460), respectively. The soil pH was monitored by a pH probing system (model IQ 170, IQ Scientific Instruments, USA), after being calibrated in the laboratory prior to utilization in the field. 2.2. Fermented beef cattle manure and manure application Fermented solid beef cattle manure used in this study was obtained from a commercial beef cattle farm in Naju, South Korea. The cattle were fed with a diet of maize silage and concentrated feed. The beef cattle manure was stored for digestion about 3 months before it was applied as fertilizer to small plots (1 m by 1 m). The fermented beef cattle manure used in this experiment had a mean pH value of 6.9, with moisture, total N, total P, and total organic carbon (TOC) contents of 72.8, 0.63, 0.57, and 23.1%, respectively (Table 1A). The beef cattle manure was applied manually on soils mainly consisting of loams and loess during 19 May 2010 by the combinations of the two different criteria: (1) 40 T ha1 on surface (S40), (2) 80 T ha1 on surface (S80), (3) 40 T ha1 at subsurface (5 cm: D40), and (4) 80 T ha1 at subsurface (5 cm: D80) (Table 1B). The measurements were then made initially from a control (C) unit (without manure application) as a reference to all four treatment types. For surface application of S40 and S80, 4 and 8 kg of fermented beef cattle manure were spread uniformly by hand within the area of 1 m2 area. For the applications at subsurface, a 5 cm thick soil layer was removed, and then the manure was uniformly applied. At last, the manure layer was covered by the 5 cm thick soil layer. In all plots, the plants were removed to avoid plant respiration which may otherwise affect CO2 emissions. The plots in our experiment were located adjacently, and soils in all plots were tilled before starting the experiment (Fig. 1S). 2.3. Flux measurement The fluxes of CH4 and CO2 were measured using a closed static chamber technique. The chamber method used in this study is comparable to those investigated actively by other researchers (Fangueiro et al., 2008; Hutchinson and Mosier, 1981; Hyde et al., 2006). The cylindrical shaped chamber with 20 L volume (0.29 m internal diameter 0.3 m internal height) was constructed of fluorinated ethylene propylene (FEP) with a Teflon lining to minimize the sorptive loss of gases onto its inner walls (Roelle et al., 2001). An impeller stirrer powered by a 12-V battery was installed on the platform inside the chamber to homogeneously mix the air. The bottom of the chamber was carefully inserted into the soil at a depth of 10 cm to form a gas tight seal and to minimize any soil disturbance. The chamber was placed at a fixed position of each slot for every sampling time from the start to the end of the experiment. The measurement frequency of CH4 and CO2 fluxes is presented in Table 1C. Flux measurements were made on the basis of one time a day interval (i.e., 2 PM) since 19 May 2010. However, measurements were extended to cover two other time bands (9 AM and 5 PM) on 20 and 21 May 2010. Emission rates of CH4 and CO2 were calculated by considering the changes in their concentration levels (inside the chamber) through time. Two samples inside the chamber were collected for the quantitation of concentrations (between initial (to) and certain time (t)) for the flux calculation.
329
The sampling interval was adjusted from as little as 15 min in the beginning stage but increased up to 60 min toward the end by considering the reduced emissions through time. Sampling was conducted in the linear range of CH4 and CO2 concentrations vs. time so that the CH4 and CO2 fluxes (f) from the soil could be estimated using the following equation (Hutchinson and Mosier, 1981):
f ¼
VðCt Co Þ At
where f ¼ gas flux (mg m2 h1); V ¼ internal volume of chamber (m3); Co ¼ initial gas concentration inside the chamber at time to (mg m3); Ct ¼ gas concentration inside the chamber at time t (mg m3); A ¼ area covered by chamber (m2); and t ¼ the interval between time to and time t (h). Gas samples were taken from the headspace of closed chambers by 30 mL polypropylene syringes and immediately transferred to pre-evacuated glass vials fit with butyl rubber stoppers. CH4 was analyzed on a gas chromatograph (HewlettePackard 5890, series II) equipped with a flame ionization detector (FID) and a stainless steel column (9 m length and 3 mm outer diameter) packed with Hayesep DB (100/120 mesh) (Alltech Associates, USA). The operation conditions of the gas chromatograph are presented in Table 2. The analysis of CO2 was made by another gas chromatograph (DS-6200, Donam Inc, Korea) equipped with an FID and a 1.8 m length 3.175 mm outer diameter stainless steel Porapak Q 80/100 mesh packed column (Restek, USA). This GC setup was equipped with the methanizer to allow conversion of CO2 to CH4 for the detection by FID (Table 2). Ultra pure nitrogen (99.999%) was used as carrier gas at 30 mL min1 (Table 2). The standard gases for the calibration of CH4 and CO2 were purchased from Rigas (Korea) with the concentrations of 101 ppm and 90%, respectively. Detailed information of CH4 and CO2 calibration is presented in Appendix A1. The basic information concerning the quality assurance (QA) of the experimental procedure (detection limit (DL) and precision) is also provided in Table 1S. The concentrations of CH4 and CO2 were not limited by the detectability, as their concentrations were always above the detection limit. The reproducibility of CH4 and CO2 analysis was assessed by the analyses of five replicate standard samples.
2.4. Statistical analysis The effects of the selected criteria for manure application on CH4 and CO2 emissions were examined by a t-test to judge the statistical significance of the observed differences (at the 0.05 significance level, 2-tailed) (George and Mallery, 2008). In addition, the possible relationship between the environmental parameters (air and soil temperature, soil moisture, and soil pH) and CH4 and CO2 emissions was also evaluated by Pearson’s correlation analyses with respect to each of the four different approaches selected for beef cattle manure application in this study.
3. Results and discussion 3.1. General trend of CH4 and CO2 emissions The emission of CH4 and CO2 can be explained in relation to a number of variables that include the manure dose, application techniques, and environmental conditions (air and soil temperature, soil moisture, and soil pH), and their ambient concentration levels. The raw data sets of CH4 and CO2 measured during this study are provided in Tables 2S and 3S, respectively. As a basic means to
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Table 2 Operational conditions of GC set for the analysis of CH4 and CO2. Compound
CH4
CO2
GC
GC/FID (HewlettePackard 5890, series II, USA) Hayesep DB 100/120 28 mL min1 (He) 30 mL min1 300 mL min1 100 C 80 C
GC/FID (DS-6200, Donam Inc., Korea)
Column Flow rate
Temperature
Carrier gas H2 Air Oven Injector Methanizer Detector
250 C
Porapack Q 80/100 30 mL min1 (N2) 30 mL min1 300 mL min1 80 C 100 C 350 C 250 C
assess the CH4 and CO2 emissions, their concentration data were evaluated by their magnitude and temporal trends. Fig. 2a shows their temporal patterns using the concentrations measured initially inside the chamber. As can be seen, the distribution of CH4 and CO2 generally exhibited similar trends. However, there were slight differences in their peak occurrences. Although the maximum CH4 concentrations of mid 2 ppm range were seen in late May, there was a slight time lag for CO2 (>600 ppm) which was seen most frequently between late May and early June (Julian days of 149e161). Fig. 3 also depicts the temporal trends of environmental parameters such as air and soil temperature, soil moisture, and soil pH. From the 7th day of experiment (Julian day ¼ 145) to the end, both temperature and moisture level exhibited a gradual increase through time. The average concentrations of CO2 from the
a
five sample types were in a fairly constant range of 544e552 ppm. Likewise, the concentrations of CH4 were also measured in the range of 1.64e1.73 ppm, although its values exhibited a slight enhancement in surface (S40 and S80) relative to subsurface samples (D40 and D80). In general, the mean initial CH4 concentrations seen in this study were similar to its global mean atmosphere concentration (1774 1.8 ppb) (IPCC, 2007c). However, initial CO2 concentrations were considerably higher than that of the global atmosphere (379 0.65 ppm) (IPCC, 2007c). The effect of amount and injection depth (surface vs. subsurface) of manure application on CH4 and CO2 emissions becomes evident through comparison of their emission patterns on a cumulative basis over the experimental period. Total emission of CH4 (mg m2) was seen fairly consistently in the ascending order of S40 (25,265), D40 (32,810), S80 (52,355), and D80 (76,160). Similar patterns were also found for its CO2 counterparts (Fig. 4a). As a simple means to assess the temporal variability of CH4 and CO2 emissions, their flux data obtained from different manure application types were plotted as a function of time (Fig. 2b). The temporal patterns of their flux data are greatly different from their concentration counterparts. In case of control unit, bidirectional exchange of CH4 was apparent throughout the study period. The results showed that the peak emissions of both compounds occurred consistently 5 days after manure application. The relative ordering of CH4 emissions after manure application was seen fairly consistently in the ascending order of S40, D40, S80, and D80, as shown in Fig. 4b. Although its emissions were seen almost
3.0
630 610 C
2.5
590
D40 D80
CH (ppm)
2.0
570
S40
550
S80
1.5 530 C
1.0
510
D40 D80
490
S40
0.5
S80
470 0.0 135
145
155
165
175
185
195
205
450 135
215
145
155
165
Julian day
175
185
195
205
215
Julian day
b 2470
600 C C
1970
D40
D80
CO flux (mg m h )
D80 S40
1470
S80
970
470
-30 135
D40
500
S40
400
S80
300
200
100
145
155
165
175 Julian day
185
195
205
215
0 135
145
155
165
175
185
195
205
215
Julian day
Fig. 2. Temporal pattern of CH4 and CO2 using (a) their initial concentrations (Co) measured in the chamber and (b) their fluxes in relation to manure application types. To simplify the temporal scale, both concentration and flux data are plotted against Julian Day.
N.-T. Phan et al. / Atmospheric Environment 63 (2012) 327e336
a
35
Temperature ( C)
30
25 Air C D40
20
D80 S40 S80
15 135
145
155
165
175
185
195
205
215
Julian day
b
25
Volumetric soil moisture (%)
20
15
10
C D40 D80
5
S40 S80
0 135
145
155
165
175
185
195
205
215
Julian day
c
9
Soil pH
8
7
331
Similar to CH4 flux pattern, notably strong emissions of CO2 were seen up to 30 days after fertilization; from the day 30 and afterward, all CO2 fluxes from four manure treatments were reduced greatly so that no more distinctions are apparent with that of control unit (Fig. 2b). Throughout the study period, the CO2 fluxes showed fairly large variations from each sample type: D80 (95.4 89.5 mg m2 h1), S80 (82.4 115 mg m2 h1), D40 (55.8 49.9 mg m2 h1), S40 (37.6 33.4 mg m2 h1), and C (12.9 11.4 mg m2 h1). The maximum fluxes of CO2 from each unit were measured as 449, 503, 232, and 168 mg m2 h1, respectively, all of which were seen within the first few hours after manure treatments (Table 3). This fast occurrence of the peak emissions may be ascribable to the release of CO2 contained in manure and those converted from HCO3 and CO3 2 during manure storage (Flessa and Beese, 2000). These authors also observed their maximum emission rates of CO2 (110e130 mg m2 h1) after applying cattle slurry with the total organic carbon (TOC) of 582 kg ha1. The maximum CO2 fluxes in our study were approximately four times higher than those of Flessa and Beese (2000), while the TOC rates of our beef cattle manure (9224 and 18,448 kg ha1) were around 16 and 32 times higher than those of Flessa and Beese (2000). Fangueiro et al. (2008) reported that CO2 emissions were significantly higher from the untreated slurry and the liquid fractions than those from the solid fractions (p < 0.05). Such distinction was apparent, although the TOC of solid fraction was considerably higher than those of untreated slurry and liquid fractions. This may be ascribable to the fact that the solid fractions contained virtually no dissolved CO2 with very low amounts of water soluble carbon. In contrast, the high emissions rates observed in the untreated slurry or the liquid slurry fractions may reflect the favorable conditions under which the CO2 dissolved in the slurry or converted from HCO3 and CO3 2 in the slurry can be released efficiently (Fangueiro et al., 2008). The high emissions of CO2 observed from the liquid fractions and untreated slurry should also be due to the fact that they can penetrate efficiently into the soil, resulting in more interactions with soil microorganisms than the solid fractions. The magnitude of CO2 emissions was also affected by the particle size of slurry fractions with the enhanced emissions from smaller fractions after soil incorporation (Fangueiro et al., 2007). 3.2. Effect of manure amount on CH4 and CO2 emissions
6
C D40 D80
5
S40 S80
4 135
145
155
165
175
185
195
205
215
Julian day Fig. 3. Temporal trend of the major environmental parameters: (a) air (and soil) temperature, (b) soil moisture, and (c) soil pH during the experiment.
consistently up to 14 days after manure application, its fluxes then approached near-zero in all treatments (Fig. 2b). This finding is in agreement with some previous studies. CH4 emissions were evident immediately after manure application to land (Chadwick et al., 2011; Chadwick and Pain, 1997). Effluent treatment resulted in elevated CH4 flux rates compared to the control unit for 3e5 days after application (Sistani et al., 2010). These emissions are commonly short lived, as methanogenesis is sensitive to O2. If O2 is penetrated into the manure on the soil, it inhibits CH4 production (Chadwick et al., 2011).
CH4 and CO2 emissions were monitored from a control unit and four plots with different manure application types. Their flux measurements from five different settings (Table 1) can be examined from a number of respects. Their basic emission characteristics can be assessed in Table 3. The mean fluxes of CH4 and CO2 from each manure treatment are also compared with those of previous studies (Table 4). The CH4 flux values of our control unit were bidirectional to show both deposition (8.59 6.01 mg m2 h1, n ¼ 15) and emission (5.35 4.55 mg m2 h1, n ¼ 7). Likewise, the CO2 results from control unit also showed deposition, although it took place only once out of 28 measurements. Hence, for the sake of simplicity, the deposition of CO2 was not considered for further evaluation of the CO2 data. For both compounds, the results derived after manure application showed the signal of emission without a single exception. In our study, soil in the control plot was also tilled before starting the experiment which might result in aerobic soil. Goulding et al. (1995) showed that CH4 was normally oxidized by aerobic soils (as sink) to make the negative flux in the control plot. The results of CH4 flux (mg m2 h1) measurement confirm the existence of a highly systematic trend across different treatment types with the systematic distinction across [1] D80 (208 515), [2]
332
N.-T. Phan et al. / Atmospheric Environment 63 (2012) 327e336
a 77000 C
C
100000
D40
D40
D80
D80
57000
80000
S40
S40 S80
S80
60000 37000 40000 17000
-3000
20000
0 135
145
155
165
175
185
195
205
135
215
145
155
165
Julian day
b
175
185
195
205
215
Julian day
350
120
320 290
100
260 230
80
200 170
60
140 110
40
80 50
20
20 -10
C
S40
D40
S80
0
D80
C
S40
Treatment
D40
S80
D80
Treatment
Fig. 4. Comparison of measurement data: (a) cumulative emissions and (b) average fluxes of five manure treatments (Error bars represent the standard error).
Table 3 Statistical summary of CH4 and CO2 concentrations and fluxes and relevant environmental parameters in this study. Parameter (unit)
Sample type C
A. Initial concentrations of CH4 and CO2 inside chamber 1.72 0.50 (1.78)a CH4 (ppm) 1.02e2.63 (22)b CO2 (ppm) 552 35.0 (548) 495e621 (28) B. CH4 and CO2 fluxes Emission 5.35 4.55 (5.49) CH4 (mg m2 h1) 0e13.3 (7) Deposition 8.59c 6.01 (8.34) (21.1) e (0.98) (15) CO2 (mg m2 h1)d Emission 12.9 11.4 (10.1) 0.77 to 59.6 (28) C. Environmental conditions 25.0 4.6 (25.8) Air temp. ( C) 16.0e32.2 (28) 23.1 3.5 (23.5) Soil temp. ( C) 16.7e29.5 (28) Soil moisture (%) 8.4 4.2 (7.8) 3.8e20.3 (28) Soil pH 6.9 0.6 (7.0) 5.8e7.8 (28) a b c d
S40 1.73 0.54 0.79e2.49 547 34.0 480e620
S80 (1.81) (22) (553) (28)
1.72 0.56 0.70e2.48 544 36.0 471e616
D40 (1.87) (22) (552) (28)
1.64 0.56 0.77e2.69 549 34.0 497e614
D80 (1.76) (22) (552) (28)
1.66 0.51 0.89e2.45 546 33.2 497e616
(1.80) (22) (548) (28)
59.3 99.2 (25.3) 7.10e461 (22)
188 425 (42.3) 12.0e1810 (22)
68.7 146 (32.8) 14.0e713 (22)
208 515 (61.0) 27.8e2323 (22)
37.6 33.4 (31.3) 6.02e168 (28)
82.4 115 (47.6) 7.72e503 (28)
55.8 49.9 (44.0) 7.72e232 (28)
95.4 89.5 (70.3) 12.6e449 (28)
25.0 4.6 16.0e32.2 21.0 2.9 16.4e27.4 10.3 5.2 2.6e21.2 7.0 0.6 5.7e8.1
(25.8) (28) (20.8) (28) (12.1) (28) (7.0) (28)
25.0 4.6 16.0e32.2 21.5 3.0 16.5e27.7 10.5 4.9 3.2e20.4 7.0 0.6 6.0e8.1
(25.8) (28) (21.3) (28) (10.1) (28) (7.0) (28)
25.0 4.6 16.0e32.2 21.4 2.9 16.4e27.5 8.8 5.4 2.7e21.0 6.7 0.5 5.6e7.8
Mean SD (median). Minemax (number of data). Positive values indicate emission, while negative ones are used for deposition. In case of CO2, differences in flux values between all matching pairs are statistically significant (p < 0.05) except S80 vs. D80 pair.
(25.8) (28) (21.4) (28) (7.7) (28) (6.7) (28)
25.0 4.6 16.0e32.2 22.0 2.9 16.7e28.0 8.7 5.6 2.5e21.4 6.6 0.6 5.2e7.9
(25.8) (28) (22.3) (28) (7.0) (28) (6.7) (28)
Table 4 Comparison of CH4 and CO2 flux data from fertilizer and manure application between the different studies. No
a b c d e
Study period
Pig slurry
Headspace measurement
Laboratory study
Swine effluent
Closed chamber
Spring 2007
CH4 flux (mg m2 h1) Em.a
Dp.b
0 2860 8750 220 2270 1510 140 970
Swine effluent
Closed chamber
27 Apr.e 20 Sept. 2007
19 Apr.e 11 Sept. 2008
Beef cattle manure
Cattle slurry
Closed chamber
Calculated from the different concentrationse
19 Maye 29 July 2010
88.4 17.7 139 35.5 240 62.1 278 76.8 13.4 2.64 40.3 5.27 121 23.7 1075 211 4.16 59.3 68.7 188 208 3571 3307
Laboratory study 595
2249 11,607 66.1
CO2 flux mg m2 h1
Application rate kg C ha1
Measuring duration
Slurry application method
Reference
17.7 86.3 86.5 212 328 1231 421 399 497 151 345 120 230 134 204 135 218 149 250 160 191 249 208 211 204 226 213 12.9 37.6 55.8 82.4 95.4 20.8 19.2 50.9 33.6 57.4 33.9
Cc 7890 7890 C C 636 636 636 636 636 636 C 636 636 636 636 636 636 636 C 798 798 798 798 798 798 798 C 9224 9224 18,448 18,448 C C 582 582 582 582
15 d 15 d 15 d 4h 72 h 4h 72 h 4h 72 h 4h 72 h 33 d 141 d 33 d 141 d 33 d 141 d 33 d 141 d 31 d 158 d 31 d 158 d 31 d 158 d 31 d 158 d CH4 (29 d) CO2 (71 d)
Control (without slurry) Surface spread Injection (5 cm depth) Control (without slurry) Control (without slurry) Surface spread Surface spread Aerway injection to holesd Aerway injection to holesd Row injection at 15 cm depth Row injection at 15 cm depth Control (without slurry) Control (without slurry) Surface application Surface application Aerway injection to holesd Aerway injection to holesd Row injection at 15 cm depth Row injection at 15 cm depth Without slurry (control) Without slurry (control) Surface application Surface application Aerway injection to holesd Aerway injection to holesd Row injection at 15 cm depth Row injection at 15 cm depth Control (without manure) Surface spread Inject at 5 cm depth Surface spread Inject at 5 cm depth Control (without slurry) Control (without slurry) Surface spread Surface spread Injection (2e10 cm) Injection (2e10 cm)
Dendooven et al. (1998)
2 9 2 9 2 9
w w w w w w
Lovanh et al. (2010)
Sistani et al. (2010)
Present study
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
Method of flux measurement
Form of fertilization
Flessa and Beese (2000)
Emission. Deposition. Control e without manure. Aerway injection to holes (7.5 cm L 1.5 cm W 20 cm D). Calculated from the air flow rate through the microcosm headspace and the difference in the CH4 and CO2 concentration between the input air and the exhaust air.
333
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S80 (188 425), [3] D40 (68.7 146), and [4] S40 (59.3 99.2). Moreover, for the same injection depth, the larger amount of manure promoted enhancement in CH4 emissions such that the flux of D80 approximately tripled that of D40. Such distinction was also observed from in the data between the different injection depths (0 vs. 5 cm), although it was not so pronounced in most cases (Table 3). Like the case of CH4, the emission fluxes of CO2 were also examined using the data collected from five different sample types measured over a little extended period of 70 days (19 Maye29 July 2010). The results of CO2 flux were also maintained in the same fashion to record the same relative ordering: D80 (95.4 89.5 mg m2 h1) > S80 (82.4 115 mg m2 h1) > D40 (55.8 49.9 mg m2 h1) > S40 (37.6 33.4 mg m2 h1). The control unit on the other hand recorded the lowest mean emission rate of 12.9 11.4 mg m2 h1 (Fig. 4b). If the flux values of CO2 are examined by the amount of manure applied, a large distinction can be found consistently from the data sets obtained between the two manure doses at 5 cm depth to show about 2 fold enhancement from D40 to D80. Similar distinctions were also found in CO2 emissions at surface application between S80 and S40. If the flux values measured at each depth (either surface or 5 cm depth) are compared by the student’s t-test in terms of manure dose difference between 40 and 80 T ha1, the patterns of dose effect contrast between CH4 and CO2. Although the differences in CO2 values are statistically significant (p < 0.05) from the data collected at each depth, it is not the case for CH4. The results of this study demonstrated that all CH4 and CO2 fluxes showed large changes with the amount of manure applied, suggesting that the manure treatment can raise CH4 and CO2 emissions in a somewhat predictable manner. It is interesting to see that cumulative emissions of CH4 and CO2 from high manure dose (S80 and D80) were significantly higher than those from their low counterparts (S40 and D40) (p < 0.05) (Table 5). 3.3. Comparison of CH4 and CO2 emissions between surface and subsurface layers Injection of slurry can minimize the running-off transport of nutrients, while facilitating the greater slurry contact with soil. As such, the slurry injection can induce favorable conditions for GHG emissions. To evaluate such effect on CH4 and CO2 emissions, their flux data were examined between surface and subsurface (at 5 cm depth) for each of the two manure doses (40 and 80 T ha1). The results of CH4 data indicate that more emissions were seen at subsurface layer, for each of the two manure amounts. In case of 40 T ha1, CH4 flux measured at subsurface (F(D40) ¼ 68.7 mg m2 h1) were 15.8% larger than that made at surface (F(S40) ¼ 59.3 mg m2 h1). These patterns were seen consistently in 80 T ha1 to show F(D80 ¼ 208 mg m2 h1) vs. F(S80 ¼ 188 mg m2 h1).
Table 5 Result of statistical comparisons of CH4 and CO2 cumulative emissions between manure treatments (t-test). A. Statistical comparisons between injection depths (surface vs. 5 cm depth)
t p
CH4 (40 T ha1)
CH4 (80 T ha1)
CO2 (40 T ha1)
CO2 (80 T ha1)
13.3 1.14E-11a
18.3 2.21E-14a
8.51 3.98E-9a
4.22 2.48E-4a
B. Statistical comparisons between manure doses (40 vs. 80 T ha1)
t p a
CH4 (surface)
CH4 (5 cm depth)
CO2 (surface)
CO2 (5 cm depth)
16.5 1.74E-13a
18.3 2.16E-14a
13.4 1.90E-13a
6.11 1.58E-6a
Indicates that the means are statistically different (p < 0.05).
Like our study, Sistani et al. (2010) reported that injection facilitated emissions of CH4 relative to surface application. Flessa and Beese (2000) also found that injection of slurry into the soil resulted in significant increase of CH4 emissions in comparison with surface application (Table 4). However, differences due to such effect are not so significant as that seen by those of the manure amount discussed above. If the flux values measured at each dose (either 40 or 80 T ha1) are compared by the student’s t-test in terms of difference between surface and subsurface, the patterns of the latter are seen to be significant (p < 0.05) only in the case of CO2 fluxes measured at 40 T ha1. In addition, according to statistical comparison (t-test), cumulative emissions of CH4 and CO2 from subsurface were significantly higher at each manure dose (either 40 or 80 T ha1) than those from surface (p < 0.05) (Table 5). The results of our analysis indicate that differences in CH4 fluxes were not statistically significant between the two soil layers which were also seen frequently in some previous studies (Perälä et al., 2006; Sommer et al., 1996). CH4 emissions can be generated from two possible sources such as one dissolved in manure prior to application or methanogenesis in the soil (Chadwick and Pain, 1997; Clemens et al., 2006; Sherlock et al., 2002; Sommer et al., 1996; Wulf et al., 2002). Injection of manure into the soil can lead to the restricted aeration with the formation of anoxic zones. Under such conditions, decomposition of injected manure has the potential to enhance the emissions of CH4 (Flessa and Beese, 2000; Sistani et al., 2010; Wulf et al., 2002). Like the case of methane, the CO2 flux data obtained during the field study were evaluated in a number of respects. The mean CO2 flux from the subsurface method (D80: 95.4 mg m2 h1) was higher than that from surface method (S80: 82.4 mg m2 h1). Similarly, in lower manure dose (40 T ha1), the mean CO2 flux was also different between D40 (55.8 mg m2 h1) and S40 (37.6 mg m2 h1). Unlike the case of the other compound (CH4) or other manure dose (relative to 80 T ha1), the CO2 results at 40 T ha1 are statistically different between surface and subsurface (Table 3). Anaerobic conditions due to the restricted air contact should have promoted anaerobic bio-decomposition of organic matters in the manure. It may thus help raise CO2 fluxes relative to the surface application. Similar to our study, Dosch and Gutser (1996) found enhanced emission of CO2 from cattle slurry after injection relative to the surface treatment. However, as was the case of CH4, contrasting exchange patterns can also be found from CO2 data sets. Sistani et al. (2010) and Dendooven et al. (1998) observed that there was no significant difference in CO2 emissions between the injection and surface application of pig slurry (Table 4). Similarly, Flessa and Beese (2000) were not able to find a direct link between the production of CO2 and the way the cattle slurry applied (between surface application and slit injection). It is striking to find the highest CO2 fluxes accompanied by the surface spray method (rather than the aerway injection) (Lovanh et al., 2010) (Table 4). According to our statistical analysis, the injection difference (surface vs. subsurface) has less clear impact on the magnitude of emission than the amount of manure (Table 3). However, as the selection of those criteria (40 vs. 80 T ha1 or 0 vs. 5 cm) was made arbitrarily, the actual effects of those variables need to be assessed more cautiously. 3.4. Factors controlling CH4 and CO2 emissions To assess the effects of the environmental conditions on CH4 and CO2 emissions, the relationship between different environmental parameters was also evaluated in Table 3. The results of correlation analysis in this study showed that strong correlations are found consistently between CO2 and CH4 fluxes (Table 4S). However, such
N.-T. Phan et al. / Atmospheric Environment 63 (2012) 327e336
relationship is found rather scarcely between their fluxes and the environmental parameters (air and soil temperature, soil pH, and soil moisture) (Table 4S). Similarly, CH4 concentrations did not exhibit strong correlations with air (and soil) temperature, while it showed good correlations with soil moisture such as C and D40 (p < 0.05) and S40 samples (p < 0.01). However, such pattern disappeared with increases in manure dose with S80 and D80 (p > 0.05). Unlike the case of CH4 data, the CO2 concentration data showed strong correlations with air temperature, regardless of manure treatment types. Perälä et al. (2006) found that there were no correlations between CH4 flux and the environmental variables (soil moisture, soil mineral N content, and air temperature). Conversely, Wulf et al. (2002) found that the effect of soil moisture on overall CH4 emissions was strong. In general, the mean pH values of the treatments in our experiment were from 6.6 to 7.0 (Table 3). Because this pH range is generally suitable for soil microbial activity, it can exert a marked effect on the growth and proliferation of soil microorganisms. Reth et al. (2005) reported that a soil pH between 3 and 7 (to 8) is good to activate biological soil microorganisms. The CO2 flux measured at soil pH value of 4 was 2e12 times higher than those with soil pH value of 3 (Sitaula et al., 1995). This pattern was attributed to the adverse effect of low pH on soil microbial activity, as the evolution of CO2 is suppressed with low respiration rate (Rastogi et al., 2002). Several other studies also reported an increase in CO2 evolution with pH (Andersson and Nilsson, 2001; Ellis et al., 1998; Hall et al., 1997; Kowalenko et al., 1978; Sitaula et al., 1995). However, soil pH beyond 7.0 is likely to affect CO2 emission more adversely. At pH 8.7, CO2 emission was reduced by 18% compared to that at pH 7.0. Moreover, when the pH was raised to 10.0, the extent of reduction in CO2 emission was 83% (Rao and Pathak, 1996). 4. Conclusions The amount and injection depth of manure application can have an influence on the emissions of the two major GHGs like CH4 and CO2. To learn more about the effect of manure application on their emissions, CH4 and CO2 fluxes were measured by the flux chamber method over about 30 and 70 days of duration, respectively. The results demonstrated that the magnitude of CH4 and CO2 fluxes tend to exhibit a systematic trend with the relative orders of the four combinations between two key variables such as: S40 < D40 < S80 < D80. Although the exchange pattern of CH4 was bidirectional from control (C), such pattern disappeared immediately after manure application. Once manure was applied, four different types of manure samples consistently exhibited CH4 and CO2 emissions with a fairly systematic trend. It was noted that the emissions of CH4 and CO2 generally increased at subsurface relative to surface, when the manure was applied independently at the two layers. The amount of manure however showed a more clear effect on the emission strengths under our experimental setups. The results of correlation analysis in this study demonstrated that the flux data generally exhibited a good correlation between CH4 and CO2 concentrations, while there was a poor correlation with the environmental parameters (air and soil temperature, soil moisture, and soil pH). However, it was recognized that CH4 and CO2 concentrations can maintain strong correlations with soil moisture and air temperature, respectively. The results of this study showed that manure dose should also exert fairly sensitive effects on CH4 and CO2 emissions than the injection depths between surface and subsurface. Although our analysis was made to assess the emissions of CH4 and CO2, manure application can lead to emissions of other GHG like N2O or other types of pollutants. Hence, more efforts are needed to describe
335
the environmental impact of manure application in various respects. Acknowledgments This study was supported by a National Research Foundation of Korea (NRF) grant funded by the Ministry of Education, Science and Technology (MEST) (No. 2010-0007876). The fourth author also acknowledges partial support made by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 20100092). Appendix A. Supplementary data Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.atmosenv.2012.09.028. References Andersson, S., Nilsson, S.I., 2001. Influence of pH and temperature on microbial activity, substrate availability of soil-solution bacteria and leaching of dissolved organic carbon in a mor humus. Soil Biology and Biochemistry 33, 1181e1191. Bertora, C., Alluvione, F., Zavattaro, L., van Groenigen, J.W., Velthof, G., Grignani, C., 2008. Pig slurry treatment modifies slurry composition, N2O, and CO2 emissions after soil incorporation. Soil Biology and Biochemistry 40, 1999e2006. Chadwick, D., Sommer, S., Thorman, R., Fangueiro, D., Cardenas, L., Amonc, B., Misselbrook, T., 2011. Manure management: implications for greenhouse gas emissions. Animal Feed Science and Technology 166e167, 514e531. Chadwick, D.R., Pain, B.F., 1997. Methane fluxes following slurry applications to grassland soils: laboratory experiments. Agriculture, Ecosystems & Environment 63, 51e60. Clemens, J., Trimborn, M., Weiland, P., Amon, B., 2006. Mitigation of greenhouse gas emissions by anaerobic digestion of cattle slurry. Agriculture, Ecosystems & Environment 112, 171e177. Daverede, I.C., Kravchenko, A.N., Hoeft, R.G., Nafziger, E.D., Bullock, D.G., Warren, J.J., Gonzini, L.C., 2004. Phosphorus runoff: effect of tillage and soil phosphorus levels. Journal of Environmental Quality 32, 1436e1444. Dendooven, L., Bonhomme, E., Merckx, R., Vlassak, K., 1998. Injection of pig slurry and its effects on dynamics of nitrogen and carbon in a loamy soil under laboratory conditions. Biology and Fertility of Soils 27, 5e8. Dosch, P., Gutser, R., 1996. Reducing N losses (NH3, N2O, N2) and immobilization from slurry through optimized application techniques. Fertilizer Research 43, 165e171. Duchateau, K., Vidal, C., 2003. Between 1990 and 2000, European Agriculture Has Reduced Its Greenhouse Gas Emissions by 6.4%. Environment and Energy Theme 8-1/2003. Ellis, S., Howe, M.T., Goulding, K.W.T., Mugglestone, M.A., Dendooven, L., 1998. Carbon and nitrogen dynamics in a grassland soil with varying pH: effect of pH on the denitrification potential and dynamics of the reduction enzymes. Soil Biology and Biochemistry 30, 359e367. Fangueiro, D., Chadwick, D., Dixon, L., Bol, R., 2007. Quantification of priming and CO2 respiration sources following the application of different slurry particle size fractions to a grassland soil. Soil Biology and Biochemistry 39, 2608e2620. Fangueiro, D., Senbayran, M., Trindade, H., Chadwick, D., 2008. Cattle slurry treatment by screw press separation and chemically enhanced settling: effect on greenhouse gas emissions after land spreading and grass yield. Bioresource Technology 99, 7132e7142. Flessa, H., Beese, F., 2000. Laboratory estimates of trace gas emissions following surface application and injection of cattle slurry. Journal of Environmental Quality 29, 262e268. George, D., Mallery, P., 2008. SPSS for Window-step by Step, eighth ed. Pearson Education Inc., The United States of America, pp. 131e141. Goulding, K.W.T., Hutsch, B.W., Webster, C.P., Willison, T.W., Powlson, D.S., 1995. The effect of agriculture on methane oxidation in soil. Philosophical Transactions: Physical Sciences and Engineering 351, 313e325. Hall, J.M., Paterson, E., Killham, K., 1997. The effect of elevated CO2 concentration and soil pH on the relationship between plant growth and rhizosphere denitrification potential. Global Change Biology 4, 209e216. Hutchinson, G.L., Mosier, A.R., 1981. Improved soil cover method for field measurement of nitrous oxide fluxes. Soil Science Society of America Journal 45, 311e316. Hyde, B.P., Hawkins, M.J., Fanning, A.F., Noonan, D., Ryan, M., Toole, P.O., Carton, O.T., 2006. Nitrous oxide emissions from a fertilized and grazed grassland in the South East of Ireland. Nutrient Cycling in Agroecosystems 75, 187e200. IPCC, 2007a. Climate change 2007: synthesis report. In: Pachauri, R.K., Reisinger, A. (Eds.), Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Geneva, Switzerland, pp. 35e41.
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IPCC, 2007b. Climate change 2007: mitigation. In: Metz, B., Davidson, O.R., Bosch, P.R., Dave, R., Meyer, L.A. (Eds.), Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 497e540. IPCC, 2007c. Climate change 2007: the physical science basis. In: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K.B., Tignor, M., Miller, H.L. (Eds.), Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 137e145. Jarecki, M.K., Parkin, T.B., Chan, A.S.K., Hatfield, J.L., Jones, R., 2008. Greenhouse gas emissions from two soils receiving nitrogen fertilizer and swine manure slurry. Journal of Environmental Quality 37, 1432e1438. Kowalenko, C.G., Ivarson, K.C., Cameron, D.R., 1978. Effect of moisture content, temperature and nitrogen fertilization on carbon dioxide evolution from field soils. Soil Biology and Biochemistry 10, 417e423. Lovanh, N., Warren, J., Sistani, K., 2010. Determination of ammonia and greenhouse gas emissions from land application of swine slurry: a comparison of three application methods. Bioresource Technology 101, 1662e1667. Misselbrook, T.H., Smith, K.A., Johnson, R.A., Pain, B.F., 2002. Slurry application techniques to reduce ammonia emissions: results of some UK field-scale experiments. Biosystems Engineering 81, 313e321. Parker, D.B., Gilley, J., Woodbury, B., Kim, K.H., Galvin, G., Bartelt-Hunt, S.L., Li, X., Snow, D.D., Odorous VOC emission following land application of swine manure slurry. Atmospheric Environment, in press. Perälä, P., Kapuinen, P., Esala, M., Tyynelä, S., Regina, K., 2006. Influence of slurry and mineral fertiliser application techniques on N2O and CH4 fluxes from
a barley field in southern Finland. Agriculture, Ecosystems & Environment 117, 71e78. Rao, D.L.N., Pathak, H., 1996. Ameliorative influence of organic matter on biological activity of salt-affected soils. Arid Soil Research and Rehabilitation 10, 311e319. Rastogi, M., Singh, S., Pathak, H., 2002. Emission of carbon dioxide from soil. Current Science 82, 510e517. Reth, S., Reichstein, M., Falge, E., 2005. The effect of soil water content, soil temperature, soil pH-value and the root mass on soil CO2 efflux e a modified model. Plant and Soil 268, 21e33. Roelle, P.A., Aneja, V.P., Gay, B., Geron, C., Pierce, T., 2001. Biogenic nitric oxide emissions from cropland soils. Atmospheric Environment 35, 115e124. Sherlock, R.R., Sommer, S.G., Khan, R.Z., Wood, C.W., Guertal, E.A., Freney, J.R., Dawson, C.O., Cameron, K.C., 2002. Ammonia, methane, and nitrous oxide emission from pig slurry applied to a pasture in New Zealand. Journal of Environmental Quality 31, 1491e1501. Sistani, K.R., Warren, J.G., Lovanh, N., Higgins, S., Shearer, S., 2010. Greenhouse gas emissions from swine effluent applied to soil by different methods. Soil Science Society of America Journal 74, 429e435. Sitaula, B.K., Bakken, L.R., Abrahamsen, G., 1995. N-fertilization and soil acidification effects on N2O and CO2 emission from temperate pine forest soil. Soil Biology and Biochemistry 27, 1401e1408. Sommer, S.G., Sherlock, R.R., Khan, R.Z., 1996. Nitrous oxide and methane emissions from pig slurry amended soils. Soil Biology and Biochemistry 28, 1541e1544. Wulf, S., Maeting, M., Clemens, J., 2002. Application technique and slurry cofermentation effects on ammonia, nitrous oxide, and methane emissions after spreading: II. Greenhouse gas emissions. Journal of Environmental Quality 31, 1795e1801.
Contents lists available at SciVerse ScienceDirect
Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv
Effect of beef cattle manure application rate on CH4 and CO2 emissions Nhu-Thuc Phan a, Ki-Hyun Kim a, *, David Parker b, Eui-Chan Jeon a, Jae-Hwan Sa a, Chang-Sang Cho a a b
Department of Environment and Energy, Sejong University, Seoul 143-747, Republic of Korea Palo Duro Research Center, West Texas A&M University, Canyon, TX 79016, USA
h i g h l i g h t s < The application of solid manure can release large quantities of greenhouse gases (GHG). < Its implication has scarcely been evaluated with respect to solid beef cattle manure. < The behavior of CH4 and CO2 was examined in relation to manure treatment conditions. < This study will help establish a management scheme for the GHGs from manure treatment.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 26 May 2012 Received in revised form 2 September 2012 Accepted 10 September 2012
In a series of field experiments, emissions of two major greenhouse gases (GHGs), methane (CH4) and carbon dioxide (CO2) were measured using a closed chamber technique in summer 2010 to evaluate the effects of solid beef cattle manure land application techniques. The treatments included a control (C: no manure), two manure application rates (40 and 80 T ha1), and two injection layers (surface vs. subsurface (5 cm)): (1) 40 T ha1 on surface (S40), (2) 80 T ha1 on surface (S80), (3) 40 T ha1 at subsurface (D40), and (4) 80 T ha1 at subsurface (D80)). The exchange patterns of CH4 and CO2 in the control were variable and showed both emission and deposition. However, only emissions were seen in the manure treatments. Emissions of CH4 were seen systematically on the ascending order of 5.35 (C), 59.3 (S40), 68.7 (D40), 188 (S80), and 208 mg m2 h1 (D80), while those of CO2 also showed a similar trend: 12.9 (C), 37.6 (S40), 55.8 (D40), 82.4 (S80), and 95.4 mg m2 h1 (D80). The overall results of our study suggest that the emissions of CH4 and CO2 are affected most noticeably by the differences in the amount of manure application. Ó 2012 Elsevier Ltd. All rights reserved.
Keywords: Beef cattle manure Greenhouse gas (GHG) Emission Flux CH4 CO2
1. Introduction Agricultural activities are estimated to account for about 13.5% of the total greenhouse gas (GHG) emissions (Intergovernmental Panel on Climate Change (IPCC), 2007a). It is estimated that total anthropogenic emissions from agricultural sources can represent 50%, 60%, and 20% of methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2), respectively (IPCC, 2007b). Application of animal manure or slurries may lead to gaseous emissions of CH4, N2O, and CO2 and ground water contamination by nitrate ðNO3 Þ via nitrification of ammonium nitrogen ðNH4 þ eNÞ (Bertora et al., 2008; Fangueiro et al., 2008; Jarecki et al., 2008; Sherlock et al., 2002). As one of the reasonable choices to sequester carbon and nutrient and to promote GHG mitigation, one can consider the use * Corresponding author. Tel.: þ82 2 499 9151; fax: þ82 2 499 2354. E-mail addresses: [email protected], [email protected] (K.-H. Kim). 1352-2310/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.atmosenv.2012.09.028
of appropriate manure management techniques (Duchateau and Vidal, 2003). In fact, runoff transport of nutrients can be reduced efficiently by injection of liquid manure; for example, runoff losses of phosphorous were reduced by more than 94e99% through direct injection of liquid swine effluent as compared to surface application (Daverede et al., 2004). Misselbrook et al. (2002) found that cattle slurry applied by shallow injection on arable land and grass land led to reductions in NH3 emission by 23 and 73%, respectively, as compared with surface broadcast. Parker et al. (in press) reported an 80e95 percent reduction in VOC emissions for injected as opposed to surface applied swine slurry. Likewise, numerous efforts have been made to assess the relationship between slurry/manure application and GHG emissions and to identify the key control factors of such exchange processes. In order to reduce GHG emissions arising from agricultural activities, it is desirable to gain a better understanding of the production, emission, and consumption of these gases in relation to such sources as manure application. The effect of liquid manure
71 7/29 210 64 7/22 203 57 7/15 196
Fig. 1. Location of the study site: Naju, Jeonnam province, South Korea.
CO2 flux measurement
c
6 5/25 145 5 5/24 144 4 5/23 143 3 5/22 142 2 5/21 141 1 5/20 140 0 5/19 139 Elapsed time (days)c Actual date (month/day) Julian day CH4 flux measurement
C. Time and frequency of flux measurements
B. Grouping of treatment and related acronyms
b
20 6/8 159 10 5/29 149 8 5/27 147
Surface Surface Subsurface Subsurface C S40 S80 D40 D80
7 5/26 146
Soil layerb Samplea
12 5/31 151
14 6/2 153
16 6/4 155
18 6/6 157
0.63 72.8
Moisture % pH
6.9 Fermented beef cattle manure
A. Chemical properties of fermented beef cattle manure used in this experiment
Table 1 Basic information of fermented beef cattle manure and experimental scheme for the field analysis of CH4 and CO2 fluxes.
The experiments were conducted on a small farm near the campus of Dongshin University, Naju city (35 020 N 126 430 E), Jeonnam province, South Korea (Fig. 1). Naju is located 350 km south of Seoul, South Korea. The measurements of CH4 and CO2 fluxes at the field started simultaneously on 19 May 2010 but lasted up to 30 days (17 June 2010) and 70 days (29 July, 2010), respectively (Table 1). Although we intended to measure N2O at the same time, we were unable to do so due to the failure of the GC-ECD setup built for that purpose. The measurements of CH4 and CO2 fluxes were not made beyond those durations, as the fluxes from all
Total N %
2.1. Site characteristics and environmental parameters
a
29 6/17 168 26 6/14 165 22 6/10 161
2. Materials and methods
C sample denotes control unit. Surface (0) vs. subsurface (5 cm). Flux measurements were made one time a day basis at 2 PM since 19 May 2010. However, 2 more measurements (9 AM and 5 PM) were made additionally on 20 and 21 May 2010.
50 7/8 189 33 6/21 172
36 6/24 175
0 40 80 40 80
TOC % Total P %
23.1
application has been studied frequently with respect to GHG emissions (Flessa and Beese, 2000; Lovanh et al., 2010; Perälä et al., 2006; Sistani et al., 2010; Wulf et al., 2002). The implication of solid manure application has however scarcely been evaluated in that respect. It is reasonable to infer that there are some chemical, physical, and biological differences in GHG emission potential between liquid and solid manure. Hence, in this study, we aimed to investigate the effect of different land application techniques for solid manure (fermented solid beef cattle manure) on CH4 and CO2 emissions. To this end, a series of field studies were conducted to measure their fluxes after the solid manure application by combining the two different criteria: (1) the rate of application between 40 and 80 T ha1 and (2) the depth of manure injection between surface and 5 cm. By conducting experiments based on these criteria, we attempted to assess the effects of such treatment conditions with solid beef cattle manure on the emission properties of the two major GHGs, CH4 and CO2.
Manure application rate (T ha1)
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0.57
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manure treatments were low and were not different from those of the control unit. During the study period, ambient (and soil) temperature and volumetric soil moisture were measured by a WatchDog Weather Station (model 2800, Spectrum Technologies, USA) equipped with an external temperature sensor (Catalog # 3667) and a WaterScout SM100 Sensor (Catalog # 6460), respectively. The soil pH was monitored by a pH probing system (model IQ 170, IQ Scientific Instruments, USA), after being calibrated in the laboratory prior to utilization in the field. 2.2. Fermented beef cattle manure and manure application Fermented solid beef cattle manure used in this study was obtained from a commercial beef cattle farm in Naju, South Korea. The cattle were fed with a diet of maize silage and concentrated feed. The beef cattle manure was stored for digestion about 3 months before it was applied as fertilizer to small plots (1 m by 1 m). The fermented beef cattle manure used in this experiment had a mean pH value of 6.9, with moisture, total N, total P, and total organic carbon (TOC) contents of 72.8, 0.63, 0.57, and 23.1%, respectively (Table 1A). The beef cattle manure was applied manually on soils mainly consisting of loams and loess during 19 May 2010 by the combinations of the two different criteria: (1) 40 T ha1 on surface (S40), (2) 80 T ha1 on surface (S80), (3) 40 T ha1 at subsurface (5 cm: D40), and (4) 80 T ha1 at subsurface (5 cm: D80) (Table 1B). The measurements were then made initially from a control (C) unit (without manure application) as a reference to all four treatment types. For surface application of S40 and S80, 4 and 8 kg of fermented beef cattle manure were spread uniformly by hand within the area of 1 m2 area. For the applications at subsurface, a 5 cm thick soil layer was removed, and then the manure was uniformly applied. At last, the manure layer was covered by the 5 cm thick soil layer. In all plots, the plants were removed to avoid plant respiration which may otherwise affect CO2 emissions. The plots in our experiment were located adjacently, and soils in all plots were tilled before starting the experiment (Fig. 1S). 2.3. Flux measurement The fluxes of CH4 and CO2 were measured using a closed static chamber technique. The chamber method used in this study is comparable to those investigated actively by other researchers (Fangueiro et al., 2008; Hutchinson and Mosier, 1981; Hyde et al., 2006). The cylindrical shaped chamber with 20 L volume (0.29 m internal diameter 0.3 m internal height) was constructed of fluorinated ethylene propylene (FEP) with a Teflon lining to minimize the sorptive loss of gases onto its inner walls (Roelle et al., 2001). An impeller stirrer powered by a 12-V battery was installed on the platform inside the chamber to homogeneously mix the air. The bottom of the chamber was carefully inserted into the soil at a depth of 10 cm to form a gas tight seal and to minimize any soil disturbance. The chamber was placed at a fixed position of each slot for every sampling time from the start to the end of the experiment. The measurement frequency of CH4 and CO2 fluxes is presented in Table 1C. Flux measurements were made on the basis of one time a day interval (i.e., 2 PM) since 19 May 2010. However, measurements were extended to cover two other time bands (9 AM and 5 PM) on 20 and 21 May 2010. Emission rates of CH4 and CO2 were calculated by considering the changes in their concentration levels (inside the chamber) through time. Two samples inside the chamber were collected for the quantitation of concentrations (between initial (to) and certain time (t)) for the flux calculation.
329
The sampling interval was adjusted from as little as 15 min in the beginning stage but increased up to 60 min toward the end by considering the reduced emissions through time. Sampling was conducted in the linear range of CH4 and CO2 concentrations vs. time so that the CH4 and CO2 fluxes (f) from the soil could be estimated using the following equation (Hutchinson and Mosier, 1981):
f ¼
VðCt Co Þ At
where f ¼ gas flux (mg m2 h1); V ¼ internal volume of chamber (m3); Co ¼ initial gas concentration inside the chamber at time to (mg m3); Ct ¼ gas concentration inside the chamber at time t (mg m3); A ¼ area covered by chamber (m2); and t ¼ the interval between time to and time t (h). Gas samples were taken from the headspace of closed chambers by 30 mL polypropylene syringes and immediately transferred to pre-evacuated glass vials fit with butyl rubber stoppers. CH4 was analyzed on a gas chromatograph (HewlettePackard 5890, series II) equipped with a flame ionization detector (FID) and a stainless steel column (9 m length and 3 mm outer diameter) packed with Hayesep DB (100/120 mesh) (Alltech Associates, USA). The operation conditions of the gas chromatograph are presented in Table 2. The analysis of CO2 was made by another gas chromatograph (DS-6200, Donam Inc, Korea) equipped with an FID and a 1.8 m length 3.175 mm outer diameter stainless steel Porapak Q 80/100 mesh packed column (Restek, USA). This GC setup was equipped with the methanizer to allow conversion of CO2 to CH4 for the detection by FID (Table 2). Ultra pure nitrogen (99.999%) was used as carrier gas at 30 mL min1 (Table 2). The standard gases for the calibration of CH4 and CO2 were purchased from Rigas (Korea) with the concentrations of 101 ppm and 90%, respectively. Detailed information of CH4 and CO2 calibration is presented in Appendix A1. The basic information concerning the quality assurance (QA) of the experimental procedure (detection limit (DL) and precision) is also provided in Table 1S. The concentrations of CH4 and CO2 were not limited by the detectability, as their concentrations were always above the detection limit. The reproducibility of CH4 and CO2 analysis was assessed by the analyses of five replicate standard samples.
2.4. Statistical analysis The effects of the selected criteria for manure application on CH4 and CO2 emissions were examined by a t-test to judge the statistical significance of the observed differences (at the 0.05 significance level, 2-tailed) (George and Mallery, 2008). In addition, the possible relationship between the environmental parameters (air and soil temperature, soil moisture, and soil pH) and CH4 and CO2 emissions was also evaluated by Pearson’s correlation analyses with respect to each of the four different approaches selected for beef cattle manure application in this study.
3. Results and discussion 3.1. General trend of CH4 and CO2 emissions The emission of CH4 and CO2 can be explained in relation to a number of variables that include the manure dose, application techniques, and environmental conditions (air and soil temperature, soil moisture, and soil pH), and their ambient concentration levels. The raw data sets of CH4 and CO2 measured during this study are provided in Tables 2S and 3S, respectively. As a basic means to
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Table 2 Operational conditions of GC set for the analysis of CH4 and CO2. Compound
CH4
CO2
GC
GC/FID (HewlettePackard 5890, series II, USA) Hayesep DB 100/120 28 mL min1 (He) 30 mL min1 300 mL min1 100 C 80 C
GC/FID (DS-6200, Donam Inc., Korea)
Column Flow rate
Temperature
Carrier gas H2 Air Oven Injector Methanizer Detector
250 C
Porapack Q 80/100 30 mL min1 (N2) 30 mL min1 300 mL min1 80 C 100 C 350 C 250 C
assess the CH4 and CO2 emissions, their concentration data were evaluated by their magnitude and temporal trends. Fig. 2a shows their temporal patterns using the concentrations measured initially inside the chamber. As can be seen, the distribution of CH4 and CO2 generally exhibited similar trends. However, there were slight differences in their peak occurrences. Although the maximum CH4 concentrations of mid 2 ppm range were seen in late May, there was a slight time lag for CO2 (>600 ppm) which was seen most frequently between late May and early June (Julian days of 149e161). Fig. 3 also depicts the temporal trends of environmental parameters such as air and soil temperature, soil moisture, and soil pH. From the 7th day of experiment (Julian day ¼ 145) to the end, both temperature and moisture level exhibited a gradual increase through time. The average concentrations of CO2 from the
a
five sample types were in a fairly constant range of 544e552 ppm. Likewise, the concentrations of CH4 were also measured in the range of 1.64e1.73 ppm, although its values exhibited a slight enhancement in surface (S40 and S80) relative to subsurface samples (D40 and D80). In general, the mean initial CH4 concentrations seen in this study were similar to its global mean atmosphere concentration (1774 1.8 ppb) (IPCC, 2007c). However, initial CO2 concentrations were considerably higher than that of the global atmosphere (379 0.65 ppm) (IPCC, 2007c). The effect of amount and injection depth (surface vs. subsurface) of manure application on CH4 and CO2 emissions becomes evident through comparison of their emission patterns on a cumulative basis over the experimental period. Total emission of CH4 (mg m2) was seen fairly consistently in the ascending order of S40 (25,265), D40 (32,810), S80 (52,355), and D80 (76,160). Similar patterns were also found for its CO2 counterparts (Fig. 4a). As a simple means to assess the temporal variability of CH4 and CO2 emissions, their flux data obtained from different manure application types were plotted as a function of time (Fig. 2b). The temporal patterns of their flux data are greatly different from their concentration counterparts. In case of control unit, bidirectional exchange of CH4 was apparent throughout the study period. The results showed that the peak emissions of both compounds occurred consistently 5 days after manure application. The relative ordering of CH4 emissions after manure application was seen fairly consistently in the ascending order of S40, D40, S80, and D80, as shown in Fig. 4b. Although its emissions were seen almost
3.0
630 610 C
2.5
590
D40 D80
CH (ppm)
2.0
570
S40
550
S80
1.5 530 C
1.0
510
D40 D80
490
S40
0.5
S80
470 0.0 135
145
155
165
175
185
195
205
450 135
215
145
155
165
Julian day
175
185
195
205
215
Julian day
b 2470
600 C C
1970
D40
D80
CO flux (mg m h )
D80 S40
1470
S80
970
470
-30 135
D40
500
S40
400
S80
300
200
100
145
155
165
175 Julian day
185
195
205
215
0 135
145
155
165
175
185
195
205
215
Julian day
Fig. 2. Temporal pattern of CH4 and CO2 using (a) their initial concentrations (Co) measured in the chamber and (b) their fluxes in relation to manure application types. To simplify the temporal scale, both concentration and flux data are plotted against Julian Day.
N.-T. Phan et al. / Atmospheric Environment 63 (2012) 327e336
a
35
Temperature ( C)
30
25 Air C D40
20
D80 S40 S80
15 135
145
155
165
175
185
195
205
215
Julian day
b
25
Volumetric soil moisture (%)
20
15
10
C D40 D80
5
S40 S80
0 135
145
155
165
175
185
195
205
215
Julian day
c
9
Soil pH
8
7
331
Similar to CH4 flux pattern, notably strong emissions of CO2 were seen up to 30 days after fertilization; from the day 30 and afterward, all CO2 fluxes from four manure treatments were reduced greatly so that no more distinctions are apparent with that of control unit (Fig. 2b). Throughout the study period, the CO2 fluxes showed fairly large variations from each sample type: D80 (95.4 89.5 mg m2 h1), S80 (82.4 115 mg m2 h1), D40 (55.8 49.9 mg m2 h1), S40 (37.6 33.4 mg m2 h1), and C (12.9 11.4 mg m2 h1). The maximum fluxes of CO2 from each unit were measured as 449, 503, 232, and 168 mg m2 h1, respectively, all of which were seen within the first few hours after manure treatments (Table 3). This fast occurrence of the peak emissions may be ascribable to the release of CO2 contained in manure and those converted from HCO3 and CO3 2 during manure storage (Flessa and Beese, 2000). These authors also observed their maximum emission rates of CO2 (110e130 mg m2 h1) after applying cattle slurry with the total organic carbon (TOC) of 582 kg ha1. The maximum CO2 fluxes in our study were approximately four times higher than those of Flessa and Beese (2000), while the TOC rates of our beef cattle manure (9224 and 18,448 kg ha1) were around 16 and 32 times higher than those of Flessa and Beese (2000). Fangueiro et al. (2008) reported that CO2 emissions were significantly higher from the untreated slurry and the liquid fractions than those from the solid fractions (p < 0.05). Such distinction was apparent, although the TOC of solid fraction was considerably higher than those of untreated slurry and liquid fractions. This may be ascribable to the fact that the solid fractions contained virtually no dissolved CO2 with very low amounts of water soluble carbon. In contrast, the high emissions rates observed in the untreated slurry or the liquid slurry fractions may reflect the favorable conditions under which the CO2 dissolved in the slurry or converted from HCO3 and CO3 2 in the slurry can be released efficiently (Fangueiro et al., 2008). The high emissions of CO2 observed from the liquid fractions and untreated slurry should also be due to the fact that they can penetrate efficiently into the soil, resulting in more interactions with soil microorganisms than the solid fractions. The magnitude of CO2 emissions was also affected by the particle size of slurry fractions with the enhanced emissions from smaller fractions after soil incorporation (Fangueiro et al., 2007). 3.2. Effect of manure amount on CH4 and CO2 emissions
6
C D40 D80
5
S40 S80
4 135
145
155
165
175
185
195
205
215
Julian day Fig. 3. Temporal trend of the major environmental parameters: (a) air (and soil) temperature, (b) soil moisture, and (c) soil pH during the experiment.
consistently up to 14 days after manure application, its fluxes then approached near-zero in all treatments (Fig. 2b). This finding is in agreement with some previous studies. CH4 emissions were evident immediately after manure application to land (Chadwick et al., 2011; Chadwick and Pain, 1997). Effluent treatment resulted in elevated CH4 flux rates compared to the control unit for 3e5 days after application (Sistani et al., 2010). These emissions are commonly short lived, as methanogenesis is sensitive to O2. If O2 is penetrated into the manure on the soil, it inhibits CH4 production (Chadwick et al., 2011).
CH4 and CO2 emissions were monitored from a control unit and four plots with different manure application types. Their flux measurements from five different settings (Table 1) can be examined from a number of respects. Their basic emission characteristics can be assessed in Table 3. The mean fluxes of CH4 and CO2 from each manure treatment are also compared with those of previous studies (Table 4). The CH4 flux values of our control unit were bidirectional to show both deposition (8.59 6.01 mg m2 h1, n ¼ 15) and emission (5.35 4.55 mg m2 h1, n ¼ 7). Likewise, the CO2 results from control unit also showed deposition, although it took place only once out of 28 measurements. Hence, for the sake of simplicity, the deposition of CO2 was not considered for further evaluation of the CO2 data. For both compounds, the results derived after manure application showed the signal of emission without a single exception. In our study, soil in the control plot was also tilled before starting the experiment which might result in aerobic soil. Goulding et al. (1995) showed that CH4 was normally oxidized by aerobic soils (as sink) to make the negative flux in the control plot. The results of CH4 flux (mg m2 h1) measurement confirm the existence of a highly systematic trend across different treatment types with the systematic distinction across [1] D80 (208 515), [2]
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a 77000 C
C
100000
D40
D40
D80
D80
57000
80000
S40
S40 S80
S80
60000 37000 40000 17000
-3000
20000
0 135
145
155
165
175
185
195
205
135
215
145
155
165
Julian day
b
175
185
195
205
215
Julian day
350
120
320 290
100
260 230
80
200 170
60
140 110
40
80 50
20
20 -10
C
S40
D40
S80
0
D80
C
S40
Treatment
D40
S80
D80
Treatment
Fig. 4. Comparison of measurement data: (a) cumulative emissions and (b) average fluxes of five manure treatments (Error bars represent the standard error).
Table 3 Statistical summary of CH4 and CO2 concentrations and fluxes and relevant environmental parameters in this study. Parameter (unit)
Sample type C
A. Initial concentrations of CH4 and CO2 inside chamber 1.72 0.50 (1.78)a CH4 (ppm) 1.02e2.63 (22)b CO2 (ppm) 552 35.0 (548) 495e621 (28) B. CH4 and CO2 fluxes Emission 5.35 4.55 (5.49) CH4 (mg m2 h1) 0e13.3 (7) Deposition 8.59c 6.01 (8.34) (21.1) e (0.98) (15) CO2 (mg m2 h1)d Emission 12.9 11.4 (10.1) 0.77 to 59.6 (28) C. Environmental conditions 25.0 4.6 (25.8) Air temp. ( C) 16.0e32.2 (28) 23.1 3.5 (23.5) Soil temp. ( C) 16.7e29.5 (28) Soil moisture (%) 8.4 4.2 (7.8) 3.8e20.3 (28) Soil pH 6.9 0.6 (7.0) 5.8e7.8 (28) a b c d
S40 1.73 0.54 0.79e2.49 547 34.0 480e620
S80 (1.81) (22) (553) (28)
1.72 0.56 0.70e2.48 544 36.0 471e616
D40 (1.87) (22) (552) (28)
1.64 0.56 0.77e2.69 549 34.0 497e614
D80 (1.76) (22) (552) (28)
1.66 0.51 0.89e2.45 546 33.2 497e616
(1.80) (22) (548) (28)
59.3 99.2 (25.3) 7.10e461 (22)
188 425 (42.3) 12.0e1810 (22)
68.7 146 (32.8) 14.0e713 (22)
208 515 (61.0) 27.8e2323 (22)
37.6 33.4 (31.3) 6.02e168 (28)
82.4 115 (47.6) 7.72e503 (28)
55.8 49.9 (44.0) 7.72e232 (28)
95.4 89.5 (70.3) 12.6e449 (28)
25.0 4.6 16.0e32.2 21.0 2.9 16.4e27.4 10.3 5.2 2.6e21.2 7.0 0.6 5.7e8.1
(25.8) (28) (20.8) (28) (12.1) (28) (7.0) (28)
25.0 4.6 16.0e32.2 21.5 3.0 16.5e27.7 10.5 4.9 3.2e20.4 7.0 0.6 6.0e8.1
(25.8) (28) (21.3) (28) (10.1) (28) (7.0) (28)
25.0 4.6 16.0e32.2 21.4 2.9 16.4e27.5 8.8 5.4 2.7e21.0 6.7 0.5 5.6e7.8
Mean SD (median). Minemax (number of data). Positive values indicate emission, while negative ones are used for deposition. In case of CO2, differences in flux values between all matching pairs are statistically significant (p < 0.05) except S80 vs. D80 pair.
(25.8) (28) (21.4) (28) (7.7) (28) (6.7) (28)
25.0 4.6 16.0e32.2 22.0 2.9 16.7e28.0 8.7 5.6 2.5e21.4 6.6 0.6 5.2e7.9
(25.8) (28) (22.3) (28) (7.0) (28) (6.7) (28)
Table 4 Comparison of CH4 and CO2 flux data from fertilizer and manure application between the different studies. No
a b c d e
Study period
Pig slurry
Headspace measurement
Laboratory study
Swine effluent
Closed chamber
Spring 2007
CH4 flux (mg m2 h1) Em.a
Dp.b
0 2860 8750 220 2270 1510 140 970
Swine effluent
Closed chamber
27 Apr.e 20 Sept. 2007
19 Apr.e 11 Sept. 2008
Beef cattle manure
Cattle slurry
Closed chamber
Calculated from the different concentrationse
19 Maye 29 July 2010
88.4 17.7 139 35.5 240 62.1 278 76.8 13.4 2.64 40.3 5.27 121 23.7 1075 211 4.16 59.3 68.7 188 208 3571 3307
Laboratory study 595
2249 11,607 66.1
CO2 flux mg m2 h1
Application rate kg C ha1
Measuring duration
Slurry application method
Reference
17.7 86.3 86.5 212 328 1231 421 399 497 151 345 120 230 134 204 135 218 149 250 160 191 249 208 211 204 226 213 12.9 37.6 55.8 82.4 95.4 20.8 19.2 50.9 33.6 57.4 33.9
Cc 7890 7890 C C 636 636 636 636 636 636 C 636 636 636 636 636 636 636 C 798 798 798 798 798 798 798 C 9224 9224 18,448 18,448 C C 582 582 582 582
15 d 15 d 15 d 4h 72 h 4h 72 h 4h 72 h 4h 72 h 33 d 141 d 33 d 141 d 33 d 141 d 33 d 141 d 31 d 158 d 31 d 158 d 31 d 158 d 31 d 158 d CH4 (29 d) CO2 (71 d)
Control (without slurry) Surface spread Injection (5 cm depth) Control (without slurry) Control (without slurry) Surface spread Surface spread Aerway injection to holesd Aerway injection to holesd Row injection at 15 cm depth Row injection at 15 cm depth Control (without slurry) Control (without slurry) Surface application Surface application Aerway injection to holesd Aerway injection to holesd Row injection at 15 cm depth Row injection at 15 cm depth Without slurry (control) Without slurry (control) Surface application Surface application Aerway injection to holesd Aerway injection to holesd Row injection at 15 cm depth Row injection at 15 cm depth Control (without manure) Surface spread Inject at 5 cm depth Surface spread Inject at 5 cm depth Control (without slurry) Control (without slurry) Surface spread Surface spread Injection (2e10 cm) Injection (2e10 cm)
Dendooven et al. (1998)
2 9 2 9 2 9
w w w w w w
Lovanh et al. (2010)
Sistani et al. (2010)
Present study
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
Method of flux measurement
Form of fertilization
Flessa and Beese (2000)
Emission. Deposition. Control e without manure. Aerway injection to holes (7.5 cm L 1.5 cm W 20 cm D). Calculated from the air flow rate through the microcosm headspace and the difference in the CH4 and CO2 concentration between the input air and the exhaust air.
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S80 (188 425), [3] D40 (68.7 146), and [4] S40 (59.3 99.2). Moreover, for the same injection depth, the larger amount of manure promoted enhancement in CH4 emissions such that the flux of D80 approximately tripled that of D40. Such distinction was also observed from in the data between the different injection depths (0 vs. 5 cm), although it was not so pronounced in most cases (Table 3). Like the case of CH4, the emission fluxes of CO2 were also examined using the data collected from five different sample types measured over a little extended period of 70 days (19 Maye29 July 2010). The results of CO2 flux were also maintained in the same fashion to record the same relative ordering: D80 (95.4 89.5 mg m2 h1) > S80 (82.4 115 mg m2 h1) > D40 (55.8 49.9 mg m2 h1) > S40 (37.6 33.4 mg m2 h1). The control unit on the other hand recorded the lowest mean emission rate of 12.9 11.4 mg m2 h1 (Fig. 4b). If the flux values of CO2 are examined by the amount of manure applied, a large distinction can be found consistently from the data sets obtained between the two manure doses at 5 cm depth to show about 2 fold enhancement from D40 to D80. Similar distinctions were also found in CO2 emissions at surface application between S80 and S40. If the flux values measured at each depth (either surface or 5 cm depth) are compared by the student’s t-test in terms of manure dose difference between 40 and 80 T ha1, the patterns of dose effect contrast between CH4 and CO2. Although the differences in CO2 values are statistically significant (p < 0.05) from the data collected at each depth, it is not the case for CH4. The results of this study demonstrated that all CH4 and CO2 fluxes showed large changes with the amount of manure applied, suggesting that the manure treatment can raise CH4 and CO2 emissions in a somewhat predictable manner. It is interesting to see that cumulative emissions of CH4 and CO2 from high manure dose (S80 and D80) were significantly higher than those from their low counterparts (S40 and D40) (p < 0.05) (Table 5). 3.3. Comparison of CH4 and CO2 emissions between surface and subsurface layers Injection of slurry can minimize the running-off transport of nutrients, while facilitating the greater slurry contact with soil. As such, the slurry injection can induce favorable conditions for GHG emissions. To evaluate such effect on CH4 and CO2 emissions, their flux data were examined between surface and subsurface (at 5 cm depth) for each of the two manure doses (40 and 80 T ha1). The results of CH4 data indicate that more emissions were seen at subsurface layer, for each of the two manure amounts. In case of 40 T ha1, CH4 flux measured at subsurface (F(D40) ¼ 68.7 mg m2 h1) were 15.8% larger than that made at surface (F(S40) ¼ 59.3 mg m2 h1). These patterns were seen consistently in 80 T ha1 to show F(D80 ¼ 208 mg m2 h1) vs. F(S80 ¼ 188 mg m2 h1).
Table 5 Result of statistical comparisons of CH4 and CO2 cumulative emissions between manure treatments (t-test). A. Statistical comparisons between injection depths (surface vs. 5 cm depth)
t p
CH4 (40 T ha1)
CH4 (80 T ha1)
CO2 (40 T ha1)
CO2 (80 T ha1)
13.3 1.14E-11a
18.3 2.21E-14a
8.51 3.98E-9a
4.22 2.48E-4a
B. Statistical comparisons between manure doses (40 vs. 80 T ha1)
t p a
CH4 (surface)
CH4 (5 cm depth)
CO2 (surface)
CO2 (5 cm depth)
16.5 1.74E-13a
18.3 2.16E-14a
13.4 1.90E-13a
6.11 1.58E-6a
Indicates that the means are statistically different (p < 0.05).
Like our study, Sistani et al. (2010) reported that injection facilitated emissions of CH4 relative to surface application. Flessa and Beese (2000) also found that injection of slurry into the soil resulted in significant increase of CH4 emissions in comparison with surface application (Table 4). However, differences due to such effect are not so significant as that seen by those of the manure amount discussed above. If the flux values measured at each dose (either 40 or 80 T ha1) are compared by the student’s t-test in terms of difference between surface and subsurface, the patterns of the latter are seen to be significant (p < 0.05) only in the case of CO2 fluxes measured at 40 T ha1. In addition, according to statistical comparison (t-test), cumulative emissions of CH4 and CO2 from subsurface were significantly higher at each manure dose (either 40 or 80 T ha1) than those from surface (p < 0.05) (Table 5). The results of our analysis indicate that differences in CH4 fluxes were not statistically significant between the two soil layers which were also seen frequently in some previous studies (Perälä et al., 2006; Sommer et al., 1996). CH4 emissions can be generated from two possible sources such as one dissolved in manure prior to application or methanogenesis in the soil (Chadwick and Pain, 1997; Clemens et al., 2006; Sherlock et al., 2002; Sommer et al., 1996; Wulf et al., 2002). Injection of manure into the soil can lead to the restricted aeration with the formation of anoxic zones. Under such conditions, decomposition of injected manure has the potential to enhance the emissions of CH4 (Flessa and Beese, 2000; Sistani et al., 2010; Wulf et al., 2002). Like the case of methane, the CO2 flux data obtained during the field study were evaluated in a number of respects. The mean CO2 flux from the subsurface method (D80: 95.4 mg m2 h1) was higher than that from surface method (S80: 82.4 mg m2 h1). Similarly, in lower manure dose (40 T ha1), the mean CO2 flux was also different between D40 (55.8 mg m2 h1) and S40 (37.6 mg m2 h1). Unlike the case of the other compound (CH4) or other manure dose (relative to 80 T ha1), the CO2 results at 40 T ha1 are statistically different between surface and subsurface (Table 3). Anaerobic conditions due to the restricted air contact should have promoted anaerobic bio-decomposition of organic matters in the manure. It may thus help raise CO2 fluxes relative to the surface application. Similar to our study, Dosch and Gutser (1996) found enhanced emission of CO2 from cattle slurry after injection relative to the surface treatment. However, as was the case of CH4, contrasting exchange patterns can also be found from CO2 data sets. Sistani et al. (2010) and Dendooven et al. (1998) observed that there was no significant difference in CO2 emissions between the injection and surface application of pig slurry (Table 4). Similarly, Flessa and Beese (2000) were not able to find a direct link between the production of CO2 and the way the cattle slurry applied (between surface application and slit injection). It is striking to find the highest CO2 fluxes accompanied by the surface spray method (rather than the aerway injection) (Lovanh et al., 2010) (Table 4). According to our statistical analysis, the injection difference (surface vs. subsurface) has less clear impact on the magnitude of emission than the amount of manure (Table 3). However, as the selection of those criteria (40 vs. 80 T ha1 or 0 vs. 5 cm) was made arbitrarily, the actual effects of those variables need to be assessed more cautiously. 3.4. Factors controlling CH4 and CO2 emissions To assess the effects of the environmental conditions on CH4 and CO2 emissions, the relationship between different environmental parameters was also evaluated in Table 3. The results of correlation analysis in this study showed that strong correlations are found consistently between CO2 and CH4 fluxes (Table 4S). However, such
N.-T. Phan et al. / Atmospheric Environment 63 (2012) 327e336
relationship is found rather scarcely between their fluxes and the environmental parameters (air and soil temperature, soil pH, and soil moisture) (Table 4S). Similarly, CH4 concentrations did not exhibit strong correlations with air (and soil) temperature, while it showed good correlations with soil moisture such as C and D40 (p < 0.05) and S40 samples (p < 0.01). However, such pattern disappeared with increases in manure dose with S80 and D80 (p > 0.05). Unlike the case of CH4 data, the CO2 concentration data showed strong correlations with air temperature, regardless of manure treatment types. Perälä et al. (2006) found that there were no correlations between CH4 flux and the environmental variables (soil moisture, soil mineral N content, and air temperature). Conversely, Wulf et al. (2002) found that the effect of soil moisture on overall CH4 emissions was strong. In general, the mean pH values of the treatments in our experiment were from 6.6 to 7.0 (Table 3). Because this pH range is generally suitable for soil microbial activity, it can exert a marked effect on the growth and proliferation of soil microorganisms. Reth et al. (2005) reported that a soil pH between 3 and 7 (to 8) is good to activate biological soil microorganisms. The CO2 flux measured at soil pH value of 4 was 2e12 times higher than those with soil pH value of 3 (Sitaula et al., 1995). This pattern was attributed to the adverse effect of low pH on soil microbial activity, as the evolution of CO2 is suppressed with low respiration rate (Rastogi et al., 2002). Several other studies also reported an increase in CO2 evolution with pH (Andersson and Nilsson, 2001; Ellis et al., 1998; Hall et al., 1997; Kowalenko et al., 1978; Sitaula et al., 1995). However, soil pH beyond 7.0 is likely to affect CO2 emission more adversely. At pH 8.7, CO2 emission was reduced by 18% compared to that at pH 7.0. Moreover, when the pH was raised to 10.0, the extent of reduction in CO2 emission was 83% (Rao and Pathak, 1996). 4. Conclusions The amount and injection depth of manure application can have an influence on the emissions of the two major GHGs like CH4 and CO2. To learn more about the effect of manure application on their emissions, CH4 and CO2 fluxes were measured by the flux chamber method over about 30 and 70 days of duration, respectively. The results demonstrated that the magnitude of CH4 and CO2 fluxes tend to exhibit a systematic trend with the relative orders of the four combinations between two key variables such as: S40 < D40 < S80 < D80. Although the exchange pattern of CH4 was bidirectional from control (C), such pattern disappeared immediately after manure application. Once manure was applied, four different types of manure samples consistently exhibited CH4 and CO2 emissions with a fairly systematic trend. It was noted that the emissions of CH4 and CO2 generally increased at subsurface relative to surface, when the manure was applied independently at the two layers. The amount of manure however showed a more clear effect on the emission strengths under our experimental setups. The results of correlation analysis in this study demonstrated that the flux data generally exhibited a good correlation between CH4 and CO2 concentrations, while there was a poor correlation with the environmental parameters (air and soil temperature, soil moisture, and soil pH). However, it was recognized that CH4 and CO2 concentrations can maintain strong correlations with soil moisture and air temperature, respectively. The results of this study showed that manure dose should also exert fairly sensitive effects on CH4 and CO2 emissions than the injection depths between surface and subsurface. Although our analysis was made to assess the emissions of CH4 and CO2, manure application can lead to emissions of other GHG like N2O or other types of pollutants. Hence, more efforts are needed to describe
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