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Journal of Food, Agriculture & Environment Vol.11 (2): 1506-1508. 2013
www.world-food.net
Effect of maize intercropped with alfalfa and sweet clover on soil carbon dioxide
emissions during the growing season in North China Plain
Jian-xiong Huang 1, Peng Sui 1, Sheng-wei Nie
1
1, 2
, Wang-sheng Gao 1 and Yuan-quan Chen
1*
2
Circular Agriculture Research Center, China Agriculture University, Beijing 100193, P. R.China. National Key Field Scientific
Observation Station of Zhengzhou Fluvo-aquic Soils Ecology Environment, Ministry of Agriculture, Institute of Plant nutrient
and Environmental Resources, Henan Academy of Agricultural Science, Zhengzhou 450002, P. R.China.
*e-mail: rardc@163.com
Received 30 November 2012, accepted 27 April 2013.
Abstract
Many studies have demonstrated that various agricultural managements can reduce soil carbon dioxide (CO2) emission and intercropping systems is
beneficial (such as higher production, effective nutrient acquisition, control of soil erosion, et al.). However, few studies have investigated whether
intercropping systems can decrease soil CO2 emission. We thus carried out a field experiment to compare such emissions produced by monocultural
maize (M) and maize-legume intercropping systems (maize intercropped with Alfalfa (MA), and maize intercropped with Sweet Clover (MSC)) in
2010. Results showed that mean seasonal fluxes of CO2 was greater for M than that for the intercropped plots. Cumulative CO2 flux for MA was
significantly reduced by 14% compared to M (6.83 t ha-1) (P<0.05). There were no signicant correlations between daily CO2 emission and soil
temperature or moisture during the observed period under dry environmental condition (P<0.05). Grain yield was slightly higher in M than that in
MA and MSC but there was no difference (P<0.05). In summary, our result indicated that appropriate maize-legume intercropping pattern could
significantly reduce soil CO2 emission without grain yield loss.
Key words: Global warming, intercropping, soil respiration, sustainable agriculture.
Introduction
Increased atmospheric concentrations of carbon dioxide (CO2)
and other greenhouse gases (GHGs), mainly nitrous oxide and
methane, as a result of anthropogenic activities are of great concern
due to the associated risk of global climate change 1. Agriculture
is a major source of CO2 emission and many studies have focused
on various forms of agricultural management to reduce this
emission 2-4. Such management practices include tillage, fertilizing
methods and crop rotation. Studies of crop-based intercropping
systems, however, have been rare.
Benefits can be found in intercropping systems 5. Our previous
study also suggested that intercropping is an effective way to
reduce nitrogen leaching and environment impact in fields with N
fertilizer over-dose 6, 7. Intercropping is thus clearly beneficial.
Although a latest and unique published paper showed that maizesoybean intercropping could significantly reduce the soil CO2
emission compared to sole maize5, it remains unknown whether
crops intercropped with one another to control soil CO2 emissions.
More research on the effects of intercropping, particularly grasslegume intercropping, on soil CO2 emissions is needed.
North China Plain is an intensive agricultural region with a winter
wheat– summer maize rotation. It produces about one-fourth of
the country’s total grain yield 8. Soil CO2 emissions from summer
maize growing season (3–4 months) was larger than those from
winter wheat growing season (8–9 months) 9. We thus conducted
field experiments to investigate the effect of maize–legume
intercropping on the prevention of soil CO2 emissions.
1506
Materials and Methods
Study site: The study site located at the Shangzhuang
Experimental Station (39.9°N, 116.3°E) of China Agricultural
University (CAU) in Beijing, China. The alkaline soil (pH = 8.1) at
the experimental site contained 5.07 g kg-1 organic matter, 0.49 g
kg-1 total nitrogen (N), 12.30 mg kg-1 phosphorous (Olsen P), and
45.73 mg kg-1 exchangeable potassium (K). The total precipitation
from seeding to the last soil gas sampling day in 2010 was 284 mm.
Experimental design: Two common intercropping patterns, MA,
maize–alfalfa (Medicago sativa L.) and MSC, maize–sweet clover
(Melilotus spp), were used to investigate the effect of
intercropping [vs. M, maize monoculture (Zea mays L.)] on soil
CO2 fluxes. To achieve a density of 60,000 seedlings per hectare,
the maize monocrop was sown on June 6 in 2010. In the
intercropped plots, legume crops were planted using common
seed rates with 80-cm inter-row spacing. Potassium sulfate (K2SO4;
120 kg ha-1) and calcium superphosphate (P2O5; 75 kg ha-1) were
applied before sowing (June 6). The total N (in the form of urea)
rate is 350 kg ha-1. Half of the N was applied at the seeding stage
and the other half was used as top dressing. Detailed information
was reported in previous study 6.
Determination of grain yield and soil organic carbon(SOC):
Maize grain yield was determined after harvest. SOC content in
the 0–20 cm depth in 2010 was sampled and determined using the
Walkley-Black method 10 after soil collection.
Journal of Food, Agriculture & Environment, Vol.11 (2), April 2013
16
N fertilizer
A
N fertilizer
6
4
M
MA
MSC
2
0
11/6
27/6
13/7
29/7
Date
14/8
10
8
6
15/9
2
11/6 27/6 13/7 29/7 14/8
Date
26
24
22
M
MA
MSC
4
30/8
C
28
12
Soil temperature (°C)
8
30
B
14
10
Soil water content (%)
Soil CO2 emission (mgm-2 min-1)
12
30/8
15/9
20
11/6
M
MA
MSC
27/6
13/7
29/7
Date
14/8
30/8
15/9
Figure 1. Soil CO2 emission (A), soil water content (B) and soil temperature (C) in different treatments.
Determination of soil CO2 fluxes: Soil CO2 fluxes were measured
using static chambers and gas chromatography 11. Each plot was
placed with one chamber (50 × 30 × 30 cm) between maize for M
and between maize and legume crop for MA and MSC. Gas samples
were taken with 100-ml plastic syringes attached to a three-way
stopcock at 6, 12, 18, and 24 min following chamber closure and
then injected into evacuated tubes. All measurements were
conducted in the morning (09:00–10:00). Gas samples were
analyzed immediately using a gas chromatograph (Agilent 7890A,
Agilent Inc., USA). Gas emission and cumulative were calculated
as described by Javed et al. 12.
Measurement of soil temperature, and soil moisture: Average
soil temperature (5-, 10-, 15-cm depth) in each plot was measured
using soil thermometers inserted into the soil near the chambers.
Averaged temperature of the three depts was used to be analysed.
Soil moisture (0–10 cm) was gravimetrically determined was by
drying at 105°C for 24 h at each gas measurement.
Statistical analyses: Statistical analyses were performed using
SPSS 17.0. Statistically significant comparisons (LSD) and linear
regression analysis were identified at the 0.05 level.
Results
Soil CO2 fluxes: Soil CO2 flux trends corresponded to agricultural
techniques, ranged from 2.09 to 9.92 mg m-2 min-1 (Fig. 1 A). Average
seasonal soil CO2 fluxes were 5.14, 4.52 and 4.94 mg m-2 min-1 for
M, MA and MSC, respectively. Two CO2 emission peaks appeared,
in response to application of N fertilizer. Cumulative CO2 emission
for the entire observation period in the M was 6.83 t ha-1 and
those in the MA and MSC were 6.17 and 5.47 t ha-1, respectively.
MA significantly reduced soil CO2 emission (P<0.05, Table 1).
Seasonal soil moisture and temperature: Figure 1 B and C present
the fluctuations in soil moisture and temperature during the
growing season. Soil moisture ranged from 4.5-14.8% during the
growing season. Due to the dry condition, soil temperature was
close between treatments. There was a positive but no significant
relationship between soil CO2 and soil temperature and moisture
(P<0.05).
Grain yield and SOC content: The grain yield of maize was not
significantly influenced by intercropping with legume. The highest
grain yield of maize occurred in M, which was 4.43 t ha-1 followed
by MSC with 4.02 t ha-1. Soil organic carbon ranged from 3.05 to
3.31 g kg-1 and there is no statistically signicant difference between
treatments (P<0.05, Table 1).
Discussion
Limited data is available on soil greenhouse gas emission rates
from intercropping systems. Kyer et al. 5 firstly evaluated soil CO2
emissions from a temperate maize-soybean intercrop system, thus
addressing a current gap in the literature and demonstrated that
intercropping may be a more sustainable agroecosystem landmanagement practice with respect to GHG emission. Our result
that maize intercropped with alfalfa but not sweet clover could
significantly reduce soil CO2 emission compared to sole maize
was in agreement with this.
We found that soil temperature and moisture positively affected
soil CO2 release, in agreement with the results of other studies 12, 13.
However, these factors were found by previous researchers to be
significant controllers, whereas they did not exert significant
influence in our study. Soil temperature was a poor and not
statistically signicant predictor of soil respiration in drought-prone
regions 14. In our study, the total precipitation from seeding to the
last soil gas sampling day was 284 mm and the soil moisture
remained in relatively low level and this led to poor dependence
of soil CO2 emission on soil temperature and moisture.
Crop productivity highly correlated to the background SOC
concentration 15. Due to low SOC content, maize yield under each
treatment was lower than that reported by Li et al. 16, but similar to
that by Ngwira et al. 17. However, grain yield in intercropping
systems were maintained in this study, this result agreed well with
our previous and other studies 6, 16.
Table 1. Grain yield, SOC content and total soil CO2 fluxes in different
treatments.
Treatment
M
MA
MSC
Cumulative soil CO2(t ha-1)
6.83 a
5.88 b
6.44 ab
Grain yield (t ha-1)
4.43 a
3.95 a
4.02 a
SOC (g kg-1)
3.05 a
3.08 a
3.31 a
Lower-case letters indicate signicant differences between treatments (P < 0.05).
Journal of Food, Agriculture & Environment, Vol.11 (2), April 2013
Conclusions
Based on our results, we found that maize intercropped with
alfalfa but not sweet clover significantly reduced soil CO2
emission compared to monocultural maize during the growing
season without grain yield loss. Intercropping may be a more
sustainable agricultural practice.
1507
Acknowledgements
This study was supported by the National Key Technology R&D
Program of the People’s Republic of China (Project Numbers
2011BAD16B15 and 2012BAD14B03).
systems under conservation agriculture in Malawi. Field Crops Research
132:149–57.
References
1
IPCC. Climate Change 2007. The Physical Science Basis Cambridge, UK:
Cambridge University Press 100 p.
2
Ball, B. C., Scott, A. and Parker, J. P. 1999. Field N2O, CO2 and CH4
fluxes in relation to tillage, compaction and soil quality in Scotland. Soil
Tillage Research 53:29–39.
3
Verge, X. P. C., Kimpe, C. D. and Desjardins, R. L. 2007. Agricultural
production, greenhouse gas emissions and mitigation potential.
Agricultural and Forest Meteorology 142:255–269.
4
Bavin, T. K., Griffis, T. J., Baker, J. M. and Venterea, R. T. 2009. Impact
of reduced tillage and cover cropping on the greenhouse gas budget of a
maize/soybean rotation ecosystem. Agriculture, Ecosystem and
Environment 134:234–242.
5
Kyer, L., Oelbermann, M. and Echarte, L. 2012. Soil carbon dioxide and
nitrous oxide emissions during the growing eason from temperate maizesoybean intercrops. Journal of Plant Nutrition and Soil Science 175:394–
400.
6
Huang, J. X., Sui, P., Nie, S. W., Wang, B. B., Nie, Z. J., Gao, W. S. and
Chen, Y. Q. 2011. Effect of maize-legume intercropping on soil nitrate
and ammonium accumulation. Journal of Food, Agriculture and
Environment 9(3&4):416 – 419.
7
Nie, S. W., Chen, Y. Q., Egrinya, E. A., Sui, P. and Huang, J. X. 2012.
Impacts of maize intercropping with ryegrass and alfalfa on environment
in fields with nitrogen fertilizer over-dose. Journal of Food, Agriculture
and Environment 10:896-901.
8
Liu, C., Yu, J. and Kendy, E. 2001. Groundwater exploitation and its
impact on the environment in the North China Plain. International Water
Resources Association 26:265–272.
9
Ding, W. X., Meng, L., Yin, Y. F., Cai, Z. C. and Zheng, X. H. 2007. CO2
emission in an intensively cultivated loam as affected by long-term
application of organic manure and nitrogen fertilizer. Soil Biology and
Biochemistry 39:669–679.
10
Walkley, A. and Black, L. A. 1934. An examination of the method for
determining soil organic matter, and a proposed modification of the
chromic acidtitration method. Soil Science 37:29–38.
11
Wang, Y. S. and Wang Y. H. 2003. Quick measurement of CH4, CO2 and
N2O emission from a short-plant ecosystem. Advances in Atmospheric
Sciences 20:842–844.
12
Javed, I., Hu, R. G., Lin, S., Ahamadou, B. and Feng, M. L. 2009. Carbon
dioxide emissions from Ultisol under different land uses in mid–
subtropical China. Geoderma 152:63–73.
13
Tang, X., Liu, S., Zhou, G., Zhang, D. and Zhou, C. 2006. Soil-atmospheric
exchange of CO2, CH4, and N2O in three subtropical forest ecosystems
in southern China. Global Change Biology 12:546–60.
14
Correia, A. C., Minunno, F., Caldeira, M. C., Banza, J., Mateus, J.,
Carneiro, M., Wingate, L., Shvaleva, A., Ramos, A., Jongen, M., Bugaho,
M. N., Nogueira, C., Lecomte, X. and Pereira, J. S. 2012. Soil water
availability strongly modulates soil CO2 efflux in different Mediterranean
ecosystems: Model calibration using the Bayesian approach. Agriculture,
Ecosystems and Environment 161:88–100.
15
Pan, G. X., Smith, P. and Pan, W. N. 2009. The role of soil organic matte
in maintaining the productivity and yield stability of cereals in China.
Agriculture, Ecosystem and Environment 129:344–8.
16
Li, W. X., Li, L., Sun, J. H., Guo, T. W., Zhang, F. S., Bao, X. G., Peng, A.
and Tang, C. 2005. Effects of intercropping and nitrogen application on
nitrate present in the profile of an Orthic Anthrosol in Northwest China.
Agriculture Ecosystem and Environment 105:483–491.
17
Ngwira, A. R., Aune, J. B. and Mkwinda, S. 2012. On-farm evaluation of
yield and economic benefit of short term maize legume intercropping
1508
Journal of Food, Agriculture & Environment, Vol.11 (2), April 2013