LOGIN
REGISTER.png)
Research Article
Effect of Soil Amendments on Methane Emission and Rice Productivity nearby the Dingaputa Haor area of Netrokona District, Bangladesh
Md. Rajib Hossain1*, Muhammad Aslam Ali2, Md. Shamsur Rahman2 and Sumaya Khatun2
1Department of Environmental Science and Disaster Management, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, Bangladesh
2Department of Environmental Science, Bangladesh Agricultural University, Mymensingh, Bangladesh
Corresponding author: Md. Rajib Hossain, Department of Environmental Science and Disaster Management, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, Bangladesh, Tel: +8801922143080, E-mail: rajib.esd@bsmrstu.edu.bd
Citation: Hossain MR, Ali MA, Rahman AS, Khatun S (2019) Effect of Soil Amendments on Methane Emission and Rice Productivity nearby the Dingaputa Haor area of Netrokona District, Bangladesh. J Environ Sci Allied Res 2019: 50-57. doi: https://doi.org/10.29199/2637-7063/ESAR-202021
Received: 21 March, 2019; Accepted: 04 July, 2019; Published: 11 July, 2019
Abstract
An experiment was conducted nearby the Dingaputa haor area of Netrokona District during boro season. The aim of the study was to find out the most suitable soil amendment for reducing CH4 emission and maximizing the yield attributes of BRRI dhan58. In this experiment six treatments, such as T1: 100% recommended dose of urea (220 kgha-1), T2: 50% Urea+Vermicompost (4 tha-1), T3: 50% Urea+Azolla incorporated (4 tha-1), T4: 25% Urea+Azolla incorporated (4tha-1)+ Vermicompost (4 tha-1), T5: 25% Urea+Azolla incorporated (6 tha-1)+Vermicompost (2 tha-1), T6: 25% Urea+Azolla incorporated (6 tha-1)+Azolla dual cropping (1tha-1) with Cyanobacterial mixture were used. At 14 DAT, CH4 flux was very low and no significant differences were observed among the treatments. At 70 DAT, CH4 emissions peaked in all treatments where highest peak was recorded (30.39 mgm–2h–1) in treatment T6 and the lowest was recorded (16.38 mgm–2h–1) in T2. The highest grain yield (6.50 th–1) was found in the treatment T4 while lowest grain yield (5.37 th–1) was found in the treatment T3. After rice harvest the soil properties such as soil pH, total nitrogen, organic carbon, phosphorus, potassium and sulphur was found 6.94, 0.16%, 1.58%, 14.52 ppm, 0.10 meq 100g–1 and 9.65 ppm respectively. Considering all the above parameters it may be concluded that, the application of 25-50% of the recommended Urea along with Azolla incorporated (4tha-1) and Vermicompost (4tha-1) amendment could be suitable for maximizing of rice yield and reducing CH4 emission.
Keywords: Methane emission; Azolla; Vermicompost; Soil amendments
Introduction
Bangladesh is an agricultural country and rice is the main food crop. Rice has been growing over 25 million hectares of land under irrigated and rain fed conditions, which cover about 84% of total cropped area in Bangladesh. The pressure on Bangladesh land resources to produce more rice will aggravate in the coming years due to increasing population and demand for food. Rice demand would increase by 25% to keep pace with population growth [1]. Rice is produced at least twice in the same crop field in Bangladesh. High fertilizer responsiveness is an essential criterion for a high yielding rice varieties and nitrogen is one of the major nutrient elements for crop production that can contribute a lot for higher yield of rice [2]. In case of Rice Fallow-Rice cropping pattern, one rice crop is fully irrigated (Boro rice) and another is mostly rainfed (T. Aman rice). The flooded rice paddy has been identified as one of the most important sources of anthropogenic CH4 emission. The CH4 is an important greenhouse gas (with a 21-fold higher global warming potential than CO2 over a 100-year time horizon, [3], which has been reported to account for 95% of total CO2 equivalent emissions from paddy fields [4]. The differences in plant growth duration among rice cultivars affected the total seasonal CH4 emission from flooded soil. Combination of various factors such as the supply of organic matter, inherent characteristic, depth of water level, size of the root space and oxidation rate in the rhizosphere have also been identified to affect the CH4 flux from various rice cultivars. To date no systematic study on organic fertilizers have been conducted to determine an optimum organic fertilizer management practice to maintain a high yield of rice grain while reducing CH4 emissions to a minimum [5]. The CH4 is produced in soils by the microbial breakdown of organic compounds in strictly anaerobic conditions at redox potential less than -150 mV [6]. There are two major sources of methane emissions, one is natural source and another is anthropogenic source. More than 50% of the global annual CH4emission is of anthropogenic origin [3]. It is reported that irrigated rice accounts for more than 75% of global rice production and these rice fields are one of the major sources of CH4 gas [7]. Since irrigated rice remains continuously flooded most of the time during growing season, this creates the ideal condition for CH4 emission. Recent estimates of CH4 emission from rice fields show that its rate varies within the range of 39 and 112 Tg CH4 year-1 which is equivalent to 6 to 18% of total global CH4 flux [7]. A statistical analysis of the CH4 emission fluxes from rice fields in Asia showed that the average CH4 flux during the growing season is significantly affected by water management, organic matter application, soil organic carbon content, soil pH, and climate [8]. It is also influenced by soil type, weather, tillage management, residues, fertilizers, and rice cultivar. Therefore, manipulation of this factor can help reduce CH4 emission. Thus, several studies were conducted to mitigate CH4 emission in rice fields through soil and water management [9]. Cyanobacteria play an important role in maintenance and buildup of soil fertility, consequently increasing rice growth and yield as a natural bio-fertilizer [10]. The agricultural importance of cyanobacteria in rice cultivation is directly related with their ability to fix nitrogen and other positive effects for plants and soil [11,12]. The beneficial effect of cyanobacteria in decreasing the headspace concentration of methane (CH4) by increasing dissolved oxygen concentration which enhance the methane oxidation at source is also reported [10]. Blue Green Algae (BGA) reduce methane (CH4) flux without reducing rice yields that can be used as a practical mitigation option for minimizing the global warming potential of rice ecosystem. Considering such thing this study was undertaken to find out the effects of soil amendments on CH4 emission during rice cultivation; to determine the soil properties after rice harvest and to determine the growth and yield of rice under different soil amendments.
Materials and Methods
The experiment was carried out during boro season (December 2015 to April 2016). The study was undertaken nearby the Dingaputa haor area located between the latitudes of 24°52′ N to 24.86°N and between the longitudes of 90°58′ E to 90.96°E in the Mohongonj Upazilla, Netrokona District under the Mymensingh division of Bangladesh. BRRI dhan-58 was used as the test crop. This variety was developed by BRRI (Bangladesh Rice Research Institute).
Experimental Design
The experimental design was laid out in a Randomized Complete Block Design (RCBD) with 3 replications. The experimental field was divided into 3 blocks with 6 treatments. Thus, the total numbers of unit plots were 18. The area of each plot was 10m2 (4m × 2.5m). There was 100 cm drain surrounding of each unit of the plot. The total area of the experimental plot was 18 plots x 10 m2 = 180 m2 (Figure 1).
|
|
Legend: Treatments: 6; Replication: 3; Total number of plot: 18; Plot length: 4.0 m; Plot width: 2.5 m; Plot area: 10 m² Peripheral drain: 1m (each side); Internal drain: Block to block: 1 m and Plot to plot: 0.5 m
Fertilizer application
Standard recommended doses of fertilizers were used in the experimental plots. At the time of final land preparation nitrogenous fertilizer in the form of urea (prilled) was applied as basal dose at the rate of 220 kg ha-1 and amounts of urea was applied in 2 equal splits at 30 and 60 days after transplanting. Organic fertilizers were applied after making sub-plots at the time of final land preparation according to the design (Tables 1-3).
Table 1: Fertilizer doses as applied to the experimental plots. |
||||||||||||||||||||
Table 2: Treatment schedule. |
Table 3: Composition of some selected soil amendments. |
||||||||||||||||||||
Source: Humboldt Laboratory, Department of Soil Science, BAU, Mymensingh.
Analytical techniques of gas sample collection
Gas samples were collected by using the closed-chamber method [13] during the rice cultivation. The dimensions of close chamber were 62 × 62 × 112 cm3. Three chambers were installed in each experimental plot. Gas sample was collected at different growth stages to get the CH4 emissions during the cropping season. Gas sample was collected in 50 ml gas-tight syringes at 0, 10- and 20-minutes intervals after chamber placement over the rice planted plot. The samples were analyzed for CH4 by using gas chromatograph equipped with an FID (flame ionization detector). The analysis column used a stainless-steel column packed with Porapak NQ (Q 80-100 mess). The concentration difference between 0, 10 and 20 min give the total emission occurred when gas chamber was closed. The temperature of column, injector and detector were adjusted at 60°C, 120°C, and 220°C, respectively. Methane emission from the paddy field was calculated from the increase in CH4 concentrations per unit surface area of the chamber for a specific time interval. A closed-chamber equation [14] was used to estimate methane fluxes during rice cultivation.
Estimation of methane emission
Methane emission from the paddy field was calculated from the increase in CH4 concentrations per unit surface area of the chamber for a specific time interval. A closed-chamber equation [14] was used to estimate methane fluxes during rice cultivation.
Calculation of CH4 flux:
F = ρ*(V/A)*(Δc/Δt)*273/T
Where
F= methane flux (mg m-2 hr-1)
ρ= gas density (0.714 mg CH4 m-3)
V= volume of the chamber (m3)
A= surface area of chamber (m2)
Δc/Δt= rate of increase of methane gas concentration in
the chamber (mg m-3 hr-1)
T= 273+mean temperature in chamber (°c)
Statistical analysis
The findings were analyzed by partitioning the total variance with the help of computer by using MSTAT program. The treatment means were compared using Duncan's New Multiple Range Test (DMRT) as outlined by [15].
Result and Discussion
A field experiment was carried out to find out the results of the study regarding the effect of different soil amendments on total CH4 emission and rice productivity.
Effect of soil amendments on CH4 emission
CH4 emission rate was significantly affected by different soil amendments (Figure 2). CH4 emission was recorded 0.88 to 2.48 mg m–2 h–1 at 14 DAT where no significant differences were observed among the treatments. Similarly, at 28 DAT or active tillering stage, CH4 emission ranged from 6.12 to 12.94 mg m–2 h–1 where treatment T6 showed the highest (12.94 mg m–2 h–1) and treatment T2 showed the lowest (6.12 mg m–2 h–1) CH4 emission. At 49 DAT or panicle initiation stage, treatment T6 and T2 further showed the highest and lowest CH4 emission (17.64 mg m–2 h–1 and 9.90 mg m–2 h–1 respectively). Similar trend was observed at 70 DAT. At 70 DAT, CH4 emissions peaked in all treatments where highest peak was recorded (30.39 mg m–2 h–1) found in the treatment T6 and the lowest (16.38 mg m–2 h–1) was recorded in T2. Finally, at 91 DAT or ripening stage treatment T6 and T2 further showed the highest and lowest CH4 emission at 18.27 mg m–2 h–1 and 11.73 mg m–2 h–1 respectively. The highest percentage of CH4 emission (30.39%) occurred when the rice plots were treated with 25% Urea+6 ton azolla incorporated ha-1+1 ton azolla dual cropping ha-1 with cyanobacterial mixture(T6) and the lowest percentage of emission was obtained (0.88%) in those plots which were treated with 50% Urea + 4 ton vermicompost ha-1 (T2). Therefore, this result revealed that the azolla with cyanobacterial mixture application as organic amendment was responsible for increasing CH4 emission in rice field as compared to urea or vermicompost. In the study on an average, CH4 emission rate during rice cultivation followed the sequences: T6> T3> T1> T5> T4> T2. [4] studied that the application of azolla incorporated and other organic fertilizers increases CH4 emission than that from inorganic fertilizers application. CH4 emission increased with increasing amounts of rice straw and a peak in CH4 emission at the end of the reproductive stage was observed in all fields receiving rice straw. Total CH4 emissions ranged from 4.04 to 40.8 g CH4 m-2 per growing season and emissions were 2-10-fold greater than from fields with no rice straw [4]. Methane emission was higher during flowering to maturity stages which dropped during later stages before harvesting. Ali MA, et al (2012) [16] Reported that, 25% recommended urea + Azolla Cyanobacteria (1 tha-1) decreased CH4 emission by 11% in low land rice field and rice grain yield was increased by 8%.
|
|
Effect of soil amendments on soil properties
Soil redox potential (Eh): The effect of soil amendments on soil redox potential is presented in Figure 3. From the Figure it is found that the redox potentials significantly decreased with the progress of time and plant growth stages. Eh ranged from –42.87 to –92.40 mV at 14 DAT, –98.23 to –171.33 mV at 28 DAT, –186.33 to –227.00 mV at 49 DAT, –196.00 to –238.33 mV at 70 DAT and 131.00 to –174.00 mV at 91 DAT. At 14 DAT or initial tillering stage, the significant value of Eh was found in T2 (–42.87 mV) and T4 (–92.40 mV) where (T2)50% Urea + Vermicompost (4 t ha-1) showed the less reduction of Eh (–42.87 mV) and treatment T4 (25% Urea + Azolla incorporated (4 t ha-1) + Vermicompost (4 t ha-1) showed the highest reduction of Eh (–92.40 mV). At 28 DAT or active tillering stage, less reduction of Eh was observed from the 50% Urea + Vermicompost (4 t ha-1) in treatment T2 and more reduction of Eh (–171.33 mV) was found in treatment T4 while lowest reduction of soil redox potential of Eh (–98.23 mV) in the treatment T2. At 49 DAT or panicle stage, highest and lowest Soil redox potential (Eh) was found 186.33 mV and –227.00 mV, respectively in the treatments of T2: (50% Urea+4 ton Vermicompost ha-1)and T6: (25% Urea + Azolla incorporated (6 t ha-1)+ Azolla dual cropping (1 t ha-1) with Cyanobacterial Mixture). At 70 DAT or flowering stage, treatment T4 showed the higher capability to reduce the soil redox potential (–238.33 mV) which was not significantly differed (196.00 mV) from T5 (25% Urea + Azolla incorporated (6 t ha-1) + Vermicompost (2 t ha-1). Finally, at 91 DAT or ripening stage, the above significant variation range of Eh revealed that, the lowest (-131.00 mV) and highest (-174.00 mV) reduction of Eh were recorded from the T6 and (196.00 mV) by T4. From the above result, it is found that the application of Azolla cyanobacteria as soil amendments significantly reduced the soil redox potential (Eh). Similar trends of changes in soil Eh was reported by [13]. In this study soil redox potential value (Eh) showed follow the sequence: T2> T4> T5> T1> T3> T6.
|
|
T1: 100% recommended dose of urea (220 kg ha-1)
T2: 50% Urea + Vermicompost (4 t ha-1)
T3: 50% Urea + Azolla incorporated (4 t ha-1)
T4: 25% Urea + Azolla incorporated (4 t ha-1)+ Vermicompost (4 t ha-1)
T5: 25% Urea + Azolla incorporated (6 t ha-1)+ Vermicompost (2 t ha-1),
T6: 25% Urea+Azolla incorporated (6 t ha-1)+ Azolla dual cropping (1 t ha-1) with Cyanobacterial Mixture.
Soil pH after harvest of rice: With the application of soil amendments pH range of post-harvest soil was significantly influenced (Table 4). It was evident that, the higher pH value (6.94) was found in the treatment T6 (25% Urea + Azolla incorporated (6 t ha-1) + Azolla dual cropping (1 t ha-1) with Cyanobacterial Mixture) and the lower (6.63) was found in the treatment T2: 50% Urea + Vermicompost (4 t ha-1). Phy C, et al (2014) [17] Reported that the soil amendments application had significant effect on soil pH.
Table 4: Effect of soil amendments on chemical properties of post-harvest soil. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
**= Significant at 1% level of probability and NS= Not significant
CV= Co–efficient of variation and LSD= Least significant difference
Total Nitrogen: Total Nitrogen content ranged from 0.13 to 0.16% and varied due to the effect of different soil amendments. Table 5 represented that treatments T4, T5 andT6 was most effective for contributing the TN content in soil as compared to other treatments. Kamara A, et al. (2015) [18] Also reported that the Azolla treated soils improved the chemical properties of soil as well as the N content compared to the control or other treated soil.
Organic Carbon: Organic carbon varied from 1.29 to 1.58% where the lowest amount of organic carbon was found from those soils which were not treated by any organic amendments (only 100% recommended dose of urea) while treatment T6 showed the higher percentage of OC (1.58%). This result revealed that only Azolla and cyanobacteria as soil amendment can be produced more OC in soil compared to urea fertilizer and similar observation was also found by [19,20] (Tables 5).
Table 5: Chemical characteristics of pre-sowing soil |
Source: Laboratory Test: Department of soil Science, BAU, Mymensingh -2202.
Organic Matter: Organic matter ranged from 2.32 to 2.84% where the lowest amount of OM was found from those soils which were not treated by any organic amendments (only 100% recommended dose of urea). This result was in agreement with the research work of [19] who also found that the Azolla and cyanobacteria treated soils improved the OM content compared to the control or without Azolla treated soil.
Available Phosphorus: The higher content of phosphorus (14.52 ppm) was recorded from the treatment T4 while T5 and T2 treatment produced statistically lower content of P (10.16 ppm and 10.40 ppm respectively) (Table 6). Kamara A, et al. (2015) [18] Stated that the application of organic fertilizers improved available phosphorus and cation exchange capacity in soils.
Table 6: Physical properties of pre-sowing soil (0-15 cm depth) of the experimental site |
Source: Humboldt Laboratory, Department of Soil Science, BAU, Mymensingh
Exchangeable Potassium: The ranges of K content were 0.07 to 0.10 meq 100g–1 while the highest content was found from those soils the treatments T3 and T4 respectively while, the lowest content (0.07 meq 100g–1) was obtained from T1 but they were statistically identical due to non-significant variation (Table 6).
Available Sulphur: The higher content of sulphur (9.65 ppm) was recorded from the treatment T4 while T5 treated soil produced lowest content of sulphur (5.59 ppm). Kimetu JM, et al (2008) and Mosier AR, et al. (1998) [21,22] Also reported that phosphorus, K, Ca, S and magnesium (Mg) concentrations were not affected or decreased on plots with the longest continuous cropping history where organic amendments were utilized.
Effect of soil amendments on growth and yield contributing characters
Plant height: The plant height ranged from 99.33 (T2: 50% Urea + Vermicompost (4 t ha-1) to 103.00 cm (T4: 25% Urea + Azolla incorporated (4 t ha-1) + Vermicompost (4 t ha-1) and did not vary significantly in different soil amendments. Rani R, et al. (2002) [23] Also conducted a pot experiment in a glass house of Varanasi in Uttar Pradesh to assess the rice production to different combination of vermicompost and nitrogen treatments significantly increased plant height.
Grain yield and Straw yield: Significantly grain yield (ha-1) and straw yield (ha-1) influenced by the use of different soil amendments. From the Table 7, it was observed that, the highest grain yield (6.50 t ha-1) was found in treatment T4 and highest straws yield (8.70 t ha-1) found in the same treatment. Similarly, lowest grain yield (5.37 t ha-1) was found in the treatment T3 and lowest straws yield (7.37 t ha-1) was found in the treatment T3. Ali MA, et al. (2012) [26] Reported that, 25% recommended urea+ Azolla Cyanobacteria (1 t ha-1) increased rice grain yield by 8% in low land rice field. Khan MA, et al. (2007) [26,27] also observed that combined application of NPK and organic fertilizers significantly increased the grain and straw yield of rice.
Table 7: Effect of soil amendments on growth and yield contributing characteristics of BRRI dhan58. |
*, **= Significant at 5% and 1% level of probability, respectively and NS=Not significant
CV= Co–efficient of variation and LSD=Least significant difference
Weight of 1000–grain: Weight of 1000–grain and it was ranged from 23.40g to 24.02 g. In the present study, it was found that 1000–grain weight was showed non-significant variation due to the application of soil amendments. Hoque MA (1999) [25] Also reported that application of organic and inorganic fertilizers increased the 1000-grain weight of rice.
Number of grains panicle–1: The number of grains panicle–1 ranged from 123.7 to 128.3 where the highest number of grains panicle–1 was obtained in treatment T2 and the lowest was recorded in treatment T6. Similar results also found by [24] that recorded as the application of nitrogen with organic fertilizers increased grains number and significantly improve the grain quality (Table 7).
Number of panicle hill–1: The number of panicle hill–1 did not vary significantly due to different soil amendments (Table 7). Number of higher (14.67) and lower (13.00) panicle ranged from T4 andT1, respectively. This result revealed that all the treatments of the present study were produced statistically same number of panicles hill–1
Harvest Index (HI %)
With the application of different soil amendments grain harvest index significantly influenced (Table 7). Harvest Index (HI) of different soil amendments influenced in different way at different stages of BRRI dhan58. It was evident that the higher harvest index (44.71%) was found in the treatment T4and the lower (41.67%) was found with the use of T3. In case of rice production, it was found that organic amendments increased the yield of rice than control treatment.
Conclusions
From the obtained results it was found that the CH4 emission was significantly varied from 0.88 mg m–2 h–1 to 2.48 mg m–2 h–1 at 14 DAT where no significant differences were observed among the treatments. Similar trend of results was also found at 48 DAT while it was ranges from 6.12 mg m–2 h–1 to 12.94 mg m–2 h–1 in treatment T6. The highest CH4 flux was observed in T6 treatment and where the lowest CH4 flus was recorded in treatment T2. However, methane emission showed the highest peak at 70 DAT in all treatments. The highest amount (30.39 mg m–2 h–1) of CH4 emission flux was observed in treatment T6 (25% Urea + Azolla incorporated (6 t ha-1)+ Azolla dual cropping (1 t ha-1) with Cyanobacterial mixture) within the 70 DAT while the lowest (16.38 mg m–2 h–1) was recorded in the treatment T2 (50% Urea + Vermicompost (4 t ha-1). After rice harvest the value of soil properties such as soil pH, total nitrogen, organic carbon, phosphorus, potassium and sulphur was observed 6.94, 0.16%, 1.58%, 14.52 ppm, 0.10 meq 100g–1 and 9.65 ppm, respectively in T6, T4 and T3 treatments. Considering the CH4 emission trend during rice cultivation the treatments sequence may be ranked as T6> T3> T1> T5> T4> T2. On the other hand, on the basis of grain yield the treatments may be ranked as T4> T6> T2> T5> T1> T3. Considering all the above parameters it may be concluded that the application of 25-50% of the recommended Urea along with Azolla incorporated (4 tha-1) and Vermicompost (4 t ha-1) amendment could be suitable for maximizing of rice yield and reducing CH4 emission. From the knowledge of this experiment, rice fields enriched with different soil amendments are the significant source of plants nutrients. Now rice growers would be able to select the suitable soil amendments for rice cultivation considering the negative effect of CH4 gas emission from rice field. It would also help the farmer to select easily the different soil amendments which can give more production on the availability to them. As a result, rice production could be increased through utilization of suitable soil amendments while CH4 gas emission could be controlled from rice field. Considering the above facts of the present study, the following recommendation may be suggested:
- Further study may be needed to ensure the studied performance in another AEZ-9 area for observing the adaptability.
- Different suitable soil amendments may be needed to include for further study to make sure the present findings of the study.
References
- Ahmed S, Li C, Dai G, Zhan M, Wang J, et al. (2009) Greenhouse gas emission from direct seeding paddy fields under different rice tillage systems in central China. Soil Tillage Res 106: 54-61.
- AIS (2008) Agricultural Information Service. Krishi Diary. Khamarbari, Farmgate, Dhaka. pp. 10-25.
- Ali MA, Farouque MG, Haque M, Abid ul Kabir (2012) Influence of Soil Amendments on Mitigating Methane Emission and Sustaining Rice Productivity in Paddy Soil Ecosystems of Bangladesh. J Environ Sci Nat Resour 5: 179-185.
- Ali MA, Oh JH, Kim PJ (2008) Evaluation of silicate iron slag amendment on reducing methane emission from flood water rice farming. Agric Ecosyst Environ 128: 21-26.
- BBS (2014) Bangladesh Bureau of Statistics, The yearbook of Agriculture Statistics. Ministry of planning Government people’s Republic of Bangladesh, Dhaka. pp. 123-127.
- Bharati K, Mohanti SR, Singh DP, Rao VP, Adhya TK (2000) Influence of incorporation or dual cropping of Azolla on methane emission from a flooded alluvial soil planted to rice in eastern India. Agric Ecosyst Environ 79: 73-83.
- Bhuiyan NI, Paul DN, Jabber MA (2002) Feeding the extra million by 2025 challenges for rice research and extension in Bangladesh. A key note paper, National workshop on rice research and extension, Bangladesh Rice Research Institute, Gazipur. Pp: 23-76.
- Denman KL, Brasseur A, Chidthaisong A, Clais PE, Holland O, et al. (2007) The physical science basis Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK/New York. Pp: 499-587.
- Gomez KA, Gomez AA (1984) Statistical Procedure for Agricultural Research. 2nd edition, John Wiley and Sons, New York. Pp: 64-77.
- Hoque MA (1999) Response of BRRI Dhan29 to S, Zn and B supplied from manures and fertilizers, MS Thesis. Department of Soil Science, Bangladesh Agricultural University, Mymensingh.
- Hossain SM, Sharma UC (1991) Response on rice to nitrogen fertilizer in acidic soil of Nagaland. Ind J Agric Sci 61: 660-664.
- IPCC-Intergovernmental Panel on Climate Change (2007) Special Report on Emission Scenario. A special report of Working Group III of IPPC Cambridge University Press, Cambridge, UK.
- Kamara A, Kamara HS, Kamara MS (2015) Effect of rice straw Biosolid on soil quality and the early growth and biomass yield of two rice varieties. Agric Sci 6: 798-806.
- Khan MU, Qasim M, Khan IU, Qasim M, Khan IU (2007) Effect of integrated nutrient management on crop yields in rice-wheat cropping system. Sarhad J Agri 23: 1019-1025.
- Kimetu JM, Lehmann J, Ngoze S, Mugendi DN, Kinyangi JM, et al. (2008) Reversibility of soil productivity decline with organic matter of differing quality along a degradation gradient. Ecosyst 11: 726-739.
- Maclean JL, Dawe DC, Hardy B, Hettel C (2002) Rice Almanac International
Rice Research Institute, Los Banos, Philippines. Pp. 253-270. - Malik FR, Ahmed S, Rizki YM (2001) Utilization of lignocellulosic waste for the preparation of nitrogenous bio-fertilizer. Pakistan J Biolog Sci 4: 1217-1220.
- Mosier AR, Duxbury JM, Frency JR, Heinemeyer O, Minami K, et al. (1998) Mitigation agricultural emissions of methane. Nature and Climate Change 40: 39-80.
- Naser HM, Nagata O, Hatano R (2005) Greenhouse gas fluxes and Global Warming Potential in crop fields on soil dressed peatland in Hokkaido, Japan. Phyton Int J Experi Botany 45: 285-293.
- Phy C, Dejbhimon K, Tulaphitak D, Lawongsa P, Keophila M, et al. (2014) Biosolid amendment to different paddy soils on CH4 production, labile organic carbon, pH and electrical conductivity dynamics: incubation experiment. Int J Environ Rural Develo 5: 7-11.
- Prasanna R, Kumar V, Kumar S, Yadav AK, Tripathi U, et al. (2002) Organic amendments: a potential supplement to nitrogenous fertilizer in rice nutrition. Int J Rice Res 22: 30-37.
- Rajni Rani, Srivastava OP, Rani R (2001) Effect of integration of organics with fertilizer N on rice and N uptake. Fertilizer News 46: 63-65.
- Rolston DE (1986) Gas flux. In: Klute, A. Methods of Soil Analysis, part 1, 2nd edition, Agronomy, Madison, WI. Pp. 1103-1119.
- Sarfaraz M, Mehdi SM, Sadiq M, Hassan G (2002) Effect of sulphur on yield and chemical composition of rice. Sarhad J Agric 18: 411-414.
- Setyanto P, Rosenani ABJ, Khanif M (2004) The effect of Rice cultivars on methane emission from irrigated rice field. Indonesian J Agric Sci 5: 20-31.
- Wang MX, Dai AG, Huang J, Ren LX, Shen RX, et al. (1993) Methane source from China. Scientia Atmospherica Sinica17: 52-64.
- Yan X, Ohara T, Akimoto H (2005) Development of region-specific emission factors and estimation of methane emission from rice fields in the East, Southeast and South Asian Countries. Global Change Biolo 9: 237-254.