**6. Management of rice paddy ecosystem to cope with climate change and sustainable rice production**

#### **6.1. Soil conservation with suitable cover crops and minimum tillage or no tillage**

Soil conservation practices such as suitable cover crops, mulches, and minimum tillage (one or two plowing with proper leveling) may be introduced in rice farming not only to control soil erosion and land degradation, while reduce production costs to sustain rice productivity. In addition, conservation tillage will improve environmental quality by lowering GHG emissions (less air pollution) through decreasing the use of diesel fuel and nonburning of rice residues [29]. It has also reported that the no-tillage system in Korean paddy field with silicate fertilization decreased total seasonal CH<sup>4</sup> flux by 53 and 36%, while maximizing grain yield by 18 and 13% over the control tillage and control no-tillage systems, respectively [30]. Soil properties were also improved with silicate fertilization under the no-tillage system. It was [31] reported that tillage (after the harvest of late rice) with the incorporation of stubble (3.5 t ha−<sup>1</sup> ) in the winter fallow season significantly decreased both the net GWP and the GHGI while maintained a high grain yield (13.0–13.3 t ha−<sup>1</sup> yr−<sup>1</sup> ) in the double-cropping rice system.

### **6.2. Introducing direct seeded rice (DSR) and puddle rice transplanting (PRT) methods**

Direct seeded rice (DSR) is a process of establishing a rice crop which is done by seeds sown in the field rather than by transplanting seedlings from the nursery. The practice of direct seeding instead of transplanting resulted in a 16–54% reduction in CH<sup>4</sup> emission [32]. CH4 emission was more significantly reduced under dry-direct seeding compared to wet-direct seeding. However, grain yield in direct seeded rice (DSR) was found lower than Puddle transplanted rice (PTR), probably due to poor crop stand, high percentage of panicle sterility, and higher weed and root-knot nematode infestation [33]. It was also observed that grain yield of direct-seeded rice (9.0 Mg ha−<sup>1</sup> ) was identical to grain yield of transplanted-flooded rice [34]. Average yield penalty of around 10% was observed for the direct seeded rice (DSR) compared with puddle transplanted rice [34]. It was reported [35] that over the rice-growing season, cumulative CH4 emissions were significantly higher in puddle transplanted rice compared to the direct seeded rice production system.

#### **6.3. Water management for sustainable rice production and minimizing GHG emissions**

anticipated, and temperatures are projected to continue to increase by about 0.7–0.9°C [25]. Furthermore, sea levels have risen by 1–3 mm/year, marginally higher than the global average [24]. Rice production systems of this region have become increasingly threatened by the effects of climate change as a large portion of the rice-growing areas are located in especially vulnerable regions. A decrease of 10% in rice yield has been found to be associated with every 1°C increase in temperature [24], while the yield of dry-season rice crops in the Philippines decreased by as much as 15% for each 1°C increase in the growing season mean temperature. These temperature and aggravating climate change effects may cause a decline in the world rice production, which have already shown negative effects on agricultural production. By 2100, Indonesia, the Philippines, Thailand, and Vietnam are projected to experience a potential fall of about 50% in rice yield due to the occurrence of extreme climatic events [24, 26]. Furthermore, rice yield would be affected severely due to sea level rise and intrusion of saline water in the coastal area, which will hamper rice growth and yield. Rising sea levels in association with heavy monsoon rainfall will create serious waterlogging and prolonged stagnant floods in major rice-growing, low lying mega-deltas in Southeast Asia, which ultimately deteriorate rice production in the deltas since only a few low-yielding rice varieties have evolved to withstand such conditions [27]. The recent natural disasters such as flash floods caused by water of Indian Meghalaya state and excessive rainfall in the low lying ha or areas of Bangladesh [28] badly affected the only cultivated rice crop, the Boro rice (winter rice), at this region; however, due to rice duck mixed farming, the overall productivity and net profit were recovered to some extent (**Table 4**).

**6. Management of rice paddy ecosystem to cope with climate change** 

**6.1. Soil conservation with suitable cover crops and minimum tillage or no tillage**

Soil conservation practices such as suitable cover crops, mulches, and minimum tillage (one or two plowing with proper leveling) may be introduced in rice farming not only to control soil erosion and land degradation, while reduce production costs to sustain rice productivity. In addition, conservation tillage will improve environmental quality by lowering GHG emissions (less air pollution) through decreasing the use of diesel fuel and nonburning of rice residues [29]. It has also reported that the no-tillage system in Korean paddy field with

yield by 18 and 13% over the control tillage and control no-tillage systems, respectively [30]. Soil properties were also improved with silicate fertilization under the no-tillage system. It was [31] reported that tillage (after the harvest of late rice) with the incorporation of stubble

Direct seeded rice (DSR) is a process of establishing a rice crop which is done by seeds sown in the field rather than by transplanting seedlings from the nursery. The practice of direct

**6.2. Introducing direct seeded rice (DSR) and puddle rice transplanting (PRT)** 

) in the winter fallow season significantly decreased both the net GWP and the GHGI

flux by 53 and 36%, while maximizing grain

) in the double-cropping rice system.

**and sustainable rice production**

100 Soil Contamination and Alternatives for Sustainable Development

silicate fertilization decreased total seasonal CH<sup>4</sup>

while maintained a high grain yield (13.0–13.3 t ha−<sup>1</sup> yr−<sup>1</sup>

(3.5 t ha−<sup>1</sup>

**methods**

Water management influences rice yield and CH<sup>4</sup> and N2 O emissions from rice cultivation systems. Irrigated rice fields are an integral part of the rice production system in Asian countries, which contribute about 75% to global rice production. Single or multiple drainages during a rice growing season (e.g., AWD) are reported to reduce CH<sup>4</sup> emissions by 48–93% compared to those observed under continuous flooding systems [36, 37]. Mid-season drainage and intermittent flooding were found effective for increasing productivity and quality of rice as well as reducing methane emissions in Japan [38]. The AWD field showed the same yield as continuous flooded field, but saved 16–24% in water costs and 20–25% in production costs. Most farmers in China, Japan, and South Korea have been practicing this mid-season drainage (5–7 days dry out) to increase rice yield and decrease GHG emissions. Mid-season drainage and intermittent irrigations may reduce methane emissions by about 50%. It was also reported [39] that the AWDI treatment (irrigation applied when water level in the pipe fell 15 cm) showed superiority for the rice yield performance and seasonal CH<sup>4</sup> emission reduction, water savings, and maximum water productivity index. However, the AWD irrigation technique increased the N<sup>2</sup> O emission by 97%, especially in DS [40].

#### **6.4. Diverse farm management practices, soil amendments, and rice cropping systems**

Feasible management approaches based on agroecosystem have to be adopted to sustain agricultural productivity in the changing climatic conditions. For example, the ground cover rice production system (GCRPS), through which paddy soils are covered by thin plastic films to conserve soil moisture nearly at saturated status, is a promising technology to increase yields with less irrigation water. However, increased soil aeration and temperature under GCRPS may cause more CH4 to N2 O emissions compared to conventional techniques. Yao et al. [41] reported that the GHG emissions for the ground cover rice production system (GCRPS, i.e., paddy soils being covered by thin plastic film) were found significantly lower (1973 kg CO<sup>2</sup> eq ha−<sup>1</sup> ) than that of traditional cultivation (4186 kg CO<sup>2</sup> eq ha−<sup>1</sup> ). Total seasonal CH<sup>4</sup> emissions under GCRPS were on average 80% lower as compared to the traditional rice cultivation. The yield-scaled GHG emissions from GCRPS were further reduced from 377 to 222 kg CO2 eq Mg−<sup>1</sup> as N2 O emissions greatly decreased while yields increased. The system of rice intensification (SRI), an agro-ecological methodology, could be a feasible technique to sustain rice productivity by changing the management of plants, soil, water, and nutrients. Successful application of SRI of increased paddy yield by 50–100% while using less inputs, in particular water, (farmers were able to reduce their water requirements by about 25–50%) [42] has already been reported. Suitable rice cropping patterns, rotations, and mixed rice-duck-fish farming hold the potential scope to sustain agricultural productivity and controlling GHG emissions in the changing climatic conditions. For example, in the Philippines, fish or ducks have been raised with rice as well as legumes such as mung bean (*Vigna radiata*), groundnut (*Arachis hypogaea*), and soybean (*Glycine max*) after two rice dropping. Rotation of crops that have their most drought-sensitive phase in different phases of the growing season may prove a valuable adaptation to limited water resources. Haque et al. reported that the nonrice-based cropping patterns had lower GWPs than the rice-rice-based cropping patterns [43]. Ali et al. reported that CH4 emissions from wetland paddy ecosystems were significantly decreased by integrated rice duck farming [28]. It has been reported that azolla application in rice field increased CH4 emission, probably due to the exudation of azolla root and decomposition of dead azolla. In contrast, reverse report on CH<sup>4</sup> emission was also found from rice soil ecosystems, probably due to the increase in redox potential in the root region and dissolved oxygen concentration at the soil-water interface. Azolla cover increased N<sup>2</sup> O emission from rice paddies due to N-fixation by azolla providing a source for N<sup>2</sup> O production through nitrification and de-nitrification, especially when the azolla died [44]. CH4 emissions have been reported to increase when crop residues are incorporated prior to planting due to higher amounts of readily available carbon stimulating soil microbial activity. Sander et al. reported that incorporation of rice residues immediately after harvest and subsequent aerobic decomposition of the residues before soil flooding for the next crop reduced CH<sup>4</sup> emissions by 2.5–5 times and also improved nutrient cycling in paddy field [45]. It was also reported that residue incorporation accelerated CH4 and N2 O emissions from irrigated rice field compared to residues (ryegrass and serradella) left on the soil surface. The open burning of crop residues emits CO<sup>2</sup> , CH4 , and N<sup>2</sup> O. Ali et al. [17] reported that silicate slag and phospho-gypsum amendments with nitrogenous fertilizer in rice cultivation significantly decreased seasonal CH<sup>4</sup> flux by 16–20% and increased rice yield by 13–18% in Korean paddy soil, whereas 12–21% reduction in total seasonal CH4 flux and 5–18% increase in rice grain yield were found in the upland rice paddy soils of Bangladesh [46]. Seasonal cumulative CH<sup>4</sup> and N2 O emissions, GWPs, and yield scaled greenhouse gas emissions were decreased by combined application of Azollacyanobacterial mixture with silicate slag, phospho-gypsum, and biochar amendments in rice paddy soils of Japan, Korea, and Bangladesh (**Table 2**) [18]. Site-specific nutrient management (SSNM) for rice developed by IRRI (2006) in Asia [47] enables rice farmers to tailor nutrient management to the specific conditions of their fields, and provides a framework for nutrientbased management practices for rice. The increase in annual grain yield with use of SSNM in on-farm evaluation trials averaged 0.9 t/ha in southern India, 0.7 t/ha in the Philippines, and 0.7 t/ha in southern Vietnam [48]. Climatic stress tolerant rice cultivars such as drought, salt/ saline, and submergence tolerant rice cultivars have to be developed to cope in the real field stress situation. It was reported [49] that indica-type rice cultivars had significantly higher yield-scaled GWP (1101 kg CO<sup>2</sup> equiv. Mg−<sup>1</sup> ) compared to Japonica (711 kg CO<sup>2</sup> equiv. Mg−<sup>1</sup> ) type rice cultivar. It was also reported that AWD irrigation practice reduced CH<sup>4</sup> emissions by 24–41%, 26–48% compared with continuous flooding, however, an increase in N<sup>2</sup> O emission

was observed in both seasons [50]. It was also reported that biochar application in paddy soil

In the context of global climate change, environment friendly agricultural management practices such as conservation tillage, rice seedling transplanting or direct line seeding, alternate wet and dry irrigation (AWDI), mid-season drainage, soil amendments with biochar, vermicompost, silicate slag and phospho-gypsum, site specific rice based cropping patterns and integrated plant nutrients system (IPNS) should be followed to ensure food security, while mitigating greenhouse gas emissions and global warming potentials. Furthermore, Azollacyanobacterial dual cropping with rice, introducing N-fixing legumes and duckling rearing with flood water rice cultivation could be practiced to sustain overall agricultural productiv-

emission [51].

http://dx.doi.org/10.5772/intechopen.83548

103

Management of Paddy Soil towards Low Greenhouse Gas Emissions and Sustainable Rice…

and Sitara Amin<sup>4</sup>

O emission, while increased CH<sup>4</sup>

ity and minimizing greenhouse gases intensity in the changing climatic conditions.

, Pil Joo Kim3

1 Department of Environmental Science, Bangladesh Agricultural University, Mymensingh,

[1] FAO (Food and Agricultural Organization of the United Nations). OECD-FAO Agri-

[2] Gagnon B, Ziadi N, Rochette P, Chantigny MH, Angers DH. Fertilizer source influenced nitrous oxide emissions from a clay soil under corn. Soil Science Society of America

[3] International Rice Research Institute. Rice Facts. Available from: http://irri.org [Accessed:

2 Soil Science Lab., Graduate School of Horticulture, Chiba University, Matsudo, Chiba,

3 Soil Chemistry Lab., Gyeongsang National University, Jinju, Republic of Korea 4 Department of Biology, Mymensingh Girls' Cadet College, People's Republic of

\*, Kazuyuki Inubushi<sup>2</sup>

\*Address all correspondence to: litonaslam@yahoo.com

significantly decreased N<sup>2</sup>

**7. Conclusion**

**Author details**

Japan

Bangladesh

**References**

Muhammad Aslam Ali<sup>1</sup>

People's Republic of Bangladesh

cultural Outlook 2011-2030. 2009

Journal. 2011;**75**(2):595-604

August 24, 2013]

was observed in both seasons [50]. It was also reported that biochar application in paddy soil significantly decreased N<sup>2</sup> O emission, while increased CH<sup>4</sup> emission [51].
