Rice is cultivated in both lowland and up- land throughout Indonesia. Lowland rice is rice grown on land that is flooded or irrigated. While, the upland crop typically being rainfed. Rice cultivation in Indonesia, generally cultivated in wetlands (Figure 4.1). According to the Indone- sian Ministry of Public Works (MPW), approxi- mately 60% of Indonesian harvested rice area is irrigated, while the remaining 40% is rainfed.
Irrigated lowland rice yields on average are about 60% higher than rainfed because most of irrigated lowland rice fields are well-watered and heavily fertilized. Lowland rice cultivation is concentrated on Java (largest producer), but is also prevalent on Sumatra and Sulawesi. These three islands are contributing about 90% of to-
tal national rice production (FAO 2020). Though upland rainfed systems and lowland irrigated systems are both well represented, lowland sys- tems tend to be heavily fertilized and can sup- port three crops per year, and as a result account for 80% of Indonesia’s rice growing area and 93% of total production, with 60% larger yields than upland areas (FAO 2020).
In Indonesia, there are typically three rice growing periods or seasons, a single wet season crop followed by two dry season crops. Approx- imately 45% of total production is usually from the wet season crop during October to April.
Indonesia’s main rice growing season for both rainfed and irrigated systems occurs at the onset of the rainy season around October and Novem- ber, with harvesting taking place at the season’s Indonesia is the third largest producer of rice in the world after China and India (FAO 2020). Rice is Indonesia’s primary production system and the most important staple crop. Rice area occupies 25% of total agriculture’s harvested area, with yields averaging 5.2 ton ha-1 between 2015 and 2019 (FAO 2020). Marked it as the highest yields in Southeast Asia, after Vietnam, and exceeded the regional average of 3.8 ton ha-1 by 36% (FAO 2020). According to Statistic Indonesia, the total rice production in 2021 is up to 55.27 million ton (increased 1.14% from 2020) from 10.52 million ha of harvested and total rice consumption reached 31.69 million ton or increased up to 1.12% compared to 2020 due to successful implementation of government policies and action programs in rice intensification. Rice is critical to Indonesia’s food security; nationally, 92% of households are net buyers of rice, including 87% of poor agricultural households who buy more rice than they sell (Sleet and Phoebe 2018). Along with this increasing, about 14% of Indonesia’s GDP comes from the agriculture sector, which is predominantly run by smallholder farmers (93%). In terms of workforce, agricultural sector absorbed more labour during the pandemic due to the decline in the manufacturing sector and other business sectors that encourage more people to become farmers in rural areas.
Food security has become a central issue in various parts of the world i.e., climate change. Climate change may cause negative effect to rice production, a decline that could jeopardize food supply. On the other hand, rice cultivation has been identified as a source of greenhouse gas (GHG) emissions, namely methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). With the potential to be further developed for national food security and exports, the agricultural sector needs to improve productivity exponentially. However, some cultivation methods for increasing rice production are likely to impact negatively on the environment if sustainable systems are not developed to intensify rice cultivation. Hence, this chapter attempts to summarize the information on the impact of climate change, the emission, the strategies to do climate change adaptation and mitigation for improving rice productivity in lowland area, to meet the future food demands.
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Figure 4.1. Rice cultivation in Indonesia
close in April (FAO 2020). In tropical area such as Indonesia, temperature and solar radiation could not be limiting factors for cultivation, thus rice cropping season is planned by a schedule of irrigation or even by farmers arbitrary decision.
The increase of rice production in Indonesia is achieved by implementing rice intensification programs. This program includes balanced fertil- ization, seed and varieties improvement, water management, pest and disease control as well as tools and machinery.
Climate change impact
Climate change has severely impacted all sectors of life, agricultural sector is no exception.
Under the adverse impacts of climate change, producing more rice for the future is an advance challenge. Rainfall is the determining factor for irrigation water supply while temperature con- trols evapotranspiration and affects the length of crop growing season. The frequency of occur- rence of extreme events (flood and drought) are increasing, which causes crop decline. Monsoon dominates Indonesia’s climate (more than 50%) which gives a degree of homogeneity across the region. El Niño is considered as one of the caus- es of forest and land fire in the region. Outbreaks of crop pests and diseases are often connected with this phenomenon. Furthermore, Climate change has led to substantial changes in the dates of planting and harvesting, which has led
to changes in the growing season due to varia- tions and uncertainties in rainfall and tempera- ture, thereby impacting food demand. Naylor et al. (2007) estimated that a 30-day delay in the onset of rainy season will diminish wet season rice production in West/Central Java and East Java/Bali by about 6.5 and 11.0 %, respectively.
Indonesia is particularly vulnerable to sea-level rise because thousands of small islands and tremendous coastlines, with the country ranked fifth highest in the world terms of the size of the population inhabiting lower eleva- tion coastal zones. Encroaching seawater and in- creased salinity in groundwater tables is causing much of the water supply and soil to become too salty to grow crops. Myers et al. (2015) pre- dicted that increasing CO2 concentration over the next 40–60 years will lead to deficiencies of essential elements, including nitrogen (protein), zinc, and iron, in C3 grains.
Mitigating potential food security issues by projecting future rice production in Indonesia through a climate projection and crop simula- tion model is crucial to anticipate the impact of climate change on rice production. Changing rainfall patterns, rising temperature, and inten- sifying solar radiation underclimate change can reduce the rice yield in all three growing sea- sons. Under the Representative Concentration Pathway (RCP) 8.5 in the 2050s, the impact on rice yield in the second dry season may decrease
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Figure 4.2. Projection of irrigated rice yield change in the dry season 2021-2035 and 2036- 2050 for the RCP4.5 and RCP8.5 scenarios using CSIROMK3.6 model (Susanti et al. 2021)
by up to 12 % in Central Java (Ansari et al. 2021).
Susanti et al. (2021) integrated downscaled cli- mate projections and crop simulation model to provide projection of on rice production anom- aly in 2035 and 2050 in Jawa Island using the Representative Concentration Pathway (RCP) 4.5 (stabilization scenario, which means the radia- tive forcing level stabilizes at 4.5 W/m2 before 2100) and 8.5 scenarios (BAU) to provide projec- tion of rice production in Jawa Island. They con- cluded that in the 2050, based on the RCP 4.5 scenario, it is projected that rice production in dry season planting will decrease by 20-30%, ex- cept in West Java, which is projected to increase by 10%, while in the RCP 8.5 scenario, most of Central Java and East Java will experience a de- cline in rice production of > 30% (Figure 4.2).
Impact of temperature increase
Temperature is considered one of the most important factors affecting the rate of devel- opment, growth and crop yields (Rehman et al.
2015). Rice yields are sensitive to the rising of minimum temperatures in the dry season; yields could decrease 10% for every 1°C increase in minimum temperature (Peng et al. 2004). Tem- perature extremely low and beyond optimum can have detrimental effects and negatively af- fects crop development, growth, and ultimately reduces the grain yield (Fahad et al. 2017). The impact of high temperature depends on intensi- ty, duration, and timing of stress, however, there are more negative effects during reproductive stage (Tenorio et al. 2013). High temperature causes various morphological symptoms, such Lowland Rice
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as leaf wilting, leaf curling and yellowing, and reduced tiller number and biomass (Xu et al.
2020). Average temperature elevation of 1°C during rice growing season reduced paddy yield by 6.2%, total milled rice yield by 7.1%–8.0%, head rice yield by 9.0%–13.8%, and total mill- ing revenue by 8.1%–11.0% (Lyman et al. 2013).
Grain-filling rate was increased and the total grain-filling duration was reduced by 21.3%–
37.1% for different genotypes at the grain-fill- ing stage due to exposure to high temperature (Shi et al. 2017). Another effects of temperature increase are water availability, the occurrence of strong winds, and the intensity and duration of sunlight. Moreover, temperature rise increas- es frequency of heat waves and the impacts on pests, weeds, and plant diseases.
Impact of elevated CO2 concentration
Rice as a C3 species has lower respiration rates and higher photosynthetic and metabol- ic efficiencies at high CO2 concentration levels.
The C3 group of plants are more sensitive to an increase in atmospheric CO2 concentration than C4 plants. Increased CO2 concentration enables faster growth due to rapid carbon assimilation (Woodward 1990). The main effects of elevated CO2 on plants are a reduction in transpiration and stomatal conductance, improved water and light-use efficiency, and thus an increase in pho- tosynthetic rate. Elevated CO2 increased grain length and width as well as grain chalkiness but decreased protein concentrations (Jing et al.
2016). However, according to Stigter and Winar- to (2013) rice yield was estimated to increase by 0.5 ton ha-1 for every increase in CO2 concentra- tion.
Impact of changeable precipitation pattern Indonesia’s climate consists simply of one wet season and one dry season each year. The distin- guishing feature of the wet season is that at least 200 mm or more of rain falls per month, and in the dry season mean rainfall is less than that
Figure 4.3. Distribution of farmers who have experienced flood and drought events in Indonesia (the rainfall intensity unit in the legend is mm/year) (Rondhi et al. 2019)
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threshold. However, Indonesian rainfall exhibits substantial variability within the year across dis- tricts as well as within districts over time. There have been changes in precipitation and cycles of droughts and floods triggered by the Austral- asia monsoon and by the El Niño Southern Os- cillation (ENSO) for the past three decades in In- donesia (Naylor R. L. 2007; Boer 2010). Thus, this has led to agricultural production damage, caus- ing negative consequences for rural incomes, food prices, and food security in Indonesia. Rain- fall variability in Indonesia is influenced by many large-scale climate phenomena, one of them is El Niño Southern Oscillation (ENSO). Figure 4.3 showed that more farmers have experienced droughts than floods and farmers outside Java are more vulnerable to climate change (Rondhi et al. 2019).
According to Surmaini et al. (2015), dam- ages to rice crops due to droughts are mostly occurred during dry season planting. The Indo- nesian Ministry of Agriculture has reported that during the El Niño years, damages to crops due to droughts have ranged between 350 and 870 thousand hectares and have led to significant crop production lost. The damage mostly occurs during dry season within May through October as illustrated in Figure. 4.4.
El Niño has played a key role by often lead- ing to droughts resulting in decreased crop yields that could further result in famine in some food insecure regions (Hansen et al. 2011; Iizu- mi et al. 2014), including Indonesia (Naylor et al.
2007; D’Arrigo and Wilson 2008; Surmaini et al.
2015; 2019). Given the strong teleconnection of ENSO and agricultural production, linking vari-
Figure 4.4. Plots of average paddy area planted (dashed line) and average paddy damaged area due to drought (solid line) in Indonesia against calendar year (Surmaini et al. 2015)
Figure 4.5. Distribution of simulated rice yields for crops planted on May 1 in Bojongsoang and Ciparay of Bandung District associated with the SOI phases I +III (El Niño), SOI phases II + IV (La Niña), and SOI phase V (Neutral) of March/April) (Boer and Surmaini, 2020)
SOI = Southern Oscillation Index Lowland Rice
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ations in crop yields with ENSO phases has the potential benefit for food monitoring and early warning systems. There are multiple metrics that can be use as ENSO indices; however, there is no consensus within the scientific community as to which index best defines ENSO years or the strength, timing, and duration of events (Han- ley et al. 2003). Boer and Surmaini (2020) used Southern Oscillation Index (SOI) March/April phase in conjunction with crop simulation to determine the likely rice yield in different ENSO scenario in Bandung District. The result showed that the averaged rice planted on dry season have experienced the lowest simulated yields following the El Niño events (Figure 4.5).
Stronger ENSO climate oscillations are ex- pected in the near future, as climate forecasts project more frequent extreme El Niño and La Niña conditions. In terms of future climate pro- jection, Indonesia is predicted to experience temperature increases of approximately 0.8°C
by 2030 and will be occurred at a rate highly variable across regions of 1.16°C to 1.58°C until 2070 (Susandi 2007). Increasing temperature causes pest’s reproduction, survival, spread and population dynamics as well as the relationships between pests, the environment, and natural enemies (Skendži´c et al. 2021). It is reported that a reduction in crop yields will occur in some parts of Asia at a level of 2.5-10% until 2020 and 5-30% until 2050 (Tesfaye et al. 2017). Studies in Indonesia estimated that climate change will likely decrease rice yield by 4% per year and it is predicted that yield reduction will be at a level of 20.3- 27.1% until 2050 (Bappenas 2011 and World Bank 2007).