Revolutionizing Rice Farming: Maximizing Yield with Minimal Water to Sustain the Hungry Planet

Abstract

Increasing rice yield while reducing water usage is crucial to feed growing population. This chapter explores techniques to enhance irrigation efficiency and water productivity in rice farming while minimizing negative impacts like groundwater depletion, land subsidence, saltwater intrusion, and soil degradation. Modern techniques for rice farming bring significant benefits by increasing productivity, reducing water usage, and conserving natural resources. Promising techniques include direct-seeded rice, aerobic rice, drip-irrigated rice, saturated soil culture, IoT-based automated irrigation, and the system of rice intensification (SRI). For example, drip-irrigated rice increases yield by up to 20% using 30–50% less water, and the SRI boosts yield by up to 50% with 25–50% less water. Implementing these techniques improves rice productivity, income, food security, and water conservation. However, effectiveness varies based on soil, climate, labor force, and socio-economic status. Selecting suitable water-saving methods is crucial for maximizing farmer livelihoods while ensuring environmental safety.

1. Introduction

India, with limited freshwater resources (only 4% of world’s fresh water) is faced with the challenge of supporting its 1.39 billion population (20% of the global population) and their water demands. The three main water-consuming sectors in 1977 were agriculture (376.1 Billion Cubic Meters (BCM)), industry (14.16 BCM), and domestic use (12.46 BCM), totaling 403.3 BCM. Over the years, this has steadily risen to around 761 BCM in 2018, with agriculture alone making up 90.4% of the water consumption [1]. India’s per capita water availability has decreased dramatically from 5600 m³ in 1951 to 1481 m³ in 2021 and is projected to decline further to below the water-stressed norm of 1700 m³ per year by 2051. This decrease in water availability is rapidly transitioning India from a water-stressed to a water-scarce country, with many regions facing compromised water supplies to its citizen. The majority of India’s water stress is due to poor water management rather than physical scarcity [1]. According to National Institution for Transforming India (NITI) Aayog (2018), the country faces a significant water crisis, with most cities lacking a 24-hour supply of drinking water and most households lacking access to safe drinking water. Approximately, 75% of residences lack on-premises access to safe drinking water, while 84% of rural households lack access to piped water. The growing population, rapid urbanization, and industrialization, along with the increased cropping intensity, has resulted in competing demand for water in India [2]. There is a growing concern among the citizens of India regarding an impending water crisis in the country.

India has 53.4% of its total land area under arid (15.8%) and semi-arid (37.6%) regions, where water scarcity deters agricultural growth and development. More than 45% of annual agricultural production comes from 18 to 20% of the world’s irrigated land using 70% of all freshwater withdrawals. Irrigated agriculture is at least twice as productive per unit of land as compared to rainfed agriculture, enabling for more crop diversification and intensification in irrigated areas. Rice is the staple food for more than half of the world’s population, and as such, its production has a significant role in achieving global food security. Rice is one of the most water-intensive crops and it is estimated that rice cultivation accounts for up to 30% of the world’s freshwater withdrawals, with some regions heavily reliant on it for their water supply in [3]. However, traditional rice farming practices have resulted in inefficient use of resources, environmental degradation, and lower yields. Some of the major problems of traditional rice farming practices include Overuse of water: Traditional rice farming practices involve the flooding of rice paddies with water to control weeds and pests. However, this method leads to the overuse of water and environmental problems such as water pollution and degradation of aquatic habitats [4]. Low yields: Traditional rice farming practices often result in low yields due to inefficient use of fertilizers and other inputs. Soil degradation: Traditional rice farming practices can lead to soil degradation due to puddling which facilitate hardpan development, and continuous use of chemical fertilizers and pesticides, which harm beneficial organisms and promote soil degradation [5]. Dependence on external inputs: It often relies on application of external inputs such as chemical fertilizers, pesticides, and herbicides, which can be expensive and lead to environmental pollution [6]. Labor-intensive: Traditional rice farming practices are often labor-intensive, requiring significant manual labor for completing tasks such as planting, weeding, and harvesting. This can be a significant constraint for small-scale farmers with limited access to labor. Vulnerability to climate change: Traditional rice farming practices are often vulnerable to the impacts of climate change, such as droughts, floods, and pest outbreaks [7]. Economic inefficiency: Traditional rice farming practices can be economically inefficient due to the high cost of inputs, low yields, and dependence on external inputs [8].

1.1 Declining groundwater table

The extraction of groundwater increased as farmers shifted from the use of monoblock water pumps in the 1980s to submersible pumps to irrigate paddy crop. In addition, the incentivizing of irrigation leads to irrational increase in the number of electric tube wells and subsequently consistent drop in groundwater table. In the last two decades, the groundwater level dropped drastically to 150 ft. to 200 ft. from 30 ft. to 60 ft. in most parts of Punjab due to indiscriminate extraction [9]. Over exploitation has made groundwater not only scarce but also increasingly alkaline. Farmers often borrow money from informal and formal sources to install tube wells and purchase powerful submersible pumps [10]. This has caused indebtedness resulting farmers suicides in many places.

1.2 Food security nexus water availability

According to the NITI Aayog’s Composite Water Management Index (CWMI) report-2019, India is facing a significant risk to its food security. Also, the country’s top ten agricultural producing states are struggling to manage their water resources effectively. India has been classified as the highest drought-prone country in the world by the world water resources institute in 2019 based on drought intensity, water stress, and vulnerability to drought, population, crop, and livestock density. Out of 634 districts in India, only 38% (241 districts) are resilient to drought, while the rest are vulnerable to varying degrees of severity: mild (180 districts), moderate (80 districts), and severe (40 districts). Only ten states in the country have more than 50% of areas that are resilient to drought or dry conditions. The water quality of rivers and lakes in India is poor, with most of the river water (70%) being unsafe for consumption due to contamination from various sources, including industries, urbanization, and agricultural chemicals [11]. As a result, India ranks 120th out of 122 countries in the Water Quality Index [1].

1.3 Climate change nexus agriculture and its impact on water resource

Climate change is affecting rainfall patterns, and droughts are becoming more frequent and severe in many rice-growing regions. By increasing irrigation use efficiency, farmers can become less reliant on rainfall and more resilient to the effects of climate change. It also reduces the amount of water, energy, and other inputs required for rice cultivation, resulting in a more sustainable production system. Droughts are becoming more severe and persistent, exacerbated by climate change, in both irrigated and rainfed agriculture around the world, posing a greater risk to rural livelihoods by reducing crop and livestock output [7, 12]. This emphasizes the need for water resource development, conservation, and efficient use.

1.4 Low water productivity

India has one of the lowest values of water use efficiency (US$ 1.9/m³) as compared to countries like Australia, USA, Brazil, Malaysia, China, South Africa, Mexico, Turkey and many Southeast Asian countries, which have an average water use efficiency of $15 per cubic meter [13]. Rice, a crop that requires a large amount of water, accounts for 50% of freshwater usage in agriculture. The water use efficiency of rice is also very low and the lowest among field crops [14]. In the state of Punjab, despite facing severe water stress, rice production relies entirely on irrigation and has a concerning annual groundwater extraction rate of 165.8%. Similarly, the trend of groundwater depletion is severe in Haryana (136.9%), Rajasthan (139.9%) followed by Tamil Nadu (80.9%) [15].

1.5 Deteriorating water quality

Pollution caused by various factors such as urbanization, industrialization, and the increased use of fertilizers and pesticides has led to significant deterioration in both surface water and groundwater quality in India. A major cause of concern is the discharge of untreated or inadequately treated industrial waste, effluents, and sewage into rivers and rivulets, which demands immediate attention [16]. Unfortunately, traditional water bodies like ponds and wells in rural areas are also at risk. Many have already been filled or encroached upon, while others have been turned into dumping grounds [17]. To make matters worse, the mixing of stormwater and sewage in many municipal towns has resulted in the contamination of water resources. A report suggests that nearly 50–60% of groundwater is still fresh and fit for consumption, 20–30% is moderately saline and of marginal quality. However, 15–25% of groundwater is saline, alkaline, and unsuitable for irrigation.

As water resources become increasingly scarce, finding sustainable solutions to manage and allocate this precious resource is becoming more critical. Moreover, irrigation accounts for a significant proportion of rice production cost, making it essential to improve irrigation efficiency to address the water crisis while simultaneously increasing yields and reducing production costs. Several agronomic technologies and production methods are available for rice that can enhance water productivity. However, each technology comes with its own practical difficulties, despite its ability to increase grain yield, save water, and reduce GHG emissions. Therefore, it is essential to study the advantages, disadvantages, and future research needs of each technology to make informed decisions about their use.

2. Technologies for saving irrigation water in rice cultivation

2.1 System of Rice Intensification

In recent years, the System of Rice Intensification (SRI) has gained attention as a revolutionary approach to rice production, offering significant opportunities for farmers to increase yields, reduce input costs, and improve environmental sustainability [18]. The SRI is a holistic approach to rice cultivation that emphasizes principles such as transplanting single, young seedlings (13–15 days old), keeping the soil moist rather than flooded, cono weeding, using organic inputs, and using wider spacing (25 × 25 cm) between plants (Figure 1). The approach is founded on the principle that rice plants do not need to be flooded to grow optimally, and by managing the plant’s growth environment more effectively, farmers can achieve higher yields with fewer inputs. These practices promote vigorous root growth, which in turn leads to healthier plants and higher yields [19]. The method also promotes the use of locally available inputs and promotes organic farming practices. By using fewer inputs and promoting soil health, SRI can also reduce input costs, making it a more economically viable approach for small-scale farmers [6]. SRI has proven to be a highly effective approach that offers significant environmental and economic advantages. With over a 60% increase in yield, it has also helped to reduce GHG emission by 40%, ground-water usage by 60%, and fossil energy consumption by 74% per kilogram of rice produced [20]. A review of 78 studies comparing SRI to traditional rice cultivation methods found that SRI resulted in higher grain yields in 80% of evaluations, yielding 24% more than Best Management Practices (BMPs) and 56% more than Farmer Practices (FPs) while reducing input of seed, water, and fertilizer, making it an effective method for increasing production with fewer resources [21]. The evaluation of SRI in India found that it increased yield by 60%, while reducing net GHG emissions by 40%, decreasing groundwater depletion by 60%, and reducing fossil-energy use by 74% [20].

Figure 1.

System of rice intensification.

However, despite its potential benefits, the adoption of SRI has been limited due to several constraints. One of the most significant constraints is the lack of awareness and understanding of the SRI approach among farmers and extension workers. This has led to limited adoption and scaling of the approach, particularly in areas where traditional rice farming practices are deeply entrenched. Another constraint is the lack of access to appropriate inputs. SRI requires inputs such as compost and organic matter, which may not be readily available or affordable for many small-scale farmers [6]. Additionally, the approach requires significant changes in traditional rice farming practices, which may be difficult for some farmers to adopt. Despite these challenges, there are several actions that can be taken to promote the adoption and scaling of the SRI approach. First, there is a need for increased awareness and education about the approach among farmers and extension workers. This can be achieved through training and education programs that highlight the benefits of the approach and provide guidance on how to implement it effectively [22]. Secondly, there is a need for increased investment in research and development to identify and promote appropriate inputs and technologies for SRI. This can include the development of locally appropriate composting techniques and the use of innovative technologies such as precision agriculture [22]. Thirdly, there is a need for policy and institutional support to promote the adoption and scaling of SRI. This can include the provision of financial incentives and technical support for farmers to adopt the approach, as well as the establishment of policies and regulations that can promote sustainable and environmentally friendly farming practices.

2.2 Saturated soil culture

Rice cultivation has traditionally relied on flooding the fields with water to create an anaerobic environment for the rice plants. However, this method is not sustainable and can lead to significant water loss through percolation. To address this issue, alternative methods viz. saturated soil culture (SSC) has been developed. In SSC, the water loss through percolation is significantly lower because the soil is kept at saturation level, without flooding the field. SSC also reduces the need for frequent irrigation (Figure 2). This makes SSC a more sustainable and water-efficient method of rice cultivation compared to conventional methods. In addition, SSC has several advantages over conventional flooded rice cultivation, including higher yields, reduced greenhouse gas emissions, improved nutrient use efficiency, and improved soil health. In SSC the crop roots are supplied with sufficient oxygen, which can improve crop growth and productivity. SSC has been shown to increase water use efficiency by reducing the loss of unproductive water outflows, allowing more water to be utilized by the rice plants [23]. It is important to note that the yield benefits of SSC can be impacted by various factors, such as water management practices, soil type, and climatic conditions. Careful management of water levels, nutrient inputs, and pest and disease control is necessary to maximize the yield potential of SSC. SSC can increase rice yields by up to 50% compared to traditional upland rice cultivation methods [24]. Sometimes, implementing the SSC practice may cause a decline in rice yields if irrigation is not managed properly [25]. Since SSC involves the alternate wetting and drying of the soil, weed growth can be a problem. Farmers may need to implement additional weed management practices to control weed growth [26]. In areas where the water used for irrigation is saline, SSC can lead to the accumulation of salt in the soil, which can reduce crop growth and productivity. SSC is suitable for regions with high rainfall or access to irrigation water, as the soil needs to be kept consistently wet. It is also best suited to soils that have good water-holding capacity, such as clay soils. Since the water level is maintained just below the soil surface, the methane emission from SSC is lower than those from traditional flooded rice cultivation. The impact of SSC on GHG emissions and yield depends on various factors, including the management practices used and the soil type [4]. However, SSC can lead to increased emissions of nitrous oxide, a potent GHG, due to the intermittent flooding and alternate wetting and drying.

Figure 2.

Saturated soil culture.

Compared to traditional farmer practice, the use of saturation soil irrigation resulted in a reduction of 10, 18, and 14% in plant height, tillers, and leaves number, respectively. However, when soil was saturated weekly at 120%, it showed higher irrigation productivity (0.69 kg/m³), rainwater productivity (1.02 kg/m³), and water-saving (90.53%) with minimal yield reduction (5 × 10⁻³ kg/m³) [27]. Yanti et al. conducted a study to investigate the impact of water availability on the growth of local rice varieties. The results indicated that plant height was unaffected by water availability, while the number of tillers was influenced. Tiller formation was observed during the vegetative phase, approximately 28 days after planting, until the start of the generative phase, around 55 days after planting. During the generative phase, unproductive tillers were eliminated or dried up [28].

2.3 Aerobic rice system

Aerobic rice approach involves cultivating rice in aerobic soil conditions, with lower water inputs and without flooding the fields. Aerobic rice cultivation requires 30–50% less water than traditional flooded rice paddies, making it a more sustainable and environmentally friendly approach [29]. By eliminating flooding, aerobic rice cultivation significantly reduces methane emissions, a potent greenhouse gas produced by traditional rice farming (Figure 3). Although aerobic rice systems have the potential to produce yields similar to or higher than those of traditional flooded rice systems, the success of the system may be influenced by a range of factors, including climate, soil conditions, and crop management practices. Proper soil management is critical to successful aerobic rice cultivation, including effective weed and pest control and nutrient management [30]. The adoption of aerobic rice systems requires changes in crop management practices, such as nutrient management, weed management, and planting density. Farmers may need training and support to adopt these new practices successfully. Aerobic rice systems require well-drained soils with good organic matter content. In areas where soil is poorly drained or low in organic matter, additional soil management practices may be necessary to ensure the success of aerobic rice systems. In an aerobic rice system, the presence of oxygen in the soil promotes the growth of aerobic microorganisms that decompose organic matter at a faster rate compared to anaerobic decomposition in waterlogged conditions [31]. This faster rate of decomposition can result in a decrease in soil organic carbon content over time, as compared to soil under waterlogged conditions. However, an aerobic rice system may offer other benefits such as improved plant productivity, better nutrient use efficiency, and reduced greenhouse gas emissions. Soil submergence or waterlogging in rice leads to less oxygen, favoring slow anaerobic decomposition and buildup of organic carbon, improving soil fertility. It also accumulates sediment and nutrients, altering soil structure and nutrient availability, affecting plant growth and ecosystem health. However, prolonged submergence may reduce productivity and increase disease susceptibility [32]. According to the survey conducted among aerobic rice farmers, several factors favored the adoption of the system, such as ease of operation due to direct seeding, an increase in resource-use efficiency, particularly for labor, higher net profitability, water-saving through reduced irrigation, and the option for crop diversification in mixed-cropping systems. Conversely, factors that discouraged repeat plantings included the unavailability of suitable fine grain basmati varieties, problems with weeds and diseases, poor germination, spikelet sterility, frequent irrigation requirements, low yields, and unsuitable soil types [33].

Figure 3.

Aerobic rice system of rice cultivation.

Here are some potential areas for new research in aerobic rice systems: Crop management practices: There is a need to develop crop management practices that are specific to aerobic rice cultivation, such as optimizing fertilizer use, irrigation scheduling, weed control, and pest management. In addition, research is needed to identify the most suitable rice varieties for aerobic conditions, and to develop improved breeding strategies for these varieties. Soil health: The long-term effects of aerobic rice cultivation on soil health and fertility are not yet fully understood, and there is a need for research to evaluate the impacts of different management practices on soil properties, including nutrient availability, organic matter content, and soil structure [31, 32]. Climate resilience: As aerobic rice systems are more susceptible to drought and other climate-related stresses than flooded systems, research is needed to identify strategies to increase the resilience of these systems to climate change, such as the development of drought-tolerant rice varieties or the use of conservation agriculture practices. Water use efficiency: Aerobic rice systems typically use less water than flooded systems, but there is a need for research to optimize irrigation practices and improve water use efficiency in these systems. Economic viability: The economic viability of aerobic rice system compared to flooded rice systems is not yet fully understood. Research is needed to evaluate the economic costs and benefits of aerobic rice cultivation, and to identify strategies to improve profitability and marketability of the produce.

2.4 Alternate wetting and drying

Alternate wetting and drying (AWD) technique involves allowing the paddy fields to dry out periodically instead of keeping them continuously flooded. This method is gaining popularity among rice farmers because it can reduce water use while maintaining or even increasing crop yields (20%), reducing methane emissions by up to 50% and increase oxygen availability to the roots [34]. In AWD, farmers must monitor the soil moisture level using a water level indicator (Figure 4). Once the water level reaches a certain point, the farmer stops the irrigation and allows the soil to dry. When the soil reaches a certain dryness level, the farmer resumes irrigation. This process is repeated throughout the growing season, depending on the rice variety and weather conditions. AWD requires careful monitoring of the soil moisture level to avoid under or over-irrigation. IRRI’s “safe AWD” recommendations, intended to minimize yield reductions, are that the soil is dried until soil water depth reaches 15 cm below the surface and that the field is re-irrigated to a standing water depth of around 5 cm [35].

Figure 4.

Alternate wetting and drying.

The benefits of AWD can vary depending on the rice variety, soil type, and weather conditions. Therefore, farmers may need to adjust their irrigation practices accordingly.AWD can increase the risk of yield loss if the soil is allowed to dry out too much, particularly during critical stages of crop development such as flowering and grain filling. If the soil is too dry, it can result in reduced nutrient uptake, decreased photosynthesis, and decreased grain yield. AWD can also lead to increased weed growth if the field is drained for too long. Here are some potential areas for new research in AWD: Water management: There is a need to develop optimized water management practices for AWD, including determining the optimal timing and duration of the wet and dry periods, and the most suitable irrigation methods to use. In addition, research is needed to identify the most effective water-saving strategies for AWD, such as the use of mulching, cover crops, or different soil types. GHG emissions: AWD has been shown to reduce methane emissions from rice cultivation. However, there is a need for further research to understand the mechanisms behind this reduction and to quantify the overall GHG emissions impact of AWD compared to traditional flooded rice cultivation. Economic viability: Research is needed to assess the economic costs and benefits of AWD and to identify strategies to improve its profitability and marketability.

2.5 Drip irrigated rice

Drip irrigation is well-suited for rice cultivation as it allows precise control of water application, which is essential for this water-intensive crop. Irrigation water is supplied to the crop through drip emitters that are placed at regular intervals along the field (Figure 5). The spacing between emitters depends on the soil type, crop variety, and other factors, and can range from 30 cm to 60 cm [36]. The water is delivered slowly and evenly to the root zone of the plants, which reduces water loss through evaporation and runoff. It facilitates the precise application of fertilizers and other inputs, which can further improve crop performance. However, drip irrigation requires careful management and maintenance to ensure that the system is functioning properly and that the plants are receiving the appropriate amount of water [37]. Factors such as soil moisture, crop growth stage, and weather conditions must be monitored regularly to adjust the irrigation schedule as needed. The timing and amount of irrigation in drip irrigated rice depend on several factors, including soil type, climate, crop stage, and water availability. The frequency of irrigation in drip irrigated rice depends on the rate of water uptake by the plants, which is influenced by factors such as temperature, humidity, wind, and plant density. In general, drip irrigated rice should be irrigated when the soil moisture content in the root zone reaches the lower limit of the desired range. This can be determined by monitoring soil moisture using a soil moisture sensor or by checking the soil moisture by hand. Similarly, the amount of water applied should be sufficient to replenish the soil moisture deficit and bring the soil moisture content to the upper limit of the desired range. The desired range depends on the soil type and can range from 60 to 80% of field capacity [38].

Figure 5.

Drip irrigated rice.

Drip irrigation reduces weed growth compared to flood irrigation, but it can also result in more weeds growing directly under the drip lines. The use of drip irrigation resulted in a 29% increase in aerobic rice yield and a 50% reduction in water usage and the water productivity of aerobic rice under drip irrigation showed a twofold increase compared to other irrigation methods. Drip irrigation for direct-seeded rice increased yield (7.34–8.01 t ha⁻¹) and water-use efficiency (0.81–0.88 kg m⁻³) while reducing water use by over 40% compared to flood irrigation (6.63–7.60 t ha⁻¹ and 0.42–0.52 kg m⁻³, respectively). Root density at 15–30 cm soil depth was also higher in drip-irrigated crops (0.86–1.05 mg cm⁻³) than in flood-irrigated crops (0.76–0.80 kg cm⁻³) [39]. Among different drip irrigation configurations tested, the subsurface drip with a lateral distance of 0.8 m and 1.0 L/h dripper discharge irrigation system demonstrated the best performance in terms of rice growth, physiology, and yield [40].

Drip fertigation can be an effective and sustainable method for fertilizing crops, providing precise and uniform delivery of nutrients while reducing nutrient, labor and water use [41]. Subsurface drip irrigation in rice-wheat cropping system reduces the nitrogen requirement by 20% in both the crop and obtain grain yields similar to that of flood irrigated crops [42]. However, it requires careful planning and management to ensure proper functioning and effective nutrient application. Drip fertigation requires specialized equipment, such as a fertigation pump, injection system, and filters. This equipment must be properly installed and maintained to ensure proper functioning. The quality of the irrigation water can impact the effectiveness of drip fertigation. High levels of dissolved salts, bicarbonates, or other impurities can lead to clogging of the emitters or reduced fertilizer uptake by plants [43]. The timing and rate of fertilizer application through drip fertigation must be carefully adjusted based on the crop stage and nutrient requirements. Over-application of fertilizers can lead to nutrient imbalances, reduced crop quality, and environmental pollution.

2.5.1 Prospects of drip irrigated rice

Drip irrigation has several advantages over traditional flood irrigation methods for rice cultivation. Water use efficiency: Drip irrigation can reduce water use by up to 50% compared to traditional flooded rice fields. This can lead to cost savings for farmers and help conserve water resources. Higher yields: Drip irrigation can improve rice yields by ensuring a consistent and adequate supply of water and nutrients to the plants. This can lead to higher grain quality and quantity. Better fertilizer management: Drip irrigation can improve fertilizer use efficiency by delivering nutrients directly to the root zone of the plants. This can reduce fertilizer leaching and runoff, which can harm the environment. Drip irrigation combined with fertigation (the application of fertilizers through irrigation water) significantly improves rice yield and nutrient use efficiency. Reduced labor requirements: Drip irrigation requires less labor for irrigation and weeding than traditional flooded rice fields, which can lead to cost savings and increased efficiency. Climate resilience: Drip irrigation can help rice farmers adapt to climate change by providing more precise control over water and nutrient delivery. This can help reduce the risk of drought and flood damage to rice crops. GHG emission: Drip irrigation can significantly reduce methane emissions from rice fields, compared to flood irrigation. Based on two-year average, Fawibe et al. found that the global warming potential is reduced by 89% under drip irrigated plastic mulch system compared to conventional flooding [44]. Soil compaction: Drip irrigation in rice cultivation helps in improving soil health by reducing soil erosion and compaction.

2.5.2 Constraints of drip irrigated rice

High initial investment: Drip irrigation systems require significant initial investment in equipment and infrastructure, such as pumps, filters, and drip lines. This can be a significant barrier for small-scale rice farmers. Technical knowledge and skills: Drip irrigation requires technical knowledge and skills in installation, operation, and maintenance. The system must be regularly maintained to ensure proper functioning, which can involve tasks such as cleaning filters, replacing emitters, and checking for leaks. This is a time-consuming and labor-intensive process. Farmers may need training and support to adopt this method successfully. Soil suitability: Drip irrigation is most suitable for well-drained soils with good water-holding capacity. Therefore, its use may be limited to regions with heavy clay soils or low water-holding capacity. Pest and disease management: Drip irrigation may increase the incidence of some pests and diseases, such as root rot and nematodes. Therefore, farmers need to implement appropriate pest and disease management practices to mitigate these risks. Energy requirements: Drip irrigation systems require energy for pumping and filtration, which can increase production costs and contribute to greenhouse gas emissions [45]. Clogging: Clogging of drip system due to the buildup of sediment, organic matter, or mineral deposits in the emitters or filters reduces the effectiveness of the system, leading to uneven application of fertilizers and water [43]. Water quality: Poor quality irrigation water requires additional treatment or management.

2.5.3 Potential areas for new research in drip irrigated rice

Drip irrigation has the potential to improve water use efficiency, increase rice yields, and reduce labor requirements. However, its adoption may depend on several factors, such as the availability of appropriate soil and water resources, farmer knowledge and skills, and the initial investment cost. Therefore, further research and extension efforts are needed to promote the adoption of drip irrigated rice among rice farmers worldwide. Here are some potential areas for new research in drip irrigated rice. Water and nutrient management: Drip irrigation provides precise control over water and nutrient application, but research is needed to develop optimized water and nutrient management practices for drip-irrigated rice, including determining the most suitable timing and quantity of water and nutrient application to maximize yield and minimize water and nutrient losses [36]. Crop management: Drip irrigation can affect crop management practices such as weed control, pest management, and disease control, and research is needed to develop integrated crop management practices for drip-irrigated rice that can optimize yield and reduce production costs. Soil health: Drip irrigation can impact soil health and nutrient availability, and research is needed to evaluate the long-term effects of this technique on soil properties, including organic matter content, nutrient availability, and soil structure. Energy use and greenhouse gas emissions: Drip irrigation requires energy to operate, and the energy use and associated greenhouse gas emissions of drip-irrigated rice need to be quantified and compared to traditional flooded rice cultivation. Economic viability: Drip irrigation has the potential to increase water and nutrient use efficiency and yield stability, but its economic viability compared to traditional flooded rice cultivation needs to be further evaluated. Research is needed to assess the economic costs and benefits of drip-irrigated rice and to identify strategies to improve its profitability and marketability.

2.6 Automated irrigation

Automated irrigation using sensors and the Internet of Things (IoT) can be an effective way to save water in rice cultivation as it requires large amounts of water to grow. This approach involves using sensors to collect data on various environmental factors such as temperature, humidity, soil moisture, and weather conditions. The data is then transmitted to a central hub via the internet, which processes the information and triggers irrigation systems as needed (Figure 6). In traditional irrigation methods, there is a risk of overwatering or underwatering, which can lead to reduced crop yield, increased water usage, and higher costs [46]. By using sensors and IoT, farmers can optimize water usage and reduce waste by ensuring that the rice fields receive only the necessary amount of water. Automated irrigation systems can also help farmers save time and labor by eliminating the need for manual monitoring and adjustment of irrigation systems [47]. This allows farmers to focus on other important aspects of rice cultivation such as soil management, pest control, and harvesting. The implementation of automatic irrigation system increased on-site water productivity by 12.7%, and the labor power required for water management decreased by 21.8%. Moreover, the investment in the automatic irrigation system yielded positive financial returns, with an internal rate of return of 8.6% higher than the discount rate of 4.5% and benefit-cost ratio was 1.23 [48].

Figure 6.

Automated smart irrigation system.

The modern drip irrigation system is highly efficient in water usage when compared to traditional irrigation methods. Automated drip irrigation can save up to 41.5% of water compared to conventional flood irrigation and 13% compared to traditional drip irrigation methods [49]. Sensors used in automated irrigation help in accurate weather predictions which assist farmers in designing optimal irrigation schedules that consider expected rainfall and evapotranspiration rates. The high accuracy weather prediction can help in preventing overwatering, which can waste water and reduce water use efficiency [50]. In addition, farmers can take preventive measures such as adjusting irrigation schedules and creating adequate drainage facilities in response to extreme weather events like droughts, floods, and storms. Moreover, better weather prediction can aid farmers in planning the timing of fertilizer and pesticide applications. This can enhance nutrient uptake and pest management, resulting in improved crop growth and water use efficiency.

2.6.1 Bottleneck for automated irrigation

There are several bottlenecks that need to be considered when implementing automated irrigation systems in rice cultivation: Cost: Implementing an automated irrigation system can be expensive, especially for small-scale rice farmers. The cost of the sensors, communication systems, and other equipment needed to set up the system can be a barrier to adoption [51]. Technical expertise: Setting up and maintaining an automated irrigation system requires technical expertise. Farmers may need training to operate the system and troubleshoot any technical issues that may arise. Infrastructure: The implementation of automated irrigation systems requires reliable internet connectivity and power supply, which may not be available in some rural areas where rice cultivation is prevalent [52]. Compatibility: Not all automated irrigation systems may be compatible with the specific needs of rice cultivation. Rice cultivation requires different water management practices at different growth stages, which may need to be factored in when setting up the system. Data analysis and interpretation: Collecting data through sensors is not enough; the data also needs to be analyzed and interpreted to trigger irrigation events effectively. Farmers may need assistance with data analysis and interpretation to ensure that the system is functioning optimally [53]. Cultural factors: Some farmers may be resistant to adopting new technology or changing traditional irrigation practices, which could limit the adoption of automated irrigation systems.

Here are some potential areas for future research in automated irrigation for rice: Sensor technology: The effectiveness of automated irrigation systems depends on the accuracy of the sensor technology used to measure soil moisture and other environmental variables. Future research is needed to develop and improve sensor technology for automated irrigation in rice, including sensors that can measure soil moisture, temperature, and other factors at various depths and locations within the field [54]. Decision support systems: Automated irrigation systems rely on decision support systems that use real-time data from sensors to make decisions about irrigation timing and quantity. Future research is needed to develop and improve decision support systems for automated irrigation in rice, including machine learning algorithms that can predict crop water demand and optimize irrigation management [55]. Crop modeling: Crop modeling can be used to simulate crop growth and water use under different irrigation scenarios and can be a valuable tool for optimizing automated irrigation systems. Future research is necessary to develop and improve crop models for rice cultivation that can accurately predict crop water demand and growth under different irrigation scenarios. Energy efficiency: Automated irrigation systems require energy to operate, and the energy use and associated greenhouse gas emissions of these systems need to be quantified and minimized. Future research is needed to optimize the energy efficiency of automated irrigation systems for rice cultivation, including the use of renewable energy sources such as solar power. Economic viability: The economic viability of automated irrigation systems for rice cultivation needs to be further evaluated, including the costs and benefits of different types of sensors, decision support systems, and energy sources [51]. Future research is needed to identify strategies to improve the profitability and marketability of automated irrigation systems for rice cultivation.

2.7 Direct seeded rice

Direct-seeded rice (DSR) is a method of rice cultivation where seeds are directly sown into the field instead of transplanting seedlings. This method is becoming increasingly popular as it saves labor, water, and time compared to traditional transplanting methods [56]. There are two types of DSR methods: wet DSR and dry DSR. In dry DSR, the rice seeds are broadcasted or drilled into dry soil (Figure 7), whereas in wet DSR, the pre-germinated rice seeds are sown on wet soil (Figure 8). Dry DSR resulted in higher yields (13–18%) and reduced total water inputs (8–12%) compared to TPR [57]. DSR has the potential to meet global demand while reducing water usage by 50%, labor costs by 60%, and increasing productivity by 5–10% [58]. Some of the common problems associated with DSR include poor seedling establishment, uneven crop emergence, weed competition, pest and disease infestations, and nutrient deficiencies. Uneven crop emergence: DSR can experience uneven crop emergence, leading to lower yields and reduced crop quality. This can be caused by factors such as uneven seed placement, variable soil moisture, and differences in soil temperature [59]. Weed competition: DSR is more vulnerable to weed competition than transplanted rice, as weeds can easily outcompete rice seedlings for nutrients and light [60]. Pest and disease infestations: DSR can be more susceptible to pest and disease infestations than transplanted rice, due to factors such as reduced plant vigor and higher weed pressure. Nutrient deficiencies: DSR can experience nutrient deficiencies, particularly during the early stages of growth, due to factors such as reduced nutrient availability and increased leaching [61]. Water management: DSR requires careful water management to ensure that the seeds do not dry out before germination, and that the young seedlings are not drowned by excessive flooding. Labor requirements: Direct-seeded rice can require more labor than traditional transplanting methods, particularly for weed control and crop establishment [62].

Figure 7.

Dry direct seeding of rice through seed drill.

Figure 8.

Wet direct seeding of rice using drum seeder.

2.7.1 Research needs for DSR include

Seed technology: Development of improved varieties that have better seedling vigor, higher germination rates, and tolerance to abiotic stresses such as drought and salinity [59]. Weed management: Development of effective and sustainable weed control strategies for DSR that minimize the need for herbicides and reduce the impact of weeds on crop yield [62]. Nutrient management: Optimization of nutrient management strategies for DSR that take into account the different nutrient requirements of direct-seeded rice and the impact of soil moisture on nutrient availability. Pest and disease management: Development of integrated pest and disease management strategies for DSR that reduce the incidence of pest and disease infestations and minimize the use of chemical pesticides. Agronomic practices: Development of agronomic practices that optimize crop establishment, promote uniform emergence, and reduce the risk of crop failure due to unfavorable weather conditions. Economics and marketability: Analysis of the economic viability of DSR compared to traditional transplanting methods and identification of strategies to improve the marketability of direct-seeded rice.

3. Other agronomic management practices

Farmers should adopt various strategies such as proper fertilization, timely and efficient weed management and the use of drought-tolerant crop varieties to improve crop growth, productivity, and water use efficiency. Building bunds or levees around the paddy fields can prevent water loss through runoff and seepage.

3.1 Best nutrient management

1. Balanced fertilizer application: Applying the right amount of fertilizers and balancing the nutrient supply with rice crop demand can improve the efficiency of water use [14]. Whereas, over-fertilization can result in excessive vegetative growth, leading to higher water demand, which ultimately results in low yield and reduced water use efficiency. Similarly, under-fertilization can negatively impact crop growth and yield potential, leading to lower water use efficiency. Therefore, maintaining an appropriate balance of fertilizers and nutrients is crucial for achieving optimal water use efficiency in rice cultivation [63].

2. Organic matter application: Incorporating organic matter, such as compost or manure, into the soil can improve soil structure and water holding capacity, which can increase water availability for plant uptake and reduce the need for irrigation.

3. Timing and placement of fertilizers: The timing and placement of fertilizers can affect the efficiency of water use. Applying fertilizers in split doses during the growing season, rather than in a single application, helps to reduce leaching losses and increase nutrient uptake efficiency [64]. Placing fertilizers near the root zone also improves nutrient uptake and reduces losses due to runoff or leaching. The increased uptake and efficient utilization of nutrients, in turn, promotes crop growth and yield, ultimately leading to improved water use efficiency.

4. Use of micronutrients: Micronutrients, such as zinc and iron, play a vital role in the growth and development of rice plants. Deficiencies of these micronutrients can reduce crop growth and yield potential, leading to lower water use efficiency. Supplementing the soil with these micronutrients can help to improve crop growth and yield potential, leading to more efficient use of water.

Nutrient deficiency is a common problem in improved rice production technologies like aerobic rice, direct seeded rice, drip irrigated rice and alternate wetting and drying [65]. Nutrient deficiency can limit the ability of crops to effectively utilize water resources. Nutrient deficiency occurs when plants do not receive adequate amounts of essential nutrients such as nitrogen, phosphorus, potassium, and micronutrients such as zinc, iron, and manganese. The lack of these essential nutrients can significantly impact crop growth and productivity, leading to reduced yields, poor quality produce, and increased susceptibility to pests and diseases which intern resulted in lower water use efficiency and water productivity. Thus, optimum fertilization based on soil fertility status and environmental factors could increase water use efficiency and water productivity.

3.2 Efficient weed management

Weeds compete with rice plants for water, nutrients, and sunlight. Thus, it is essential to manage weeds effectively to reduce their negative impact on crop growth, yield and water use efficiency [66]. When weed populations are high, they can reduce the amount of water available to the rice plants by increasing the water loss from the soil through transpiration. As a result, more water may need to be applied to the field to maintain the same level of soil moisture, leading to decreased water use efficiency. Weeds also interfere with the uptake of nutrients by rice plants. This can lead to reduced plant growth and development, which in turn can reduce water use efficiency. Weeds also act as hosts for many pests and diseases that can infect rice plants. This can lead to reduced plant growth and yield, and again, reduce water use efficiency. Controlling weeds can reduce their competition for water, nutrient, space and light, thereby increasing water availability, water use efficiency and yield of rice plants [67]. Therefore, it is more advantageous to implement early weed control measures such as pre-emergence herbicides, manual weeding, and mechanical weed removal, as opposed to late season weed control, to maximize water use efficiency in rice cultivation [68].

3.3 Selecting suitable cultivar

Planting drought-tolerant rice varieties can reduce the amount of water needed for cultivation while maintaining yields. Selecting drought-tolerant cultivars is an important strategy for improving water use efficiency in rice production [69]. Drought tolerant cultivars have better yield stability (able to maintain yield under water-limited conditions) than conventional cultivars. If a region is expected to experience a drought, farmers may choose to plant drought-tolerant rice varieties that can thrive in dry conditions. Drought-tolerant rice cultivars have several adaptations such as deep root system, smaller and thicker leaves, stomata closing during the hottest part of the day, osmoregulation, early maturity and improved photosynthesis that enable them to thrive well in dry conditions. By using less water, drought-tolerant cultivars can help in reducing the environmental impact of rice production. This includes reducing water consumption, greenhouse gas emissions, and nutrient runoff.

Globally several drought tolerant cultivars are developed in different countries (Table 1). Example, BRS Primavera cultivar was developed by the Brazilian Agricultural Research Corporation (EMBRAPA) is known for its high yield potential, tolerance to low soil fertility and shown to perform well in aerobic rice cultivation systems in Brazil. NSIC Rc222 cultivar was developed by the Philippine Rice Research Institute (PhilRice) is known for its tolerance to drought, heat, and low soil fertility. Aerobic Rice 1 cultivar was developed by the International Rice Research Institute (IRRI) and is known for its tolerance to low soil fertility and high yields in non-flooded conditions. It has been tested and shown promising results in several countries in Asia. IR72 cultivar was also developed by the IRRI and is known for its tolerance to drought and low soil fertility. CT9993-5-10 cultivar was developed by the Chinese Academy of Agricultural Sciences and is known for its tolerance to drought and low soil fertility. WAB56-104: This cultivar was developed by the West Africa Rice Development Association (WARDA) and is known for its tolerance to drought, pests, and diseases. It has been shown to perform well in aerobic rice cultivation systems in West Africa. Ariete cultivar was developed by the International Center for Tropical Agriculture (CIAT) and is known for its tolerance to low soil fertility and high yields in non-flooded conditions. It has been tested and shown promising results in several countries in Latin America.

Cultivar	Duration	Yield (t/ha)	Ecology	Tolerance
Sahbhagi Dhan (DRR Dhan 42)	120 days	5.0–5.5	Upland and drought prone shallow lowlands	Drought tolerant
CR Dhan 801	140 days	Normal condition—6.3; Under submergence—4; Under drought—2.9	Climate-smart rice variety suitable for all ecology	Submergence as well as drought tolerance
CR Dhan 802	139 days	Normal condition—6.5; Under submergence—4.3; Under drought—2.3
MAS 946-1 (Sharada)—Aerobic Rice Variety	120 days	5.51	Irrigated rice ecosystem	Drought tolerance
Rajalaxmi (CRHR-5)	130 days	6–7	Irrigated rice ecosystem	Submergence, cold at seedling stage, salinity/alkalinity tolerance

Table 1.

Drought tolerance rice varieties.

4. Conclusion

Revolutionizing rice farming to maximize yield with minimal usage of water is crucial for sustaining a hungry planet. The overuse of water for rice cultivation in conventional rice cultivation method, particularly in regions with limited water resources, has placed a significant strain on water availability and led to various environmental issues, including greenhouse gas emissions. The development of innovative farming techniques such as the SRI, DSR, AWD, SSC and aerobic rice system and the use of drought-resistant varieties of rice has shown promise in reducing water wastage while increasing yield. Smart irrigation utilizing sensors and IoT is poised to revolutionize irrigation management in rice cultivation. Furthermore, incentivizing the adoption of improved irrigation methods through carbon and water credits can promote water conservation in rice farming. In addition to water conservation, researchers are taking a systems approach to address various issues in rice cultivation, including labor, greenhouse gas emissions, weed control, nutrient use efficiency, pest and disease management, production cost, and cropping intensity. Many of these improved irrigation methods are addressing most of the problems in rice cultivation beside saving irrigation water and improving water productivity. It is essential to continue research and development efforts in this area to ensure food security for the growing population while preserving our precious water resources. Through collective efforts, we can work towards a sustainable future where we produce more with less water, ensuring food security for all.

Acknowledgments

Authors would like to extend sincere gratitude to the authors whose research findings have greatly contributed to the writing of this chapter.

Conflict of interest

All the authors declare that there are no potential conflicts of interest associated with this submission.