Measuring the implicit value of paddy irrigation water: application of RPML model to the contingent choice experiment data in Japan

For efficient use of water as a limited resource, evaluation on the water value is critical, but there is little information in Asian paddy irrigation. This paper proposes the method for measuring implicit price of paddy irrigation water by using the choice experiment (CE) data with contingent scenarios. Empirical results demonstrated that (a) the estimated implicit price of water showed reasonable value as compared to the production indexes, (b) the random parameter multinomial logit model was more suitable than the conventional multinomial logit model to treat the CE data, and (c) the implicit price is much lower than the full cost price, indicating that full cost pricing probably damages and ruins rice production too seriously in Japan. As seen above, the method proposed here is useful for decision making on water pricing policies and easy to apply to different irrigation systems under limited data of water value.

Water transfer from agriculture to urban uses: lessons learned, with policy considerations

This paper sets forth the accomplishments to date of the international collaborative study program on efficient and equitable transfer of water from agriculture to other uses. The research consists of several components. First a bibliographical review was prepared of literature available on the practice of inter-sector water transfer. Second, nine case studies have been prepared that illustrate inter-sector water transfer under a variety of physical and economic and political environments. Third, a framework has been developed for characterizing and comparing water transfer options and compensation among case studies. We discuss the pricing of irrigation water in determining compensation. We develop a decision tree that traces the paths to the various sector water transfer options. Finally, we discuss water transfer policy options with specific reference to Taiwan, though they have more general relevance. Three options are identified which reflect different objectives for government intervention.     

Social capital accumulation through public policy systems implementing paddy irrigation and rural development projects

In Japan, a developed country in Asia, the Land Improvement Act systems have worked as a measure of social capital accumulation as well as an adjective law in implementing irrigation projects since 1949. This paper illustrates the status and problems in applying the concept of social capital to agricultural and rural development policy systems in developing countries, EU and Japan. The results obtained are summarized as follows: (1) it is desirable that governments formulate public policies that are appropriate for correcting inefficiencies in resource distribution for accumulating social capital, so that the governments play a significant role in developing and supporting social capital; (2) the effect of policies in the areas, where government-supported land improvement projects have been implemented, has been improved, subsequent to which the efficient use of the national budget allocated for the projects has been improved, while the projects significantly contribute to the national land conservation and social stability by continuously promoting minimum social capital accumulation nationwide. In addition, Japan and countries in the Asian monsoon region, which hold the five elements in common that constitute the characteristics of rice field irrigation in humid climates, should take over the advantages of the land improvement project system while learning from the success achieved by the LEADER+ programme in Europe, where society precedes Asian countries concerning the problems of decline in the birth rate, and expansion of an aging society.

Transferring water from irrigation to higher valued uses: a case study of the Zhanghe irrigation system in China

The Zhanghe irrigation system (ZIS) is located in the Yangtze River Basin approximately 200 km west of Wuhan in Hubei Province. The reservoir was designed for multiple uses—irrigation, flood control, domestic water supply, industrial use, aquaculture, and hydropower. Over a period of more than 30 years a steadily increasing amount of water has been transferred from irrigation to other uses. Activities on the part of government, irrigation system managers, and farmers made this transfer possible with only modest decline in rice production. Most important factor was the steady increase in rice yields. The water pricing system provided an incentive for ZIS to reduce irrigation releases. With the steady decline in releases, farmers were forced to find ways to save water. Farmers improved existing ponds and built new ones to store water (improved infrastructure). Access to pond water on demand facilitated the adoption of alternate wetting and drying (technology) particularly in dry years. The establishment of volumetric pricing (price policy) and water user associations (institutions) may also have provided incentives for adoption of AWD, but more research is needed to establish their impact. These activities taken together can be seen as potentially complementary measures. Farmers received no direct compensation for the transfer of water, but recently farm taxes have been reduced or altogether abolished. Further reduction in water releases from the ZIS reservoir could adversely affect rice production in normal or dry years.     

Pesticide discharge and water management in a paddy catchment in Japan

Concentrations of several pesticides were monitored in a paddy block and in the Kose river, which drains a paddy catchment in Fukuoka prefecture, Japan. Detailed water management in the block was also monitored to evaluate its effect on the pesticide contamination. The concentrations of applied pesticides in both block irrigation channel and drainage canal increased to tens of μg/L shortly after their applications. The increase in pesticide concentrations was well correlated with the open of irrigation and drainage gates in the pesticide-applied paddy plots only 1–3 days after pesticide application. High concentration of other pesticides, mainly herbicides, was also observed in the inflow irrigation and drainage waters, confirming the popularity of early irrigation and drainage after pesticide application in the area. The requirement of holding water after pesticide application (as a best management practice) issued by the authority was thus not properly followed. In a larger scale of the paddy catchment, the concentration of pesticides also increased significantly to several μg/L in the water of the Kose river shortly after the start of the pesticide application period either in downstream or mid–upstream areas, confirming the effect of current water management to the water quality. More extension and enforcement on water management should be done in order to control pesticide pollution from rice cultivation in Japan.     

Increasing water productivity for paddy irrigation in China

This paper introduces the research on practices to increase water productivity for paddy irrigation in China and summarizes the experience on implementation of the alternate wetting and drying (AWD) irrigation technique. The widespread adoption of the AWD practice on 40% of the rice growing area provides an opportunity for China to produce more food in the water-surplus south where it is wet and the traditional based paddy field agriculture is dominant. Physical and institutional measures leading to increasing water and land productivity in rice-based systems are discussed. Research studies show that AWD practice does not reduce rice yield, but does increase the productivity of water. Water use and thus water charges can be reduced. However, experience shows that demonstrations and training are needed to encourage farmer adoption. Furthermore, there are a range of complementary policies and practices, such as volumetric pricing or farm pond development, which provide incentives for adoption of AWD. Finally, there remain many scientific issues to be addressed. Application of the AWD technique in some regions is still very difficult because of both bio-physical and socio-economic problems. In conclusion, the widespread adoption of AWD is only a first step in the continuing effort to find practices that will increase water productivity for paddy irrigation in China.Dr. Yuanhua Li was a Professor and Dean in Wuhan University of Hydraulic and Electric Engineering from 1996 to 2000. After that, he has been a Professor and Deputy Director General of the National Centre for Irrigation and Drainage Development, Ministry of Water Resources, China. He has been doing research on irrigation principally for paddy since 1982.Dr. Randolph Barker is an agricultural economist and Professor Emeritus Cornell University. From 1966 to 1978 he served as head of the Economics Department, International Rice Research Institute, Los Banos, Philippines and from 1995 to 2004 was principal researcher, International Water Management Institute, Colombo, Sri Lanka.     

Effects of irrigation deprivation and ground cover (Trifolium repens) in the tree row on brown rot incidence in peach

Brown rot can lead to considerable fruit losses in peach orchards and cultural practices likely to contend this major disease have to be promoted. In order to limit peach brown rot incidence in a three-year-old mid-season maturing peach orchard of the cultivar ’Ruby Bright’, four combinations of irrigation and soil management treatments were assessed: conventional (Conv) irrigation (I) and soil management (S) (ConvI+ConvS); modified (Mod) irrigation and soil management (ModI+ConvS); conventional irrigation and modified soil management (ConvI+ModS); and modified irrigation and soil management (ModI+ModS). Conventional irrigation and soil management in the tree row consisted of irrigation scheduling using tensiometer readings and herbicide use, respectively. Modified irrigation and soil management in the tree row consisted of water deprivation during stage III of fruit development and ground cover with white clover, respectively. For four consecutive years (2010–2013), in the conditions of the Middle Rhone Valley in France, the lowest and highest brown rot incidence were detected under (ModI+ModS) and (ConvI+ConvS), respectively, whereas brown rot incidence under (ModI+ConvS) and (ConvI+ModS) was intermediate. This lower brown rot incidence under the modified treatments occurred from one to two weeks before fruit maturity and was still observed for several days in post-harvest storage. Ground cover with white clover was shown to limit water availability in the soil after heavy rainfall compared to bare soil, probably limiting peach growth variations, well-known as a possible source of detrimental microcracks at the fruit surface. This suggests that under our conditions appropriate cultural practices, water deprivation and a clover crop cover in the tree row possibly decrease peach disease sensitivity, which might lead to the reduced use of pesticide sprays to control brown rot in the orchard.     

Assessment and water saving issues for Ningxia paddies,upper Yellow River Basin

In the Hetao Irrigation Districts of the Ningxia autonomous region, Upper Yellow River Basin, the continuous deep flooding irrigation method is used for the rice paddies. The field irrigation water use during the rice-growing season is two to three times higher than in other regions of North China where water-saving practices have been introduced. This paper, based on the data measured in experimental rice fields and sub-branch canal systems, presents main results concerning crop evapotranspiration, percolation and irrigation requirements for deep and shallow water irrigation. Causes for water waste relate to both the lack of regulation in supply and distribution canals and to the poor management of paddy fields. The potential for water saving is discussed using water balance data. Improved irrigation techniques and water management strategies, including the shallow water irrigation method, are suggested considering the expected impacts and benefits. Replacing the current continuous deep flooding with the shallow-ponded water irrigation method may reduce the growing season irrigation water use from 1,405 to 820 mm in average, with a likely increase in yields of 450 kg/ha. Water productivity would then increase from 0.49 to 1.03 kg/m³. Adopting improved canal management and modernization of regulation and control structures may lead to decreasing the gross irrigation demand from the present 3,100 mm to about 1,280 mm, which would highly benefit the environmental conditions in the area.     

Evaluation of water intake rate using the diffusive tank model in the low-lying paddy area

The subject of this study is water management in low-lying paddy fields. The objective of this study is to quantify the water requirement, and estimate an appropriate volume and facilitate management of irrigation water in areas where it is difficult to estimate the flow rate continuously. A field observation was conducted at a 14-ha study site located in the Kuwabara area, Fukuoka City, southwest of Japan, to evaluate water management conditions in the command area of the reservoir. This site near the reservoir was selected, because it was impossible to understand the water supply situation in the entire command area. The farmers in this region have been unable to retain sufficient irrigation water. The observation results indicate that the water depth fluctuates widely in every irrigation canal. The canals are frequently empty because rotational irrigation is conducted by water managers; this makes quantifying the flow rate in the irrigation canal very difficult. To quantify the water requirement, an improved tank model was introduced. The accuracy of the model was examined by comparing the observed and calculated ponding depths at a paddy field. The simulation results agreed with the observed data. Using this model, water management for the reduction of water managers’ labor was simulated. Simulation results indicated that rotational irrigation effectively reduces labor and saves irrigation water.     

Appropriation of Río San Juan water by Monterrey City, Mexico: implications for agriculture and basin water sharing

Monterrey metropolitan area’s growth has resulted in water transfers from the Río San Juan basin with significant impacts for downstream water users, especially farmers in the Bajo Río San Juan (BRSJ) irrigation district. El Cuchillo dam is the centerpiece of the basin’s water management infrastructure and has become the flashpoint of a multi-faceted water dispute between the states of Nuevo León and Tamaulipas as well as between urban and agricultural water interests in the basin. Subsequent to El Cuchillo’s implementation in 1994, the BRSJ irrigation district has been modifying its irrigation operations to adjust to the new water availability scenario. Compensation arrangements for farmers have been established, including crop loss payments on the order of US$ 100 per hectare un-irrigable due to the diversion of water to Monterrey plus 60% of the water diverted to be returned to farmers as treated effluent via the Ayancual Creek and Pesquería River, a process with its own water competition and environmental implications. The Mexican irrigation sector will continue to face intense competition for water given: (a) low water productivity in agriculture leading decision-makers to allocate water to higher productivity uses particularly in cities, (b) priority accorded to the domestic use component of municipal water supply, and in the BRSJ case, (c) Mexico’s national interests in meeting its water sharing obligations with the United States.     

Issues of scale in water productivity in the Zhanghe irrigation system: implications for irrigation in the basin context

In the context of increased competition for water, growing more rice with less water will be one of the major challenges of the 21st century. This paper examines water savings and issues of scale in water productivity. The main objective is to understand if and how field-scale interventions scale up to subbasin-scale water savings in the Zhanghe Irrigation District (ZID) in Hubei Province, central China. Our results confirmed that on-farm water-saving practices result in higher water productivity per unit of irrigation water at the field scale due to lower irrigation water input. However, the question is, if these field-scale practices have led to real water savings; savings which can be transferred to other agricultural and non-agricultural uses without lowering existing production levels. To investigate this question, we examined water use and productivity at four different scales: field scale, meso scale, main canal command scale, and subbasin scale using the water accounting methodology. The study clearly demonstrates the high dependence on the scale of water use and productivity parameters. Depleted fraction and water productivity per unit of gross inflow and irrigation water varied dramatically across scale. Thus, it is not possible to conclude from field-scale observations that basin level water savings will or will not take place. The major reasons for these scale effects are the lateral flow of water across boundaries, differing land use patterns across scales, and changing water management patterns across scales. In the ZID, going from field and meso scale to even larger scales, water productivity per unit of irrigation increases to even higher levels than at the field scale. Here it becomes clear that the ZID, with its possibilities of reuse of drainage return flows and capturing rainfall and runoff in all the reservoirs within the system, is very effective in capturing and using water productively. Factors that influence water productivity and depleted fraction are on-farm water savings as well as the reuse of drainage water, effective capturing and utilization of rain, and canal water management. The scope for additional real water savings in the Zhanghe Irrigation District is limited. Only 13% of the combined rainfall and Zhanghe reservoir irrigation water releases flow out of the basin. A further reduction in drainage surface outflow from the ZID may have negative downstream effects on other water uses, including environmental uses. The main lessons learned are that (1) employing a combination of factors—on-farm practices, reuse, and canal operations—can be an effective means of conserving water resources within irrigation systems, (2) the scope for savings must be considered by an analysis at larger scales (i.e. irrigation system or basin scale), and may be less than thought because of the interactions of these factors. The results clearly indicate that scale effects are important for understanding and planning for water savings and water productivity.     

Abiotic stress and water scarcity: Identifying and resolving conflicts from plant level to global level

Irrigated crops are increasingly facing water scarcity and other forms of abiotic stress, including the presence of salts and other pollutants in soil and irrigation water, waterlogging and flooding of soils, low pH in acid sulfate soils, and anaerobic and toxic conditions in the rootzone. More progress has been made with the alleviation of some of these stresses than with others. This paper examines why salinity of soil and irrigation water is common and nearly inevitable in the irrigated lands of the semi-arid tropics and subtropics. It considers opportunities for and constraints in making management changes that would increase the productivity of water (i.e., the yield per unit of water diverted from the source or consumed in evapotranspiration) at system and basin level. Success of water management interventions in reducing the impact of abiotic stresses on rice production under saline conditions and on acid soils depends on improved control over the components of the water and ion balances at field and basin level. One of these measures is the installation of drainage systems. The benefits and costs of sub-surface drainage are illustrated by an example from Egypt's Nile Delta. An integrated approach to water resource management is an essential but not sufficient condition to prevent conflicts between different users and consumers of the scare resource.     

Assessment of irrigation efficiencies and water productivity in paddy fields in the lower Mekong River Basin

Improving irrigation performance is a crucial issue for agriculture and irrigation development in the Lower Mekong River Basin to secure food production for people’s livelihoods. Irrigation efficiency is the most important indicator to determine the performance of an irrigation scheme. This study looks at water management practices and irrigation efficiency in three pilot sites in the Lower Mekong River Basin: the Numhoum scheme in Laos, the Huay Luang scheme in Thailand, and the Komping Pouy scheme in Cambodia. Irrigation efficiency and water productivity were analyzed using a water balance approach at the irrigation scheme level and results in the pilot areas show efficiencies that are definitely higher using this approach than by using the classical concept. Lower water productivity was observed at pilot schemes in areas of single cropping and higher productivity in areas where multiple agricultural activities were practiced. Strict and active water management is required to control and save water to meet agricultural demand and have sufficient water to expand cultivation areas while avoiding shortages. Promoting multiple uses of water for various agricultural activities in command area will increase water productivity.

Experiences of water transfer from the agricultural to the non-agricultural sector in Taiwan

Two type of water transfer have occurred in Taiwan, namely, regular and emergency transfers. According to the prevailing Water Law, water is permitted to transfer among water rights holders whenever they need and agree upon relevant compensation. As for the emergency transfer, in the event of extensive drought, every water user sector will suffer serious water shortages resulting in unavoidable economic losses. The Government should step in to perform emergency water transfer by suspending agricultural water rights a course of action considered to cause smaller losses even when an entire rice crop is abandoned, to minimize overall losses to the national macro economy. This study has examined two typical water transfer cases that were implemented in Taiwan. The first one involved the regular transfer of agricultural water from the Changhwa and Yunlin Irrigation Associations (IAs) to the industrial user Formosa Petrochemical Corporation (FPC). The second one involved the transfer of agricultural water from the Taoyuan, Shimen and Shinchu IAs to domestic and industrial uses during the period from 2002 to 2006 as an emergency transfer. From the perspective of water transfer options, Taiwanese case studies have demonstrated that an officially recognized marketing oriented water transfer mechanism has yet to be established. However, water transfer is still undertaken whenever necessary. In this respect, regardless of the type of water transfer undertaken, water rights can only be suspended but not terminated. In spite of the types of water transfer, it is inevitable to affect the ecological and environmental functions. Therefore, further investigations with related topics should be broadly taken into account. Ecosystem services of paddy fields have attracted increasing recognition in the monsoon Asian countries. Currently, there is a research program collaborating with the International Water Management Institute (IWMI) on the impact and influence induced by water transfer with a major concern on the ecosystem services of paddy fields in Taiwan.     

Cost sharing and sustainability of Pongsak Muang Fai irrigation system

The centuries-old, self-organizing Muang Fai community irrigation institution in northern Thailand has high potential in illustrating exemplary practices in irrigation cost sharing. This paper examines the cost sharing structure of the Pongsak Muang Fai Irrigation System in Mae Hong Son Province and its relationship with the system water management and sustainability. Results show that this primitive and high cost system accepts costs of the weir, the entire length of main ditch, not only the individually related ditch sections, and the management as common costs that should be equally shared so that it can gather sizeable membership to support the system. The capacity of this small scale run-of-the-river irrigation system with no river flow limitation is a simple summation of all determined farm intake capacities. The maintenance cost of the system every year depends on how much water should be diverted and conveyed, hence the use of “relative” scale of each farm intake capacity as the basis for sharing cost in the wet season paddy farming. Such structure is directly related to the water management under which every intake shall be served with continuous supply without permitting mid-canal water check-up and the members prefer to take collective action to keep enough water supply without leaving any room for suspicion of unfair water distribution. The direct relationship makes the members understand the purpose of payment and be willing to share the costs which are transparently estimated in easily understood terms and clearly de-aggregated into categories.     

Modeling of continental-scale crop water requirement and available water resources

The relationship between agricultural water demand and supply has been of interest to government decision makers and scientists because of its importance in water resources management. We developed a water cycle model for eastern Eurasia that can estimate water requirements for crop growth and evaluate the demand–supply relationships of agricultural water use on a continental scale. To produce an appropriate water cycle, the model was constructed based on small drainage basins. To validate the model performance with respect to simulated runoff, which is here considered as the available water resource, we compared our outputs with those of other models and with observed river discharges. The results show that this model is comparable to other models and that it is applicable for the evaluation of water cycles at continental scale. We defined two types of crop water deficits (CWDs) as indicators of agricultural water demand. These were formulated by considering the physical processes of crop water use; we did not include water consumption that is dependent on cultivation management practices, such as water losses in irrigation systems. We assessed the reliability of our indicators by comparison with indicators from other studies and with published statistics related to agricultural water use. These comparisons suggest that our indicators are consistent with independent data and can provide a reasonable representation of water requirements for crop growth.     

Alternate Furrow Irrigation with Different Irrigation Intervals for Maize (Zea mays L.)

Abstract

This research was conducted to determine the yield and water-use efficiency of maize under fixed and variable alternate furrow irrigation (fixed AFI, variable AFI) and every furrow irrigation (EFI) at different irrigation intervals in areas with shallow and deep groundwater. In variable AFI, water was applied to the furrow, which was dry in the previous irrigation cycle. The results indicated that even at 4-day irrigation intervals the water needs of maize on a fine textured soil in both areas (with deep and shallow water table) are not met by AFI. The decrease in grain yield due to water stress was mainly due to the decrease in the number of grains per cob and to a lesser extent to the decrease in 1000-grain weight. At the Kooshkak site with shallow groundwater (between 1.31 and 1.67 m), grain yields in AFI at 4- and 7-day intervals were comparable to those obtained in EFI at 7- and 10-day intervals, respectively. This might be due to the contribution of groundwater to the water use of the plant (about 5-10%). In the Badjgah area, with deep water depth, grain yield in AFI at 7-day intervals was statistically lower than that obtained in EFI at 10-day interval. In AFI, a shorter irrigation interval (4-day) may alleviate the water stress and result in no yield reduction compared with that in EFI at 7-day intervals even though water application was reduced. Furthermore, in the area with a shallow water table, AFI at 7-day intervals may be superior to EFI at 10-day irrigation intervals. When seasonal irrigation water is less than 700 mm, it may be preferable to use AFI at 10-day intervals to increase water-use efficiency, especially in areas with shallow groundwater. In general, when water was insufficient for full irrigation, the relative grain yield (yield per unit water applied) of maize under AFI was higher than those under EFI.     

Pearl Millet Developed Deep Roots and Changed Water Sources by Competition with Intercropped Cowpea in the Semiarid Environment of Northern Namibia

abstract

The practice of intercropping pearl millet with cowpea is widespread among subsistence farmers in northern Namibia. In this region, the scarce and erratic rainfall may enhance competition for the limited soil water between intercropped plants. Trials were conducted on a field of the University of Namibia (on-station) and on a farmer’s field (off-station) to determine the effects of competition between pearl millet and cowpea on the water sources and plant growth of each crop. The deuterium analysis showed that pearl millet, intercropped with cowpea, significantly increased its dependence on the recently supplied labeled irrigation water. Intercropped cowpea also showed an increased trend of the dependence but it was not statistically significant. At the university field, intercropped pearl millet showed higher dependence on the irrigation water than monocropped pearl millet. At the farmer’s field, the dependence of intercropped pearl millet on the irrigation water was low in the pearl millet-dominant zone. In contrast, the dependence on the irrigation water was high in the cowpea-dominant zone, indicating that the dependence on the irrigation water changes according to the size of the pearl millet canopy. The water sources of cowpea did not show a significant difference at either pearl millet-dominant or cowpea-dominant zone, indicating a stable water uptake trend under competitive conditions. Competition with cowpea significantly increased the root-weight density of intercropped pearl millet in the deep soil layers, but decreased that in the shallow layers. The root-weight density of intercropped cowpea, however, was reduced in most of the soil layers. In conclusion, cowpea has a higher ability to acquire existing soil water, forcing pearl millet to develop deep roots and shift to the surface irrigation water.     

Chlorophyll meter-based nitrogen management of rice grown under alternate wetting and drying irrigation

Farmers have adopted alternate wetting and drying (AWD) irrigation to cope with water scarcity in rice production. This practice shifts rice land away from being continuously anaerobic to being partly aerobic, thus affecting nutrient availability to the rice plant, and requiring some adjustment in nutrient management. The use of a chlorophyll meter (also known as a SPAD meter) has been proven effective in increasing nitrogen-use efficiency (NUE) in continuously flooded (CF) rice, but its use has not been investigated under AWD irrigation. This study aimed at testing the hypotheses that (i) SPAD-based N management can be applied to AWD in the same way it is used in CF rice, and (ii) combining chlorophyll meter-based nitrogen management and AWD can enhance NUE, save water, and maintain high rice yield. Experiments were conducted in a split-plot design with four replications in the 2004 and 2005 dry seasons (DS) at IRRI. The main plots were three water treatments: CF, AWD that involved irrigation application when the soil dried to soil water potential at 15-cm depth of −20 kPa (AWD₋₂₀) and −80 kPa (AWD₋₈₀) in 2004, and AWD₋₁₀ and AWD₋₅₀ were used in 2005. The subplots were five N management treatments: zero N (N₀), 180 kg N ha⁻¹ in four splits (N₁₈₀), and three SPAD-based N-management treatments in which N was applied when the SPAD reading of the youngest fully extended leaf was less than or equaled 35 (N_SPAD35), 38 (N_SPAD38), and 41 (N_SPAD41). In 2005, N_SPAD32 was tested instead of N_SPAD41. A good correlation between leaf N content per unit leaf area and the SPAD reading was observed for all water treatments, suggesting that the SPAD reading can be used to estimate leaf N of rice grown under AWD in a way similar to that under CF. SPAD readings and leaf color chart (LCC) values also showed a good correlation. There were no water × nitrogen interactive effects on rice yield, water input, water productivity, and N-use efficiency. Rice yield in AWD₋₁₀ was similar to those of CF; yields of other AWD treatments were significantly lower than those of CF. AWD₋₁₀ reduced irrigation water input by 20% and significantly increased water productivity compared with CF. The apparent nitrogen recovery and agronomic N-use efficiency (ANUE) of AWD₋₁₀ and AWD₋₂₀ were similar to those of CF. The ANUE of N_SPAD38 and N_SPAD35 was consistently higher than that of N₁₈₀ in all water treatments. N_SPAD38 consistently gave yield similar to that of N₁₈₀ in all water treatments, while yield of N_SPAD35 about 90% of that of CF. We conclude that a combination of AWD₋₁₀ and SPAD-based N management, using critical value 38, can save irrigation water and N fertilizer while maintaining high yield as in CF conditions with fixed time and rate of nitrogen application of 180 kg ha⁻¹. Treatments AWD₋₂₀ and N_SPAD35 may be accepted by farmers when water and N fertilizer are scarce and costly. The findings also suggested LCC can also be a practical tool for N-fertilizer management of rice grown under AWD, but this needs further field validation.