Study on structure and function of an earthen bund irrigation system in Northeast Thailand

In Northeast Thailand, which overlaps with an erosional plain that is not suitable for irrigation because of poor water resources and terrains that prevent efficient water distribution, farmers have long supplied water to surrounding paddy fields by blocking rivers completely with earthen bunds. Although such a traditional irrigation system fits well with the characteristics of Northeast Thailand, those who are concerned with modern irrigation development projects in Northeast Thailand seem to have been paying little attention to it. The present study was performed to facilitate development of more appropriate irrigation systems in Northeast Thailand by providing information regarding traditional irrigation methods. We investigated the traditional irrigation methods with earthen bunds at three study sites, and our results indicated that styles of irrigation vary with riverbed slope. The traditional irrigation system that is used in most of Northeast Thailand is different from ordinal weir irrigation, in that paddy fields are not irrigated by gravity flow but by backwater of earthen bunds. Our results suggest that the development of more successful irrigation systems would be possible through improvement of the design ideas of traditional irrigation methods.

Accounting for geographic heterogeneity of multifunctional rice policy in Taiwan

Through empirical simulations of the Taiwanese rice market, we estimate the effects of agricultural policies designed to ensure optimal levels of two multifunctional outputs, groundwater recharge, and methane emissions. Optimal policy instruments differ by region to reflect land quality and the conditions of the aquifers in major rice production regions. The effects on rice production, resource allocation, and returns to farm assets differ as well.

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.

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.

Protocols for estimating magnitudes and values of paddy rice multiple functions

This paper presents protocols for estimating the magnitudes and monetary values of two non-market outputs from paddy rice production. The protocols were developed during a workshop held in Taiwan in 2004 to set guidelines or protocols for measuring the multi-functional attributes of positive and negative externalities of paddy rice. The externalities attributed to paddy rice include groundwater recharge, subsidence reduction, flood damage amelioration, change in water quality, change in air quality, and preservation of scenic value. Methodologies were set forth for measuring and valuing each of these externalities. Two that reflect differences in complexity – groundwater recharge and change in air quality – are discussed here. The protocols consider regional variation, the need for evaluation of net effects, and the avoidance of double counting. The conclusions presented are those from the workshop as a whole.

Assessment of sediment exclusion efficiency for several modified labyrinth weirs

A trapezoidal labyrinth weir is a general transverse hydro-structure typically placed across rivers that causes longitudinal sediment discontinuity and affects riparian ecological system. A sediment exclusion labyrinth (SEL) weir is a modification designed to increase sediment exclusion from upstream to downstream over or through it. Hydraulic model experiments were carried out in straight rectangular cross-sectional open channel (15 m in length and 0.82 m in width). Four different shapes of weirs were examined. type 1 was a general labyrinth weir, whereas types 2–4 were SEL weirs with an inclined bottom slope (type 2), open slots (type 3), and reversed-wedge type holes (type 4). Standard sand (Jumunjin, Korea, d ₅₀ = 0.56 mm, σ _g = 1.48, SG = 2.65) was uniformly supplied upstream using an in-house grooved drum, and sediment exclusion efficiency was calculated from the ratio of sediment amount to excluded sediment yield for each type of weir. Higher efficiencies were founded in all SEL weirs compared with the sediment exclusion efficiency of the type 1 weir. In particular, type 2 and type 4 weirs were easy to construct and their flow patterns and hydraulic performance were similar to those of type 1. Finally, their sediment exclusion efficiencies were higher under a normal water level (F _r ≤ 0.2), whereas the type 3 weir was the pattern favorable for a high water level (F _r > 0.2) because its discharge capacity was significantly higher. Sediment exclusion characteristics were analyzed in terms of flow rate based on the decomposition analysis of residual sediment particle size distribution. It is expected that the results from this study will be used to design SEL weirs as basic materials if more hydrodynamic parameters are studied and combined with field monitoring.     

The multi-functionality of paddy farming in Korea

The multi-functionality of paddy field and irrigation water has become a hot issue recently in Asian monsoon regions. Asian people know why they have to conserve the paddy farm where the sustainable functions have been historically inherited and maintain the rural community where the unique cultures have been traditionally created. But, the real value of multi-functionality has not been clearly highlighted as much worthy as it has. We should evaluate the characteristics of multi-functionality of paddy farming correctly and transmit them to the people of Western countries under quite different conditions of upland fields. In Korea, several studies on the multi-functionality of paddy farming have been performed with positive and negative viewpoints. This paper shows the results and the discussion of the researches to get global recognition on the multi-functionality of paddy farming.

A benefit incidence analysis on the far-reaching effects of paddy-field consolidation projects

A paddy-field consolidation (PC) project was carried out with large subsidies as a public investment by prefectural governments in order to improve agricultural productivity in Japan. The purpose of this study is to analyze the quantitative benefits and costs of the PC projects. A benefit incidence (BI) analysis was used in view of the far-reaching effects on farmers to consumers. The results were as follows. First, with the recent decline in rice price, certain farmer benefits primarily derived from the projects have been transferred to consumers through rice price. The transfer ratio was more than half of the total improvement effect of rice productivity which occurred on the farmers’ side, and all economic sectors including farmers and consumers received net benefit even though all sectors paid construction costs or taxes. Therefore, maintaining flexibility in rice price plays an important role to secure net benefits and obtain an agreement of all people involved in the project. Second, some benefits with regard to effects on the rural environment that was not expected at the time of planning were revealed on many project sites. Evaluating these intangible effects will be more important for the tax payers in order to evaluate how the environment friendly planning of the project achieved benefits.

Water transfer from agriculture to urban domestic users: a case study of the Tone River Basin, Japan

Agricultural water reorganization measures (AWRM) is an approach that has been adopted in Japan for more than 30 years to capture excess water from agriculture for other uses by relying on the modernization of existing irrigation infrastructures. This paper reviews the history and processes of four such permanent water transfers by AWRM in the Tone River Basin, specifically those conducted in the Saitama Prefecture, Japan. The benefit of AWRM for the agricultural sector is the lowering of rehabilitation costs by sharing part of it with the city sector. AWRM does not require saving water at the on-farm level. Instead, the labor requirement of farmers is reduced by the rehabilitation and installation of pipelines. The benefit to the city is the lower cost, when compared with costs for the development of new water resources, and the relatively short duration of the project, which are important factors in an environment of the rapid increase in domestic water demand.

The Lower Rio Grande Valley: a case study of a water market area

The Lower Rio Grande Valley is a sub-tropical area with a productive irrigated agriculture, but with an over-committed single water resource. It is experiencing a rapidly growing population that is placing increasing pressure on the water resource. This, combined with expanding urban areas and land moving out of agriculture, has resulted in a vigorous water market, with transfers from agriculture to municipal uses. For the US portion of the valley, transfers from agriculture to municipalities are either short-term (usually 1 year) or permanent. Prices vary depending upon the location and timing, and result from negotiations between the parties. Over time, and not without difficulty, the water market has been facilitated by appropriate enabling legislation, water rights that have been validated judicially, and an efficient transfer mechanism that has a minimum of transaction cost. Government involvement is primarily for protection of the public, and to facilitate the transfer process.

Multifunctionality and non-trade concerns: implications for future agricultural policy in Asia

Agriculture's multifunctional role as provider of non-commodity outputs has received increased attention in the debate on the future of agricultural policy. To identify appropriate economic policies, a distinction must be made between concerns involving market failure and a consequent misallocation of resources, and those relating to distributional issues. We argue that it is essential to restrict the concept of multifunctionality to non-commodity outputs involving technical externalities or public goods and for which market failure and the misallocation of resources are important (e.g., amenity values and agricultural pollution). Other non-trade concerns, such as rural incomes and employment and food security, involve distributional issues, but no resource misallocation. This distinction makes it possible to identify different types of domestic policy measures to address them effectively and efficiently. Through reference to an empirical application to Taiwanese paddy rice policy, we illustrate that the most effective way to reconcile non-trade concerns is through policy measures that correct for market failure by valuing non-commodity outputs appropriately and a separate set of measures that address distributional issues.

A model driven by crop water use and nitrogen supply for simulating changes in the regional yield of rain-fed lowland rice in Northeast Thailand

Climate change will have significant impacts on the rain-fed rice production ecosystem, and particularly on the ecosystem’s hydrology and water resources. Under rain-fed lowland conditions, substantial variations among fields in grain yield are commonly observed, but a method that can account for field-scale yield variability to produce regional-scale yield estimates is lacking, thereby limiting our ability to predict future rice production under changing climate and variable water resources. In this study, we developed a model for estimating regional yields of rain-fed lowland rice in Northeast Thailand, by combining a simple crop model with a crop calendar model. The crop model incorporates the effects of two important resources (water and nitrogen) on crop growth. The biomass accumulation is driven by water use, whereas the nitrogen supply determines canopy development and thereby constrains crop water use. Accounting for the wide range of planting dates and the strong photoperiod-sensitive characteristics of rice varieties through the calendar model is an essential component in determining regional yield estimates. The present model does not account for the effects of mid-season drought or flooding, but was nonetheless able to explain the spatial and temporal yield variations at the province level for the past 25 years. Thus, it can be used as a prototype for simulating regional yields of rain-fed lowland rice.     

Agriculture–urban water transfers: a case study of Hyderabad, South-India

Hyderabad is one of the fastest growing cities in India. To meet its rapidly expanding water needs, it constructed and began withdrawals from the Singur reservoir, located on a tributary of the Godavari River, in 1991. Administrative rules define allocation of water from the reservoir but prioritize Hyderabad urban needs over much longer established agricultural uses. Furthermore, the agricultural sector receives less water than even these rules allow, and urban withdrawals have changed the quantity and the timing of the water, which is available to agriculture. An increase in groundwater use by farmers may have been one response to these changes, with possible implications for surface and groundwater users further downstream. While proposals have been put forth to compensate the agricultural sector in general and the farmers directly affected by reallocation, for example by improving access to wastewater for irrigation downstream from Hyderabad or by conveying wastewater for irrigation purposes downstream Singur reservoir, compensation has not been implemented to date. The Hyderabad case study clearly highlights the advantages for devising and implementing arrangements to regulate the transfer of water from agriculture to cities, allowing a move from sectoral competition for water to efficient management of a scarce resource.

Environmental multifunctionality of paddy fields in Taiwan: an application of contingent valuation method

This paper aims to evaluate the social value of the environmental multifunctionality of paddy fields in Taiwan; through individual consumers’ direct expressions of their perceived benefit and to provide the empirical data thus collected for the reference of the decision makers in the government. This study use contingent valuation method (CVM) to evaluates the value of environmental multifunctionality of paddy fields from the purposefully selected pool of samples in Taiwan. The result shows if judged by the threat that free trade poses to the retention of arable land, most respondents give a value of 114 NT/household/month to 115 NT/household/month for 1% reduction of arable land to be restored to the existing level; and168 NT/household/month to 181 NT/household/month for a reduction rate of 4%. There are 7,394,758 households in Taiwan. The aggregating result is 10,116,028,944 NT/year to 10,204,766,040 NT/year for 1% reduction of arable land to be restored to the existing level; and 14,907,832,128 NT/year to 16,061,414,376 NT/year for a reduction rate of 4%.

Delay of heading date as an index of water stress in rainfed rice in mini-watersheds in Northeast Thailand

Drought is recognized as a primary constraint for rainfed rice production. In this study, the spatial distribution of heading date of rainfed rice and its relation to field water conditions were investigated for 2 years in mini-watersheds called Nong in Northeast Thailand, in order to clarify the toposequential variation in the degree of water stress of rice. Although the difference in the relative field elevation in the mini-watersheds was only a few meters, the water availability in terms of standing water and soil moisture markedly decreased with ascending elevation. Rice cultivars, KDML 105 and RD 6, the two dominant genotypes in Northeast Thailand, reached the heading stage at nearly the same day in the absence of water stress, independent of transplanting or seeding date under customary management. As the water availability decreased with ascending field elevation, the heading date of rice was markedly delayed. The delay seemed to be related to the cumulative water stress before heading of rice. The rice harvest index and yield at farmers’ fields decreased linearly with the delay of heading. The observed toposequential distribution of heading date indicated that quite severe water stress was imposed in the uppermost fields of the mini-watersheds, while practically no water stress occurred in the lower fields, at least in the lower half of the mini-watersheds. These results suggest that the delay of heading is a good index for rice water stress in rice in Northeast Thailand and can be applicable to field classification with respect to drought risk.     

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.

An Ethical Assessment of Cisgenesis in Breeding Late Blight Resistant Potato

Because of objections and worries related to genetically modified organisms (GMOs), the approval of GMO crops is a long and expensive process. Recently some researchers argued that a specific form of genetic modification, cisgenesis, would be safer and ethically more acceptable and therefore require a less stringent assessment. In this paper cisgenesis, as defined in recent literature, is ethically evaluated. After some general remarks on ethics in science and technology, two different basic attitudes towards reality are sketched as an evaluative framework for interventions in nature. Combined with general characteristics of biotechnology in agriculture and a view of the role of genetic information in organisms, that framework helps to formulate an ethical distinction between and evaluation of cisgenesis and transgenesis. It is argued that there is a significant ethical difference between transgenesis and cisgenesis, but that nevertheless any form of genetic modification should be integrated in a broader normative understanding of agriculture in order to work towards a more sustainable agriculture.

Modeling the dependence of the crop calendar for rain-fed rice on precipitation in Northeast Thailand

Rain-fed lowlands are major agricultural ecosystems used for rice production in Northeast Thailand. Developing a tool to assess the effects of variable water conditions on the regional scale yield is also important to predict the effects of climate change on food supply. To estimate regional yields, we need a simple but accurate measure of the crop calendar (i.e., the distribution of planting dates), which has a strong influence on grain yield. In this article, we modeled the dependence of the crop calendar on rainfall patterns based on a survey of the region’s farmers as a part of an effort to provide a stronger basis for regional yield estimates. Our survey, conducted in 11 provinces for 2 years, confirmed the existence of large windows for sowing and transplanting versus narrow windows for heading and harvesting for rain-fed lowland rice culture in all the provinces. Variable water, soil, and toposequential conditions in the paddy fields were responsible for the large sowing and transplanting windows, whereas the use of photoperiod-sensitive varieties explained the narrow windows for heading and harvesting. The crop calendar was well expressed as a function of cumulative precipitation from June onward. When the crop calendar model was combined with a simple phenology-based model that uses growing degree-days adjusted by a day-length factor, we could estimate the rice crop calendar under rain-fed lowland conditions with acceptable accuracy. The model described in this article will be combined with a crop growth model to improve regional yield estimates for rain-fed lowland rice.     

Relay-Intercropping of Stylosanthes guianensis in Rainfed Lowland Rice Ecosystem in Northeast Thailand

We evaluated the usefulness of the Stylosanthes guianensis (stylo)- rice relay-intercropping system for increasing agricultural productivity in Northeast Thailand. Although large production variability was observed, the relay-intercropping system produced an average of 350 g m-² stylo dry matter during the dry season under non-irrigated and non-fertilized conditions in the experimental fields at the Ubon Rice Research Center. Utilization of the stylo production as green manure increased rice yield, but only slightly. The relay-intercropping also slightly improved soil chemical properties, but not significantly. The trial of the relay-intercropping in farmer’s fields produced a maximum of 367 g m-² stylo dry matter. Since the stylo production did not decrease the subsequent rice production, the rice-stylo relay-intercropping system is worth considering as one way to utilize the paddy fields during the dry season in Northeast Thailand.     

Identification of Nutrients Limiting Rice Growth in Soils of Northeast Thailand under Water-Limiting and Non-Limiting Conditions

Summary

Glasshouse nutrient omission trials are useful in identifying nutrient limitations for plant growth in soils under the same environmental conditions. Soils of low fertility are commonly used for production of rainfed lowland rice (Oryza sativa L.), and the crop often encounters water stress. Nutrient requirements may be modified when standing water disappears from the field. Two experiments with rice seedlings were conducted in a glasshouse at Ubon Rice Research Center, Thailand, to identify the nutrients which limit rice growth in soils of Northeast Thailand, and to determine whether nutrient limitations are affected by water availability. In Experiment 1, rice was grown on two soils (Roi et and Ubon series) under well-watered and water-limiting conditions, and 15 nutrient treatments were imposed. In Experiment 2, six soils from Northeast Thailand were examined using the same 15 nutrient treatments. The nutrients which clearly limited the growth of rice plants in soils of Northeast Thailand were nitrogen (N) and phosphorus (P). In some cases, potassium (K) and sulfur (S) also limited growth, and in one soil zinc (Zn) and boron (B) also limited growth. A shortage of N was the most important limitation for plant growth in all soils except one in which P was more important. The low supply of P decreased plant height and leaf area development during early growth ; low N supply had a greater effect later during growth. The omission of P had a larger detrimental effect on growth when water supply was limited. In the Roi et soil, the omission of S had a large effect on leaf area and total dry matter production only under water stress conditions, but this was not found in the other soils examined. These results from glasshouse studies show that the nutrients limiting rice growth depend on soil type and water availability in soils of Northeast Thailand.