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1.
To optimize the use of limited water resources, surface irrigation systems in parts of China have introduced a new water saving irrigation method for rice termed alternate wetting and drying (AWD). The basic feature of this method is to irrigate so that the soil alternates between periods of standing water and damp or dry soil conditions from 30 days after crop establishment up to harvesting. However, many Chinese rice farmers still practice the continuous irrigation method with late- season drying of the soil.A comparative assessment of these two methods of on-farm water management for rice was conducted at two sites within the Zhanghe Irrigation System (ZIS) in Hubei province of China for the 1999 and 2000 rice crops. The objective was to evaluate the impact of AWD on crop management practices and the profitability of rice production. In conjunction with irrigation district officials, two sites within ZIS were selected for study, one where AWD was supposed to be widely practiced (Tuanlin, TL) and one where it had not been introduced (Lengshui, LS). It was found that farmers at both sites do not practice a pure form of either AWD or continuous flooding. However, farmers in TL did tend to let the soil dry more frequently than their counterparts in LS.Because most farmers practice neither pure AWD nor pure continuous flooding, an AWD score was developed that measures the frequency with which farmers allow their soil to dry. This AWD score was not significantly correlated with yield after controlling for site and year effects and input use. AWD scores were also not correlated with input use. We conclude that AWD saves water at the farm level without adversely affecting yields or farm profitability.  相似文献   

2.
This paper introduces an irrigation system developed in the floodplain of a lake and studies the water management technique of the irrigation system by estimating the total water balance of the whole system. The system is characterized by a reservoir combined with a dike system in the floodplain of the Tonle Sap Great Lake and an irrigation system. Two main models are used for calculating the total water balance. The first model is the water balance of the reservoir. The inputs to the model are water level of the reservoir, precipitation, lake evaporation, infiltration, and area–volume curve of the reservoir. The outputs are inflow and outflow of the reservoir. The supply from the reservoir to paddy fields is computed from the outflow. The second model is the water balance of paddy fields, based on which the water requirement in paddy fields is derived. The reference evapotranspiration needed to calculate the water requirement is simulated for monthly time series using the FAO Penman–Monteith model. Since there is no drainage network in the irrigation system, surface drainage and runoff are not included in the calculation of the water balance, and seepage is considered negligible in the flat floodplain area. The evapotranspiration, rice variety, soil type and irrigated area are used to simulate water consumption in paddy fields. Finally, the two models are connected to produce the total water balance from the reservoir to paddy fields. The total outflow from the reservoir is estimated and the total water consumption for dry season cultivation is also determined. Finally, the efficiency of the whole system is examined.  相似文献   

3.
Increasing water productivity for paddy irrigation in China   总被引：4，自引：0，他引：4  
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.  相似文献   

4.
This study aims to investigate recent practices on water allocation and cultivation in the Upper East Bank of the Chao Phraya Delta in Thailand, by using data collected by RID local offices, questionnaires, and analyses of satellite images. As a result, we have identified the advantage that upstream areas of irrigation canals have enjoyed, namely the preferential water allocation over the downstream areas. This advantage was strongly associated with the intensive cropping patterns of rice: the upstream areas were estimated to conduct almost continuous rice cultivation throughout a year. In addition, the intensive rice cultivation would partly be supported by water from private shallow wells, which were mostly concentrated in the upstream areas of main canals. Those shallow wells would be used at the beginning of the dry season and in drought years, when farmers could not expect water supply from irrigation canals. The result indicated that the conjunctive use of surface and ground water would be practiced in this region.  相似文献   

5.
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 (NSPAD35), 38 (NSPAD38), and 41 (NSPAD41). In 2005, NSPAD32 was tested instead of NSPAD41. 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 NSPAD38 and NSPAD35 was consistently higher than that of N180 in all water treatments. NSPAD38 consistently gave yield similar to that of N180 in all water treatments, while yield of NSPAD35 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 NSPAD35 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.  相似文献   

6.
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.  相似文献   

7.
Intensive cultivation of rice and wheat in north-west India has resulted in air pollution from rice straw burning, soil degradation and declining groundwater resources. The retention of rice residues as a surface mulch could be beneficial for moisture conservation and yield, and for hence water productivity, in addition to reducing air pollution and loss of soil organic matter. Two field experiments were conducted in Punjab, India, to study the effects of rice straw mulch and irrigation scheduling on wheat growth, yield, water use and water productivity during 2006-2008. Mulching increased soil water content and this led to significant improvement in crop growth and yield determining attributes where water was limiting, but this only resulted in significant grain yield increase in two instances. There was no effect of irrigation treatment in the first year because of well-distributed rains. In the second year, yield decreased with decrease and delay in the number of irrigations between crown root initiation and grain filling. With soil matric potential (SMP)-based irrigation scheduling, the irrigation amount was reduced by 75 mm each year with mulch in comparison with no mulch, while maintaining grain yield. Total crop water use (ET) was not significantly affected by mulch in either year, but was significantly affected by irrigation treatment in the second year. Mulch had a positive or neutral effect on grain water productivity with respect to ET (WPET) and irrigation (WPI). Maximum WPI occurred in the treatment which received the least irrigation, but this was also the lowest yielding treatment. The current irrigation scheduling guidelines based on cumulative pan evaporation (CPE) resulted in sub-optimal irrigation (loss of yield) in one of the two years, and higher irrigation input and lower WPI of the mulched treatment in comparison with SMP-based irrigation scheduling. The results from this and other studies suggest that farmers in Punjab greatly over-irrigate wheat. Further field and modelling studies are needed to extrapolate the findings to a wider range of seasonal and site conditions, and to develop simple tools and guidelines to assist farmers to better schedule irrigation to wheat.  相似文献   

8.
《Plant Production Science》2013,16(2):237-242
Abstract

This study aimed to clarify the effects of water storage-type deep irrigation (WSDI) on the yields of various rice cultivars used in the Tohoku district of Japan. We compared a WSDI plot (DP) with a standard irrigation plot (SP) with regard to the growth, yield, and yield components of the rice cultivars grown in these plots during 4 years (2002–2005) in Sendai, Japan. In 2003, which had a cool summer, the yields in DP were considerably higher than those in SP, thus confirming that WSDI mitigated the cool summer-induced damage to rice. The yields in DP were not lower than those in SP during the other 3 years (normal climatic years), indicating that various cultivars could adapt to WSDI. Although high-yielding rice plants cultivated by well-experienced farmers under deep-water irrigation regimes have large panicles, the spikelet number per panicle and the yield in DP were not higher than those in SP. Based on the results of the comparison between the cultivation system of WSDI and that of high-yielding deep-water irrigation regimes practiced by such farmers, we speculated that to achieve a higher yield under WSDI, other cultivation techniques need to be incorporated into WSDI.  相似文献   

9.
The case study is aimed at assessing impacts of on-farm level irrigation development and management on dry season rice production in the main irrigated rice production area of Myanmar. The study was carried out from 2003 to 2009 in the middle reaches of the Ngameoeyeik irrigation area of 28,000 ha. In addition to collecting information on water management and institutional arrangement of the study area, hydrologic and agronomic parameters were monitored during the study period. Results showed the effectiveness of on-farm level infrastructural development for increasing rice productivity owing to increased amount of water delivery, increased flexibility of water distribution, and improved drainage conditions. Besides, encouraging the involvement of farmers in design and implementation of the development led to improved farmer participation in the operation and maintenance of the irrigation system. The outcomes of this study demonstrated the importance of balancing between infrastructural and institutional development in irrigation systems of Southeast Asia. Such infrastructural development should be in close association with institutional development and capacity building, and the interactions between those two aspects should be well understood.  相似文献   

10.
China, the biggest rice-producing country in the world, has put considerable effort into finding ways to conserve water in rice cultivation. One very promising practice, intermittent submerged irrigation (ISI) was reported to be applied on farmers fields over a large area in the Zhanghe irrigation system (ZIS), which serves about 160,000 ha of irrigated land, which is intensively cultivated with rice. To better understand the actual farmer practices, the degree to which farmers adopt ISI, the resulting water productivity, and implications for farm and system water management, a water accounting methodology developed by IWMI was applied at farm and a larger meso scale. Two areas were observed: Tuanlin, where ISI was reported to be widespread (with ISI), and Wenjiaxiang, where farmers were reportedly not adopting ISI (without ISI). The field water level measurements demonstrate that farmers at the with ISI site follow a practice similar to the theoretical ISI techniques by letting ponding levels drop to the soil surface several times during the cropping season. At the without site, farmers keep higher water levels ponded, and do not let water levels drop to the soil surface as often as the with site. A major determinant of practice is ease of access to water. At the with site, farmers have access to a variety of sources such as ponds and drains. At the without site, access to water was primarily from canal water, without the degree of flexibility as areas that had a water source near the field. The process fraction of gross inflow at field scale (rice evapotranspiration divided by irrigation plus rain) ranged between 0.66 and 0.93, remarkably high values showing how effective farmers are in converting water sources to productive evapotranspiration. The on-farm water accounting results show that with ISI, the average values of irrigation water applied over two years 1999–2000 are 22% less than without ISI, and the yields approximately the same. The resulting water productivity values per unit of irrigation water (WPirrigation) are 20% higher under ISI practices, but per unit of evapotranspiration water productivity results are similar. The meso site study yielded surprising insights into overall water management in the area. In the years 1999 and 2000, at the meso sites, the irrigation duty in Tuanlin (with ISI) was 29% and 21% less than in Wenjiaxiang (without ISI), respectively, resulting in WPirrigation values of 24% and 26% higher at Tuanlin than Wenjiaxiang. But values of process fraction of gross inflow were considerably reduced at the meso scale ranging between 0.12 and 0.29, with considerable drainage outflow observed. Different land uses, trees, roads, villages, and ponds, begin to play an important role in overall water resource management at this scale. Drainage water from fields plus runoff served as supplies to ponds within the meso area as well as downstream reservoirs. Ponds play a very important role as an additional source of water, and in fact facilitate the uptake of ISI practices. This demonstrates that there are multiple strategies at play influencing water savings and productivity beyond ISI in the management of water within the area.  相似文献   

11.
Water-saving technologies that increase water productivity of rice are urgently needed to help farmers to cope with irrigation water scarcity. This study tested the ability of the ORYZA2000 model to simulate the effects of water management on rice growth, yield, water productivity (WP), components of the water balance, and soil water dynamics in north-west India. The model performed well as indicated by good agreement between simulated and measured values of grain yield, biomass, LAI, water balance components and soil water tension, for irrigation thresholds ranging from continuous flooding (CF) to 70 kPa soil water tension.Using weather data for 40 different rice seasons (1970-2009) at Ludhiana in Punjab, India, the model predicted that there is always some yield penalty when moving from CF to alternate wetting and drying (AWD). With an irrigation threshold of 10 kPa, the average yield penalty was 0.8 t ha−1 (9%) compared with CF, with 65% irrigation water saving, which increased to 79% at 70 kPa with a yield penalty of 25%. The irrigation water saving was primarily due to less drainage beyond the root zone with AWD compared to CF, with only a small reduction in evapotranspiration (ET) (mean 60 mm).There were tradeoffs between yield, irrigation amount and various measures of WP. While yield was maximum with CF, water productivity with respect to ET (WPET) was maximum (1.7 g kg−1) for irrigation thresholds of 0 (CF) to 20 kPa, and irrigation water productivity (WPI) increased to a maximum plateau (1.3 g kg−1) at thresholds ≥30 kPa.Because of the possibility of plant stress at critical stages known to be sensitive to water deficit (panicle initiation (PI) and flowering (FL)), treatments with additional irrigations were superimposed for 2 weeks at one or both of these stages within the 10, 20 and 30 kPa AWD treatments. Ponding for two weeks at FL was more effective in reducing the yield penalty with AWD than ponding at PI, but the biggest improvement was with ponding at both stages. This reduced the average yield loss from 9% (0.8 t ha−1) to 5% (0.5 t ha−1) for AWD with thresholds of 10 and 20 kPa. However, maximum WPI (1.1 g kg−1) was achieved with an irrigation threshold of 20 kPa combined with more frequent irrigation at FL only, but with a greater yield penalty (8%). Thus the optimum irrigation schedule depends on whether the objective is to maximise yield, WPET or WPI, which depends on whether land or water are most limiting. Furthermore, the optimum irrigation schedule to meet the short term needs of individual farmers may differ from that needed for sustainable water resource management.  相似文献   

12.
We conducted interview survey with rainfed rice farmers at a commune in southern Cambodia to identify the determinants of their adoption or rejection of the system of rice intensification (SRI) for the wet season of 2014. SRI was first introduced to the commune in 2003 and spread among the farmers, but the number of farmers discontinuing the practice has increased since 2011. We classified the farmers into four categories: those who practice SRI in all their fields (OA), farmers who practice SRI in some of their fields (PA), farmers who had practiced SRI but discontinued it (DA), and farmers who have never practiced SRI (CR). Farmers in different categories of SRI adoption differed in their access to water sources. The majority of OA and PA farmers had supplementary water sources, which was, however, available to less than 50% of DA farmers and only 15% of CR farmers. Both PA and DA farmers mentioned water shortage as the reason for not practicing SRI in some (PA) or any (DA) of their fields, but they differed in the number of rice fields. All the PA farmers had more than one field, whereas a majority of DA farmers had only one field. Labor shortage and difficulty of planting in a regular grid pattern were also mentioned as the reason for not practicing SRI by the farmers, particularly by DA farmers. Water constraint and difficulties in transplanting were thus identified as two major determinants of SRI adoption/rejection at the study site.  相似文献   

13.
This paper examines irrigation management conduct within the Japanese Water Users Association (WUA), namely the Land Improvement District (LID). LID is regarded as a successful case of participatory irrigation management (PIM), in which there are few conflicts over water between farmers so that it attains high social cost performance. However, the management system of LID still remains obscure. We throw light on this system assuming the existence of "the rule of fairness". Farmers operate the irrigation facilities in a self-serving way and have their own rule of fairness, such as upstream superiority, based on the long-term experiences of irrigation systems. We defined this rule of fairness as made up of two components: one is "fairness of outcome" and the other is "fairness of procedure". Finally, we discovered that the approach of LID staff is the essential factor to satisfying the farmers' criteria of fairness and maintaining peace; LID staff place importance on farmers' customary rules, taking care to remain neutral in arbitrating quarrels between farmers and trying to ensure organizational transparency to farmers. This can be also a good lesson for future PIM projects.  相似文献   

14.
Rice (Oryza sativa L.) is the most important staple food crop in the southern region of Asia, and Indian subcontinent being one of the major producers. Production of conventional transplanted rice requires a large amount of irrigation water, labor, and energy. The scarcity of irrigation water has encouraged farmers to adopt an alternative rice production system, i.e. the direct-seeded rice (DSR), which is proposed to be farmers’ friendly with a potential to save water. Our study reports the performance of DSR with respect to yield and water expense efficiency based on different irrigation regimes and dates of sowing. A field experiment was conducted in the semi-arid region of northern India during the rainy season of 2011 with two treatment combinations (dates of sowing: 15th May and 5th June and three irrigation regimes: irrigation scheduled at irrigation water-to-cumulative potential evapotranspiration; IW/CPE ratio of 1.0, 1.5 and 2.0) in a completely randomized design. We found statistically higher water expense efficiency of DSR sown on 5th June as compared to DSR sown on 15th May without any significant differences in growth and yield. A significant yield difference between DSR grown with irrigation regimes of IW/CPE 1.0 and 1.5 and DSR grown with irrigation regimes of IW/CPE ratio 2.0 were observed. The DSR grown with irrigation regimes of IW/CPE ratio of 1.5 resulted in significantly higher water expense efficiency than the one with IW/CPE ratio of 2.0. Obtaining a higher yield of DSR under scarce irrigation water might be a trade-off between optimum water use and maximum yield avoiding excess ground water exploitation in sub-tropical semi-arid regions of India. Our study suggests that sowing time and irrigation regimes are two important aspects of “rice production” to attain “win–win” solution. Thus, strategic and judicial use of irrigation water with management of sowing time could potentially escalate the rice production in water scarce regions of India.  相似文献   

15.

The Plaichumpol Irrigation Project, in Nan Basin of Thailand, is selected as a case study of impact study, where farmers depended on both surface and groundwater sources (especially in the dry year), to assess the impact on irrigation systems. The study used the MRI-GCM data to project the future climate condition and assess the impact on irrigation systems focusing on water shortage and groundwater pumping aspects in the selected consecutive dry years. The responses from farmers on the impact and adaptation were also gathered via site interviews and analyzed. Based on the bias-corrected MRI-GCM data, the annual rainfall in Nan Basin will decrease in the near future (2015–2039), compared with the past average data (1979–2006), while the rainfall will increase in the far future (2075–2099) compared with past. Water supply from dam will decrease in wet season and dry season, while water demand in both of near future and far future will increase in wet season and dry season. Less water shortage and groundwater pumping in both near-future and far-future periods are expected in the future consecutive dry years compared with the past, though the groundwater is still an important supplementary irrigation water source in the dry year. From the field interview, the farmers are ready to adapt to the changing situations and join in the water use meeting to follow up with irrigation officers about the adjustment of plant calendar and water allocation due to the climate change and to prepare adaptation measures as necessary.

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16.
There are various avenues for intensifying agricultural production, the most common being increased use of fertilizers, supplemental irrigation of crops, and adoption of high-yielding varieties. These options are rather widely known to farmers around the world, but they have not been widely adopted by smallholders in sub-Saharan Africa. The low adoption rate is related to complex technical and socio-economic issues, such as poor extension services, lack of capital, failure to mobilize the requisite water, or simply, poverty. The System of Rice Intensification (SRI) is in a special category of innovation in that, farmers stand to gain multiple benefits from its use, including the possibility of increasing rice yields substantially, saving water, and getting better grain quality, using differently the assets that they already have. A major impediment for the adoption of SRI in Africa has been lack of knowledge about this intervention, especially for farmers already practicing irrigated agriculture. Farmers generally have good business sense and will adopt technologies or practices once the benefits are proven and the risks are seen as minor. SRI should be attractive for these reasons, but there are various issues to be resolved before large numbers of farmers can adopt the method. This article reports on the steps taken and the technical and socio-economic issues addressed in efforts to introduce SRI and promote it in Kenya, specifically in the Mwea Irrigation Scheme. A diverse set of individuals and institutions in Kenya together embarked on the evaluation and dissemination of SRI methods in this East African country beginning in July 2009. If the new methods can perform in Kenya as in other countries, this will bring much benefit to rice farmers and rice consumers in the region. SRI is coming to Kenya relatively late, as it was the thirty-ninth country from which favorable SRI results have been reported. This means that Kenyans can learn from others’ experience and evaluations, and there is also now more of a supportive institutional framework. The initial results from on-farm SRI trials have been positive, although not conclusive. They have given impetus to Kenyan farmers and institutions to collaborate within a multi-sectoral, multi-level coalition that has provided an informal, multi-faceted platform for the evaluation, adaptation and dissemination of SRI practices. The initiative in Kenya is now gaining more formal status and more resources. This experience is presented to show the kinds of things that have been and can be done to utilize the SRI opportunity for raising land, labor, and water productivity in the rice sector.  相似文献   

17.
The OECD has introduced a water pricing mechanism and listed eight categories gleaned from experience in OECD countries. However, in the Asian humid tropics, it is too early to apply water pricing because there is seldom a concept of water right, or practical organization of water management. In almost all irrigation projects in Japan, area charge has been applied, and collected fees have recovered entire operation and maintenance costs. Although effective volumetric charge is employed in several regions in Japan, most farmers pay area-based annual charges at several times of the year via Land Improvement Districts. In the Asian humid tropics, it is important to facilitate the establishment of sound management organizations of irrigation water before introducing a strict water pricing mechanism to levy the charge.  相似文献   

18.
The irrigation trend in Asia has been characterised as a shift from gravity to lift irrigation, but the importance of individual lift irrigation using surface water remains to be documented. Surveys on field water application by farmers using lift were undertaken in three sites and across the 44,600 ha Cau Son irrigation and drainage area in the spring crop season. Lift irrigation was found to be practised by 82 % of households. The main lift technology was mechanical pump (petrol and electric), followed by traditional swing and long-handle baskets. The main source for lifting was on-farm canals. Although gravity irrigation was the dominant field application method, the area solely irrigated by individual lift ranged from 25 to 52 % of the irrigated areas. Scaling up from the sites, individual lift accounted for 29 % by irrigation area and volume, with 17 and 12 % attributed to mechanical and manual lift. The application of mechanical pumps was a response to locally high-field elevations and significantly increased with the distance of water delivery from the main canal. The impact of mechanical pumping on flexibility and reliability was significant and positive. Petrol driven pumps had relatively high operational and investment costs, but farmers gained higher flexibility and reliability and compensated by applying less water. Farmers using electric pumps applied significantly more water and thereby wasted electric energy as a compensation for uncertain electric power supply. The importance of individual lift irrigation suggests that it should be explicitly considered in irrigation management policies and performance assessments.  相似文献   

19.
In water-efficient rice production, grain yield is often constrained by panicle size. The objective of this study was to genetically dissect the response of panicle morphology to irrigation regimes in aerobic rice culture. We grew ‘Akihikari’ (a lowland japonica cultivar) × ‘IRAT109’ (an upland japonica cultivar) backcross inbred lines in aerobic soils with full or limited irrigation for 2 years, and examined 4 panicle traits—number of florets per panicle (FPP), number of primary branches per panicle (BPP), number of florets per primary branch (FPB), and frequency of pre-flowering floret abortion (%FA)—and grain yield. QTLs for BPP were detected in both the irrigation regimes but QTLs for FPB and %FA were detected mostly only in either of the irrigation regimes. The QTL for FPP on chromosome 2 (RM3421–RM213) coincided with that for yield under full irrigation, showing that this QTL is related to sink capacity and yield potential in aerobic rice culture. On the other hand, the QTL for FPB on chromosome 1 (RM3148–RM243) coincided with that for yield under limited irrigation, when water deficit was moderate. The QTL for root axis length at vegetative stage, previously identified in the same mapping population, was located near this region. This study unravelled the complicated genetic control on panicle morphology in aerobic rice culture, and suggested the positive roles of the dehydration avoidance mechanism by vigorous root growth on panicle size and yield under dry soil conditions.  相似文献   

20.
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.
Yoji KunimitsuEmail:
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