Quantitative analysis of reusing agricultural water to compensate for water supply deficiencies in the Nile Delta irrigation network

The main problem facing farmers in the Nile Delta is water shortages at the ends of irrigation networks and canals. These problems have worsened as water demands have increased. Egypt’s Ministry of Water Resources and Irrigation is currently trying to avoid water deficits by returning agricultural drainage water to the irrigation canals. In the Kafr El-Sheikh Governorate, some canals have an oversupply in some months and deficits in others. Ministry officials started a project by constructing culverts connected canal ends with the main drain (Bhr Nashrat) to provide supplemental agricultural drainage backflows (SADB) channeled through these culverts. However, this return is not controlled, and flows are based only on differences in the hydraulic head. In this study, we evaluated the effectiveness of SADB to counteract water shortages when the water supply from head regulators (WSHR) is insufficient. Our analysis considered the adequacy of the water supply and indicators of dependability and equity of supply. We tested two water supply conditions: (1) WSHR only and (2) WSHR plus SADB. During the summer (May–September) of 2008, SADB significantly improved the system’s ability to meet the irrigation water requirements (IWR) in some months. Adequacy and dependability, therefore, improved from “fair” to “good.” During the following winter (October–April), SADB improved adequacy and equity only in March and April, since water availability was generally sufficient under WSHR.     

Assessment of irrigation practices at the tertiary canal level in an improved system—a case study of Wasat area, the Nile Delta

Egypt faces great challenges due to its limited water resources by enforcement policies to improve the performance of the existing delivery system and its development. The improvement of irrigation systems in the Nile Delta is one of the most important attempts in Egypt to implement more effective irrigation technologies. This study was carried out to evaluate improved tertiary canal level and farmers’ practices by comparing with other unimproved systems to understand the farmers’ practices in their farms after modifying the existing irrigation system. This study area applied to the Wasat command area’s most commonly used to the cultivation of a paddy field in Egypt, which contributes 40 % of production. The overall results indicate that the water-use application at the improved system level improved. This was due to the role of water user association in the successful management and operation of the water-supply system on the private level of water distribution network. So, water users’ association has the positive effect on managing of the improved tertiary canal. Although, there are main problems of water delivery in the irrigation networks that was a water shortage in the main canal owing to its location at the tail of the feeder canal system in the Nile Delta, and other reasons include the absence of crop production planning by farmers, especially rice farmers in summer, and the greater demand of some fields than supply.     

The influence of seepage from canals and paddy fields on the groundwater level of neighboring rotation cropping fields: a case study from the lower Ili River Basin,Kazakhstan

In the large-scale irrigation schemes of the lower Ili River Basin of Kazakhstan, crop rotation combines paddy rice and non-rice crops. Continuous irrigation is practiced in paddy fields, whereas other crops are sustained from groundwater after only limited early irrigation. The water table in non-rice crops is raised by seepage from canals and the flooded paddy fields. We investigated the areal extent to which the groundwater level of non-irrigated fields is influenced by seepage from canals and paddy fields by examining the relationship between distance (from canal and paddy field) and groundwater level in upland fields. The groundwater level was influenced for up to 300 and 400 m from the canals and paddy fields, respectively. Geographic information system analysis of crop and canal patterns in the 11 selected years showed that if the zone of influence is 300 and 400 m from the canals and paddy fields, respectively, the groundwater level of most of the area of upland fields was raised by seepage. We conclude that the water supply to cropping fields by seepage from irrigation canals and paddy fields is adequate, but the spatial distribution of the paddy fields may be an important factor that needs more attention to help improve water use efficiency in this irrigation district.     

Performance diagnosis of Mae Lao Irrigation Scheme in Thailand (I) Development of Unsteady Irrigation Water Distribution and Consumption model

The Mae Lao Irrigation Scheme is one of the largest irrigation projects in Northern Thailand. According to the field reconnaissance, water shortage usually occurs during the dry season. And it is very difficult to equally distribute available water to the paddy fields from the upstream to the downstream parts of the system. To understand and identify the causes of the problems, the measurement of water level and flow rate along all canals may be effective. However, it is not easy to achieve this in such a large-scale irrigation system. Thus, the numerical simulation becomes the second option. The objective of this study is to identify and quantify the real water shortage causes by developing an Unsteady Irrigation Water Distribution and Consumption model which can simulate the water movement and consumption in the whole irrigation system. The beneficial area of the right main canal is modeled based on the physical aspect of the system. The components of the model consist of canal networks, control structures, and paddy fields. A canal is divided into several portions called reach. The Saint-Venant equations are applied to describe the unsteady water movement in each reach. Flow movement at the control structure is expressed by the boundary condition. The paddy fields are modeled to make paddy block and connected to each reach. The water consumption in each paddy block is estimated by Paddy Tank model. The numerical model is successfully developed showing the ability to simulate the water movement and consumption properties in this irrigation system.     

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.     

冷浸田条件下不同类型品种的表现和高产栽培方式研究

2009年在宁乡县、桃源县、永兴县3地冷浸田条件下进行了品种筛选和不同栽培方式的比较试验。结果表明:(1)不同品种在3个地点产量表现基本一致,早稻以陆两优996和陵两优211表现较好,平均产量分别达到5.68 t/hm2和5.28 t/hm2,晚稻以钱优1号、天优华占和丰源优299表现较好,产量分别达到5.08,4.94和4.81 t/hm2;(2)不同栽培方式产量表现地点间不一致。桃源点早稻和晚稻以翻耕移栽和免耕抛栽产量较高,永兴点早稻免耕抛栽产量最高,晚稻以垄厢移栽产量最高,宁乡点早稻和晚稻都以翻耕移栽产量最高。     

水分胁迫下稻作幼苗酯酶等同工酶的 分析

利用电泳技术对稻作异养期幼苗在水分胁迫下的茎叶、根进行酯酶等同工酶的分析,以探讨稻作抗旱性和生化基础。研究结果表明：（１）水分胁迫后,水旱稻一些品种茎叶的ＳＯＤ（超氧化岐化酶）和过氧化物酶的若干同工酶酶带活性增强,但在根系中酶带活性均出现不同程度的减弱。（２）水分胁迫后,水旱稻茎叶中的酯酶同工酶出现一条新的酶带Ａ３。（３）水分胁迫后,早稻根系的酯酶同工酶Ａ１酶带活性减弱程度明显轻于水稻。水旱稻杂种     

Simulation model of rainfed rice production on sloping land in northeast Thailand

In northeast Thailand, the rapid expansion of rainfed paddy fields has decreased the stability of rice production. This paper describes a model that computes rice production on the basis of the hydrologic conditions of rainfed paddy fields on hill slopes. The model well expressed the hydrologic processes, rice yield, and production at the study site. We simulated rice production as uphill paddy plots are abandoned, increasing catchment area, under various rainfall conditions. The simulation showed that rice yield and stability increase as uphill plots are abandoned, although the total rice production decreases. Thus, the effect of catchment size on rice production in each plot was quantified. The model proved to be useful for analyzing rainfed rice production under various land and water conditions.     

Effects of Phosphorus on Grain Quality of Upland and Paddy Rice under Different Cultivation

We investigated how upland and paddy japonica rice responded to phosphorous(P) fertilizer under two cultivation methods.The upland rice Zhonghan 3 and the paddy rice Yangfujing 8 were both grown under moist cultivation(MC,control) and bare dry cultivation(DC) with three P levels,low(LP,45 kg/hm2),normal(NP,90 kg/hm2) and high(HP,135 kg/hm2).As P level increased,grain yields of both upland and paddy rice increased under DC.There were no significant differences in grain yields between HP and NP for either rice,although upland rice slightly increased and paddy rice slightly decreased in grain yield.Under DC at LP,Zhonghan 3 showed a higher head milled rice rate and better appearance,cooking and eating qualities than at HP or NP.Yangfujing 8 was similar to Zhonghan 3 except that Yangfujing 8 had better appearance quality at NP.Under MC,Zhonghan 3 had a higher head milled rice rate at LP and better cooking and eating qualities at NP.Yangfujing 8 was similar to Zhonghan 3 except in appearance quality.DC improved head milled rice rate and appearance quality of both upland and paddy rice,and cooking and nutrient qualities of paddy rice.Compared with paddy rice,upland rice had better processing,nutrient and eating qualities.The results suggest that upland and paddy rice respond differently to cultivation method and phosphorus level.     

水分管理调控水稻镉污染的研究与应用进展

我国稻田镉污染严重,稻米安全问题突出,发展能够有效调控水稻镉污染的产品与措施尤为迫切.稻田生态系统高度复杂,并易受多种因素影响,水稻镉污染调控难度大.大量研究表明,合理的水分管理不仅能够保障水稻正常的生长发育、产量和稻米品质,同时还能有效减少水稻镉积累.本文综述了水分对土壤理化性质、微生物动态变化以及植物生长发育的影响...     

开花灌浆期干旱胁迫对水、陆稻细胞膜透性和产量性状的影响

 在开花灌浆期对三个水、陆稻品种进行干旱胁迫处理。结果发现,叶片中自由水含量较高的湘粳2号（粳型水稻）在复水后细胞膜透性仍然较高,束缚水含量下降,平均减产幅度最小,表现出明显的耐旱特性。而湘中籼3号（籼型水稻）的表现相反,是不耐旱品种。陆稻品种奉爱的抗旱性明显较强,但产量较低,有待进一步改良。     

香米品质与微量元素含量特征关系的研究

采用“江永香稻”与、香稻80－66”两个香稻品种，在香稻产地与非产地同时进行大田试验，对其稻米、灌溉水与土壤中的11种微量元素含量与稻米品质各项指标进行了分析。结果表明：不同产地同一品种稻米品质与不同品种稻米品质存在明显差异；江永香米的Zn,Mn,Cr含量均比普通稻米及香稻80－66的含量高，香稻80－66香米中Zn含量也较普通稻米高。香米产地香米香味长期不退化，可能与灌溉水中Zn元素含量较高有关。     

苯醚甲环唑在水稻和稻田中的残留

  为明确苯醚甲环唑在稻田系统的使用安全性,调查了我国3个不同水稻种植区域(湖南长沙、吉林长春和浙江杭州)苯醚甲环唑在稻田系统中的残留消解动态以及在糙米、稻壳、水稻茎秆和土壤中的最终残留量。按高剂量(112.5 g/hm2)施药1次后,苯醚甲环唑在不同种植区域水稻植株、稻田水和土壤中的半衰期分别为6.1~8.9 d,5.3~6.2 d和3.8~4.1 d。各试验点最终残留结果表明,施药后28 d采样时糙米中苯醚甲环唑的最终残留量均<0.01 mg/kg,水稻茎秆中含量最高,土壤中均未检出苯醚甲环唑(<0.01 mg/kg)。结合生产实际,按该试验设计的施药剂量、施药次数和采收间隔期,糙米、水稻茎秆和稻壳中苯醚甲环唑的残留量是安全的,但若是稻渔共作种植方式,则应尽量避免该农药的使用,以免对鱼类造成不利影响。     

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.     

Effects of Applying Potassium,Zeolite and Vermiculite on the Radiocesium Uptake by Rice Plants Grown in Paddy FieldSoils Collected from Fukushima Prefecture

Abstract

Radionuclides were released into the environment as a consequence of the Fukushima Daiichi Nuclear Power Plant accident that occurred on 11 March 2011. Radiocesium at an abnormal concentration was detected in brown rice produced in paddy fields located in northern part of Fukushima Prefecture. We examined several hypotheses that could potentially explain the excessive radiocesium level in brown rice in some of the paddy fields, including (i) low exchangeable potassium content of the soil, (ii) low sorption sites for cesium (Cs) in the soil, and (iii) radiocesium enrichment of water that is flowing into the paddy fields from surrounding forests. The results of experiments using pots with contaminated soil indicated that the concentration of radiocesium in rice plants was decreased by applying potassium or clay minerals such as zeolite and vermiculite. The obtained results indicated that high concentrations of radiocesium in rice are potentially a result of the low exchangeable potassium and sorption sites for Cs in the soils. Application of potassium fertilizer and clay minerals should provide an effective countermeasure for reducing radiocesium uptake by plants. Radiocesium-enriched water produced by leaching contaminated leaf litter was used to irrigate rice plants in the cultivation experiments. The results indicated that the radiocesium concentrations in rice plants increased when the radiocesium-enriched water was applied to the potted rice plants. This indicated the possibility that the radiocesium levels in brown rice will increase if the nuclide is transported with water into the rice paddy fields from surrounding forests.     

Optimal gate operation of a main drainage canal in a flat,low-lying,agricultural area using a tank model

Chiyoda basin is located in Saga Prefecture in Kyushu Island, Japan, and lies next to the tidal compartment of the Chikugo River to which the excess water in the basin is drained away. Chiyoda basin has a total area of about 1,100 ha and is a typical flat and low-lying paddy-cultivated area. The main problem in this basin is the appropriate operation of drainage structures during and after flood events in order to minimize the inundation damages for crop yield and to fulfill the irrigation requirement in the irrigation period. This paper presents a mathematical model of a drainage system in Chiyoda basin for calculating the flood inundation and optimizing the operation of gates in a main drainage canal. First, the algorithm of gate operation was simulated and the drainage model was then evaluated by comparing the simulated water levels with those observed during an actual rainfall event. The results show that the observed and simulated water levels are in good agreement, indicating that the proposed model is applicable for drainage and inundation analyses in flat, low-lying paddy-cultivated areas. Second, the optimization of gate operation was investigated by trial and error method using a stochastic rainfall time series with a return period of 30 years and the tidal conditions of spring and neap tides in the Chikugo River. Comparing a total inundation time, a total inundation area and maximum inundation depth in the paddy tanks at the upstream and the downstream ends, it was concluded that the present operation based on the gate operators’ experience was almost the optimal one, and the sooner start of opening operation and the later start of closing operation within the operationality of check gates were recommended to minimize the inundation damage. The present operation could be able to minimize the total inundation time, the total inundation area and the maximum inundation depths in paddy tanks and to meet fully both the drainage and the irrigation requirements.     

Experimental study on soil erosion characteristics in flooded terraced paddy fields

This experimental study assesses the effects of event rainfall on soil erosion characteristics in terraced rice paddy fields. A 0.75-ha terraced paddy field located in Northern Taiwan was used to investigate the soil erosion under the regular cultivation of rice during two crop seasons. The environmental changes were investigated in the neighboring areas in which terraced paddy fields have been converted to other land usages. The annual rate of soil erosion calculated from the observed rainfall runoff and suspended solid contained was 0.77 ton/ha, which is significantly less than the erosion rate associated with upland crop cultivation reported by other research conducted in Taiwan. Experimental results also showed that the terraced paddy field retained the highest percentages of clay, silt, and organic matter's content, as compared to those of other upland crops, indicating that the topsoil was less susceptible to rainfall erosion under flooded conditions of rice-cultivation. The results of this study show that the rice-planted terraced paddy offers the highest level of soil conservation. The function of soil and water conservation in terraced paddy fields could be further increased by effective maintenance of embankment and to raise the height of the bund. Poor management, abandoned cultivation, and converse to other upland crops of terraced paddy fields are regarded as major contributors to increased soil erosion in mountainous areas. The government in Taiwan should formulate effective measures and maintain sustainable rice cultivation in the terraced paddies.     

Appraisal of affordable green subsidy of rice paddy in Taiwan

The study synthesizes the spatiotemporal changes of the multifunctionality and benefit of Taiwanese paddy. The internal and external economic values of the paddy are quantitatively determined. Nationwide as well as regional variation of multifunctionality and benefits from 1999 to 2007 were considered. The substitution cost method was adopted to quantify the external economical values of rice paddy. Moreover, the compensating variation concept was applied to appraise the rational green subsidy of rice paddy in Taiwan. The result shows that the multifunctional benefits of rice paddy from 1999 to 2007 reduce 55, 18, 31, 13, and 28% in north, center, south, east regions, and nationwide of Taiwan, respectively. The reduction is mainly attributable to the significant decrease of rice-planting area. The external benefit may be further diminished if the fallow area increases continuously. In order to maintain the multifunctionality of rice paddy, we appraise a reasonable green subsidy to the cultivated paddy farmers. According to the results of the amount of green subsidy evaluated by the compensating variation concept, the estimated green subsidy is 21,000 NT$/ha for the nationwide paddy farmers. The government may consider to award the appraised green subsidy to paddy farmers directly for the sustainable management of rice paddy in Taiwan.     

IT field monitoring in a Japanese system of rice intensification (J-SRI)

A demonstration study on Information Technology (IT) field monitoring was conducted in a rice field under the System of Rice Intensification (SRI) environment in Shinshiro City, Aichi Prefecture, Japan. The IT system used in this study consisted of an intelligent sensor node web-server that is equipped with in situ camera and sensor networks for agrometeorological, soil, and plant growth monitoring. Dynamic changes in soil moisture, water level, agrometeorological, and environmental conditions were measured and monitored. With this precision farming set-up, understanding and easy assessment of the salient field conditions and phenomena such as cyclic soil wetting and drying as well as critical crop growth stages were made possible. Based on the findings of the demonstration experiment, the system was effective, reliable, and efficient in monitoring soil moisture parameters and agrometeorological information in remote rice field environment. The actual field conditions were captured well by a combination of images, numerical, and graphical data sets. With this precise information, the frequency of irrigation was found to be every 7 days. The rice field was irrigated up to a moisture level of 0.592 m³/m³ (~600 mV) and allowed to be depleted to a moisture level of 0.417 m³/m³ (~400 mV). With this alternate drying and wetting method (AWD), a 25.71% of irrigation water was saved. In this study, rice production was made more scientific and more reliable. Hence, the use of IT field monitoring system represented a viable medium for the realization of better rice productivity which leads to the ethic of sustainable agriculture.     

A quick determination of root resistance to water transport in paddy rice

Hydraulic resistance in plants is one of the most important factors responsible for changes in leaf water potential that is an indicator of plant water stress. Although the hydraulic resistance to passive water transport (R_pa) is a robust index in paddy rice (Oryza sativa), measurement is both time-consuming and labour-intensive. Here, we describe on a quick method to measure hydraulic resistance to osmotic water transport (R_os) by measuring the xylem sap exudation rate and osmotic water potential. In a greenhouse experiment, R_os responded significantly to soil temperature, but under field conditions soil temperature varied considerably less than air temperature. In the field experiment, R_os of six rice cultivars at two growth stages was strongly positively correlated with R_pa. We conclude that measuring R_os could be used to evaluate root water transport capacity in paddy rice under conditions with adequate soil water.