低洼稻田改制模式初探

分析了南县低洼稻田的现状及存在的问题 ,提出了一系列种植结构调整综合配套措施。     

改革稻田耕作制度，提高农业生产效益

针对双峰县稻田生产中存在的问题 ,根据该县特点 ,提出了全县耕作制度改革的基本原则、推广模式和具体对策。     

Imidacloprid concentrations in paddy rice fields in northern Vietnam: measurement and probabilistic modeling

Paddy and Water Environment - Uncertainties associated with pesticide exposure forecasts arise from many sources such as spatial and temporal variability of factors influencing pesticide behavior,...     

岳阳市稻田改制种植模式及配套技术

介绍了近年来岳阳市稻田改制的种植模式，按作物种类分为三大类型，即粮一经型，经作型，粮一粮（饲）型，总结了目前稻田改制种植模式的主要技术，提出了推广稻田改制种植模式的配套技术。     

Land leveling and changes in soil properties in paddy fields of Guilan province,Iran

Paddy and Water Environment - The aim of this study was to evaluate the impacts of land leveling on some of soil properties. Land leveling as an effective strategy for paddy land management is one...     

Comparison of steady- and unsteady-state drainage equations for determination of subsurface drain spacing in paddy fields: a case study in Northern Iran

In Northern Iran paddy fields, waterlogging is a serious problem. Provision of subsurface drainage seems to be a prerequisite for optimal crop production. Considering specific characteristics of the paddies, application of a suitable equation for planning of subsurface drainage systems is of great importance. In this study, five steady-state equations including Hooghoudt, Kirkham, Dagan, Ernst, and Ernst–Hooghoudt; and three unsteady-state equations including Glover–Dumm, Van-Shilfgard, and De-zeeuw–Hellinga were implemented to compute drain spacing. Required field data were obtained from 52 ha of paddy fields of “Haraz Human-Agriculture Resources Development Center,” located in Mazandaran province of Iran. The computed drain spacings were evaluated using dynamic equilibrium concept and DRAINMOD model. The minimum and maximum drain spacings were found to be 26 and 63 m corresponding to Glover–Dumm and Ernst equations, respectively. Based on the dynamic equilibrium concept, the averages of the computed water table depths for the drain spacings obtained by the unsteady-state equations were 0.5–0.63 m as compared with those obtained by the steady-state methods which were in the range of 0–0.43 m. According to the DRAINMOD model simulations, the maximum relative yield was 80.2 % which was obtained when the drain spacing was 26 m and it reduced to 73.5 % when the drain spacing was increased to 63 m. The computed drain spacings suggested by the unsteady-state equations were found to be more suitable than those obtained from the steady-state equations for the study area.     

Multifunctionality of paddy fields in Taiwan

Paddy rice is the staple food in Taiwan, where rice farming always plays an important role in agricultural activities. The paddy fields and irrigation activities hold diversified functions, such as production, eco-environmental and living-associated functions. This paper is to provide information regarding the potential magnitude and monetary value of seven functions of paddy fields in Taiwan, including flood mitigation, fostering water resources, preventing soil erosion, purifying water, cooling air temperature, refreshing atmosphere and recreation. For quantification of the above values, replacement cost method (RCM), contingent valuation method (CVM), and the travel cost method (TCM) are adopted. In addition, the ratio of monetary value and their rice production commodity value (R) was also estimated. The results indicated that the flood mitigation function had a monetary value of US$ 389 million each year, and the ratio to the rice production value R was estimated at 37%. Water resource fostering function was US$ 501 million and R at 47%; soil erosion reduction function was US$ 433 million and R at 41%; water quality purification function was US$ 3 million and R at 0.3%; cooling air temperature function was US$ 961 million and R at 91%; refreshing air function was US$ 196 million and R at 19%, health and recreation function was US$ 987 million and R at 93%, respectively. Due to the significant importance of these externalities, it is recommended that the government should properly take into account the multifunctionalities in policy making to ensure sustainable development of agriculture.     

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.     

Optimal conjunctive use of aqua-agriculture reservoir and irrigation canal for paddy fields (case study: Tajan irrigation network,Iran)

Paddy and Water Environment - Aqua-agriculture reservoirs have been used as one of the main resources for supplying water to paddy fields, particularly under water shortage conditions. In this...     

湖南稻田耕作制度改革的形势与对策

总结了湖南从1999年以来实施稻田耕作制度改革所取得的主要成效，阐明了这一轮稻田耕作制度改革的新特点，分析了存在的主要问题．并有针对性地提出了稳步推进我省稻田耕作制度改革的对策措施。     

Systematic assessment of flood mitigation in a tank irrigated paddy fields area

Flood mitigation in irrigation tanks and paddy fields is their favorable aspect though its practical effect is not known very well. A dynamic and systematic approach is presented to assess flood mitigation in a tank irrigated paddy fields area in the worst case where no static buffer function is expected. Based on the linear control theory, transfer function models for runoff process in catchments are identified. Hydraulic models are developed to represent flood dynamics in irrigation tanks, paddy fields, and drainage channels. These models are integrated as an ordinary differential equations system. Then, using the perturbed linear system, flood mitigation in each component of the system is examined in terms of frequency response. An application example demonstrates that a tank irrigated paddy fields area has a significant flood mitigation effect as a low-pass filter. This method has the advantage of assessing flood mitigation even in the case of an increase in the total runoff ratio.     

永州市稻田种植制度新特点及优化模式分析

分析了永州市稻田种植制度新特点，讨论了稻田改制的主要模式及经济效益，提出了值得推广的几种主要稻田高效种植模式。     

宁远县中低产稻田工程改良治理研究

1999～2000年．对宁远县刘家洞的129hm^2冷浸潜育型低产稻田进行了工程改良。根据本地实际。对工程中的沟渠整体布局、沟渠结构及规格进行了具体的设计。通过对比试验分析．改良后的稻田地下水位降低．水温和泥温升高，土壤养分含量增加，早晚稻产量均大幅度提高，取得了明显的治理效果。     

Spatial variation of infiltration rate and compactness in paddy fields

Percolation loss of water in rice fields is a major cause of low water use efficiency. Variation of infiltration rate and soil compactness in four paddy fields (with clay, silty clay, clay loam, and loam textures) was investigated in northern Iran. In each field, in longitudinal and transverse directions, points located 0.5, 2.5, 6.5, 12.5, … m from the bunds were selected and water infiltration rate and resistance to penetration of a pocket penetrometer were measured. The results showed that in clay soil, average final infiltration rate (f _c) in longitudinal direction, transverse direction, and center of the field was 0.216, 0.136, and 0.08 cm day⁻¹, respectively. The f _c for loamy soil was 2.77, 2.32, and 0.409 cm day⁻¹, respectively. Similar differences were observed in the other two soil textures. In general, effect of direction of the field for measuring infiltration rate was not statistically significant. Loam and clay loam soils, with resistance to penetration of 0.37 and 0.33 kg cm⁻², were not significantly different. But, clay and silty clay soils with resistance to penetration of 0.25 and 0.14 kg cm⁻² were significantly different (P < 0.05). Resistance to penetration of the penetrometer was not affected significantly (P < 0.05) by direction of measuring this parameter in the field. The conclusion is that if measured soil physical properties in a paddy field are going to be representative of the whole field, they should be measured at different locations, especially near the bunds. Another strategy for obtaining a representative infiltration rate or compactness for a paddy field is uniform puddling of the field.     

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%.

Assessment of nitrogen contamination of groundwater in paddy and upland fields

This study aims to assess the nitrogen contamination of groundwater in paddy and upland fields. A reactive chemical transport model PHREEQC and a variable saturated groundwater flow and transport model FEMWATER were used to evaluate the vertical transport of nitrogen compound in various soil types of paddy and upland. The shallow groundwater quality monitoring data of 2003, 2006, 2009 in the Choushui river alluvial fan, the major agriculture production area in Taiwan, were applied to support the validity of the numerical simulation findings. Results from PHREEQC and FEMWATER simulations showed that the organic-rich impermeable plow sole layer underneath the muddy layer of rice paddy can effectively reduce NO₃ ⁻ and N₂ to NH₄ ⁺ and retard the movement of NH₄ ⁺. However, in the upland field which has no plow sole layer, the NH₄ ⁺ can move easily to the shallow aquifer and contaminate the groundwater. The spatiotemporal distribution of NO₃ ⁻–N and NH₄ ⁺–N in the Choushui river alluvial fan revealed that high nitrate–N contamination areas were located mainly in the upland field of the proximal fan, where the granular unconfined aquifer was vulnerable to surface contaminants. Moreover, the unconfined nature of the aquifer allows the oxidization of NH₄ ⁺ to NO₃ ⁻ and accelerates the plume movement. High ammonium–N concentration areas were mostly dispersed in the distal-fan area where upland planting and aquacultural farming were prevailed. The high NH₄ ⁺–N found in the northern Choushui river alluvial fan was attributed to the alternative planting of rice and upland crops, and the plow sole layer was broken to maintain the quick drainage upland crop needs.     

Behavior of radiocesium in decontaminated paddy fields in Fukushima Prefecture,Japan

Paddy and Water Environment - The 2011 Great East Japan earthquake and tsunami led to dispersal of radionuclides into the surrounding area from the Tokyo Electric Power Company’s Fukushima...