Agricultural and environmental changes after irrigation management transfer in the Develi Basin,Turkey

Develi Basin is a semi-arid basin in central Turkey where water sustains both irrigated agriculture and an internationally important wetland, the Sultan Marshes. Agricultural and environmental changes in the Develi Basin have occurred since irrigation management was transferred in 1994 from a state authority (DSI) to irrigation associations (Kovalı and Ağcaaşar IAs). In this paper we evaluate the practices of the IAs using extensive data from interviews with farmers and IA officials, as well as data from reports prepared by DSI and the IAs, using comparisons with case studies reported in the scientific literature. Irrigated areas and surface water use in the Develi Basin showed significant fluctuations from 1995 to 2003. The area allocated to high water-consuming plants increased. Maintenance activities became dependent on fee collection rates. Quality of the irrigation water did not changed significantly. Ground-water levels, flow rates from springs, and water levels in the Sultan Marshes all dropped. Overall analyses indicate that the water requirements of the Sultan Marshes have not been met, while water use for irrigation has been effective but not efficient. To reconcile agricultural and wetland water requirements, a basin-wide approach in water planning is recommended. Amounts of water to be allocated to the IAs and wetlands need to be clearly defined. DSI has to monitor canal maintenance by the IAs more closely, and IAs need to be given more responsibilities for future rehabilitation of the canals. Realistic water pricing, increased reliability of irrigation scheduling, higher on-farm irrigation efficiency, and in the long-term, modernization of the irrigation system need to be considered.     

荒漠草原区灌溉和旱作条件下蒙古冰草和新麦草产草量的构成因素

对荒漠草原区灌溉和旱作条件下蒙古冰草和新麦草的适应性、单株产草量构成因子及其贡献率进行了研究。结果表明:灌溉条件下蒙古冰草和新麦草单株产草量及其各构成因子产量或数值皆大于旱作条件下;旱作条件下蒙古冰草产草量构成因子对单株产草量的贡献率大小顺序为,茎重>株高>穗重>分蘖数>叶重,新麦草为茎重>分蘖数>株高>叶重>穗重;灌溉条件下蒙古冰草产草量构成因子对单株产草量的贡献率大小顺序为,茎重>分蘖数>株高>穗重>叶重,新麦草为茎重>株高>分蘖数>叶重>穗重。     

灌水量与夏玉米光合性能及产量的关系

利用大型防雨设施池栽,研究灌水量与夏玉米光合性能及产量的关系。结果表明,灌水量与夏玉米光合性能及产量呈高度正相关,不同灌水量对群体光合速率、单叶光合速率、光合速率日变化、叶面积发展动态、干物质积累量及干物质生产率产生显著差异,并随生育进展而加剧。根据产量与耗水量的关系,夏玉米13 500 kg/hm²产量水平的耗水量在630 mm左右,9 000 kg/hm²产量水平的耗水量在490 mm左右,200 mm左右为夏玉米经济产量形成的耗水临界值。穗期、花粒期土壤水分状况不同是导致产量及光合性能差异增大的重要原因之一,保证夏玉米中、后期水分适宜是提高光合性能及产量的重要条件之一。     

灌溉制度对冬小麦耗水及产量的影响

研究结果表明,随灌水量的增加,冬小麦总耗水量明显增加,土壤贮水消耗量相应减少;随总耗水量的增加,冬小麦生育后期耗水所占的比例明显增加;当灌水量相同时,灌水越早的处理耗水量越多。不同的灌溉制度对冬小麦产量结构与产量有显著影响,起身水主要增加穗数,拔节水显著增加穗粒数,而孕穗期或开花期灌水对提高千粒重有明显作用;1水以孕穗期,2水以拔节期和开花期,3水以拔节期、开花期和灌浆期灌水效果最佳。适当控制开花前耗水量,增加开花后耗水量,有利于增加产量和提高水分利用效率。     

冬小麦灌溉制度对土壤贮水利用的影响

足墒条件下冬小麦播种时200cm土体总贮水量为619.6mm,有效贮水量为329.5mm。冬小麦播种～拔节期主要消耗0～100cm土层内土壤有效贮水;由于有效贮水能满足作物需水,因此拔节期不出现土壤水分亏缺。拔节～开花期对照(CK)耗水深度为200cm土层,起身期灌1水(Ⅰ-1)处理为160cm,其他处理为130cm;至开花期CK和Ⅰ-1处理0～60cm土层内已呈现一定程度的水分亏缺。开花～成熟期各处理200cm 土体内土壤有效水含量均呈不同程度下降,但主要供水层为0～130cm土层;冬小麦成熟期除春后起身～孕穗～灌浆期(Ⅲ-1)、拔节～开花～灌浆期(Ⅲ-2)灌3水和起身～拔节～开花～灌浆期(Ⅳ)灌4水处理外,大部分处理0～80cm或0～60cm土层内均呈明显的水分亏缺。随灌水次数或灌水量的增加,土壤贮水利用率呈明显下降趋势。     

Transfer of irrigation scheduling technology in Mexico

In Mexico most of the agricultural production originates from large irrigation districts in the northern part of the country. This region is characterized by its semiarid desert climate with a winter rainy season dominated by frontal storms, and a summer monsoon season dominated by highly localized convective storms, yielding most of the annual precipitation. Essentially all irrigation needs must be met by surface water stored in various reservoirs. Precipitation is, therefore, the most important limiting factor in Mexico's agricultural production. Traditionally, long-time averages of statistical climate data from few and widely-spaced weather stations were used to determine frequency and amount of water applied, and the algorithms employed usually did not consider the effects of great spatial climate variability and plant physiology. In the past five years, great parts of Mexico, especially in the North, have been affected by severe water shortages resulting from insufficient precipitation (perhaps related to the ‘El Niño' phenomenon), combined with inefficient water resources management. Irrigation districts increasingly have to deal with the considerable uncertainty in water resources availability as a limiting factor in the decision making process. In order to address these irrigation water shortages, the Mexican National Water Commission and the Mexican Water Resources Institute are introducing new technologies using agrometeorological networks for more efficient, real-time irrigation scheduling in the main irrigation districts of Mexico. Validation plots established in one particular irrigation district (Carrizo Valley, Sinaloa), demonstrate water savings in the order of at least 20% without any appreciable decrease in crop yields.     

西双版纳地区傣族传统水利灌溉技术体系研究

傣族传统水利灌溉技术体系主要包括四个环节：水源与水渠、分水器、水田和水稻、计量标准。文章对这四个环节进行了历史资料的收集、整理和分析,并结合稻作农艺进行了论述。     

Influence of irrigation frequencies and phosphate fertilization on actual evapotranspiration rate, yield and water use pattern of rajmash (Phaseolus vulgaris L.)

The hypothesis was tested, whether soil wetness and phosphorus status could regulate the evapotranspiration rate (ET_R), which is of special interest in the lower Gangetic Plain. Rajmash was grown during November-February of 2003-2004 and 2004-2005 on a sandy loam soil, and was irrigated when cumulative pan evaporation (CPE) attained the value of 33 mm (CPE₃₃); 44 mm (CPE₄₄) and 66 mm (CPE₆₆). Four levels of phosphate application were 0 kg P₂O₅ ha⁻¹ (P₀); 30 kg P₂O₅ ha⁻¹ (P₃₀); 60 kg P₂O₅ ha⁻¹ (P₆₀) and 90 kg P₂O₅ ha⁻¹ (P₉₀). Seed yield under CPE₃₃ was 1.37 Mg ha⁻¹ and reduced by 18% and 35%, respectively under CPE₄₄ and CPE₆₆. Continuous increasing trend in yield was recorded with an increase in phosphate level (PL). Irrespective of growth stages, similar trends were recorded for leaf area index (LAI). Maximum variation in LAI among the treatments was recorded at 60 days after sowing. On average, actual ET_R was 1.37 mm day⁻¹ under CPE₃₃ and declined by 13% and 16% under CPE₄₄ and CPE₆₆, respectively. Variation in ET_R under different PL was highest under CPE₃₃ and lowest under CPE₄₄. Except P₉₀, irrespective of PL, highest value of water use efficiency (WUE) was obtained under CPE₄₄. However, magnitude of net evapotranspiration efficiency (WUE_ET) and irrigation efficiency (WUE_I) attained the highest level under CPE₃₃ regime. All water use indices showed an increasing trend with the increase in phosphate level from 0 to 90 kg ha⁻¹. Impact of phosphorus on various parameters was pronounced under CPE₃₃.     

Evaluation on the irrigation and fertilization management practices under the application of treated sewage water in Beijing, China

Irrigation and fertilization management practices play important roles in crop production. In this paper, the Root Zone Water Quality Model (RZWQM) was used to evaluate the irrigation and fertilization management practices for a winter wheat–summer corn double cropping system in Beijing, China under the irrigation with treated sewage water (TSW). A carefully designed experiment was carried out at an experimental station in Beijing area from 2001 to 2003 with four irrigation treatments. The hydrologic, nitrogen and crop growth components of RZWQM were calibrated by using the dataset of one treatment. The datasets of other three treatments were used to validate the model performance. Most predicted soil water contents were within ±1 standard deviation (S.D.) of the measured data. The relative errors (RE) of grain yield predictions were within the range of −26.8% to 18.5%, whereas the REs of biomass predictions were between −38% and 14%. The grain nitrogen (N) uptake and biomass N uptake were predicted with the RE values ranging from −13.9% to 14.7%, and from −11.1% to 29.8%, respectively. These results showed that the model was able to simulate the double cropping system variables under different irrigation and fertilization conditions with reasonable accuracy. Application of RZWQM in the growing season of 2001–2002 indicated that the best irrigation management practice was no irrigation for summer corn, three 83 mm irrigations each for pre-sowing, jointing and heading stages of winter wheat, respectively. And the best nitrogen application management practice was 120 kg N ha⁻¹ for summer corn and 110 kg N ha⁻¹ for winter wheat, respectively, under the irrigation with TSW. We also obtained the alternative irrigation management practices for the hydrologic years of 75%, 50% and 25%, respectively, in Beijing area under the conditions of irrigation with TSW and the optimal nitrogen application.     

Effect of irrigation water salinity on transpiration and on leaching requirements: A case study for bell peppers

Maximization of crop yields when the salinity of irrigation water is high depends on providing plant transpiration needs and evaporative losses, as well as on maintaining minimum soil solution salinity through leaching. The effect of the amount of applied irrigation water was studied regarding transpiration, yields, and leaching fractions as a function of irrigation water salinity. Bell pepper (Capsicum annum L. vars. Celica and 7187) in protected growing environments in the Arava Valley of Israel was used as a case study crop to analyze water quantity–salinity interactions in a series of lysimeter, field and model simulation experiments. Leaching fraction was found to be highly influenced by plant feedback, as transpiration depended on root zone salinity. Increased application of saline irrigation water led to increased transpiration and yields. The higher the salinity level, the greater the relative benefit from increased leaching. The extent of leaching needed to maximize yields when irrigating with saline water may make such practice highly unsustainable.