Effects of Crops, Soil Types and Irrigation Methods on Digestion Capacity of Biogas Slurry

In the research, pot experiment and field testing were conducted to study the effect of different crops, soil types, and irrigation modes on biogas slurry diges- tions. The results showed that when silage maize, sweet sorghum and Chinese cabbage were planted in purple soils, the quantities of digested biogas slurry were of 57, 157.5, and 34.5 t/hm2, respectively, while the quantities of digested biogas slurry were 70.5, 157.5 and 40.5 t/hm2 in yellow soils. Besides, the digested biogas slurries reached 36 and 27 t/hm2 as per flood irrigation and sprinkling irrigation when Chinese cabbages were planted in yellow soils. The research indicated crop variety, soil type, and irrigation method all have effects on farmland digestion of biogas slurry.

Leaching and Transformation of Nitrogen Fertilizers in Soil After Application of N with Irrigation: A Soil Column Method

A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH4+-N + NO3- -N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH4+-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4+-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4+-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4+-N fixation or volatilization in the soil during the fertigation process.

Effect of Different Irrigation Methods on Dissolved Organic Carbon and Microbial Biomass Carbon in the Greenhouse Soil

The objective of this study was to investigate the contents and distribution of dissolved organic carbon （DOC） and microbial biomass carbon （MBC） at 0-100 cm soil depth under three irrigation treatments, viz., subsurface, drip and furrow irrigation in the greenhouse soil. The soil samples were collected at different depths （0-100 cm）, and the contents of soil total organic carbon （TOC）, DOC and MBC were analysed. The experiment was conducted for 10 yr, during which period the application of fertilizers and crop management practices were kept identical. The results showed that the contents of TOC, DOC and MBC were significantly affected by different irrigation regimes, decreased with the increase of soil depth. TOC at 0-10 and 80-100 cm soil depths followed the order of furrow irrigation 〉 subsurface irrigation 〉 drip irrigation, whereas at the depth of 10-80 cm followed the order of subsurface irrigation 〉 furrow irrigation 〉 drip irrigation. DOC and MBC contents at 0-100 cm soil depths followed the order of furrow irrigation 〉 drip irrigation 〉 subsurface irrigation, and drip irrigation 〉 furrow irrigation 〉 subsurface irrigation, respectively. The ratios of DOC and MBC to TOC accounted for 4.98-12.87% and 1.48-2.82%, respectively, which were the highest in the drip irrigation treatment, followed were in the furrow irrigation treatment, and the lowest in subsurface irrigation treatment. There were significant positive correlations among the contents of DOC, MBC and TOC in all irrigation treatments. The furrow irrigation facilitated the accumulation of TOC and DOC, while drip irrigation increased the MBC. The content of TOC and the ratios of DOC to TOC were the lowest in subsurface irrigation treatment.

Effect of drip irrigation method, nitrogen source, and flushing schedule on emitter clogging

Field experiments were carried out at the National Research Center farm, Nubaria area, Behura Governorate, Egypt, to study the effect of nitrogen source, flushing schedule and irrigation method on emitter clogging. Peanut Giza 5 variety (Arachishy pogaea L.) was planted in sandy soil during two successive growing seasons (2010-2011) in the 1st week of May and harvested after 130 days. Treatments used are: 1) two irrigation methods: surface drip irrigation and sub-surface drip irrigation (SDI;SSDI), 2) nitrogen source (NS):NH4NO3, (NH4)2SO4 and Ca(NO3)2 (NS1, NS2 and NS3) and 3) flushing number (FL) 0, 1 and 4 (FL1, FL2;FL3). The experiments design was split-split plot and three replicates were used. Data obtained were subjected to statistical analysis. The main effects of treatments used on clogging per cent could be written the following ascending orders: SDI 3 2 1, NS1 2 3. Concerning the 1st interaction the following ascending orders denote their effects on clogging percent: SDI × FL3 2 1, SDI × NS1 2 3, SSDI × FL3 2 1, SSDI × NS1 2 3, FL1 × NS1 1 × NS2 1 × NS3, FL2 × NS1 2 × NS2 2 × NS3 and FL3 × NS1 3 × NS2 3 × NS3. The differences between any two treatments and/or any two interactions in clogging percent were significant at the 5% level. The effect of the 2nd interaction on clogging percent was significant at the 5% level. The maximum value of clogging (20.18%) and the lowest one (3.9%) were archived in the interactions: SSDI × FL1 × NS3 and SDI × FL3 × NS1, respectively.

Impact of Evaluation of Different Irrigation Methods with Sensor System on Water Consumptive Use and Water Use Efficiency for Maize Yield

The sensor system is one of the modern and important methods of irrigation management in arid and semi-arid areas, which is water as the limiting factor for crop production. The study was applied for 2016 and 2017 seasons out in Al-Yousifya, 15 km Southwest of Baghdad. A study was conducted to evaluate coefficient uniformity, uniformity distribution and application efficiency for furrow, surface drip and subsurface drip irrigation methods and it was (98, 97 and 89)% and (97, 96 and 88)% for 2016 and 2017 seasons;respectively. And control the volumetric moisture content according to the rhizosphere depth for depths of 10, 20 and 30 cm by means of the sensor system. The results indicated that the height consumptive water use of furrow 707.91 and 689.69 mm·season-1 and the lowest for subsurface drip with emitter deep at 20 cm 313.93 and 293.50 mm·season-1 for 2016 and 2017 seasons;respectively. As well, the highest value of water use efficiency for subsurface in drip irrigation at a depth of 20 cm, was 2.71 and 2.99 kg·m-3 and the lowest value for furrow irrigation was 1.12 and 1.20 kg·m-3 for the 2016 and 2017 seasons;respectively.

Effects of Different Water-saving Irrigation Methods on Fruit Quality and Yield of Snow Melon

[Objectives]This study was conducted to explore the most suitable irrigation integration mode for"Tinglin snow melon"in Jinshan District,Shanghai City.[Methods]With the field water holding capacity as the standard,different upper limits of irrigation were set in the four growth stage of snow melon to investigate the effects of such three water-saving irrigation modes as single-row drip irrigation pipes,double-row drip irrigation pipes and drip arrows on the traits and yield of melon plants under the same growth conditions.[Results]The results showed that different irrigation modes had certain effects on the growth,comprehensive quality and yield of snow melon,and the drop arrow mode was better than other two modes.Under the drop arrow mode,the number of snow melons was the highest,7.34 per plant,and the yield was the highest,reaching 15463.35 kg/hm^(2),showing the best yield increasing effect.In addition,the contents of soluble solids and vitamin C in the drop arrow mode were higher than those in the drip irrigation pipe mode.[Conclusions]Compared with other irrigation methods,the drop arrow mode was more suitable for the production of snow melon.

Fractional four-step finite element method for analysis of thermally coupled fluid-solid interaction problems

An integrated fluid-thermal-structural analysis approach is presented. In this approach, the heat conduction in a solid is coupled with the heat convection in the viscous flow of the fluid resulting in the thermal stress in the solid. The fractional four-step finite element method and the streamline upwind Petrov-Galerkin （SUPG） method are used to analyze the viscous thermal flow in the fluid. Analyses of the heat transfer and the thermal stress in the solid axe performed by the Galerkin method. The second-order semi- implicit Crank-Nicolson scheme is used for the time integration. The resulting nonlinear equations are lineaxized to improve the computational efficiency. The integrated analysis method uses a three-node triangular element with equal-order interpolation functions for the fluid velocity components, the pressure, the temperature, and the solid displacements to simplify the overall finite element formulation. The main advantage of the present method is to consistently couple the heat transfer along the fluid-solid interface. Results of several tested problems show effectiveness of the present finite element method, which provides insight into the integrated fluid-thermal-structural interaction phenomena.

Rainfall Distribution Functions for Irrigation Scheduling: Calculation Procedures Following Site of Olive (<i>Olea europaea</i>L.) Cultivation and Growing Periods

In Tunisia (36.5oN, 10.2oE, Alt.10 m), rainfall is the major factor govering olive production. Annual and seasonal falls are variable following years and regions, making yields of olive trees fluctuating consistently. Irrigation was applied since the 70th in the intensive olive orchards to improve and stabilize olive production. This study aimed to determine the crop water needs of olive orchards and the rainfall frequencies at which they are covered following age and site of olive production. For this purpose, the rainfall distribution functions were established for different cities of Tunisia (Tunis, Bizerte, Béja, Nabeul, Sidi Bouzid, Gabes and Sousse). For all sites and growing periods, the reference evapotranspiration (ET0) was computed by using several methods. Their performance against the PM-ET0 (Penman-Monteith) estimates was evaluated graphically and statistically for a better adaptation them to the existing environmental conditions, particularly when data are missing to compute ET0-PM. Results show that ET0 estimates strongly correlate with ET0-PM with r values of up to 0.88. Particularly, the methods of Turc and Ivanov appropriately predict the ET0-PM in all climatic regions of Tunisia, constituing an appropriate alternative for determining ET0 when data are missing to compute ET0-PM. However, although the Turc method performs well with all climatic zones of Tunisia, the Ivanov method appears to be more appropriate to the northern areas (Béja and Bizerte), though a poorer agreement was found when using the Eagleman method. Estimates of ET0 by using the Hargreave-Samani (HS) formula for the east-southern area (Gabes, arid climate) show satisfactory agreement with ET0-PM estimates. It appears also that at a given site, the most appropriate method for ET0 estimation at annual scale may be different from that giving the best value of ET0 when considering the growing stages of the olive tree, for example, the method of Turc, although it was appropriate when estimating the annual ET0 value for Sousse, it wasn’t adequate at seasonal scale. In opposite, although the method of BC is suitable for stages 1, 2, 4 and 5 at Sousse, the appropriate method for the overall cycle is that of Turc. This indicates that there is no weather-based evapotranspiration equation that can be expected to predict evapotranspiration perfectly under every climatic situation due to simplification in formulation and errors in data measurement. However, we can say that when data are missing, ET0 can be estimated with a specific formula;that of Turc can be appropriately used for Tunis, Sidi Bouzid, Sousse and Béja at annual scale despite of their appartenance to different climatic regions, while the method of Ivanov is quite valuable for Bizerte and Nabeul. Results show also that values of P-ETc recorded during the irrigation period are negative even for young plantations, with lowest and highest deficits observed at Béja and Gabes cities, respectively. The driest period is that of July-August for all sites with F values exceeding 0.9 in most cases. Only 10% of water needs are supplied by rainfall during this period of fruit development. Therefore, irrigation is needed all time for adult trees even at the rainiest locations. For young plantations, irrigation becomes necessary beginning from the second period of tree development, i.e. April-June for Bizerte, Béja, Nabeul and Tunis and since the early spring period for both young and old plants for Gabes and Sidi-Bouzid. It appears from this analyze based on the seasonal rainfall frequencies and water needs computed with the PM-method, that there is a need for irrigating olive plantations aging more than 5 years in most case studies and especially when olive is cultivated in the western areas of Tunisia. Results indicate also that the use of no adequate method to estimate ET0 allowed overestimating or underestimating of irrigation water needs. So it is desirable to have for Tunisia a method that estimates ET consistently well and future research is needed to reconcile which should be the standard method of calculating the change in the crop coefficient over time. However, despite a quite good performance of the PM-equation in most applications, particularly when it is used for irrigation scheduling purposes, some problems may appear because of lack of local information on Kc-values and determination of the effective rainfall. Additional research is needed on developing crop coefficients that use the Penman-Monteith equation when calculating ET. In conclusion we can say that on the basis of the results produced, we can decide for each region and growing period if complementary irrigation is needed or not. Indicative amounts are given for each case study.

WATER AND SALT MOVEMENTS IN SIMULTANEOUS FLOOD-IRRIGATION AND WELL-DRAINAGE OPERATIONS

This paper describes a new technology for solonchak soil reclamation in which surface flood irrigation of fresh water and pumped wells drainage of salty groundwater are combined. The comprehensive investigation of water and salt movement has been conducted through field test, laboratory simulation and numerical calculation. The dependence of desalination on irrigation water quantity, drainage quantity, leaching time and other parameters is obtained based on the field tests. The entire desalination process under the flood-irrigation and well-drainage operations was experimentally simulated in a vertical soil column. The water and salt movement has been numerically analysed for both the field and laboratory conditions. The present work indicates that this new technology can greatly improve the effects of desalination.

Improvement of Supplementary Irrigation Water Quality for Rain-Fed Agriculture in the Semi-Arid Region Using Magnetization Techniques

Rain-fed agriculture depends on the groundwater as a supplementary source of irrigation. The poor quality of water from the hard rock area is applied to the crops to save the crop. Continuous irrigation leads to degradation of soil, drip irrigation system as well plants. This study assessed the damages on the drip irrigation system and soil, inflicted by the use of low-quality irrigation water. The quality of water was improved with reference to raw water in terms of pH (1.57% - 5.88%), EC (3.08% - 10.08%), ions (0.96% - 46%) by using magnetization method, without disrupting the existing irrigation system in the basaltic aquifer in semi-arid to the arid condition. This was demonstrated before the farmers in central India.

A Study on Planned and Applied Irrigation Modules in Irrigation Networks: A Case Study at Büyük Menderes Basin, Turkey

In this study, irrigation modules calculated in planning and actualized operational stage of the irrigation networks are examined. Irrigation module used irrigation networks is a constant discharge parameter, meeting the needs of irrigation water requirement smonthly of crops in one hectare of irrigation area and it is a constant discharge flowing continuously for a month. Extent of the overlapping between the irrigation planning module and the operation module actualized during the operational stage of the irrigation network depends on changes in the cropping patterns, differences in the effects of field irrigation methods used by farmers on the capacity of the constructed system, the increases or decreases in the water demands depending on the irrigation period, as well as the extent of sustainability according to the selected operation method. A2 irrigation area of Aydin plain irrigation network, locating in the Büyük Menderes basin, Turkey is selected as study area, with an area of 2500 ha. Irrigation planning module calculated for this network is q = 1.16 l/s/ha and it has been designed as per the supply demand operation method. For the study;actualized irrigation module in the operation stage has been compared with the planning irrigation module by using Excel software and taking parameters such as actual crop pattern and percentage distributions, actualized irrigated areas, irrigation networks and water distribution, water intake of irrigation networks which have been calculated without operation losses, as well as with 5%, 10%, and 15% operation losses. The July operation module calculated for the examined irrigation network generally conforms to the planning module, as it has received the values close to or below the value of irrigation planning modules.

Productive Performance and Response of Green Chilli （Capsicum annum L.） to Drip Irrigation Schedules under Water Limited Conditions

Drip irrigation is often preferred under water limited conditions over the other irrigation methods because of its high water application efficiency on account of reduced surface evaporation and percolation losses. The major limitation of drip irrigation is its initial investment. Therefore, there is a need to reduce the cost of drip installation by altering the planting geometry besides enhancing the productivity and moisture use. Results of the two years field study conducted on sandy loam soils revealed that drip irrigation at 1.0 Epan with normal row system （60 cm×30 cm） registered significantly higher yield of green chilli（ 14.08 t ha^-1） which was on par with 0.8 Epan two rows paired system （90-45-90 cm×30 cm：13.45 t ha^-1） and significantly lowest was noticed with 0.6 Epan four rows paired system（45-45-45-120 cm×30 cm ） （5.50 t ha^-1）. The quality parameters viz; TSS and Ascorbic acid were significantly higher with drip irrigation at 1.0 Epan with normal row system and lowest was observed with 0.6 Epan four rows paired system. Total water used was maximum in 1.0 Epan （691.7 mm） followed by 0.8 Epan irrigation （590.2 mm） and the lowest was recorded in 0.6 Epan irrigation （488.8 mm）. There was a saving of water by 14.68 percent and 29.34 percent under 0.8 and 0.6 Epan drip irrigation schedules respectively over 1.0 Epan. Indications of less leaf water potential in 1.0 Epan drip irrigation （-0.58 to-0.67 MPa） followed by 0.8 Epan （-0.61 to-0.68 MPa） and more negative leaf water potential in 0.6 Epan （-0.71 to-0.88 MPa） in relation to water applied were observed. Water use efficiency recorded was maximum in 0.6 Epan normal row systems （24.1 Kg ha-mm^-1） and the least was recorded in 0.6 Epan four rows paired system （11.3 Kg ha-mm^-1）. The significantly higher root growth characters such as root length （42.6 cm）, number of primary roots （28.7）, root dry weight （11.05 g plant^-1） and maximum depth of penetration were recorded with 0.6 Epan four rows paired system and the least was observed with 1.0 Epan with normal row system. This indicating root proliferation under stress conditions and marked performance in terms of yield under water limited environments. Significantly higher Benefit： Cost ratio was recorded with 0.8 Epan two rows paired system （2.24：1） and was on par with 1.0 Epan two rows paired system （2.00：1） and 1.0 Epan normal row system （1.85： 1 ）. The significantly lowest B： C ratio was noticed with 0.6 Epan four rows paired system.

Enhancing the crop yield through capacity building programs: Application of double difference method for evaluation of drip capacity building program in Tamil Nadu State, India

A capacity building program on drip irrigation (TNDRIP) was undertaken in certain regions of the Indian State of Tamil Nadu during 2009-2010. An assessment of the impact of the program in terms of effective use of drip irrigation and increased crop yields was made in 2011 by applying double difference method (a combination of both with and without and before and after approaches). The results had indicated that the drip capacity building program resulted in a yield increase of 2.5 t/ha for Banana 1, 1.9 t/ha for Banana 2, 3.3 t/ha for sugarcane and 0.3 t/ha for turmeric. The conventional method using the before and after situations had shown a yield increase of 4.3 t/ha for Banana 1, 12.1 t/ha for Banana 2, 40.6 t/ha for sugarcane and 2.6 t/ha for turmeric. The conventional approach is highly upward biased in estimating the impact of the drip capacity building program and thus the double difference method will be an appropriate method to evaluate the impact of the programs that involve both with and without as well as before and after situations.

湖北漳河灌区中稻气象产量变化特征及预测模型

准确的气象产量是正确评估气象条件对粮食产量影响的前提。为了探究湖北漳河灌区单季稻气象产量的时间序列变化规律,尝试通过三点滑动平均法、HP滤波法和一次指数平滑法、二次指数平滑法4种方法将漳河灌区1975—2020年的水稻单产数据分离为水稻趋势产量及气象产量,通过相关分析筛选水稻8个生育阶段的主要气象因子,然后与分离的气象产量构建水稻预测模型。结果表明:4种分割方法均能较好地反映气象产量序列与湖北省生产力发展水平的区域一致性特点,多年平均气象产量占总产量的比例约为3.39%,但2008年以后其占比达到10.1%。相关分析识别出抽穗开花期最低气温、拔节孕穗期最高气温、分蘖后期平均气温、返青期最低气温、乳熟期蒸发量和育苗最低气温是影响气象产量的主要因子,该模型在率定期(1976—2014年)和验证期(2015—2020年)的相对误差均在5%以内,模型的决定系数R 2为0.994。预测模型有助于研究未来气候变化下的区域水稻产量的变化。

秸秆复合管地下灌溉对冬小麦生长与水分利用效率的影响

为了推进秸秆复合管地下灌溉技术的应用,以冬小麦为供试作物,通过田间试验,研究了秸秆复合管地下灌溉对冬小麦生长及水分利用效率的影响。结果表明,与无灌溉对照相比,秸秆复合管地下灌溉、地表滴灌和地下滴灌对冬小麦的生长与产量的提升均有促进作用,其中秸秆复合管地下灌溉的提升效果最显著。与地表滴灌相比,秸秆复合管地下灌溉显著提升了冬小麦起身期至抽穗期的株高、开花期之后的叶面积指数及地上干物质量,冬小麦穗长和穗粒数分别增加了5.84%和9.23%,产量提升了15.55%,水分利用效率与灌溉水利用效率分别提高了21.88%与15.55%,净收益提高了77.95%。与地下滴灌相比,秸秆复合管地下灌溉提高了冬小麦返青期后的株高、叶面积指数与开花期后的地上干物质量,冬小麦穗长和穗粒数分别增加了5.15%和9.8%,产量提高了5.11%,水分利用效率与灌溉水利用效率分别提高了8.81%与5.11%,净收益提升了23.53%。秸秆复合管地下灌溉有助于促进拔节期以后冬小麦生长,提高冬小麦的产量与水分利用效率,经济效益较高,在补充灌溉区对大田密植作物具有较好的推广应用前景。

刚性约束下人民胜利渠灌区水资源优化配置方案研究

为解决人民胜利渠灌区水资源利用的“瓶颈”制约问题,创新性地构建了基于刚性水资源约束的灌区水资源优化配置模型,并引入高效的改进型非支配遗传算法(NSGA-II)求解,生成规划水平年2035年不同供水保证率的100组优化配置方案。采用结合层次分析法(AHP)与CRITIC权重法的综合权重计算方法,利用TOPSIS法进行方案排序与优选,从众多可行方案中遴选出最优配置方案,为人民胜利渠灌区水资源节约集约利用提供参考,并有助于实现水资源的可持续利用。

灌溉方式与磷素对紫花苜蓿生产性能和营养品质的影响

为探究灌溉方式与磷素的互作模式对紫花苜蓿(Medicago sativa)生产性能及营养品质的影响,本研究采用双因素裂区设计,设置漫灌(F)、喷灌(S)、地下10 cm滴灌(D10)、地下20 cm滴灌(D20)和地下30 cm滴灌(D30)5种灌溉方式和0 kg·hm^(-2)(P0),60 kg·hm^(-2)(P1),120 kg·hm^(-2)(P2)和180 kg·hm^(-2)(P3)4个施磷(P 2O 5)梯度。研究水磷耦合条件下苜蓿生产性能、饲草品质和水磷利用效率。结果表明:3种地下滴灌处理的土壤含水量、生产指标、营养指标、水分利用效率和磷肥偏生产力均显著高于漫灌和喷灌处理;灌溉方式和施磷水平对苜蓿株高、分枝数、干草产量、粗蛋白含量、酸性洗涤纤维和相对饲喂价值均有显著影响。通过主成分分析得出,在地下30 cm滴灌方式下,施P 2O 5120 kg·hm^(-2)时的水磷组合模式最好,产量和营养品质综合排名第一,在生产上应用可得到优质牧草。

人民胜利渠灌区水资源安全综合评价

基于灌区水资源安全理论,构建水量、用水效率、生态3个准则层,选取水资源总量、每公顷农田灌溉水量、万元工业增加值用水量、生态用水量占比等10个指标,并依据人民胜利渠灌区2015—2020年社会、自然、经济和水资源等相关数据及统计资料,采用熵权法-层次分析法评价模型,对人民胜利渠灌区水资源安全进行综合评价。结果表明:2015年、2016年和2020年人民胜利渠灌区水资源处于基本安全状态,2018年和2019年处于安全状态,2017年处于不安全状态。通过深入辨识分析影响人民胜利渠灌区水资源安全的各项指标,发现提升水资源利用效率、推广节水灌溉技术以及实现水资源供需均衡,是确保人民胜利渠灌区水资源安全的关键。

不同冬灌方式对紫花苜蓿次年生长及土壤水热的影响

为探寻干旱半干旱地区冬季灌水对土壤水分、温度以及翌年紫花苜蓿返青、生长和产量的影响,进而提出适宜于伊金霍洛旗地区紫花苜蓿高产的灌溉方式,采用大田试验的方法,以未冬灌小区作为对照(CK),设置地下滴灌(DI)和畦灌(BI)2种灌溉方式,灌水定额设置为30 mm,共3个试验处理,每个处理3次重复,共9个试验小区。结果表明冬灌对次年紫花苜蓿返青时各土层土壤含水率和土层温度均有一定影响,地下滴灌和畦灌,均能提高紫花苜蓿返青前的土壤含水率、提高土壤温度、改善紫花苜蓿的越冬环境、提高紫花苜蓿的越冬率。冬灌后次年紫花苜蓿返青率较未冬灌处理小区高13.77%,且滴灌处理条件下返青率最高,有利于后期紫花苜蓿产量的提高。地下滴灌冬灌处理条件下紫花苜蓿第1茬产量最高,鲜草产量为31020 kg/hm^(2),干草产量为6150 kg/hm^(2),相对未冬灌处理分别增产23.32%、21.67%。综合考虑地下滴灌条件下冬灌对次年紫花苜蓿生长及土壤水热的影响,建议伊金霍洛旗地区紫花苜蓿在越冬期进行地下滴灌条件下的冬灌。

参考作物蒸散量的计算及不同作物灌溉需水量的特征分析

【目的】研究分析参考作物蒸散量结合作物系数估算作物各生育阶段灌溉需水量特征,为农业用水调配提供依据。【方法】基于新疆阿克苏市气象站点1980~2010年逐日气象数据,采用Hargreaves-Samani(H-S)、Irmark-Allen(I-A)和Priestley-Taylor(P-T)3种方法模拟计算参考作物蒸散量(Reference Crop Evapotranspiration,ET 0),依据R 2、nRMSE和MAPE评价3种模拟方法的精度,并分析ET 0在年际间和月尺度下的变化规律。分析不同典型年冬小麦、棉花、春玉米、夏玉米的需水规律。【结果】(1)H-S法、I-A法和P-T法计算的研究区ET 0模拟值与标准值的R 2分别为0.965、0.949、0.946,MAPE分别为20.85%、26.46%、66.71%。(2)研究区全年ET 0累计值30年均值为960 mm,5~8月较大,12月和1月较小。(3)冬小麦、棉花、春玉米、夏玉米分别在返青-拔节期、开花-吐絮期、抽穗-乳熟期、抽穗-乳熟期的灌溉需水量最大,其对应值为108、308、131和136 mm。(4)全生育期内,冬小麦、棉花、春玉米、夏玉米的灌溉需水量分别为448、533、394和385 mm。【结论】H-S法和I-A法在新疆阿克苏市ET 0计算有良好的普适性;研究区ET 0累计值年际间变化不大,年内呈先增大再减小的趋势;冬小麦、棉花、春玉米、夏玉米的关键需水期分别为返青-拔节期、开花-吐絮期、抽穗-乳熟期、抽穗-乳熟期;全生育期内,棉花灌溉需水量最大,其次为冬小麦、春玉米、夏玉米。