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645 |
Effects of non-adsorptive ions′ changing concentrations on infiltration characteristics of red soil |
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LIU Weijia,, LI Zhanbing*, ZOU Dasheng, PEI Qingbao,
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To study the effect of non-adsorption ions′ concerntrations changing on the migration characteristics and distribution of moisture solute in red soil, we simulated it by HYDRUS model and one-dimensional vertical infiltration. The result shows that the initial concentration of Cl- has a strong influence on the advancing and infiltration capacity. The higher the initial concentration was, the faster the wetting front advance, and the accumulated infiltration and the stable infiltration rate increase correspondingly. However, it is not obvious during the initial 100 min. Besides, the initial concentration of Cl-also effects soil moisture content and the Cl- content in soil, and they become higher with the initial concentration increasing at the same depth in soil. Because the average relative error is small and NSE is above 0.85,HYDRUS model is within 9.3%, the model′s applicability is satisfactory. The research results can provide guidance for the study of the moisture solute migration in water-fertilizer irrigation of red soil. |
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2018 Vol. 36 (8): 645-650
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398 )
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651 |
Effects of different water quality and irrigation methods on red soil water repellency and physical-chemical properties |
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HU Tingfei, WANG Hui*, HU Chuanwang, LU Jiayu, ZHU Jinbin
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In order to research the effect of different irrigation methods and water quality on acidic soil water repellency, pH, salt and organic matter content, four kinds of low-quality water such as reclaimed water and diluted 2, 4, 6 times of reclaimed water were selected, distilled water as contrast, using reclaimed water for continuous irrigation as well as alternate irrigation with reclaimed water and distilled water to do red soil column infiltration exreriments for more than 1 year. Results show that induction of subcritical water repellency following different irrigation with reclaimed water, the contact angle of red soil under the continuous irrigation grew by an average of 23.1° as against alternate irrigation. Both irrigation methods increase the acidity of red soil as well as salt and organic matter content, and the growth rate under continuous irrigation is larger than that of alternating irrigation. In the continuous irrigation, the soil water repellency, pH, salt and organic matter content can be described by quadratic function with the change of water quality, and the determination coefficient is above 0.9. In the alternate irrigation, the relationship between red soil water repellency, salt and water quality can be described by quadratic function, and the determination coefficients are all above 0.9, but the soil pH and organic matter content have no obvious correlation between it. In the two irrigation conditions, soil water repellency is negatively correlates with pH, it is positively correlates with salt content, and it is negatively correlates with organic matter content in the continuous irrigation, while in the alternate irrigation it is opposite. The alternate irrigation with reclaimed water and distilled water can restrain the generation of soil water repellency. |
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2018 Vol. 36 (8): 651-655
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397 )
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666
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656 |
Water regulating effect on Jatropha curcas repair cadmium-contaminated soil |
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YANG Ying, YANG Qiliang*, WU Zhenzhong, WANG Huanchang
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The growth status of Jatropha curcas saplings at different irrigation treatments(W1:30%FC,W2:50%FC,W3:70%FC,W4:90%FC)and cadmium mass ratio(Cd0:0 mg/kg,Cd1:50 mg/kg,Cd2:100 mg/kg,Cd3:200 mg/kg), irrigation water use efficiency(WUE)and the characteristics of cadmium enrichment of Jatropha curcas were studied through the greenhouse pot experiment.The results show that cadmium content increases with the increase of cadmium mass ratio(P <0.01), while with the increase of cadmium mass ratio, soil cadmium transfer coefficient(TF), bioaccumulation coefficient(BF)and WUE decrease(P <0.05).The content of cadmium, TF and BF in Jatropha curcas increases first, then decreases with the increase of irrigation amount, and the ability of its organs to enrich cadmium in sequence from high to low is root,stem,leaf. Under the conditions of this study, the optimum combination of irrigation and cadmium mass ratio is beneficial to W3Cd1. |
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2018 Vol. 36 (8): 656-661
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364 )
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673
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662 |
Effects of alternate root-zone irrigation on physiological growth and yield of processing tomatoes in northern Xinjiang |
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ZHAO Di,, WANG Zhenhua,*, LI Wenhao,, ZHANG Jinzhu,, LYU Desheng,, ZHANG Jifeng,
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Alternate root-zone irrigation is widely used in horticultural crops and crops to achieve the purpose of high efficiency and water saving. In this study, a barrel planting experiment was conducted to study the physiological growth and yield changes of processing tomatoes at three irrigation levels(W1: 5 850 m3/hm2, W2: 4 500 m3/hm2, W3: 3 150 m3/hm2)by combining three irrigation metho-ds(AI, FI, CI)with drip irrigation film mulching. The results show that under W1 condition, AI, compared with CI, significantly increases root dry matter quality, yield and water use efficiency by 5.95%, 16.87% and 17.29% respectively. Compared with FI, it increases root dry matter quality, yield and water use efficiency by 14.62%, 19.77% and 8.33% respectively. The maximum value of SPAD, Fv/Fm, Qp, Pn and iWUE are all in AIW1 treatment, the maximum value of non-photochemical quenching coefficient Npq is appeared in FIW3 treatment. There is a good correlation between yield, net photosynthetic rate and root-shoot ratio. In summary, AIW1 is the best irrigation mode that is conducive to the efficient water-saving and yield increase of processing tomatoes. |
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2018 Vol. 36 (8): 662-667
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532 )
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675
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668 |
One-dimensional vertical infiltration of water under gravel fragments condition |
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WEI Tong, TAN Junli ,,*, GE Min, MA Zhongsheng
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In order to study the effect of sand press on the vertical infiltration law of soil moisture, sandy and loam soils were selected as the research object. The soil column experiment was used to simulate the effect of sand and loam on the vertical movement of water infiltration under sand pressure. We set separately two kinds of soil without pressure sand control test and analyzed the effect of sand pressure on the vertical movement of water infiltration of two kinds of soil. The results show that gravel fragments improve the infiltration capacity of the soil including the sand layer, but inhibit the infiltration performance of the soil under the sand layer. The empirical equation between cumulative infiltration and infiltration time that is obtained through function fitting has a great degree of synergy. Sand pressure conditions have a greater impact on the initial infiltration rate of the soil. The initial infiltration rate of sandy soil under pressure sand conditions is 1.67 times that of non-pressure sand and 2.37 times that of loam, and the effect of sand pressure on the infiltration rate of loam is even greater. Obviously, stable infiltration rate is small, and sand pressure has no obvious effect on the infiltration rate of the two soils. Sand pressure can inhibit the depth of the two soils with the change of cumulative infiltration, and the inhibitory effect on the loam is stronger. The relationship between the depth of the wetting front and the cumulative infiltration of both soils after removal of the sand layer is approximately linear. |
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2018 Vol. 36 (8): 668-672
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480 )
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673 |
Effects of irrigating water quotas on growth and grain yield of summer maize under deficit irrigation |
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QIU Xinqiang,, WANG Yanping,, HE Gang,, QIN Haixia,, ZHANG Yushun,, LU Zhenguang,*
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In order to seek the reasonable water-saving and high efficiency irrigation indexes of summer maize, lysimeter experiments were imposed to study the variation of two agronomic characters, grain yield and water use efficiency(WUE)under four irrigating water quotas and two soil water deficits. The results show that the leaf area index(LAI)of the early stage of summer maize is increasing with the increase of irrigating water quotas, and the normal plant height can still be guaranteed by timely rewatering after light drought. The water consumption and grain yield decrease with the increase of drought severity, but there is no trend change with the increase or decrease of irrigating water quotas. The WUE is generally higher under irrigating water quota 75, 90 and 105 mm, invariably light drought treatments can attain higher WUE under the same irrigating water quotas. In combination with actual production, with the goal of high yield and high moisture productivity, It is recommended that irrigating water quota 60 mm before jointing and 75 mm after jointing as reasonable water-saving irrigating water quotas, 45% field capacity(FC)at the seedling stage, 50%-55% FC at the jointing stage, 60% FC at the tasseling stage, and 50%FC during the grain filling period as reasonable lower limit of irrigation control. |
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2018 Vol. 36 (8): 673-678
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405 )
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625
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679 |
Effects of water-nitrogen addition on Jatropha curcas L. physiological characteristics under salt stress |
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LIU Bing, YANG Qiliang*, XU Man
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In order to study the effects of different water-nitrogen treatments on the physiological characteristics of Jatropha curcas saplings under salt stress, three levels of irrigation were used(Irrigation volume per irrigation was T1: 3.2 L/plant, T2: 5.4 L/plant, T3: 9.6 L/plant), and 4 nitrogen application levels(NZ: 0 g, NL: 10 g, NM: 30 g, NH: 50 g)were subjected to a greenhouse plot test. The results show that appropriately adding irrigation volume under salt stress can effectively increase the net photosynthetic rate of Jatropha curcas. Under salt stress and without nitrogen application, T2 and T3 can promote the net photosynthetic rate, transpiration rate and stomata of Jatropha curcas. Conductivity, stomatal and leaf-water potentials increase, T3 increases photosynthetic rate compared with T1 and T2. Appropriate soil water-nitrogen regulation help to increase photosynthesis of Jatropha curcas. Under the same conditions of salt stress and irrigation, by comparison with NZ, the net photosynthetic rate, transpiration rate and stomatal conductance of Jatropha curcas under NL, NM and NH increase, and the leaf-water potential decreases. Compared with T3NH, the photosynthetic rate, transpiration rate, stomatal conductance and leaf-water potential of T3NM increase significantly by 5.15%, 5.86%, 8.81%, and 23.25%, respectively. In summary, under salt stress, the optimal treatment for the physiological characteristics of Jatropha curcas is T3NM. |
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2018 Vol. 36 (8): 679-684
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370 )
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664
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685 |
Theoretical model and experiment on fluidic sprinkler wet radius under multi-factor |
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LI Yangfan, LIU Junping*, LI Tao, XU Jien
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In order to thoroughly study the theoretical formula of the complete fluidic sprinkler under multi-factor conditions, the complete fluidic sprinkler wet radius model was predicted. The experimental program of the complete fluidic sprinkler that was used to measure working pressure, installation height, nozzle size, nozzle elevation was designed by the combination method, and the variation law of the complete fluidic sprinkler wet radius under the multi-factor conditions was summed. The 1stOpt software was used to analyze the data to get the calculation formula of the complete fluidic sprinkler wet radius, and the formula was compared with the formula of two commonly-used sprinkler wet radius. The results show that with the change of the working pressure, the sprinkler wet radius changes greatly, and with the increase of the nozzle elevation, the curve of the sprinkler wet radius has a parabolic shape that first increases and then decreases. The installation height has little effect on the sprinkler wet radius, and the larger the nozzle size, the larger the sprinkler wet radius. The relationship between the wet radius of the complete fluidic sprinkler and the single factor is well fitted to the model established in this paper, and it shows a relationship of a power function. The difference between the theoretical formula wet radius and the experimental wet radius is less than 8%, which can provide a theoretical basis for the prediction of the complete fluidic sprinkler wet radius. |
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2018 Vol. 36 (8): 685-689
[Abstract]
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388 )
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916
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690 |
Brushless DC motor drive characteristics and system for reel-type irrigator |
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YANG Lei*, TANG Yue, TANG Lingdi, WU Chen
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Aiming at the problem that the existing electric drive reel irrigation machine can not achieve the wireless connection and control of operation information, a brushless direct-current(DC)motor drive and control system based on mobile APP were designed. To replace the mechanical type water turbine DC motor as driving device of reel sprinkling machine, reel sprinkling machine field operation model was analyzed and built. Using STM32 as a system controller, introducing the incremental PID motor, mobile phone client and to remotely monitor the reel sprinkling machine industry were designed, completed the automatic correction system. Through experiments, the drive motor can be stable at a set speed, can be quickly returned to the set value in 10% the disturbance of load speed. The mobile phone client can run the remaining time, remote monitoring the residual time of the reel sprinkling machine, PE pipe length motor speed, reel speed and recovery rate of PE pipe, which provides the guarantee for the realization of sprinkler irrigation wisdom. |
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2018 Vol. 36 (8): 690-695
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778 )
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814
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696 |
Design and dynamics simulation of a new three-fold spraying arm structure |
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YU Cong*, TANG Lingdi, TANG Yue
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A three-fold spraying arm structure was designed aiming at the problems that the single nozzle sprinkler car of the reel sprinkler was high hydraulic power consumption,and the truss type sprinkler car could not be automatically folded, meanwhile the overall dimensions and the connection of each member were determined. Further, the dynamics equation based on Lagrange′s method of multi-rigid-body dynamics theory was established. The dynamic characteristics of the structure driven by sine function were analyzed using ADAMS virtual prototyping technology. The simulation results show that the folding movement of the structure is stable. After completely tucked inside bar folding angle is 86.2°, there appears the maximum stress of mutations at the fold angle of 85.6°. At this time, the maximum thrust of the hydraulic cylinder output is 2 800 N, and the maximum stress of each rod is 10 MPa, which is far enough to meet the requirements of tensile strength of 130 MPa.This shows that it has a better folding effect, and each rod meets to the structural strength requirements, which provides the basis for the rationality of the design of the three-fold spraying arm structure and the feasibility of machining physical prototype. |
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2018 Vol. 36 (8): 696-701
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418 )
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790
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707 |
Research advance on ecological design of irrigation channel |
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BI Bo, CHEN Dan*, TANG Shuhai, CHEN Jing, BI Lidong
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To solve the problem of habitat degradation and fragmentation due to inappropriate design of irrigation and drainage ditch, the methods and practices of ecological design of irrigation channel were riviewed and analyzed from the aspects of constructing ecological revetment, habitat conditions and biological corridor. Studies have shown that the current research mainly concentrates on hydrophilic materials, the diversity of flow characteristics, the geomorphological features of water channel, soil bioengineering and ecosystem conservation. The related research and application in China is still in the star-ting stage. Based on the concept and functions of ecological channels, seven kinds of ecological restoration techniques are recommended to restore the damaged irrigation district ecosystem to a healthy status. The characteristics, advantages and disadvantages of these technologies are comparatively analyzed, and the hot issues and development direction of ecological design of irrigation channel are also proposed. |
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2018 Vol. 36 (8): 707-712
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395 )
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713 |
Background segmentation and parameter detection of Jatropha seeds images |
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WANG Huanchang, YANG Qiliang*, YANG Ying
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In order to solve the problems of low efficiency, strong subjectivity, high error rates and poor real time that when selecting the quality of Jatropha seeds by experience, the images of Jatropha seeds were analyzed by digital image processing technology in this paper. Aiming at the characteristics of Jatropha seeds images, the R,G,B color components by arithmetic were firsty fused, then the arithmetic results were processed for noise cancellation by morphological opening operation, the adaptive threshold selection method was used for these images which were converted into binary images according to the method of OTSU and the edge extraction of images was realized by way of LOG operator. The portion of Jatropha seeds morphology parameters with the procedure of image processing finally was also calculated and got. Compared with the artificial segmentation method, the experimenal results show that although the background segmentation of Jatropha seeds images produces certain errors because the Jatropha seeds which are irradiated by light generate unequal shaded area in various display modes, overall average error of segmentation is less than 0.63%, the maximum error is 1.07% and the mean square error σ is not over 0.006 4 in 90 images of Jatropha seeds. Above all, this algorithm can achieve the accurate and reliable background segmentation and parameter detection of Jatropha seeds images. |
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2018 Vol. 36 (8): 713-718
[Abstract]
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398 )
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579
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719 |
Vertical spiral mixing mechanism of tomato straw particles based on discrete element method |
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WU Shuo,*, LI Pingping, ZHANG Xiliang, XU Yunfeng, LIU Jizhan, WANG Jizhang
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In this paper, the intrinsic and contact parameters of tomato straw particles were determined. Based on the natural angle of repose of the material, the discrete element simulation method parameters were calibrated by orthogonal test. Based on these parameters, a series of experiments were carried out. It is found that the particles form a macroscopic convective mixing process. The particles of that material form a certain angle in the normal direction of the surface of the blade to do divergent motion, and the farther away from the blade, the smaller the particle velocity. There are many turbulent regions between the upper and lower blades. The particle movement shows the process of spiral ascending and spiral descending, and there is no obvious diffusion movement in the diameter direction. The increase of blade rotation speed, the increase of pitch and the decrease of filling height are beneficial to the improvement of material mixing effect. The high-efficiency mixing mechanism is revealed, which provides a theoretical basis for the later equipment development and optimization. |
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2018 Vol. 36 (8): 719-724
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396 )
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736
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725 |
Modeling waterlogging process of paddy field at flat irrigation district in South China |
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XIONG Yujiang, XU Junzeng*, LI Yalong, LI Jiang′an, SUN Yong
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A simulation model for the waterlogging process in paddy field at flat irrigation district was constructed based the on the tank model. The rain runoff processes were observed in the typical paddy fields at Gaoyou irrigation district, and the adaptive genetic algorithm method was used to verify the flexibility of the paddy tank model. It is found that the performance of the paddy tank model for waterlogging process simulation is well in both calibration and validation periods. For rain runoff from paddy field simulation, the root mean square error ranges from 0.17 to 0.28 mm/h, the correlation coefficient is more than 0.95,and the Nash coefficient varies from 0.79 to 0.96 at calibration period. While the root mean square error ranges from 0.06 to 0.29 mm/h, the correlation coefficient is more than 0.88, the Nash coefficient varies from 0.73 to 0.93 at the validation period. For storage depth in paddy fields, the root mean square error ranges from 15 to 20 mm, the correlation coefficient is more than 0.95, the Nash coefficient varies from 0.84 to 0.90. The results indicate that the proposed paddy tank model can provide an alternative and effective method for the waterlogging process simulation in flat irrigation district in South China. |
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2018 Vol. 36 (8): 725-731
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471 )
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705
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738 |
Comparisons of reference evapotranspiration forecasting methods with public weather forecasts for Youth Canal Irrigation District in Guangdong |
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YAN Chengming,, LIU Meng, LUO Yufeng*
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Accurate method for forecasting reference evapotranspiration(ET0)in Youth Canal Irrigation District of Guangdong province was investigated to develop accurate irrigation forecasts and reduce agricultural water use. Daily weather observation data of the Zhanjiang Weather Station from January 1, 2003 to May 31, 2017 and daily public weather forecast data of 7 days ahead from January 1, 2016 to May 31, 2017 were collected. Forecasted ET0 from weather forecasts and Hargreaves-Samani(HS)method, reduced set Penman-Monteith(PT), and the daily average modification method were compared with calculated ET0 with FAO-56 Penman-Monteith and observed weather data. The results show that the average values of mean absolute error(MAE)of the 3 methods above are 0.908 3, 0.903 1 and 0.947 9 mm/d respectively, the root mean square errors(RMSE)are 1.099 1, 1.099 9 and 1.192 4 mm/d respectively and the correlation coefficients are 0.649 5, 0.649 8 and 0.615 9,respectively. Among the 3 methods, the PT has the best values of MAE and correlation coefficients. The PT method has the highest accuracy for the forecast horizon of 1—5 day while the HS method is the best for the forecast horizon of 6—7 days. Therefore, the PT method is recommended for ET0 forecasting Youth Canal Irrigation District. |
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2018 Vol. 36 (8): 738-743
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324 )
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586
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744 |
Virtual water flow and its impact on agricultural water utilization among provinces of China |
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GUO Xiangping,, YU Tao, WU Mengyang, GAO Shuang, CAO Xinchun,*
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Based on simulating the virtual water flow among provinces, the effect of virtual water flow on agricultural water use in China was evaluated from the perspectives of water-saving effect and regional water use efficiency. The results show that the virtual water of food flows from north to south on the whole. Heilongjiang and Jilin account for 69.1% of the tatal output, Guangdong, Zhejiang, Fujian, and Shanghai account for 56.2% of the total input. Meanwhile, the virtual water flow among provinces has saved 199.4 millions m3 of water resources in China, the WFP and WUP in the whole input regions and the WFP in the main input regions are increased, the WUP and WFP in all output regions except Heilongjiang and Jilin are descended. All the provinces, cities and autonomous regions should formulate strategies for the effective utilization and management of water resources based on their respective local condition and goal orientation, the main grain-producing areas in Northeast China should develop regional water-saving agriculture and improve the efficiency of agriculture water use. |
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2018 Vol. 36 (8): 744-749
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472 )
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805
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750 |
Water-nitrogen coupling effect by mulched drip irrigation on dry matter and yield of maize |
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Feng Yayang, Shi Haibin*, Li Ruiping, Qi Yinglong, Jia Qiong
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A field experiment was conducted to study the water-nitrogen coupling effect by mulched drip irrigation on the dry matter and yield of maize. Three levels of water were set. Low, medium and high water were set according to the upper and lower limits of soil water content per cent of the field water holding capacity, i.e. low water W1(60%~80% before jointing, 55%~80% after jointing), medium water W2(65%~85% before jointing, 60%~85% after jointing), and high water W3(before jointing 75% to 95%, 70% to 95% after jointing). Nitrogen application gradients were set at 224, 270, and 330 kg/hm2 for low, medium, and high nitrogen. The suitable amount of water and nitrogen for maize mulched drip irrigation suitable for Kezuozhongqi was sought to provide a theoretical basis for corn mulched drip irrigation to achieve high yield and efficiency. The results show that in the combination of high water level and 270 kg/hm2 fertility, higher total dry matter biomass can be obtained, but the harvest index is lower than that in the combination of medium nitrogen and medium water. A higher harvest index can be obtained, which can better regulate the distribution of photosynthetic products between grains and vegetative organs; under typical local and climatic conditions, maize is grown by the mode of mulched drip irrigation to increase water and nitrogen inputs, which can increase production and have a diminishing effect on the yield. Changes in single-factor application levels resulting in changes in yield is more affected by water than by nitrogen. |
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2018 Vol. 36 (8): 750-755
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322 )
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756 |
Effects of nitrogen fertilizer regulation on soil nitrogen uptake and production efficiency in root zone of summer maize |
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GAI Zhaomei, LIU Jilong*
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In order to study the effects of different nitrogen regulation models on summer maize productivity, and seek a reasonable and efficient management mode of nitrogen fertilizer, three fertilization levels(N1:280 kg/hm2,N2:320 kg/hm2,N3:360 kg/hm2)were set up in the black soil cultivation area of the Songnen Plain, and three fertilization ratios(F1:20%-30%-50%,F2:33%-33%-33%,F3:50%-30%-20%)were used for each treatment, with total 9 treatments. The characteristics of root system, plant nitrogen accumulation, crop yield and plant production efficiency were compared and analyzed under different treatments. At the same time, the correlation effect of plant root surface area on nitrogen accumulation was revealed by correlation analysis, and the correlation function between plant nitrogen uptake and crop harvest index was constructed. Finally, the optimal nitrogen control mode was selected. The results show that the root system of plants is affected by nitrogen regulation, the total root length of plants under N1F2 and N1F3 treatments increases by 306.4 cm and 436.1 cm, respectively, compared with N1F1, and its root surface area and root mass also show increasing in different degrees. At the same time, at the N2 and N3 fertilization levels, the three kinds of fertilization treatments show the same rule, but the N3 level is weakened compared with N2. There is a close relationship between plant root surface area and nitrogen accumulation, with the increase of nitrogen supply, the increase of root surface area has the most obvious effect on nitrogen accumulation at N2 fertilization level. The partial productivity of nitrogen fertilizer reaches 33.89 kg/kg1 under N2F3 treatment, and the utilization efficiency of nitrogen fertilizer reaches the optimum level. In addition, there is a significant quadratic function relationship between plant nitrogen uptake, crop yield and harvest index, indicating that there is the best threshold between nitrogen supply and plant productivity. Based on the factors such as root growth, nitrogen accumulation, and production efficiency, the N2F3 regulatory mode is finally determined to be the most suitable for this region. |
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2018 Vol. 36 (8): 756-761
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426 )
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663
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767 |
Soil respiration characteristics and its influencing factors in cotton fields under mulched drip irrigation |
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LIU Fangting,, FAN Wenbo,*, ZHANG Jinxi,, JIANG Yu,, YANG Haimei,, DONG Qianqian,, LI Changxiao,
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To study the dynamic changes of soil respiration and its impact factors of cotton fields under mulched drip irrigation, during growth periods of cotton, adopting Li-8100A automatic determination of soil carbon flux, soil respiration rate and environment factors on the ridge were continuously observed, in the ridge and bare land. The results show that the daily variation of soil respiration rate of the three samples expresse a single peak curve, and the peak appeares at 14:30. The soil respiration rate of the three samples increases first and then decreases with the seasonal change, and the soil respiration rate reaches the highest level in the middle and late July. The soil respiration rate and soil organic carbon quality ratio of the three sample plots are significantly different, the sequence of which from high to low is on the ridge, in the ridge and bare land, and the total amount of soil respiration on the ridge is the largest, which is 1.5 times and 2.8 times that in the ridge and bare land, while the sequence of soil temperature difference from high to low is bare land, on the ridge, in the ridge. According to the research by the method of correlation analysis, the correlation between soil respiration rate and soil moisture content is weak, but it is positively correlated with soil organic carbon quality ratio. Soil temperature can explain the variability of soil respiration rate from 75.1% to 84.4% and show a higher exponential positive correlation. The sensitivity of soil respiration to temperature is significantly different in three types of soil, the sequence of which from high to low is on the ridge(2.208), in the ridge(2.160)and bare land(1.675). |
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2018 Vol. 36 (8): 767-772
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381 )
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561
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773 |
Effects of different water-nitrogen combinations on potato water consumption, yield and quality under sprinkler irrigation |
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ZANG Wenjing, LI Jingjing, PEI Shasha, LI Yaojun, YAN Haijun*
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To investigate the appropriate combination of water and nitrogen for the potatoes, two irrigation levels(W1 and W2)and four nitrogen application rates F1(45 kg/hm2), F2(56.6 kg/hm2), F3(70 kg/hm2)and F4(86.6 kg/hm2)were conducted to evaluate the effects of combinations of water and nitrogen on water consumption, yield and quality of potatoes under center-pivot irrigation system at Keshan County, Heilongjiang Province. For assessing the effects of frequency of nitrogen application on the growth, yield and quality of potato, two frequencies of nitrogen application were also compared(C1:the nitrogen topdressing was applied once in the tuber enlargement stage; C2:the nitrogen topdressing was applied twice in the tuber enlargement stage). This study designed rainfall-fed zone as control. The results show that the total water consumption of the potato is ranged from 313 to 332 mm during the growing season. The tuber enlargement obtains the highest stage water consumption, which accounts for 63.4%-66.0% of the total water consumption. The seedling stage and the tuber formation stage are the critical periods for the potato water requirement, which indicates that the appropriate irrigation should be supplemented according to the local rainfall. The treatment of W2F4C2 obtains the highest yield, reaching 46 525 kg/hm2. No significant differences exists in starch, vitamin C, crude protein content and commodity rate of potatoes among the different treatments. The crude protein content of potatoes decreases first and then increases with the increment of nitrogen application rates. Therefore, the irrigation amount of 100 mm, nitrogen application rate of 86.6 kg/hm2 and nitrogen topdressing applied twice in the tuber enlargement stage are recommended for potato producers in semihumid areas of Heilongjiang province. |
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2018 Vol. 36 (8): 773-778
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Prediction for reference crop evapotranspiration in arid northwest China based on ELM |
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ZHANG Haojie, CUI Ningbo,*, XU Ying, ZHONG Dan, HU Xiaotao, GONG Daozhi
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To predict ET0 accurately with limited meteorological data, four representative meteorological sites were selected in arid northwest China to construct extreme learning machine(ELM). This model was used to predict ET0 and compare with other three models. The results show that when only based on the temperature and the wind speed data, the simulation accuracy of ELM7 is high(GPI ranks the 4th). When only based on the temperature and the radiation data, the simulation accuracy of ELM5 model(GPI ranks the 6th)is greater than that of Iramk model and Jensen-Haise model. When only based on the temperature data, the simulation accuracy of ELM9 model(GPI ranks the 8th)is greater than that of Hargreaves-Samani model. The results of ELM model portability show that ELM7 model in arid northwestern China has high simulation accuracy based on different sites′ datas. Thus, ELM5, ELM7 and ELM9 models can be used as a recommended model for the prediction of ET0 based on limited meteorological data in the northwest arid area of China. |
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2018 Vol. 36 (8): 779-784
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