Time filter

Source Type

Yang J.,Chinese Israeli International Center for Research and Training in Agriculture | Yang J.,China Agricultural University | Yang J.,Ningxia Academy of Agriculture and Forestry science | Huang G.,Chinese Israeli International Center for Research and Training in Agriculture | And 15 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2010

In order to investigate the best irrigation management mode with saline water for spring wheat in the Yellow River irrigation district of Ningxia, the SWAP model was calibrated and validated with the experimental data carried out in 2007, then the model was applied to evaluate the saline water irrigation scheduling for the experimental year and different hydrological years. Calibration and validation results indicated that the simulated soil water content, salt concentration and crop growth indices were in good consistent with the measured data. Results implied that the model had been well calibrated and validated, and the model could be used as a management tool to evaluate the effects of various irrigation management practices on water and solute dynamics and crop yield. The simulated results indicated that the optimal irrigation management practice of spring wheat was to irrigate the field with four times of mixed irrigation (1:1 saline and fresh water) at total amount of 2400 m3/hm2 for the experimental year. The optimal irrigation practices of spring wheat for the hydrologic years of 75% and 50% were four times of mixed irrigation each for pre-sowing, jointing, heading and filling stages with total irrigation amount of 3000 m3/hm2 and 2300 m3/hm2, respectively. And for the hydrologic year of 25%, application of two times of mixed irrigation each for jointing and heading stages with total amount of 2000 m3/hm2 was the optimal saline water irrigation practice of spring wheat. The optimal irrigation mode has guiding significance to effective irrigation of saline water in Yellow River Irrigation District.


Wang K.-L.,Chinese Israeli International Center for Research and Training in Agriculture | Wang K.-L.,China Agricultural University | Huang G.-H.,Chinese Israeli International Center for Research and Training in Agriculture | Huang G.-H.,China Agricultural University
Shuidonglixue Yanjiu yu Jinzhan/Chinese Journal of Hydrodynamics Ser. A | Year: 2010

The heterogeneity of permeability is the primary factor which has significant impact on groundwater flow and solute transport. In this study, the improved successive random additional (SRA) algorithm was used to generate a two-dimensional permeability field with the increments of logarithmic permeability (lnK) following a Levy-stable distribution. The Monte Carlo simulation was then used to investigate the effect of the heterogeneity of lnK on groundwater flow and solute transport process in an area with its size of 128 m × 128 m. Results indicated that the heterogeneity of the permeability increases as the decreases of Levy index α. Under the conditions of the increments of lnK following a Levy-stable distribution, the increments of logarithmic velocity (lnv) in longitudinal direction follows the Levy-stable distribution as well. Nevertheless, the values of the Levy index of lnv (α lnv) are approximately the same as the corresponding values of the Levy index of lnK (α lnk). The longitudinal component (M x) of the first-order spatial moments of the contaminant plume increases as the mean value of lnK increases, while M x is independent of the values (α). For the same mean value of lnK, M x increases with the increase of time, while the transverse component (M y) is independent of time. The second-order spatial moments of the contaminant plume (M xx and M yy) increase with the decrease of the values (α), which means that larger degree of spatial variability in permeability field leads to larger dispersion of the contaminant plume. According to above mentioned the conclusion can be obtained that the heterogeneity of permeability field is essential to the estimation or prediction of groundwater flow and solute transport.


Wang S.,China Agricultural University | Huang G.,China Agricultural University | Huang G.,Chinese Israeli International Center for Research and Training in Agriculture | Yang J.,Ningxia Academy of Agro forestry Science | And 3 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2010

To obtain the suitable alternative of saline water irrigation for spring wheat, a field experiment was conducted in Huinong Irrigation District, Ningxia, North-West China in 2007 and 2008 respectively. The collected datum were used to analyze the effects of saline water irrigation on water-salt dynamics and yield of spring wheat. Results indicated that soil water content and salinity at the upper layer of 0-30 cm had relatively large variations, whereas the variations of soil water content and soil salinity in layers below 30 cm were relatively small. Canal irrigation resulted in the desalination of root zone soils, while well-canal combined irrigation kept the salinity in root zone soils being stable even at relatively dry years, but irrigation with well water caused a significant salt accumulation in root zone soils. Evapotranspiration and water use efficiency of spring wheat decrease with the increase of irrigation water mineralization degree. Compared with Canal irrigation, the well-canal combined irrigation only led to a slight decrease of crop yield, whereas a 20%-30% decrease of crop yield was caused by the well irrigation. The alternative with 1:1 ratio of ground water to surface water is recommended for irrigation of spring wheat in Yinbei Huinong Irrigation District.


Hao Y.,China Agricultural University | Hao Y.,Chinese Israeli International Center for Research and Training in Agriculture | Xu X.,China Agricultural University | Xu X.,Chinese Israeli International Center for Research and Training in Agriculture | And 6 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

Soil moisture and salinity are two key factors for crop production in arid irrigation districts. It is critical to modify soil water-salt dynamics and crop growth on a regional scale for the sustainable agriculture. In this paper, a distributed agro-hydrological model that well considers the spatial variability of soil and hydrological factors was developed to simulate soil water movement, solute transport and crop growth process on the regional scale. Jiefangzha Irrigation System (JIS) of the Hetao Irrigation District was selected as the study area. The JIS was divided into 201 homogeneous simulation units based on the combinations of weather-soil-crop-irrigation. In this way, the one-dimensional agro-hydrological model-HYDRUS-EPIC (HYDRUS-1D coupled with EPIC crop growth module), was used and expanded to the regional scale. Field experiments were conducted in 2012 and 2013. The dataset of soil moisture, soil solute concentration, leaf area index (LAI) and crop yield were collected at 40 monitoring points, and used for model calibration and validation. Simulated soil moisture and salinity concentration in the root zone showed good agreement with the measured values. During the calibration process, root mean square error (RMSE), mean relative error (MRE) and coefficient of determination (R2) for soil moisture were 0.03 cm3/cm3, 0.3% and 0.67, respectively. For salinity concentration, RMSE, MRE and R2 were 2.72 g/L, -13.5% and 0.53.LAI and crop yields were fitted well with the observations. MRE values for the estimated and measured LAI and crop yields were 1.0% and 1.1%, and R2 were both larger than 0.90 for these two items. During the validation process, RMSE, MRE, and R2 were 0.04 cm3/cm3, 2.6%, 0.57 for soil moisture, and 2.62 g/L, -4.5%, 0.51 for salinity concentration, respectively. And MRE and R2 were 9.1%, 0.88 for LAI, and -1.9%, 0.92 for crop yields. These results showed that the distributed agro-hydrological model was able to simulate the soil water flow, salt transport, and crop growth process in JIS with accuracy. The calibrated and validated model was then applied to predict spatial distribution of soil moisture, salinity concentration, crop evaporation and crop yields of the study area in present irrigation water management practices. Effective saturation and salinity concentration in the root zone were chosen to represent soil water and salinity stress on crop growth. Results showed that effective saturation ranged from 0.44 to 0.90 with an average of 0.7 for the JIS. In most areas, soil water could meet crop water consumption needs. In the areas where groundwater depth (GWD) was less than 1.3 m, root water uptake was limited due to waterlogging. The average salinity concentration in the root zone varied from 3.1 g/L in the northwest to 13.5 g/L in the northeast with an average of 6.4 g/L for the whole district. High soil salinity concentration limited crop production seriously. Corresponding to the spatial distribution of salinity concentration in the root zone, crop relative yield (ratio of actual yield and average yield of JIS) ranged from 0.33 to 1.33.The results suggested that for the northeastern part, where GWDs were larger than 2.0 m, more irrigation was needed for leaching salt. It was also better to plant more salt tolerant crops in these areas. In northwestern and southwestern parts, shallow groundwater levels intensified water logging or salinity accumulation problems. The study indicated that it is better to keep the groundwater depth not shallower than 1.3 m for maintaining the crop yields. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved.


Hao Y.,China Agricultural University | Hao Y.,Chinese Israeli International Center for Research and Training in Agriculture | Xu X.,China Agricultural University | Xu X.,Chinese Israeli International Center for Research and Training in Agriculture | And 4 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2014

Reduction of water diversion from the Yellow River will intensify water shortage problems in the Yinbei Irrigation District (YID). Reasonable use of groundwater for irrigation is helpful to maintain the agricultural production. Groundwater exploitation may cause groundwater level declines in local areas. This helps to reduce the salinity accumulation in the root zone but decreases the capillary rise. Thus, it is important to figure out the responses of soil water-salt dynamics and crop yields to groundwater table fluctuations for salinity control and stable yields. In this study, HYDRUS-1D model was modified by coupling with the EPIC (erosion-productivity impact calculator) crop growth module for simulating agro-hydrological processes. The new crop module could simulate crop height, leaf area index (LAI), above-ground biomass and crop yield. The information between HYDRUS-1D and EPIC was exchanged by daily step. Root water uptake under water and salt stress was calculated with HYDRUS-1D and imported to EPIC to limit crop growth. EPIC module estimated crop height, LAI and root depth for HYDRUS-1D to calculate soil water-solute dynamics. HYDRUS-1D assumed that soil evaporation remained at the potential rate unless pressure head of the soil surface decreased to a prescribed value. After then this prescribed value was set as a constant head to renew the top boundary condition. However, it cannot reasonably reflect the decrease stage of soil evaporation when using the constant head boundary. This may overestimate soil evaporation. Therefore, a new soil evaporation module, estimating soil evaporation reduction coefficient using soil water content of the top layer (0-10 cm), was added for better describing the soil evaporation under shallow water tables. With the experimental data collected from the maize field in 2008, the model was calibrated by the data of groundwater irrigation treatment and validated by the data of canal irrigation treatment. Simulated soil water content and solute concentration in the root zone (0-90 cm) showed good agreement with the measured values. Root mean square error (RMSE), mean relative error (MRE) and coefficient of determination for soil moisture were 0.03 cm3/cm3, 3.4% and 0.78, respectively. For solute concentration, RMSE, MRE, coefficient of determination were 1.6 g/L, 1.3% and 0.29, respectively. LAI and above-ground biomass values were fitted well with the observations. MRE values for estimated and measured LAI and above-ground biomass were 5.9% and 10.6%, and R2 were both larger than 0.95 for these two items. The model was then used to assess the impacts of groundwater table and irrigation changes on soil water-salt dynamics and maize yields. Nine groundwater depth (GWD) scenarios (100, 110, 125, 140, 155, 170, 185, 200 and 250 cm) and 6 irrigation treatments (0.6, 0.8, 1.0, 1.2, 1.4 and 1.6 times of the present irrigation) were considered. The results showed that soil water content and salt storage in the root zone declined with the reduction of groundwater level and irrigation amount. Due to the decrease of groundwater contribution and soil moisture, lowering groundwater depth resulted in a gradual increase of the average solute concentration in the root zone. Maize yields increased first and then decreased as the groundwater table declined. Generally, the maximum yields were achieved when GWD was between 140 and 155 cm. The maize yields may decrease with reducing the irrigation amount, therefore water-saving strategies were not recommended for local farmers with low incomes. Finally, the optimum groundwater depth of 140-155 cm was suggested, and three irrigations with an amount of 900 m3/hm2 for each will be applied during maize growing period. ©, 2014, Chinese Society of Agricultural Engineering. All right reserved.


Xu X.,China Agricultural University | Xu X.,Chinese Israeli International Center for Research and Training in Agriculture | Huang G.,China Agricultural University | Huang G.,Chinese Israeli International Center for Research and Training in Agriculture | And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2013

The quantitative description of soil water flow, solute transport and crop growth processes at field scale is significant for the decision-making of appropriate water use practices in arid irrigation districts. In this study, a modified agro-hydrological model (SWAP-EPIC) for coupled simulation of soil water flow, solute transport and crop growth was developed based on SWAP (soil water atmosphere plant) model and EPIC (environmental policy integrated calculator) crop growth model. The variable active-node method was adopted into the original SWAP model for reasonably simulating the soil water and solute transport processes during soil thawing period. Additionally, the S-shaped osmotic head-dependent functions for describing water and salt stress were also introduced. Further, the EPIC crop growth model, which could simulate the crop growth process and actual crop yield with moderate data input and parameters, was coupled into the SWAP model. Then the field applicability of SWAP-EPIC model was respectively tested using the field experiment data of spring wheat and spring maize at Huinong experimental site in Ningxia. The simulated and observed soil moisture, salinity concentration, and crop growth indicator (leaf area index and dry above-ground biomass) were compared for spring wheat and spring maize. The results showed that the soil moisture was matched very well, with MRE (mean relative error) and RMSE (root mean square error) close to zero and NSE (NSE and Sutcliffe model efficiency) approached to one. The simulated and observed salinity concentration showed an agreement with some slight discrepancy. The simulated LAI and above-ground biomass both matched well with observed ones. Meanwhile, the simulated crop yield was also close to the observations, with relative errors of 4.9% for spring wheat, and 3.3% for spring maize. The results indicated that the modified model (SWAP-EPIC) could be efficiently used to simulate the soil water and salt dynamics, crop growth, and their relationships at field scale.

Loading Chinese Israeli International Center for Research and Training in Agriculture collaborators
Loading Chinese Israeli International Center for Research and Training in Agriculture collaborators