Autumn Irrigation Alerted the Geochemistry of Groundwater in Hetao Irrigation District：Take Yichang Irrigation District as an Example北大核心CSCD

【Objective】Surface infiltration could change biogeochemical reactions in groundwater thereby alerting its chemical compositions. The aim of this paper is to investigate the responsive change in chemical composition of groundwater to infiltration following the autumn irrigation in irrigation districts.【Method】The experiment was conducted in Hetao Irrigation District, during which we measured the change in concentration of Na+, K+, Ca2+, Mg2+, SO42-, Cl-, HCO3- and CO32- and then statistically analyzed them.【Result】The irrigation increased the concentration of Cl-, SO42-, KNa, Mg2 and HCO3-, but slightly reduced the concentration of Ca2+. The TDS was higher in south and lower in north of the irrigation district. The Piper diagram showed that the Cl-Na was the dominant groundwater type, accounted for 75% and 61% of the studied area before and after the irrigation respectively. Irrigation turned groundwater in 16.7% of the studied area to Mg-SO4-Cl type. The Gibbs model and ion proportional coefficient diagram revealed that the chemistry of groundwater in the studied region was mediated by evaporation, weathering and leaching of silicate and evaporite, and is independent of precipitation. 【Conclusion】The mean TDS in the groundwater increased by 32.9% after the autumn irrigation, indicating the impact of soil leaching. Improving drainage after the autumn irrigation is hence essential. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Spatiotemporal Changes in Hydro-chemistry of Groundwater in Irrigation District within the Kaidu River Basin北大核心CSCD

【Objective】This paper studied the spatiotemporal changes in hydro-chemical properties of groundwater in irrigation districts within the Kaidu River basin, as well as the factors that affect these changes.【Method】Groundwater samples were taken in January, March, July and September in 2017 from the irrigation area in the Kaidu river basin. Spatiotemporal change in hydro-chemical properties of the groundwater and its impacting factors were analyzed using statistics, spatial interpolation, and Piper and Gibbs diagram.【Result】①The groundwater quality was generally good, with low TDS and being dominated by HCO-3, Na+, Ca2+ and SO2-4. The mean TDS was high in winter and low in summer, and it was related to the depth of groundwater table. ② Na+, Ca2+ and SO2-4 varied erratically both in time and space. ③The hydro-chemical type of the groundwater in the studied area was HCO-3-SO2-4-Na+-Ca2+, and remained almost unchanged in the four seasons. ④The rock weathering appears to affect the hydro- chemical propertied of the groundwater most. The impact of human activities was mainly in spring, summer and autumn in the oasis and lakeside region, and it was stronger in irrigation season than in non-irrigation season.【Conclusion】Our results suggest that pumping groundwater for irrigation should be rationally managed and the associated change in chemical properties of the groundwater should be monitored; this applies not only to the studied sites but also to regions on the southern slope of the Tianshan Mountain. © 2019 Authors. All rights reserved.     

Effect of Irrigation Frequency on Water Use Efficiency and Yield of Cotton after Loosening the Deep Soil北大核心CSCD

[Objective]The objective of this paper is to experimentally investigate the responsive change in yield and water use efficiency of cotton to irrigation frequency after soil loosening.[Method]The experiment was conducted from 2016 to 2017 after deeply loosening soil. By keeping the irrigation amount the same, we compared three irrigation frequencies: Irrigating once in each 4 day (D4), 7 days (D7) and 10 days (D10) respectively. The associated irrigation times were 17, 10 and 7 respectively. In each treatment, we measured soil moisture, dry matter accumulation, water consumption, water use efficiency and the yield of the crop.[Result]After deep loosening, keeping irrigation frequency at a moderate level (D7) significantly enhanced water-holding capacity of the 0~ 20 cm soil, thereby facilitating distribution of dry matter to different organs in the bud and boll and consequently improving the water use efficiency (WUE). Compared to D4 and D10, D7 increased WUE by 15.5% and 10.5% in 2016 and 16.5% and 9.2% in 2017, respectively. Increasing irrigation frequency promoted vegetative growth and reduced distribution of the dry matter to organs in the bud and boll. In contrast, reducing irrigation frequency reduced the accumulation of total dry matter, storage of water in the top soil and water consumption. Compared to D4 and D10, D7 increased the yield by 13.8% and 7.0% in 2016, and 17.3% and 6.1% in 2017. The main mechanism underlying in yield increase in D7 was the increase in boll number and average weight of the bolls in each plant. [Conclusion]Irrigating once after each 7 days, together with deep soil loosening, can effectively promote vegetative growth and organ production from dry matter, thereby facilitating the conversion of dry matter to organs and improving cotton yield and its water use efficiency. © 2019 TEST-ZL Publishing, LLC. All rights reserved.     

Calculation of Irrigation Infiltration Recharge Coefficient and Analysis of Influencing Factors in the Lower Reaches of Aksu River北大核心CSCD

【Objective】In order to obtain the irrigation infiltration recharge coefficient in the lower reaches of Aksu river and improve the numerical simulation accuracy of groundwater in the study area,the influencing factors of the irrigation infiltration recharge coefficient in this area were analyzed. 【Method】In this paper,field sampling and indoor irrigation experiments were carried out by selecting representative points under different irrigation schemes,vadose zone thickness and soil structure in the lower Aksu area,and numerical simulation of vadose zone flow was carried out in combination with Hydrus-1d. Hydrus-1d model was used to calculate irrigation inflow under this soil structure by changing irrigation schemes and vadose zone thickness. Change of seepage recharge coefficient. On the basis of the calculation results of the model,the relationship between irrigation schedule,aeration zone thickness and irrigation infiltration recharge coefficient is analyzed firstly,and then the main factors affecting irrigation infiltration recharge coefficient in soil structure are analyzed with the method of model calculation and mathematical statistics. 【Result】The results showed that the irrigation infiltration recharge coefficient ranged from 0.320 to 0.474 under drip irrigation and from 0.408 to 0.561 under border irrigation. The irrigation infiltration recharge coefficient varied under different irrigation schemes,while the irrigation infiltration recharge coefficient decreased with the increase of aeration zone thickness. The main factors affecting irrigation infiltration recharge are soil permeability coefficient,soil bulk density and initial soil water content. 【Conclusion】According to indoor experiment combined with numerical model to calculate the irrigation infiltration coefficient under different irrigation system range, it is concluded that the influence factors of irrigation infiltration coefficient of irrigation system, the thickness of the vadose zone and reflects soil permeability coefficient of soil structure, soil quality and soil initial moisture content, volume for the downstream area irrigation infiltration coefficient selection in arid areas and provides the theory basis for further research. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Experimental Study of the Suitable N-fertilizer Amount for Corn under Drip Irrigation in Aeolian Sandy Soil北大核心CSCD

【Objective】The purpose of this paper is to determine the suitable N-fertilizer amount for corn under drip Irrigation in Aeolian sandy soil. 【Method】The experiment was conducted in a field, and the amount of water and N-fertilizer were selected as experiment factors. Two levels of water amount (high and low) and three levels of N-fertilizer dosage (high, middle and low) were scheduled and thus six treatments were carried out. Effects of treatments on the growth and yield of corn were studied. 【Result】The results showed that, under low watering condition, increasing N-fertilizer amount was good for plant growth and had higher plant height and larger leaf area index, while under high watering condition, the positive effects were limited. Under both water condition, the fresh and dry weight of over ground part increased as N-fertilizer application increased, while its water contend, stem diameter and SPAD litter varied. Besides, higher N-fertilizer amount was beneficial to get longer ear, larger diameter, and more seeds, also was likely to got higher yield. The yield of high N-fertilizer amount under low and high watering condition were 13.0 and 13.7 t/hm2 respectively, 20.4% and 17.1% higher than the yield of low N-fertilizer amount treatments. 【Conclusion】In Aeolian sandy soil, higher N-fertilizer amount would be conducive plant growth and yield, especially when irrigation water was limited. Therefore, according to the experiment, N-fertilizer amount of 300 kg/hm2 was recommended in Aeolian sandy soil of northwest Liaoning. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Spatial Variability of Soil Moisture at Different Scales in Sandy Loam in Northern Henan Province北大核心CSCD

[Objective]Soil moisture plays an important role in ecosystem function and hydrological processes. This paper investigated the hieratical distribution of soil moisture at different scales over a maize field.[Method] The studied site was a 50 m×50 m plot at the Experiment Station of Chinese Academy of Agricultural Sciences in Xinxiang, Henan province. We measured soil moisture in 0~100 cm soil from 36 locations at 10 m×10 m and 2 m×2 m scale, respectively.[Result]Geostatistical analysis revealed that the soil moisture was normally distributed and its confidence level at every scale was higher than that of logarithmic normal distribution. The value of the confidence level decreased as the sampling scale increased, and the difference between average soil moisture content at fine scale and moderate scale was smaller than the difference between moderate scale and large scale. In general, the confidence interval, standard deviation and coefficient of variation of the soil moisture increased with sampling scale. At large scale, the semi-variance function increased with lag distance, while at small and moderate scale, the variation function appeared to be independent of the lag distance. To achieve the same confidence level and accuracy in estimating soil moisture, the number of samples needed to be taken from the field increased with sampling scale. We also found that in estimating soil moisture, the number of samples needed to be taken depended on the required accuracy more than on the confidence level.[Conclusion]The probabilistic distribution and statistical characteristics of soil moisture in the field was scale-dependent. In estimating soil moisture, the number of sampled taken from the field needs to consider the scales to which the measured data will be applied. © The Author(s) 2019.     

Ammonia Volatilization from Pit Wall under Different N Top-addressing from Water Storage Irrigation Pit in Apple Orchard北大核心CSCD

【Objective】Water storage pit is a common technology to bank precipitation for irrigation in arid region. In this paper, we studied ammonia volatilization from the wall of the pits under different N top-addressing in an apple orchard.【Method】We compared seven nitrogen top-addressing in the experiment: topdressing 600, 300 and 0 kg/hm2 at anthesis stage and fruit enlargement stage respectively. The ammonia volatilization from the wall of the water storage pit was measured using glycerophosphate-ventilation. We analyzed the dependence of ammonia volatilization on soil ammonium, soil nitrate, soil temperature, air temperature and humidity respectively.【Result】Ammonia volatilization increased with the topdressing amount after irrigation and fertilization. Top-addressing after anthesis stage could prolong ammonia volatilization for a significant period with a peak within 52.93 to 576.80 mg/(m2·d) occurring 3~5 days after the top-addressing. Top-addressing during fruit enlargement stage resulted in a short period of ammonia volatilization with a peak within 81.11 to 1 047.79 mg/(m2·d) occurring two days after the top-dressing. The accumulated ammonia volatilization (calculated by N) after one-off topdressing after anthesis stage and fruit expansion stage was 3 332.88~7 052.01 mg and 2 178.14~5 126.97 mg respectively. Compared to one-off topdressing, two top-addressing reduced ammonia volatilization to 2 013.21~ 4 642.11 mg, 34.17%~39.60% lower than that under one-off topdressing after the anthesis stage. Ammonia volatilization from the water storage pit wall accounted for 0.57%~1.40% of nitrogen loss, being the highest under one-off topdressing at anthesis stage followed by one-off topdressing at fruit expansion stage. Ammonia volatilization was positively correlated with soil ammonium and air temperature (P<0.05). Soil temperature and nitrate also played a role in ammonia volatilization. Rise in air humidity and rainfall after fertilization can reduce ammonia volatilization, and the dynamical change in accumulated ammonia volatilization can be well described by the Elovich dynamic equation, in which the rate constant parameter was positively correlated to the amount of top-addressing nitrogen and negatively correlated to soil temperature, both at significant level.【Conclusion】Ammonia volatilization from water storage pit wall can be controlled by managing the amount of fertilizer application and time at which the fertilizer was applied. Our results suggested that reducing the top-addressing amounts and top-addressing twice can effectively reduce nitrogen loss via ammonia volatilization. © 2019 Authors. All rights reserved.     

Response in Growth,Quality and Water Consumption of Greenhouse Tomato to Change in Matric Potential at 20 cm below the Emitter of Drip Irrigation北大核心CSCD

[Objective]Irrigation schedule needs to know the spatiotemporal dynamics of soil moisture in root zone. The objective of this paper is to investigate the feasibility of using matric potential measured at 20 cm below the drip emitter as a proxy for soil moisture in the root zone to schedule irrigation.[Method]The experiment was conducted in a greenhouse and the model plant was tomato. We compared seven matric potential (SMP) thresholds in that whenever the measured soil matric potential dropped below them, drip irrigation was resumed. The values of the SMP thresholds varied from flowering and fruit-setting stage to fruiting stage, and the seven combinations (flowering and fruit-setting stage/fruiting stage) were -15 kPa/-15 kPa (S1), -15 kPa/-30 kPa (S2), -15 kPa/-45 kPa (S3), -25 kPa/-25 kPa (S4), -30 kPa/-15 kPa (S5), -30 kPa/-30 kPa (S6), and -30 kPa/-45 kPa (S7). In each treatment, we measured growth, fruit quality, water consumption and water use efficiency of the tomato.[Result]Stem diameter increased with SMP threshold at both flowering and fruit-setting stage and fruiting stage, whereas the plant height was only responsive to SMP at flowing and fruit-setting stage. The relative chlorophyll content in leaf (SPAD) did not show significant difference between treatments at flowering and fruit-setting stage but inversely increased with the SMP threshold at fruit setting stage. Decreasing the SMP threshold at flowering and fruit-setting stage could reduce the percentage of defective fruits and increase soluble solids content. Yield increased inversely with SMP threshold at fruit setting stage, peaking when SMP was -45 kPa. Lowering the SMP threshold increased irrigation amount and hence water consumption, thereby decreasing water use efficiency. [Conclusion]Our experimental results suggest that setting the SMP at -30 kPa at the flowering and fruit-setting stage and -45 kPa at the fruiting period appears to be optimal to best balance yield, fruit quality, irrigation water use efficiency and water use efficiency for winter-spring tomato grown in solar greenhouse in North China. © The Author(s) 2019.     

关于评选优秀论文的公告北大核心CSCD

为鼓励创新,本刊已开启优秀论文评选活功,每年评选优秀论文10篇,每篇奖励1000元,颁发获奖证书,届时将在期刊网站首页展示,同时微信公众号推送。欢迎广大读者、作者积极向我刊投稿。     

关于评选优秀论文的公告北大核心CSCD

为鼓励创新,本刊已开启优秀论文评选活功,每年评选优秀论文10篇,每篇奖励800元,并颁发获奖证书,届时将在期刊网站首页展示,同时微信公众号推送。欢迎广大读者、作者积极向我刊投稿。     

Sensitivity Analysis of the Reference Evapotranspiration in Ebinur Lake Oasis北大核心CSCD

【Objective】The evapotranspiration of crop depends on many factors and this paper analyzed its sensitivity to various meteorological factors in Ebinur lake oasis.【Method】Monthly ET0 in Ebinur lake oasis was calculated using the Penman-Monteith formula based on meteorological data measured from 1962 to 2016 at four meteorological stations in the region. The sensitivity of ET0 to the highest and lowest temperature, relative humidity, sunshine duration and wind speed was calculated using sensitivity analysis; and the possible existence of any trends in the ET0 was analyzed using the MK trend test. We also calculated the variation of the sensitivity coefficient for each site.【Result】The MK trend test revealed that the evapotranspiration, sunshine duration and wind speed in the region have been in decline, while the highest and lowest temperature and the relative humidity have been in rise. Analysis found that the ET0 was sensitive to meteorological factor in an order of relative humidity > the highest temperature > wind speed > the lowest temperature > sunshine duration. The sensitivity coefficient of ET0 to different meteorological factors varies spatially, with the coefficients for the highest and lowest temperature, wind speed and relative humidity being high at Alashan pass-way in northern Ebinur lake, and low at Wenquan station. Wenquan station had longer sunshine duration than Alashan pass-way.【Conclusion】ET0 is most sensitive to relative humidity in Ebinur lake oasis, and least sensitive to sunshine duration. © 2019 Authors. All rights reserved.     

Multi-factor Analysis of the Effective Precipitation for Crops in Semi-arid Region北大核心CSCD

【Objective】The purpose of this paper is to present a method to estimate the effective precipitation for crops in arid region.【Method】The model considered precipitation, soil and crop, and it was based on four modules: canopy interception, soil water tolerance, surface runoff, precipitation and deep percolation. The results calculated by the model were compared to those calculated from water balance using the data measured from the field. We applied the model to calculate spatiotemporal distribution of the effective precipitation for crops in five counties in Hebei plain.【Result】①The coefficient of determination (R2) and Nash-Sutcliffe efficiency (NSE) in all results were above 0.85, proving the reliability of the model. ②The effective precipitation for growing season of the wheat-maize in the five counties was 400.03 mm, and the infiltration coefficient of precipitation was 0.84. In wet, normal and dry year, the effective precipitation for crops was 419, 454 and 355 mm respectively, and infiltration coefficient of precipitation was 0.76, 0.86 and 0.83 respectively. The effective precipitation for crops in Luancheng and Yuanshi was higher than that for other counties.【Conclusion】The proposed model was reliable for estimating effective precipitation for crops at large scale in semi-arid region. © 2019 Authors. All rights reserved.     

Comparative Analysis of Stratified Physical Characteristics of Seasonal Snow Cover With or Without Shading北大核心CSCD

【Objective】Snow melting runoff is an important recharge component of arid inland rivers. Seasonal snow cover is very sensitive to environmental change. Therefore, it is of great significance to study and control the key factors affecting seasonal snow accumulation and snow melting process for basin safety and sustainable utilization of water resources under changing environment. 【Method】By observing the physical characteristics of seasonal snow layers under the conditions of sheltered or not (under canopy and open land) in the Urumqi River Basin experimental area on the northern slope of Tianshan Mountains in Xinjiang from November 2017 to February 2018, the differences of physical characteristics of seasonal snow layers were analyzed. 【Result】① the temperature of open land was slightly higher than that of under canopy, and the relative humidity under canopy was higher than that of open land. ②The average depth of snow under canopy was less than that of open land, and the proportion of deep frost layer to coarse snow layer was larger in stratified snow cover. ③The vertical profile of snow density under canopy was basically the same as that under open land. The snow density increased gradually from the new snow layer down to the peak of coarse snow layer (open land) and medium-sized snow layer (under canopy). ④ Snow temperature and liquid water content of layers under canopy and open land increased from new snow layer to deep frost layer. ⑤ The variation trend of snow water equivalence under canopy and open ground was basically the same during observation period. The value of snow water equivalence under open ground was obviously larger than that under canopy. 【Conclusion】Snow surface temperature is a significant factor affecting the liquid water content of snow under canopy and open land. © 2019 Office of Journal of Irrigation and Drainage, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences. All rights reserved.     

Evaluation and Driving Force of Water Resources Carrying Capacity in Dianchi Basin北大核心CSCD

【Objective】The purpose of this paper to explore the coordination relationship between the water resources carrying capacity of the Dianchi Lake Basin and the socio-economic development and environment of the basin. 【Method】Select the water resources, social economy and environment-related indicators to construct a comprehensive evaluation model for the water resources carrying capacity of the Dianchi Lake Basin. The trend of pressure index, bearing capacity index, coordination index and water resources carrying capacity index of the basin from 2011 to 2015 was calculated and analyzed. The factor analysis method was used to further evaluate the water resources carrying capacity of the basin, and the main factors extracted were used. The driving force model of water resources carrying capacity was constructed to identify the main driving forces that affect the water resources carrying capacity of the Dianchi Lake Basin. 【Result】The water resources carrying capacity index of Dianchi Lake Basin showed an upward trend from 2011 to 2015; The main driving forces of water resources carrying capacity in Dianchi Basin were human activity factors and natural factors, including urbanization rate, economic development factors and annual average temperature and annual. Precipitation. GDP per capita and annual precipitation wrer positive drivers, and urbanization rates and annual average temperatures are negative drivers. 【Conclusion】Based on the sustainable development of social economy and the coordinated development of water resources system, the construction of water transfer project from the outer basin to Dianchi Lake Basin should be increased to form a multi-water source combined water transfer pattern, and the population quantity should be controlled on the basis of ensuring vigorous economic development. Establish a sound water resource efficient allocation and unified scheduling scheme for multi-source water supply in the basin water resources system. © 2019 Office of Journal of Irrigation and Drainage, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences. All rights reserved.     

Effects of Waterlogging on Morphology and Chlorophyll Fluorescence Characteristics of Cherry Tomato at Seedling Stage北大核心CSCD

【Objective】The aim of this study was to investigate the responses of cherry tomato to waterlogging at seedling stage, and to provide reference for waterlogging resistance cultivation of off-season cherry tomato in the tropical area.【Method】Five different varieties of cherry tomatoes were used as materials in pot culture experiment, with soil waterlogging treatment and normal moisture treatment as the control (CK). The morphological characteristics indexes of shoot and root and chlorophyll fluorescence parameters in leaves of cherry tomato were measured in different days of waterlogging. And the effects of waterlogging on morphological characteristics and chlorophyll fluorescence parameters at seedling stage of cherry tomato were analyzed.【Result】Results showed that waterlogging significantly decreased the plant height, stem diameter, leaf area, leaf number and SPAD value of cherry tomato, but had no significant effect on leaf thickness. The root diameter of cherry tomato had no significant affects, but the root volume was significantly increased in HongFei 6 and TaiwanZanMei during waterlogging. Compared with CK, the root length and root surface area of HongFei 6 increased significantly, while that of QianXi decreased significantly during waterlogging. Additionally, waterlogging increased the initial fluorescence (Fo) and non-photochemical quenching coefficient (NPQ), and significantly decreased the maximum photochemical efficiency (Fv/Fm), apparent electron transfer rate (ETR) and photochemical quenching coefficient (qP) of cherry tomato leaves, besides HongFei 6.【Conclusion】The results above indicated that during waterlogging the growth and development and chlorophyll fluorescence in leaves of cherry tomato were seriously affected, but there had different effects among five different varieties . Among five varieties of cherry tomatoes, the strongest waterlogging resistance was HongFei 6, while the weakest waterlogging resistance was QianXi. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Physical and Chemical Properties of Soil at Southeastern Edge of Anabasis salsa in Junggar Basin北大核心CSCD

【Objective】Soil is heterogenous and its physical and chemical properties vary spatiotemporally. The purpose of this paper is to present the results of an experimental study on the physical and chemical properties of soil in Anabasis salsa in Gobi region at the southeastern edge of Junggar basin.【Method】We measured organic matter, total phosphorus, total nitrogen, electrical conductivity, pH and water content in soil at locations 5 cm and 10 cm from the center of shrubs, and 20 cm from the outer edge of shrubs.【Result】In horizonal direction, there was no significant difference in organic matter, total nitrogen, total phosphorus, electrical conductivity, pH and water content in the 0~50 cm soil at all locations. In vertical direction, the organic matter and total phosphorus in the proximity of the Anabasis salsa decreased monotonically along the soil profile, while the total nitrogen increased first with the depth followed by a decrease. Both electrical conductivity and pH increased with depth, and soil moisture peaked somewhere within the soil profile.【Conclusion】Our results showed that the physical and chemical properties of soil in Anabasis salsa did not show significant change in lateral direction but varied erratically in the vertical direction. © 2019 Authors. All rights reserved.     

The Use of Brackish and Reclaimed Waste Water in Agriculture: A Review北大核心CSCD

Due to poor water resources management and appropriate water treatment technologies, freshwater resources depletion and water quality deterioration has made reclaimed waste water, brackish water and rainwater, called unconventional water, an important complementary resource for irrigation. However, due to its unique chemical quality, irrigating with unconventional water might lead to some detrimental impact on environment and impose health risks, which has attracted increased attention in both scientific and public community. This paper reviews the current situation of the usage of unconventional water resources for irrigation in both China and beyond, and summarized the potentially ecological risks of unconventional water, as well the national standards for regulating unconventional water irrigation. We also put forwards suggestions to improve safe and sustainable use of unconventional water resources for irrigation. © 2019 Authors. All rights reserved.     

Efficacy of Fertilization in Improving Soil Aggregation,Carbon and Nitrogen in Soil Reclaimed from Subsided Areas Caused by Coal Mining北大核心CSCD

【Objective】The objective of this paper is to present experimental results on efficacy of fertilization in improving aggregation and carbon and nitrogen accumulation in soil reclaimed from subsided areas caused by coal mining.【Method】The experiment was conducted under conventional irrigation with non-fertilization as the CK. We compared three treatments: applying organic fertilizer, inorganic fertilizer, and mixture of organic and inorganic fertilizer. For each treatment, we measured the size of soil aggregates, and carbon and nitrogen content in 0~20 cm and 20~40 cm soil in a coal mining-induced subsided area at Jincheng City in Shanxi Province.【Result】Compared to CK, organic fertilizer significantly increased the content of macro-aggregates sized >1 mm, and reduced the content of micro-aggregates sized < 0.25 mm. Inorganic fertilization enhanced formation of micro-aggregates, compared to organic fertilization. Applying organic fertilizer significantly increased the average weight diameter (MWD) and geometric mean diameter (GMD) of the aggregates, and reduced the fractal dimension D of the aggregates. The content of organic carbon and total nitrogen in soil under organic fertilization was the highest, followed by organic-inorganic fertilization. The content of carbon and total nitrogen in soil with a single application of inorganic fertilizer was much lower than that under organic fertilization. Majority of organic carbon and total nitrogen were found in aggregates > 0.2 mm, 1～2 mm and 0.25～1 mm, especially under organic and organic-inorganic fertilization. The C∶N ratio in all aggregates (except those in 0.053～0.25 mm) was much lower under organic and organic-inorganic fertilization than under CK, and C∶N ratio in CK and inorganic fertilization was comparable.【Conclusion】Fertilizations, especially organic fertilizer, can enhance macro-aggregation in reclaimed soil from subsided areas induced by coal mining. It also increased the content of organic carbon and total nitrogen in the aggregates. © 2019 Authors. All rights reserved.     

Mean Velocity Measuring Point of Semi-circular Open Channel Section Based on Flow Partitioning Theory北大核心CSCD

【Objective】The purpose of this paper is to reveal the characteristic position of the mean velocity along the normal line of the semi-circular channel wall and provided a novel method for flow measurement in non-uniformed channel, the physical model experiments were conducted in semi-circular channel.【Method】Based on the measuring results of flow velocity under different hydraulic conditions, the theoretical formula for calculating the mean velocity characteristic position along the normal line of the semi-circular channel wall was derived from flow partitioning theory. Considering the influence from side wall to friction velocity, the mean flow velocity of the entire semi-circular channel section can be obtained by measuring the flow velocity at the characteristic location.【Results】This paper proposed the theoretical formula and the measurements achieved a good agreement within 10% error. The formula can clearly reflect the distribution of the semi-circular open channel well. The velocity distribution should be analyzed along the normal line,thus the analysis methods was more reasonable. 【Conclusion】The theoretical results on determining mean velocity characteristic position fitted well the results from experiment and it indicated the formula has higher precision. The flow velocity at a specific position can be measured to further estimate the mean flow velocity of the section, so as to quickly and accurately determine the flow rate of the channel section in the project. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Study on the Variation Characteristics of Rising Capillary Water of Layered Soil under Variation of Sand Layer and Thickness北大核心CSCD

【Objective】The purpose of this paper is to solve secondary salinization of soil in Northwest China. 【Method】the capillary water rising movement characteristics of layered soil has been analyzed through indoor test. And the variation characteristics of capillary water movement under the influence of common change of layer and thickness of sand layer has been considered in this paper, and functional relationship between groundwater recharge and height of capillary water rising with time changing has been built. Furthermore, contour distribution of groundwater recharge and capillary water rising height has been also comparative analyzed.【Result】There was a very significant positive correlation between the horizon and the volume constant and the height constant （P<0.01）. And there was a significant negative correlation between the horizon and the stable recharge rate of groundwater and the rate of steady increase of capillary water （P<0.05）. There was a significant negative correlation between the thickness of sand layer and stable recharge rate and steady rising rate（P<0.05）. When the duration of the capillary water height was rising was 0~4 days, the sandy layer was 30~50 cm, the thickness of sand layer was 0~15 cm, which has a significant effect on the change of groundwater recharge and height of capillary water. When the duration of the capillary water height was rising was 4~12 days, the sand layer is distributed in 15~30 cm, the thickness of sand layer was 15~30 cm, which has a significant effect on the change of groundwater recharge and height of capillary water. To summarize, the results of this study were of great significance for the study of water salt movement and soil salinization in layered soils.【Conclusion】The fitting parameters of the function including volume constant (v), stable recharge rate (q*), groundwater recharge time constant (τQ), capillary water rising height (υ), steady rising rate (μ*) and rising height time constant (τh) were determined by the variation of capillary groundwater recharge and capillary water height with time changing respectively. © 2019 Journal of Irrigation and Drainage. All rights reserved.