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A network of soil moisture sensors is an effective tool for dynamic variable rate irrigation (VRI) management, which helps to determine the irrigation time in real time, thus solving the difficulty in dynamic monitoring of soil water content for remote sensing technology. To improve the decision accuracy of VRI management, this study optimized the placement of soil moisture sensors by analysing the variation in soil water content along the vertical profile and its temporal stability in the horizontal direction. The experimental site was located in the semiarid region of the North China Plain. The 7.07 ha experimental plot was controlled by a three-span centre pivot irrigation system with a zone controlled VRI system. Two treatments of uniform rate irrigation (URI) management and dynamic VRI management based on infrared thermometers mounted on the sprinkler irrigation system were set with equal areas. The number of Trime access-tubes placed in each treatment was 27 in 2021 and 13 in 2022. Measurements of soil water content were taken in 0.2 m increments with a depth of 1 m every 7–10 days. The results demonstrated that the similarity in the spatial distribution pattern of the soil water content in the VRI treatment was greater than that in the URI treatment, and their difference reached a significant level in the 2022 season of winter wheat. Significant linear regressions were detected between the mean clay percentile in each soil layer and the clay percentile representing the mean soil water content sites with a determination coefficient greater than 0.85. In the vertical profile, both the average soil water content at depths of 0–60 cm and 0–80 cm could be represented well by the soil water content at the 20–40 cm layer. These results demonstrated that during dynamic VRI management, soil moisture sensors could be placed at the 20–40 cm soil layer, and their locations in the horizontal direction could be selected according to the clay content distribution.

To determine the specific application rate for each management zone of a variable rate irrigation system, the yield and water use efficiency (WUE) of winter wheat were evaluated during two growing seasons at different deficit levels in the alluvial flood plain of the North China Plain. One 1.64-ha quadrant irrigated by a variable rate center pivot system was delineated into four management zones with available soil water holding capacity, and varied soil profiles were detected in these zones. Each zone was divided into several subzones to be irrigated at different deficit levels. In the 2016 season, each subzone was managed individually with irrigation trigger points of 55%, 65%, 75%, and 80% of field capacity along with a rain-fed treatment. In the 2017 season, all subzones were irrigated simultaneously with 0%, 33%, 67%, 100%, and 120% of the base application depth. For the two-season study, the rain-fed treatment produced significantly lower yield and WUE than the irrigated treatments, and both the maximum yield and the maximum WUE were obtained in zone 2, where a more uniform soil profile was detected. A linear crop water production function was determined for zones 1 and 3 in the 2017 season, while a quadratic equation fit the crop water production function well for other zones in the two seasons. The relationship between WUE and crop water use in the three zones can be represented by a curvilinear equation for both seasons. Taking the optimal application rate of maximizing WUE in zone 1 as a basis, 89% and 94% of the rate in zone 1 was recommended for zones 2 and 3, respectively, to achieve the maximum WUE in the entire field. Our results also suggested that the existing layered-textural soil profile can greatly influence crop productivity and should therefore be considered in mapping irrigation prescriptions.

Neurons are the structural and functional unit of the nervous system. Precisely regulated dendrite morphogenesis is the basis of neural circuit assembly. Numerous studies have been conducted to explore the regulatory mechanisms of dendritic morphogenesis. According to their action regions, we divide them into two categories: the intrinsic and extrinsic regulators of neuronal dendritic morphogenesis. Intrinsic factors are cell type-specific transcription factors, actin polymerization or depolymerization regulators and regulators of the secretion or endocytic pathways. These intrinsic factors are produced by neuron itself and play an important role in regulating the development of dendrites. The extrinsic regulators are either secreted proteins or transmembrane domain containing cell adhesion molecules. They often form receptor-ligand pairs to mediate attractive or repulsive dendritic guidance. In this review, we summarize recent findings on the intrinsic and external molecular mechanisms of dendrite morphogenesis from multiple model organisms, including Caenorhabditis elegans, Drosophila and mice. These studies will provide a better understanding on how defective dendrite development and maintenance are associated with neurological diseases.

Objective Globally, developed countries such as the United States, Canada, Germany, Korea, have carried out long-term and systematic biomonitoring programs for environmental chemicals in their populations. The China National Human Biomonitoring (CNHBM) was to document the extent of human exposure to a wide array of environmental chemicals, to understand exposure profiles, magnitude and ongoing trends in exposure in the general Chinese population, and to establish a national biorepository. Methods CNHBM adopted three-stage sampling method to obtain a nationally representative sample of the population. A total of 21,888 participants who were permanent residents in 31 provinces were designed to interviewed in this national biomonitoring (152 monitoring sites × 3 survey units × 2 sexes × 6 age groups × 4 persons = 21,888 persons) in 2017–2018. Unlike the US National Health and Nutrition Examination Survey, the CNHBM will follow the same participants in subsequent cycles allowing for dynamic, longitudinal data sets for epidemiologic follow-up. Each survey cycle of CNHBM will last 2 years and each subsequent cycle will occur 3 years after the prior cycle’s completion. Results In 2017–2018, the CNHBM created a large cohort of Chinese citizens that included districts/counties questionnaire, community questionnaire collecting information on villages/communities, individual questionnaire, household questionnaire, comprehensive medical examination, and collection of blood and urine samples for measurement of clinical and exposure biomarkers. A total of 21,746 participants were finally included in CNHBM, accounting for 99.4% of the designed sample size; and 152 PSUs questionnaires, 454 community questionnaires, 21,619 family questionnaires, 21,712 cases of medical examinations, 21,700 individual questionnaires, 21,701 blood samples and 21,704 urine samples were collected, respectively. Planned analyses of blood and urine samples were to measure both inorganic and organic chemicals, including 13 heavy metals and metalloids, 18 poly- and per-fluorinated alkyl substances, 12 phthalate metabolites, 9 polycyclic aromatic hydrocarbons metabolites, 4 environmental alkylated phenols, and 2 benzene metabolites. Conclusions CNHBM established the first nationally representative, prospective cohort in the Chinese population to understand the baseline and trend of internal exposure of environmental chemicals in general population, and to understand environmental toxicity.

Objective Hypopharyngeal squamous cell carcinoma (HSCC) is a common type of malignant tumor. Long non-coding RNAs (lncRNAs) are known to participate in HSCC development, while the role of lncRNA MALAT1 in HSCC remains largely unknown. We aimed to explore function of the lncRNA MALAT1/miR-429/ZEB1 axis in HSCC progression. Methods Levels of MALAT1, miR-429 and ZEB1 in HSCC tissues samples were assessed. The FaDu cells were respectively treated with relative sequence or plasmid of MALAT1, miR-429, or ZEB1. Then, CCK-8 assay, colony formation assay, flow cytometry and Transwell assay were used to determine the cell proliferation, apoptosis, cell cycle, migration and invasion of the cells. The PI3K/Akt/mTOR signaling pathway-related proteins, proliferation-related proteins, cell cycle-related proteins, apoptosis-related proteins, and migration-related proteins were detected using Western blot analysis. The cell growth in vivo was observed. The targeting relationships between MALAT1 and miR-429, and between miR-429 and ZEB1 were confirmed. Results MALAT1 and ZEB1 expression in HSCC was upregulated while miR-429 expression was downregulated. Reduced MALAT1 and ZEB1, and upregulated miR-429 inactivated the PI3K/Akt/mTOR signaling pathway, suppressed in vitro viability, colony formation ability, migration and invasion, as well as cell growth in vivo, and promoted the apoptosis of FaDu cells. Downregulated miR-429 reversed the role of MALAT1 inhibition in FaDu cell growth. LncRNA MALAT1 served as a sponge of miR-429, thus regulating ZEB1 expression. Conclusion Inhibition of MALAT1 was able to elevate miR-429 to suppress the progression of HSCC via reducing ZEB1. Our research provided a potential therapeutic target for HSCC.

To improve the management of variable-rate irrigation (VRI) systems in semi-humid climates, three different soil-based irrigation management methods were evaluated on their potential for reducing irrigation water use and maximizing crop yield and water use efficiency (WUE) during the 2016 and 2017 growing seasons of summer maize in the North China Plain. The three irrigation management methods evaluated were soil water balance modeling (SWB), measured soil water content (SWC), and a combination of SWB and the rain forecast for the next three days (RF). The experiments were implemented on four management zones delineated by available soil water holding capacity of a center-pivot VRI system. A similar irrigation trigger point (70% of field capacity) was used for the three irrigation management methods in the four management zones. In the two seasons, the total water application in the SWC treatments varied in a larger range among the management zones, and the irrigation water applied was 22% and 21% less than in the SWB and RF treatments, respectively. Similar yields were obtained among the irrigation management methods in both seasons. The maximum WUE was always observed with the SWC treatments for the four management zones in the 2017 season. The WUE with the SWC treatments was 36% and 23% higher than with the SWB and RF treatments, respectively. Considering the amount of irrigation water applied, yield, and WUE, our results demonstrated that the SWC method was more suitable for VRI management than the SWB and RF methods in this semi-humid climate. Keywords: Center pivot, Soil water balance, Soil water content, Rain forecast, Summer maize, Yield.

Reducing deep percolation (DP) across the field is one of the main objectives of a variable rate irrigation (VRI) system under a semi-humid climate. A study was conducted in the North China Plain during the 2016 and 2017 maize growing seasons in a 1.64-ha one-quadrant plot irrigated by a VRI centre pivot irrigation system. The study was designed to quantify and compare the DP dynamics of three irrigation strategies, including soil water balance (SWB), measured soil water content (SWC), and a combination of SWB and rain forecasting for the next three days (RF). The area irrigated by the VRI system was delineated into three management zones (zones 1, 2, and 3) based on the available soil water holding capacity (AWC). Based on the seasonal cumulative DP, the zone-specific crop coefficient (Kc) for each zone was quantified to enhance the accuracy of the SWB method. The results indicated that high daily DP rates occurred during the initial and end growing seasons as well as following rainfall and irrigation events during the mid-season. The delay of DP after an intermittent large rainfall was observed in both seasons. The cumulative DP in zone 2 with a medium AWC and a uniform soil profile was 36% less than the mean values of DP for zones 1 and 3. Compared to the SWC and SWB methods, the cumulative DP for the RF treatment was reduced by 10% and 36%, respectively. During both seasons, the maximum DP values were observed in zones 2 and 3 under the SWB methods. The SWC method tended to increase the risk of DP for a coarse profile, whereas a lower sandy content soil tended to increase the risk for the SWB method. The mean Kc values derived based on DP for the initial, mid-season, and end of the late season stages were 0.86, 0.73, and 0.91 for zones 1, 2, and 3, respectively, with a 7% reduction compared to the Kc without considering DP. The seasonal crop water requirement determined by zone-specific Kc was reduced by 31 mm compared with the uniform Kc in different management zones. Our results suggested that the RF method exhibited promise for reducing DP, and the zone-specific Kc values were helpful to enhance the water savings of the SWB method for a VRI system.

Developing placement criteria for soil moisture sensors is crucial in increasing the practical functionality of a variable rate irrigation (VRI) system. In this field study, the temporal stability pattern of soil water content was compared between VRI and uniform rate irrigation (URI) treatments during growing seasons of winter wheat and summer maize to determine the placement criteria of soil water sensors. The 1.64-ha experimental site located in a highly variable alluvial flood plain was divided into four management zones according to the available water holding capacity ranging from 152 to 205 mm within the 0.6 m soil profile. In each zone, two sub-zones were created to represent VRI and URI treatments. A temporal stability analysis of soil moisture was conducted by regularly measuring soil water contents at 62 locations in the field during the growing seasons. Results showed that the VRI management changed the overall similarity of soil moisture spatial patterns when crop water consumption was provided mainly by irrigation water rather than precipitation. In each management zone, every measuring position was a time-stable location with respect to the mean soil water content. Significant linear regressions were detected between the mean clay percentile in each management zone and the clay percentile representing the mean soil water content sites, and a nearly equivalent value of fitted equation coefficient was obtained for winter wheat (1.15) and summer maize (1.19). These results demonstrated that the temporal stability of soil water content spatial patterns still existed in each management zone with the VRI management, and the clay percentile supplied a priori identification for placement of soil moisture sensors.

Subsurface drip irrigation is a sound method to apply sewage effluent, but there is a risk of nitrate and pathogen leaching. Field experiments were conducted during the maize growing seasons of 2014 and 2015 in the North China Plain to investigate the effects of lateral depth, irrigation level, and water quality on the deep percolation and the nitrate (NO3–N) and Escherichia coli (E. coli) leaching under semi-humid conditions. The experiments were designed with three lateral depths of 0 cm (D1), 15 cm (D2), and 30 cm (D3) beneath the soil surface along with three irrigation levels of 70% (I1), 100% (I2), and 130% (I3) of crop evapotranspiration requirements. Secondary sewage effluent and groundwater were used as irrigation water. The results indicated that the intensive rainfall caused most of the deep percolation and NO3–N leaching during the maize growing seasons. A high irrigation level usually produced more deep percolation and NO3–N leaching, but no significant difference was found among the treatments. In general, the cumulative NO3–N leaching beyond the root zone increased as lateral depth increased. In addition, the lateral depth obviously influenced the distribution of E. coli in soil, and subsurface drip irrigation usually induced E. coli contamination deeper in the soil. With relatively high nitrate and E. coli concentration, sewage effluent irrigation significantly increased the risk of NO3–N leaching beyond the root zone in the 2014 season, but imposed an insignificant influence on the presence of E. coli in soil. Furthermore, no E. coli was detected in the leachate following an irrigation event with sewage effluent or a rainfall event during the both maize growing seasons. A dripline depth of 15 cm with deficit irrigation can be conductive to reducing NO3 leaching as well as avoiding sewage effluent contact contamination during the maize growing season in the semi-humid region of the North China Plain.

Effective management of variable-rate irrigation (VRI) is a critical factor for maximizing the benefit of a VRI system. In this study, the influences of soil properties on winter wheat and summer maize were studied to verify whether differences in soil available water holding capacity (AWC) had an influence on crop growth parameters, yield, and water productivity (WP). A center-pivot VRI system was employed to deliver irrigation water across the field in an alluvial flood plain in China, and AWC was used to delineate VRI management zones. Three management zones with substantial differences in AWC were created, with AWC varying from 152 to 161 mm, from 161 to 171 mm, and from 171 to 185 mm for zones 1, 2, and 3, respectively. All zones were managed using the same allowed depletion. In the two-year study, the seasonal irrigation amount was basically equivalent among management zones for both winter wheat and summer maize. Differences in crop growth parameters were detected in plant height and leaf area index for winter wheat. The maximum plant height and leaf area index observed in zone 2 were 5 cm and 2.1 greater, respectively, than in the other zones. For both winter wheat and summer maize, the highest yield and WP were observed in zone 2, except for summer maize WP in the 2014 season. Compared with the average value for this field, the yields in zone 2 were 27% and 23% greater for winter wheat and 4% and 11% greater for summer maize in the 2014 and 2015 seasons, respectively. We demonstrate that AWC is an effective parameter for zone identification in VRI management, and differences in AWC and the layered-textural soils in a field may influence the crop growth parameters, yield, and WP of winter wheat and summer maize. Keywords: Center-pivot irrigation, Critical soil moisture deficit, Management zone, Summer maize, Variable-rate irrigation, Winter wheat.

Nano-CT provides a brand new tool for the research of biology, life sciences, archeology and artifacts, and new materials for its excellent nondestructive detecting capability, especially in the non-destructive testing of carbon and hydrogen polymer light element materials. However, typical conventional Nano-CT cannot perform high-resolution and contrast imaging on structure of materials with small differences in X-ray absorption, and the traditional color CT which can achieve this function has low ray intensity and poor image quality when observed on light-element materials. Therefore, a true-color Nano-CT based on FEI Quanta 600 SEM is proposed in this paper. Three different material targets, Cr, Cu, and W, are introduced to obtain different energy rays. High-sensitivity CCD detector and single-circle scanning method are used to acquire projection data and reconstruct three CT images with different energies. Finally, principal component analysis (PCA) algorithm is used to extract the three principal components as color and the three primary colors of the image are combined to form a true-color image. The true-color Nano-CT can perform high-resolution imaging of substances with similar attenuation coefficients but different compositions with high resolution.

The Micro-CT uses X-ray to detect the internal structure of a sample on micro&nano scale without destroying it, the main challenges in manufacturing a high power Micro-CT is a target with fast heat dissipation to produce high power intensity of X-ray. In this manuscript, we introduce our progress in manufacturing a target that can withstand higher power of electron beam than previous. Firstly, Monte-Carlo simulation (Genat4) is constructed to determine the optimal thickness of the tungsten film, which optimize the intensity of X-ray. In addition, we examine heat dissipation of tungsten and aluminum by finite element method and find that diamond is the most suitable material for substrate, because it results in the lowest temperature near the impact point according to our simulation. Thirdly, the magnetron sputtering method is used to fabricate a tungsten film on the diamond substrate. We highlight that the Micro-CT based on this target achieve a high resolution of 3μm, and the power of electron beam is 10 watts. Based on these improvements, the experiments show that our tungsten-diamond target provides much better performance with quicker heat dissipation rate (i.e. with lower temperature near the impact point) and the stronger power of X-ray than previous works.

The number of fertigation splits through center pivot irrigation system is a major concern for implementing sprinkler fertigation due to the possible losses caused by drift and volatilization. Field experiments were conducted at two sites of the semi-arid regions in the North China Plain with different soil fertilities to investigate the influence of the number of fertigation splits and the nitrogen applied on the nitrogen content, yield, and nitrogen use efficiency of winter wheat in the 2018 and 2019 seasons. In the experiments, one (N1), two (N2), and three fertigation splits (N3) in season based on soil Nmin-method was used. A treatment without in season fertilization (CK1) and a treatment with local fertilizer management method (CK2) were applied as control. Similar amounts of basal fertilizers and irrigation schedules were applied for all treatments. In the two-year study, both the nitrogen applied and sprinkler fertigation splits had significant influence on nitrogen content in winter wheat grain, and these effects varied with the changes of soil fertility. At the Beijing site of low soil fertility, the significantly great yield was obtained in the in-season N management treatments and the yield increased with the increasing of fertigation splits. The average yield in N3 treatment in both seasons was 32.5% and 15.1% higher than that in CK1 and CK2 treatments, respectively. At the Hebei site where inherent soil fertility was higher than that at the Beijing site, there was no significant differences in yield among all treatments, and the maximum yield within in-season N management treatments was obtained in N3 and N2 treatment in the 2018 and 2019 season, respectively. In both sites and seasons, the maximum partial factor productivity from applied N (PFPN) was obtained in CK1 treatment. The average PFPN in in-season N management treatments was 29.5% and 71.7% higher than that in CK2 treatment at the Beijing and Hebei site, respectively. More frequent fertigation was recommended for soils with low inherent fertility level.

In this paper, the problem of the expansion of a wedge of gas into vacuum is investigated. Let $\theta$ be the half angle of the wedge. For a given $\bar{\theta}$ determined by the adiabatic exponent $\gamma$, we prove the global existence of the solution through the direct approach in the case $\theta\leq\bar{\theta}$, extending the previous result obtained by Li, Yang and Zheng. Our analysis relies on the special symmetric structure of the characteristic form as well as characteristic decompositions.

X-ray MicroandNano imaging is developed based on the conventional x–ray tomography, it can not only provide nondestructive testing with higher resolution measurement, but also be used to examine the material or the structure with low atomic number and low density. The source with micro-focal spot size is one of the key components of x-ray MicroandNano imaging. The focused electron beam from SEM bombarding the metal target can generate x-ray with ultra-small size. It is convenient to set up x-ray microscopy based on SEM for laboratory use. This paper describes a new x-ray microscopy using reflection targets based on FEI Quanta600 SEM with tungsten filament. The flat panel detector is placed outside of the vacuum chamber with 300μm thickness Be-window to isolate vacuum from the air. A stage with 3 DOFs is added to adjust the positions of the target, the SEM’s sample stage is used to move sample. And the shape of target is designed as cone with 60° half cone angle to get the maximum x-ray dosage. The attenuation coefficient of Bewindow for x-ray is about 25%. Finally, the line pair card is used to evaluate the resolution and the result shows that the resolution of the system can receive less than 750nm, when the acceleration voltage is 30keV, the beam current is 160nA, the SEM working distance is 5mm and the acquisition time of the detector is 60s.

A microfocus electron-impact X-ray source with micro-beam was introduced in this paper. The tungsten cathode electrogun is used as emitting system, and the focusing system is consists of two magnetic solenoid lenses, it is effective, light and handy. The matching problems between emitting system focusing system are studied on the microfocus X-ray source. The current of the first focusing lens and the second focusing lens is 0.8A and 1.64A at the voltage of 90kV respectively, and the filament current is 2.5A. Under the condition, the micro-beam spot X-ray is gained. The test results of stability showed that the X-ray source have a excellent stability, X-ray intensity of which is 110.6±0.03μSr/hr, target current of which is 185.5±1.5μA, and the target temperature of which is 96.5±0.5°C.The resolution of micro-focus X-ray source is about 4μm by the analysis of JIMA, which meet the application requirement of microfocus X-ray source.

X-ray Nano-Computed Tomography (Nano-CT) is widely used in micro device nondestructive testing, material science, life science and other applications fields. Micro-focus X-ray source is one of the key components of Nano-CT and is directly affected by the quality of electron beam. Diameter is the key performance index of electron beam. The detection of electron beam spot diameter is of great significance for monitoring the performance of Nano-CT and quantitatively evaluating the qualities of design and fabrication of the electron gun and electron optical system. In this paper, the diameter direct detecting method is presented and applied to the FEI Quanta 600 SEM. The relationship between electron beam diameter and detecting curve is analyzed at first, then the application feature of diameter detecting methods, including crosshair detecting method, slit detecting method and single edge detecting method, is researched and compared. Furthermore, the experimental results demonstrate that the edge detection has higher detecting accuracy and lower requirement on the sampler, and that after computation the detecting error is within 20 nm.

Irrigation efficiency is an important consideration for selecting a suitable irrigation method in arid and semiarid regions. Crop canopy interception and wind drift may reduce sprinkler efficiency. However, the evapotranspiration suppression resulting from temperature reduction and humidity increase in sprinkler-irrigated fields versus non-irrigated fields, defined as microclimate modification in this article, imposed a positive effect on sprinkler efficiency. In this study, a sprinkler efficiency model based on the Cupid program was proposed for considering the effects of microclimate modification. The air temperature, relative humidity, plant transpiration, soil evaporation and sprinkler efficiency during the irrigation season of corn in the North China Plain were simulated using the model. The results indicated that the microclimate within the sprinkler-irrigated field could be modified during irrigation, and the effects continued for 10–20 h after the application finished. When evapotranspiration suppression was considered, sprinkler efficiency could be improved by 5 percentiles versus non-irrigated fields. A sensitivity analysis of sprinkler efficiency was conducted by classifying the input variables of the model into three categories: constant, hourly and daily variables. It was found that the sprinkler efficiency was only generally sensitive to the leaf thermal emissivity for all constant and daily variables investigated. The sensitivity to hourly variables was greatly dependent upon the specific soil, plant and weather conditions during an irrigation event.

The effects of drip irrigation system uniformity and nitrogen application rate on the distribution of water and nitrate in the soil were investigated through field experiments to modify the current design and evaluation standards for drip irrigation uniformity. The experiments were conducted in a solar-heated greenhouse in the 2009 and 2010 growing seasons of Chinese cabbage. Three statistical uniformity coefficients (Us = 55%, 73%, and 95%) and two nitrogen application rates (150 and 300 kg ha-1) were evaluated in 2009. In 2010, three Us values (53%, 65%, and 94%) and one nitrogen application rate (225 kg ha-1) were tested. The distribution of the soil water content and bulk electrical conductivity was monitored continuously with equally spaced frequency domain reflectometry (FDR) sensors located along a dripline. Gravimetric samples of soil for each plot were collected regularly to determine the distribution of nitrate. For all of the tested system uniformities, the soil water content displayed high uniformity coefficients throughout the entire growing season. The effects of system uniformity and nitrogen application rate on the seasonal mean water content and bulk electrical conductivity (ECb) and on the seasonal mean uniformity of water content and bulk electrical conductivity were insignificant at a significance level of 0.05. The uniformity coefficient of the soil bulk electrical conductivity and nitrate content was substantially lower than that of the soil water content and was dependent on the uniformity of the initial salt and nutrient constituents in the soil. Moreover, the system uniformity and nitrogen application rate had an insignificant effect on the uniformity of the nitrate content. The results of this study showed that uniformity values that are lower than those recommended by the current standards can be used in drip irrigation systems if sufficient irrigation and fertigation events are conducted to approach a uniform distribution of water and nutrients in the soil.

Because of the special environment in the greenhouse and the partial wetting character of drip irrigation, the water requirement of crop was difficult to estimate or measure accurately. Water requirement of drip irrigated tomato grown in a solar-heated greenhouse in North China Plain was determined using a water balance method in this research. The continuous soil moisture status in the wetted soil volume with respect to crop spacing and root effective depth over the tomato growing season was monitored with a combination of volumetric and tensiometric sensors to calculate the water content variation and drainage. Based on the actual water requirement of tomato, the crop coefficients and pan coefficients were updated. Results indicated that the drainage occurred in the root effective depth (40 cm) obviously lagged behind the irrigation event because of the small amount of water applied by drip irrigation. The seasonal average percentage of drainage in the application amount was 13%. Water requirement increased with tomato growing and then decreased at the late season growth stage, resulting in water consumption intensities ranging from 1.5 to 4.2 mm·d -1 . The measured K c values were 1.01 and 0.61, being 5% and 8% lower than the K cmid and K cend values recommended by FAO, respectively. The ratio between 20 cm diameter pan coefficient and class A pan / sunken Colorado pan coefficient reported by FAO was 1.19 and 0.89, respectively. The experiment recommended that a crop-pan evaporation coefficient of 0.47, 0.85 and 0.59 for development stage, midseason stage and late season stage of tomato, respectively.

The effects of drip fertigation uniformity and nitrogen applied on the distributions of water and nitrate in soil were investigated in a solar heated greenhouse in 2009 and 2010 growing seasons of Chinese cabbage to modify the current design and evaluation standards of drip irrigation uniformity. Three Christiansen uniformity coefficients (CU) of 0.62, 0.80 and 0.96 and two levels of nitrogen applied at 150 and 300 kg hm-2 were used in 2009. In 2010, three CU levels of 0.55, 0.72, and 0.95 and one nitrogen applied of 225 kg hm-2 were tested. The distributions of soil water content and bulk electrical conductivity were monitored continuously by equally spaced TDR probes along a dripline. Gravimetric samples of soil around each TDR probe were collected regularly to determine the distributions of nitrate and ammonium nitrogen contents. A substantially high uniformity coefficient of soil water content was observed during the whole growing season for all fertigation uniformities tested. The effects of fertigation uniformity and nitrogen applied on the mean and the uniformity of water in the soil were insignificant at a significance level of 0.05. The uniformity coefficient of soil bulk electrical conductivity and nitrate in soil was substantially lower than that of soil water content, being greatly dependent upon the nonuniformity of initial nitrogen contents in the soil. An insignificant influence of fertigation uniformity on the uniformity of soil bulk electrical conductivity and nitrate content in soil was also observed. It was supported by this study that lower uniformity values of drip irrigation system than those recommended by the current standards could be used if the system mainly aimed at producing a uniform distributions of water and nitrogen in the soil.

Application efficiency is an important consideration for selecting a suitable irrigation method in arid and semi-arid regions. Crop canopy interception and wind drift can reduce sprinkler application efficiency. However, the gradient to drive plant transpiration and soil evaporation may be reduced by the modification of field microclimatic parameters resulting from evaporation of water intercepted by canopy, leading to a suppression of plant transpiration and soil evaporation. In this study, a new concept of sprinkler efficiency was proposed with considering the effects of microclimate modification compared with non-irrigated area or surface irrigated fields. Then a model in which the sprinkler ballistic theory was incorporated into an energy balance approach was used to estimate the microclimate modification and evapotranspiration suppression. The temperature, relative humidity, plant transpiration, and soil evaporation for a sprinkler event during the irrigation season of corn in 2005 were simulated using the model. The results indicated that the microclimate within the sprinkled field was modified during water application and this modification would continue for a period of time after the application ceased. The recession of microclimate modification and sprinkler efficiency was closely related to application time. The best application time was from 6:00 a.m. to 12:00 noon. For an irrigation application of 20 mm, the predicted suppression to corn transpiration and soil evaporation was 5.2 % and 1.2 %, and it consequently raised the sprinkler efficiency about 6.1 %.