Search

【Objective】 HYDRUS is a software widely used to simulate soil water movement, but it requires evapotranspiration which is difficult to obtain at large scales. In this paper, we investigated the feasibility of combining it with remote sensing to simulate spatiotemporal soil water dynamics at large scales. 【Method】 The experiment was conducted in a summer maize field in Daxing District, Beijing. The evapotranspiration estimated from the MODIS data and the surface energy balance system (SEBS) model was decoupled into soil-surface evaporation and plant transpiration, which were combined with the HYDRUS-1D to simulate spatiotemporal water dynamics in soil profile. Field-scale soil water dynamics was modelled by embedding the HYDRUS-RS model with the geographic information system (GIS) platform. The models were then applied to simulate spatiotemporal changes in soil water in the summer maize field during its growing season in 2018. 【Result】 The SEBS model was the best in modelling Rn, with the coefficient of determination (R2), bias and root mean square error (RMSE) being 0.81, 11 W/m2, and 54.8 W/m2, respectively. In the experimental area, the estimated daily ET during the growing season of the maize in 2018 varied between 3 and 6 mm/d. This differed slightly from that directly estimated from the soil moistures measured from pre-defined sampling points, but their temporal variation trends were the same. During growing season of the summer maize, soil moisture simulated by the proposed HYDRUS-RS model for the 40-60 cm soil layer was accurate, with the bias, RMSE, and R2 being 0.2%, 2.1% and 0.80, respectively. 【Conclusion】 Combining remote sensing with HYDRUS-1D provides a robust and accurate method for simulating large-scale soil water dynamics in agricultural lands. For the summer maize crop we studied, this integrated approach effectively predicts the changes in soil moisture, particularly in the 40-60 cm root zone.

【Background and Objective】 The adoption of artificial intelligence technology, particularly through adaptive learning, is reshaping the landscape of intelligent construction in the field of irrigation. This innovative perspective is divergent from traditional research paradigms, as numerous intelligent algorithms and technologies have been employed in the realm of irrigation water dispatching decisions. However, existing results often lack user-friendliness and ease of operation, preventing them from practical implementation. In light of this, this paper undertakes a comparative analysis of the Random Forest model and the BP Neural Network model in artificial intelligence technology. 【Method】 Building on this insight, the study divides historical data, based on measured values, into various gradients. These gradients encapsulate water irrigation scheduling variables, resulting in 9.82×1011 water dispatching scenarios. A pre-trained Random Forest model is employed to predict the dispatching flow corresponding to each scenario, ultimately constructing a fundamental database mapping the relationship between irrigation area water dispatching scenarios and dispatching flow values. This process enriches and encodes the scheduling scenario database through the utilization of machine learning models and existing scheduling history data. Leveraging this scenario database, and Neo4j technology, a knowledge map-based water dispatching flow prediction model is established for the Pishihang irrigation district. 【Result and Conclusion】 The key advantage of this model is its user-friendly approach. Irrigation area water scheduling managers can effortlessly determine the approximate gradient value of each scheduling variable within the knowledge graph model for a specific scheduling scenario. By doing so, they can readily access the corresponding scheduling flow prediction value through a simple query. Application results demonstrate that the knowledge map-based scheduling flow prediction model boasts a remarkable accuracy within the cognitive range of Pishihang irrigation district water management, facilitating real-time scheduling flow inquiries. This research represents a significant step toward more user-friendly and effective irrigation water management.

【Objective】 Water flow and solute transport in soil is important not only for plant acquisition of resources from soil but also for soil and water environment. In terrestrial ecosystems, they are impacted by numerous factors. The objective of this paper is to investigate the effects of drip irrigation amount on spatiotemporal change in water and nitrogen in Hetao Irrigation District, Inner Mongolia. 【Method】 A field experiment was conducted to measure the movement of water, nitrate and ammonium in soils, with the irrigation amount controlled at 6 mm (D1) or 60 mm (D2). The measured data was used to calibrate the HYDRUS-2D model, and the calibrated model was then used to elucidate how increasing the irrigation amount to 120 mm would affect water and nitrogen movement. 【Result】 Irrigation increased soil water content in all growth stages. Following irrigation and fertilization, ammonium and nitrate contents both increased rapidly and then decreased. On average, ammonium and nitrate in the 0~10 cm soil layer decreased by 60.0%~62.0% and 40.0%~46.7%, respectively, after the D1 and D2 irrigations, with the decreasing rate varying with growing stage. Compared to D2, D1 increased soil water content at jointing, heading and filling stage by 5.9%, 8.0% and 6.7%, respectively. Soil ammonium and nitrate both decreased along the soil depth. Nitrate accumulation decreased gradually when the crop grew from jointing stage to filling stage. The simulated soil water content and nitrogen agreed well with the measured data. 【Conclusion】 Experimental data and simulated results showed that irrigating the maize by 120 mm of water can effectively reduce accumulation of nitrate in the 0~60 cm soil layer, and that increasing irrigation frequencies can further curtail nitration accumulation in the 60~100 cm soil layer. These results provide guidance for improving irrigation and fertigation for maize production in Hetao Irrigation District.

【Objective】 Precision agriculture needs a rapid diagnosis of water and nutrient deficits, which is challenging at large scales in the field. Taking maize as an example, this paper proposes to estimate nitrogen content in maize canopy using remote sensing data. 【Method】 The study was carried out at Hetao Irrigation District using UAV multi-spectral imagery data measured in 2020. A variety of vegetation indices extracted from the imageries were used to calculate nitrogen content in the canopy when the crop grew to different stages. The model was validated against ground-truth data and was then used to evaluate critical nitrogen concentration and potential nitrogen pollution at different growth stages. 【Result】 The planted area of maize in Hetao Irrigated District in 2020 was 275 000 hm2. The suitable vegetation indices for calculating canopy nitrogen varied with growing stages; the canopy nitrogen at elongation, early and late tasseling stage and flowering stage was best estimated by GBNDVI, RVI, NRI, and NDVI, respectively. It was found that nitrogen concentration in the canopy was low at the flowering stage, and high at the elongation and later tasseling stage, during which nitrogen pollution could occur. Analysis showed that the risk of nitrogen pollution was Grade 4 in early tasseling stage and zero in flowering stage. 【Conclusion】 The UAV multispectral image data can be used to estimate nitrogen content in plant and assess the potential of nitrogen pollution at different growing stages at large scales in the field. It can help improve fertilization and reduce the potential of non-point source pollution.

【Background and objective】 Gold pear is a main fruit in northern China and its production relies on irrigation and fertilization. The purpose of this paper is to study the effects of different combinations of irrigation and nitrogen-fertilization on nitrogen uptake by roots and its translocation in the trees. 【Method】 The experiment was conducted in an orchard; it consisted of three irrigation treatments by keeping the lowest soil water content controlled for irrigation at 75 (HW), 65 (MW) and 55% (LW) of the field capacity, respectively, and three nitrogen treatments by applying 486 kg/hm2 (HF), 324 kg/hm2 (MF) and 162 kg/hm2 (LF), respectively. Standard irrigation and fertilization used by local farmers was taken as the control (CK). In each treatment, we measured nitrogen content in different parts of the tree at different growth stages. 【Result】 At fruit-expansion stage, the total nitrogen content in spring shoots and leaves were the highest in MW+MF, increasing by 26.20% and 8.66% respectively, compared to CK; the total nitrogen content differed significantly in spring shoots but not in leaves between the treatments. At maturity stage, the total nitrogen content in spring shoots was the highest in MW+MF, reaching 0.74 g/kg, and least in HW +MF, dropping to 0.54 g/kg. The total nitrogen content in the leaves in HW+MF was the highest, reaching 1.83 g/kg, and least in HW+LF being 1.70 g/kg. The nitrogen content in fruits in LW+HF was the highest, reaching 0.82 g/kg, a 52.70% increase compared to CK. The treatments did not result in considerable changes in total nitrogen contents in spring shoots and leaves, but significantly changed the total nitrogen contents in shoots and fruits. Correlation analysis did not find correlation between total nitrogen contents in spring shoots, leaves and fruits. The total nitrogen content in spring shoots and fruit were positively but insignificantly correlated, while total nitrogen content in leaves was negatively but insufficiently correlated with the total nitrogen content in spring shoots and fruits. 【Conclusion】 For all treatments we compared, keeping the lowest soil water controlled for irrigation at 65% of the field capacity combined with 300~350 kg/hm2 of nitrogen fertilization is optimal for yield and fruit quality of the golden pear in the studied area.

【Objective】 Decades of management of various irrigation districts have accumulated valuable experiences, but how to make most of these experiences has not yet been appreciated. The purpose of this paper is to fill this gap, proposing a method to harness these experiences to improve water allocation calculation in irrigation districts. 【Method】 The analysis is based on data measured over a three-year period from an irrigation area at the Waxi branch in the Pishihang irrigation district. We consider spatial variation in variables such as temperature, rainfall and soil moisture in integrating the interpretation method of the random forest model with the SHAP model. Nonlinear quantitative relationship between the target water allocation and each variable was constructed using limited data samples. 【Result】 The model obtains the important scores and changes in each variable in a long time series for different typical years. In addition to the combination of characteristic variables suitable for actual water dispatching, the indexes of characteristic variables that dispatchers mainly refer to different dispatching scenarios can be analyzed and obtained. Combined with the analysis of SHAP value, the positive and negative directions of the response of water dispatching target flow to each characteristic variable is obtained. 【Conclusion】 The method proposed has realized quantitative representation of historical experience of water dispatching in irrigated areas and provided guidelines for rational prediction of different water dispatching flows in irrigation districts.

Intensive agriculture and other anthropogenic activities have led to soil degradation in many regions across China. Improving soil fertility and restoring soil functions is important to maintain sustainable agricultural production and safeguard food supply in China. In this paper, we systematically review the methods and technologies developed over the past decades to improve soil fertility, which includes the concept of soil fertility, index and methods for evaluating soil fertility, the relationship between soil fertility and crop yield, as well as the prospects of soil fertility improvement. In particular, we analyze and discuss the applications of various organic materials including processed biochar and commodity organic fertilizers for improving soil fertility and their efficacy for different soils. We conclude that establishing standards of biochar and organic fertilizers and their application as soil improvers will be an important research area for long-term improvement of soil fertility.

【Objective】 Hetao Irrigation District is one of the largest irrigation districts in China. Its irrigation relies on Yellow River water. As the available river water for the district continually dwindles, drip irrigation has been increasingly used to improve irrigation water use efficiency. This paper is to study the impact of drip irrigation combined with mulching on dynamics of soil salt in corn fields. 【Method】 The experiment was conducted in a field with the Jintian No. 8 variety used as the model plant. It compared two drip irrigation amounts: 76 mm (F1) and 60 mm (F2), and the intra-rows were mulched with plastic film. In each treatment, we measured the changes in soil moisture and salt content at different soil depths, and the measured data were used to calibrate the HYDRUS-2D. The calibrated model was used to study the response of soil water and soil salt to other irrigation amounts: 81 mm (W1), 135 mm (W2), 171 mm (W3) and 204 mm (W4). 【Result】 During growth period of the corn, the total salt content in the 0~100 cm soil layer and the salt in soil outside the mulched zone were lower in F1 than in F2, while the temporal change in salt in the soil underneath the film was not distinguishable between F1 and F2. During the growth period, the time-trending of the salt in soil underneath the film was approximately the same for F1 and F2. After harvesting, F1 and F2 desalinated the 0~100 cm soil layer by 50.1% and 10.8%, respectively, of which the associated desalinization of the soil underneath the film was 44.7% and 148.5% respectively. Before the autumn irrigation, F1 and F2 increased the total salt in the 0~100 cm and 0~60 cm soil layers; F1 reduced the total salt in the 0~100 cm of soil and reduced the increase of salt in soil underside the film, compared to F2. There is a good agreement between measured and simulated water content ant soil salinity, indicating that the parameters and the model correctly capture the soil properties and water and salt flow in the soil. When the irrigation amount was 162 mm, salinity of the 0~20 cm soil was low after the irrigation and it took more time for the salt to re-accumulate in this soil layer. When the irrigation amount was reduced to 108 mm, salinity of the 0~40 cm of soil after the irrigation remained high. 【Conclusion】 The drip irrigation water volume of 171 mm and 204 mm not only reduces salinity of the root zone (0 to 40 cm ), but also removes the salt from the root zone to soil outside the mulched zone - the non-root zone. Our results have practical implications for managing mulched drip-irrigated corn in Hetao Irrigation District.

【Background and objective】 Soil salinity is an abiotic stress hindering agricultural production worldwide, especially in coastal areas where the groundwater is usually shallow. The aim of this paper is to study experimentally how irrigation affects translocation of major cations from soil to the roots of maize in saline-alkaline soils. 【Method】 The experiments were conducted at a maize field in a coastal saline-alkali region. We compared four irrigation methods: conventional drip irrigation with irrigation amounts of 10 mm (LI10) and 20 mm (LI20) respectively, and mulched drip irritation with the same irrigation amounts (FI10 and FI20). In each treatment, we measured the changes in K+, Ca2+ and Na+ in both the rhizosphere and roots, from which we derived regression models to analyze how the irrigation method and irrigation amount modulated the cations contents in soil and their translocation to the maize roots. 【Result】 Mulched drip irrigation reduced Na+ content in the rhizosphere more significantly than the conventional drip irrigation. Increasing irrigation amount in the mulched drip irrigation increased K+/Na+ content in the maize stem in the whole growth season, but only increased their content in the leaves at early growth stage. Conventional drip irrigation affected the relationship between the concentrations of K+/Na+ and Ca2+ in the rhizosphere and the K+/Na+ content in the roots more than the mulched drip irrigation. The increase in Ca2+ in the rhizosphere due to irrigation was likely to have made K+/Na+ less mobile in soil, thereby reducing their translocation from soil to roots and benefiting the crop growth as a result. 【Conclusion】 Drip-irrigating maize in coastal saline-alkali soil can effectively improve the translocation of cations from soil to crop roots, especially the mulched drip irrigation, thereby ameliorating salinity stress to the crop. It can thus be used as an improved irrigation technology for crop production in such regions.

In order to analyze the ecological risk of the heavy metals in road dust. The improved potential ecological risk index was established. In the improved method, the toxicity of different chemical speciations of heavy metals were considered. Since residual fraction of Cd are non-toxic in the improved method, the results of the improved method were much lower than the traditional method.The results showed that the total risks of 3# and 15# were medium risk. The highest risk appeared on14# with the value 337.49, which belonged to high risk, and the total risk of the other sampling sites were low risk. Therefore, 14# should be the primary control site. The improved method established in this study is more scientific.

Herein, a new floating porous graphite carbon monolith (FCM) was prepared using the graphite powder and peanut shells as the carbon skeleton and using FAC and sepiolite as the swelling agent. The multi-hierarchical porous FCMs were obtained by two-step acid activation method. The effects of the addition of biomass and phosphoric acid on the physical properties and pore structure of the prepared material were investigated. The FCM was combined with codoped titania to develop a new floating photocatalysts. The results showed an increase in the amount of biomass materials during FCM preparation increased the ratio of mesoporous structure in the products. In addition, a high micropore volume ratio and the strongest adsorption effect were achieved by optimizing the phosphoric acid impregnation ratio. After process optimization, the densities of the prepared FCMs ranged between 0.75 and 0.89 g/cm3, and the specific surface area and diameter range of the large pores of the material were 104.5 m2/g and 3-50 μm, respectively. Moreover, the new floating catalysts displayed the excellent photocatalytic properties and recyclability performance.

Abstract Background P24 protein is the major core protein of HIV virus particle and has been suggested as a specific target for antiviral strategies. Recombinant p24 protein with natural antigenic activity would be useful for various studies, such as diagnostic reagents and multi-component HIV vaccine development. The aim of this study was to express and purify the p24 protein in soluble form in E.coli. Results According to the sequence of the p24 gene, a pair of primers was designed, and the target sequence of 700 bp was amplified using PCR. The PCR product was cloned into pQE30 vector, generating the recombinant plasmid pQE30-p24. SDS-PAGE analysis showed that the His-tagged recombinant p24 protein was highly expressed in soluble form after induction in E. coli strain BL21. The recombinant protein was purified by nickel affinity chromatography and used to react with HIV infected sera. The results showed that the recombinant p24 protein could specifically react with the HIV infected sera. To study the immunogenicity of this soluble recombinant p24 protein, it was used to immunize mice for the preparation of polyclonal antibody. Subsequent ELISA and Western-Blot analysis demonstrated that the p24 protein had proper immunogenicity in inducing mice to produce HIV p24 specific antibodies. Conclusion In this work, we report the high level soluble expression of HIV-1 p24 protein in E. coli. This soluble recombinant p24 protein specifically react with HIV infected sera and elicit HIV p24 specific antibodies in mice, indicating this soluble recombinant p24 protein could be a promising reagent for HIV diagnosis.