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The development and utilization of unconventional water resources has become a strategy to alleviate the agricultural water crisis in many countries and regions. To understand the research progress, hot spots, and future trends in the field of unconventional water agricultural irrigation (UWAI), this paper systematically analyzes 6738 publications based on the core database of Web of Science 1990–2023 using the scientific bibliometric analysis software CiteSpace, VOSviewer, and Scimago Graphica. The results showed that the research on UWAI is always rapidly developing. Soil science, crop science, and bioengineering are the main disciplines involved. Most research on WUAI has occurred in China and the United States. Countries with higher levels of development tend to have more influence. Collaboration among authors is fragmented, and collaboration between authors and states needs to be strengthened. Through keyword analysis, the research hotspots are summarized as follows: (1) The effects of traditional and emerging pollutants brought by unconventional water irrigation on soil physicochemical properties, crop growth, and groundwater quality; (2) the health threats caused by pollutants entering the food chain and groundwater; (3) unconventional water utilization technologies, including rainwater harvesting agriculture, precision agriculture, and urban agriculture. Future research hotspots will focus on the mechanisms of pollutant solute transport and transformation in the water–soil–crop system under non-conventional water irrigation conditions and crop physiological responses. We suggest that the research on traditional and emerging pollutants in unconventional water should be strengthened in the future, and the risk control system of unconventional water irrigation should be improved. International cooperation should be strengthened, especially with poor countries in arid regions, to promote the formation of unified international standards and guidelines for non-conventional water irrigation in agriculture. [ABSTRACT FROM AUTHOR]

[Objective]Soil moisture sensors have been increasingly used in different fields to measure soil water content at high temporal resolution, but its reliability depends on many factors. In this paper, we investigate the effect of soil salinity on their accuracy.[Method]The laboratory experiment was conducted at the Irrigation Test Station of the First Division of Xinjiang Alaer Corps. FDR and TDR sensors were used in the experiment. We compared five salinity treatments: 2, 3, 5, 7, 9 mS/cm; the soil moisture was adjusted to the field capacity followed by natural evaporation. The absolute error (AE), relative error (RE) and standard deviation (SD) were used to evaluate the accuracy and consistency of the sensors.[Result]Soil moisture and salinity both affected accuracy and consistency of the sensors. Without calibration, the accuracy of the CSF11 and ML2x sensors was high and measurements were consistent, while the EC-5 and TDR305H sensors were less accurate and consistent due to the combined influence of soil salinity and moisture. Calibration significantly improved the accuracy and consistence of all four sensors. [Conclusion] Considering accuracy and consistency, the expensive ML2x sensors worked best when salt content does not exceed 9 mS/cm. The less expensive CSF11 sensors also worked well when soil salt is low. The EC-5 sensors can measure soil moisture reasonably well for soil with moderate and high salinity. When the soil moisture is less than 20 cm³/cm³, TDR305H sensors is accurate and reliable. [ABSTRACT FROM AUTHOR]

(Objective) Aggregation is an important soil health indicator modulating many soil functions including nutrient bioavailability and carbon sequestration. It is affected by a multitude of factors. The purpose of this paper is to study the effect of irrigation and nitrogen fertilization on soil aggregation and soil organic carbon. (Method) The experiment was conducted in a winter wheat field. It consisted of two nitrogen applications: 0 (N0) and 180 kg/hm2 (N180), two irrigation treatments: sufficient irrigation (F) and deficit irrigation using 65% of the water in F. In each treatments, we measured water-stable aggregates and soil organic carbon.(Result) 1 Deficit irrigation coupled with nitrogen fertilization increased water-stable macroaggregates with diameter ≥0.25 mm. Nitrogen fertilization increased organic carbon in the top 0~30 cm soil layer by more than 3.59% when irrigation was the same, while deficit irrigation increased organic carbon in the same soil layer by more than 2.86% when nitrogen fertilization was the same. 2 Soil moisture directly affected soil carbon, explaining 83.9% of the change in total organic carbon, while nitrogen indirectly affected soil carbon, explaining 46.89% of change in the total organic carbon. 3 The direct impact of water-stable aggregates on soil carbon was negative, while its direct influence was positive.(Conclusion) The effect of nitrogen fertilization on soil aggregation was modulated by irrigation. Nitrogen fertilization combined with deficient irrigation boosted carbon accumulation in the topsoil. [ABSTRACT FROM AUTHOR]

BACKGROUND: In this study, we investigated the effects of water–nitrogen interaction on the grain quality of two varieties of japonica rice grown on the North China Plain, based on evaluations of grain biochemical components, starch X‐ray diffraction properties, thermal and pasting characteristics, and particle size distribution. RESULTS: We found that, under controlled irrigation, increasing levels of nitrogen resulted in a reduction in grain starch content and an increase in protein content. Nitrogen fertilization, irrigation, and their interaction had significant effects on the particle size and size distribution of rice flour. Under both controlled and flooding irrigation, the lowest values of pasting parameters for cultivars Xindao22 and Xindao10 were observed in response to moderate and high nitrogen application, respectively. Under flooding irrigation, Xindao22 exhibited lower mean value of gelatinization onset, peak, and conclusion temperatures and enthalpy in response to control irrigation, whereas in Xindao10 these parameters were relatively stable with respect to nitrogen and irrigation treatments. However, we observed no significant effects of either nitrogen or irrigation on amylopectin chain length distribution or starch relative crystallinity. CONCLUSION: Nitrogen application rate and irrigation methods had distinct effects on the physicochemical properties of flour derived from treated rice plants. The findings will provide support for scientific irrigation and fertilization in order to improve rice grain quality. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Sine-cosine algorithm (SCA) has found a widespread application in various engineering optimization problems. However, SCA suffers from premature convergence and insufficient exploitation. Cylindricity error evaluation is a typical engineering optimization problem related to the quality of cylindrical parts. A hybrid greedy sine-cosine algorithm with differential evolution (HGSCADE) is developed in this paper to solve optimization problems and evaluate cylindricity error. HGSCADE integrates the SCA with the opposition-based population initialization, the greedy search, the differential evolution (DE), the success history-based parameter adaptation, and the Levy flight-based local search. HGSCADE is tested on the CEC2014 benchmark functions and is employed in cylindricity error evaluation. The results show the superiority of HGSCADE to other state-of-the-art algorithms for the benchmark functions and cylindricity error evaluation. [ABSTRACT FROM AUTHOR]

Collecting accurate real-time soil moisture data in crop root zones is the foundation of automated precision irrigation systems. Soil moisture sensors (SMSs) have been used to monitor soil water content (SWC) in crop fields for a long time; however, there is no generally accepted guideline for determining optimal number and placement of soil moisture sensors in the soil profile. In order to study adequate positioning for the installation of soil moisture sensors in the soil profile, six years of field experiments were carried out in North China Plain (NCP). Soil water content was measured using the gravimetric method every 7 to 10 days during six growing seasons of winter wheat (Triticum aestivum L), and root distribution was measured using a soil core method during the key periods of winter wheat growth. The results from the experimental data analysis show that SWC at different depths had a high linear correlation. In addition, the values of correlation coefficients decreased with increasing soil depth; the coefficient of variation (CV) of SWC was higher in the surface layers than in the deeper layers (depths were 0–40 cm, 0–60 cm, and 0–100 cm during the early, middle, and last stages of winter wheat, respectively); wheat roots were mainly distributed in the surface layer. According to an analysis of CV for SWC and root distribution, the depths of planned wetted layers were determined to be 0–40 cm, 0–60 cm, and 0–100 cm during the sowing to reviving stages (the early stage of winter wheat), returning green and jointing stages (the middle stage of winter wheat), and heading to maturity stage (the last stage of winter wheat), respectively. The correlation and R-cluster analyses of SWC at different layers in the soil profile showed that SMSs should be installed 10 and 30 cm below the soil surface during the winter wheat growing season. The linear regression model can be built using SWC at depths of 10 and 30 cm to predict total average SWC in the soil profile. The results of validation showed that the developed model provided reliable estimates of total average SWC in the planned wetted layer. In brief, this study suggests that suitable positioning of soil moisture sensors is at depths of 10 and 30 cm below the soil surface. [ABSTRACT FROM AUTHOR]