查看更多>>摘要：? 2022 Elsevier B.V.Soil moisture of maize has an extremely important impact on the growth and development of maize. Failure to accurately estimate soil moisture will lead to severe reductions in maize yields and thus intensify the global food crisis, so it is extremely important to accurately estimate soil moisture of maize. This study proposes a new hybrid machine learning model (SVM-SWOA) that incorporates the Whale Optimization Algorithm (WOA) into sinusoidal chaotic graphs and couples it with a support vector machine (SVM). The model is with both high convergence speed and high accuracy. After using the data from two maize agricultural districts in Iowa, USA for model creation, Taylor plots and significance tests were used to enable the model for identifying input variables. To verify the performance of the model, SVM-SWOA was comprehensively evaluated with both SVM and SVM-WOA models. Results showed that SVM-SWOA was improved 14%, 13%, 41.5%, and 14% over SVM-WOA at 60 cm depth for MAE, RMSE, MAPE, and MBE, respectively, and 20%, 29.5%, 44.5%, and 38% over SVM, respectively. It implies that the SVM-SWOA meta-heuristic algorithm can provide better guidance for smart agriculture and precision irrigation.
查看更多>>摘要：? 2022 Elsevier B.V.A robust water supply system is significant to the local ecosystem of riparian vegetation in the arid basin. Considering the elasticity and relative importance of ecological water use in different regions of the basin, this study defines the ecological water rights on a multi-year scale, divides the priority of those rights based on the ecological network, and proposes a rights allocation method. The application of the method to the mainstream watershed of Tarim River in China shows that when the overall available ecological water is only 77% of the ecological water demand, it can ensure that the ecological water demand of vegetation in important areas is fully met and the growth condition is good. However, the demand in non-important areas must be less than 50% and the growth condition will deteriorate. This method expands the existing definition and distribution of water rights, and the approach of coupling ecological networks can be used for the efficient management of ecological water supply in other arid basins.
查看更多>>摘要：? 2022 Elsevier B.V.Unconfined aquifers are often directly impacted by high irrigation demands. Therefore, accurate recharge estimates are crucial for sustainable groundwater management. It is important over time to re-examine the existing hydrologic understanding of aquifers, taking into account developments in knowledge and changing climate conditions. The last in depth study into the Assiniboine Delta Aquifer located in Manitoba, Canada, that gave a recharge estimate was conducted in the 1980s (Render, 1988). This work re-examined the Assiniboine Delta Aquifer, employing new methods and data to estimate recharge rates. Twelve one-dimensional models were created in the software HYDRUS-1D to model the soil water fluxes in the unsaturated zone to analyze the historic recharge from 1996 to 2019. Remote weather station data, measured hydraulic conductivity, soil texture distribution, soil moisture content, and soil temperature data were used to initialize and run the models. Inverse calibration used the measured moisture contents to calibrate the models, which resulted in Root Mean Square Error in the calibration and validation periods averaging 0.034 and 0.051 m3/m3, respectively, above the 0.025 m3/m3 sensor measurement error. Rough estimates of soil texture distribution across the aquifer was determined to assist in the final recharge estimate. The historical regional recharge average was estimated to be 68 mm/year, double the previous estimate for the aquifer (Render, 1988). Modelled periods were limited to less than a year due to limitations in the general HYDRUS-1D software model code under frozen soil conditions, which the Assiniboine Delta Aquifer experiences during the winter months. Assumptions on initial soil moisture contents, snowpack heights, and model start dates were best estimated for historical years. Results show these estimates can have significant impacts on the resulting recharge. Suggested future work includes implementing the HYDRUS-1D freeze-thaw code to allow for model spin-up and multi-year simulations to enhance the reliability of model results.
查看更多>>摘要：? 2022 Elsevier B.V.The integrated Structure-Actor-Water framework (iSAW) was used to develop a set of indicators to select an irrigation system according to its sustainability impact on agriculture. The analysis hierarchical process (AHP) was used to explore the views of 60 agricultural water stakeholders, such as specialists, extension experts, agricultural NGO staff, and farmers across Ardabil Province in Iran. Participants were selected using the snowball method and interviewed using a 42-item questionnaire to measure the relative importance of nine indicators for choosing the best irrigation system. The results reveal that (i) all groups of stakeholders preferred pressurized irrigation systems (PISs) (69%) with respect to agricultural sustainability; (ii) indicators of employment and income had a relative weight of.26, productivity.20, improved quality of life.16, and agricultural expansion.14, when it comes to making decisions regarding irrigation systems; and (iii) with the exception of specialists, the other participants - farmers, NGO staff, and extension experts - made similar decisions when choosing the best irrigation systems. The results show the usefulness of iSAW as a decision-making framework and the proposed methodological approach to decision-making concerning water issues in highlighting the socio-economic aspects that must be closely coordinated in order to meet sustainability objectives for the irrigated agriculture sector.
查看更多>>摘要：? 2022 Elsevier B.V.Developing water-saving agriculture must balance the interests of stakeholders in terms of economic benefits, food and ecological security objectives. The production-based water footprint (PWF), the energy-based water footprint (EWF), and the net benefits-based water footprint (NBWF) (including grey water footprint (GWF)) can be used to evaluate food and ecological security, water use efficiency, and benefits objectives. However, little attention is paid to the multi-dimensional evaluation of water consumption in agriculture. This study quantified the annual PWF, EWF, and NBWF of grain crops, cash crops, and feed crops in the Hetao Irrigation District (HID) over 1995–2017, and analyzed their spatiotemporal evolution characteristics and comparative advantages, then clarified the implications of the three types of water footprints for stakeholders in the HID for crop planning. The results showed the water use efficiency was decreasing and the benefits were increasing. The GWF deserves more attention as it contributed 35%? 40% of the total water footprint. The comparative advantages of the three water footprints revealed that the current crop distribution in the HID only favors benefits. Considering the crop distribution issues in the HID, the adjustment objectives can be determined by combining the connotations of the three types of water footprints, GWF, PWFblue-green/EWFblue-green, and NBWFblue-green, corresponding to stakeholders’ environmental and social-economic interests. This study could provide basic guidance for crop planning and agricultural water management in the HID and similar areas.
查看更多>>摘要：? 2022 Elsevier B.V.The thermal region of the electromagnetic spectrum might provide valuable information for assessing plant water status. Nevertheless, the plant's physiology and the scale of measurement, (e.g. sensor viewing geometry and the canopy aggregation) are critical for quantifiying and monitoring water stress. This study compares the Crop Water Stress Index (CWSI) of a peach orchard obtained using on-the-ground, and airborne-based canopy temperature (Tc). The temporal evolution of CWSI under mild water stress conditions was assessed for three different irrigation strategies (over-irrigation, OI; farmer irrigation, FI; and non-irrigation, NI). Two aerial campaigns per irrigation season (2017–2018) were performed with an airborne thermal sensor: a first flight under well-watered conditions, and a second flight once mild water stress was developed. At the time of the flights, Tc and net photosynthesis (Pn), stomatal conductance (gs) and stem water potential (Ψs) were measured on the ground with a hand-held thermal camera, a portable gas exchange system and a pressure chamber, respectively. The canopy temperature obtained from the hand-held thermal camera, averaging the sunlit and shaded parts of the canopy, agreed with that derived from the airborne measurements (Y=1.00X; RMSE= 1.97 K). The CWSI values calculated from both approaches detected peach water status under different irrigation strategies. In general, Ψs was better predicted from the aircraft (R2 up to 0.72 for CWSI obtained from the aircraft versus R2 =0.51 for Tc ground measurements), whereas the use of ground measurements was preferred for estimating gs and Pn (R2 up to 0.73 and 0.74 for Tc ground measurements versus R2 =45 and 0.56 for Tc and CWSI derived from the aircraft). Regardless the approach used for deriving Tc, and due to the consideration of different meteorological conditions (i.e different dates), CWSI provided a better relationship with Ψs than Tc, whereas the latter was more closely related with gs and Pn.
查看更多>>摘要：? 2022 Elsevier B.V.The purpose of this short communication is to establish a discussion about the correct use of the terms Julian Day and Day of the Year. The Day of the Year is used for environmental modelling and calculating daily solar radiation and evapotranspiration. The concept of Julian Day is misused in the field of agricultural and environmental sciences. Specifically, the use of the term Julian Day might have been misleading or incorrect for the last ten years in the journal Agricultural Water Management. In this brief communication we intend to clarify the concept of Julian Day, and expose the most commonly used equations, so that the concept might be used with more rigor and precision in the future.
查看更多>>摘要：? 2022 Elsevier B.V.Water shortage and poor soil fertility are the main factors restricting the sustainable development of peanut production in semi-arid areas of Northeast China. It is thus essential to have a deep understanding of the soil water-nitrogen dynamics and crop water/nitrogen use for developing water and nutrient strategies. Three levels of irrigation treatment (W65, 65% of field capacity; W55, 55% of field capacity; W45, 45% of field capacity) and a rain-fed treatment (CK) were implemented in field experiments conducted for peanut during the growing seasons of 2016 and 2017 in Liaoning, Northeast China. The AHC (Agro-Hydrological & chemical and Crop systems simulator) model was calibrated and validated, and then applied to assess peanut yield, water productivity (WP) and nitrogen use efficiency (NUE) for the present situation and future irrigation scenarios. The results indicated that the AHC model was capable of simulating soil water and nitrogen status and peanut growth. Simulations of soil water/nitrogen contents and crop growth indicators (Leaf area index, aboveground biomass, plant height and yield) fitted well with field observations. Simulated dynamics showed that 9–21% of the total water input and 14–27% of the total N input were leached out the root zone (0–60 cm). Rainfall was the main cause of water percolation and nitrogen leaching. The highest average yield (5701 kg ha–1) and NUE (26.77 kg kg–1) were obtained in the W55 treatment. The WP was not obviously decreased under the W55 treatment, and was only 4.1% lower than that of the CK treatment, in which the WP was highest. Based on scenario analysis with the consideration of crop yield, WP and NUE, the optimal irrigation amount of 80–97 mm is recommended for peanut cultivation in this region. We demonstrated that the AHC model could be used to develop water management strategies for peanuts in Northeast China to conserve water while sustaining agriculture.
查看更多>>摘要：? 2022 Elsevier B.V.Determination of crop evapotranspiration (ETc) and root zone soil-water dynamics/distribution coupled with nitrogen (N) management strategies is important for effective management of agricultural fields for enhancing production efficiency. However, limited data and knowledge exist that sufficiently inform how soil-water dynamics and ETc response may vary with coupled irrigation levels and different N application timings under different irrigation methods. Extensive field experiments were conducted in 2016 and 2017 under center pivot (CP), subsurface drip irrigation (SDI), and furrow irrigation (FI) at full irrigation treatment (FIT), 80% FIT, 60% FIT, and rainfed treatment (RFT) with N application timing treatments of traditional N (TN), non-traditional-1 (NT-1), and non-traditional-2 (NT-2) to quantify and compare seasonal maize (Zea mays L.) grain yield, soil-water dynamics, ETc, and ETc vs. seasonal irrigation and total water supply relationships. Soil-water status and plant water extraction exhibited substantial differences between the irrigation levels and N management and with the irrigation methods. Irrigation method significantly (p < 0.05) influenced ETc. CP had significantly higher ETc than SDI; and SDI had significantly higher ETc than FI. The NT-1 and NT-2 treatments had significantly higher ETc than TN. ETc was greatly influenced by the water availability more than N timing applications. The slope of maize ETc exhibited inter-annual and intra-annual variation between N treatments, irrigation methods, and years. CP had higher slope than FI and SDI and FI had higher slope than SDI under traditional and NT N management in both years (except NT-2 at SDI in 2017). These important findings can provide guidance to improve maize production efficiency by considering the coupled irrigation and N management strategies under different irrigation methods.
查看更多>>摘要：? 2022 Elsevier B.V.Increasing the saffron quantity and quality is essential and should be considered to achieve the desired performance. In this regard, to study the effect of nutrient and irrigation management on the quality and yield of saffron, an experiment was carried out at the research station, the Ferdowsi University of Mashhad, Iran, in 2013–2015. The study was performed as a split-split plot based on a Randomized Complete Block Design with 18 treatments. Experimental factors were: 1- superabsorbent (S.A.) [application and non-application (non-S.A.)], 2- irrigation intervals [every two, three, and four weeks], and 3- nutrient management [humic acid, mycorrhiza (Glomus intraradices) and control]. Among all treatments, the application of S.A. increased on average 61% fresh saffron flower and dry stigma yields in both growing seasons. S.A. + four weeks irrigation intervals + humic acid were increased number of flower, dry stigma yields (175.33 per m2 and 7.472 kg.ha-1, respectively), and water productivity of irrigation of saffron stigma (2.138 g.ha-1) in 2015. The use of S.A. and humic acid compensated for water shortage and increased stigmas' yield. Furthermore, the maximum L observed in S.A. + three weeks irrigation intervals + humic acid (32.44). Among all treatments, the lowest amount of b value and Hue was observed in shorter irrigation intervals; so, application of S.A. + two weeks irrigation intervals + humic acid resulted in the minimum amount of Hue (?0.1783) that was a desirable trait. The maximum crocin and picrocrocin obtained in S.A. + three weeks irrigation intervals + mycorrhiza (225.9 A4401% and 86.58 A2541%, respectively) and the highest safranal content observed in S.A. + four weeks irrigation intervals + humic acid (47.03 A3301%). In general, it seems that the application of humic acid, mycorrhiza, S.A., and longer irrigation intervals can significantly increase the quality and yield of saffron.
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