查看更多>>摘要：? 2022This two-year field study compared the industry-standard rice (Oryza sativa L.) irrigation practice, a continuous-flood delivered using cascade distribution (CASC), to two related levee-based systems (multiple-inlet rice flood distribution (MIRI) and MIRI plus alternate wetting-drying flood management (AWD)) and one furrow-irrigated with end-blocking (ROW) system. Seasonal applied irrigation, soil volumetric water holding content, water depth, grain yield and irrigation water use efficiency (IWUE) were determined for sixteen 16-ha commercial rice fields sown using the same hybrid each year. Also, runoff from one field for each system was measured each year. Average seasonal irrigation applications were 824 ± 197 mm for CASC, 641 ± 165 mm for MIRI, 696 ± 181 mm for AWD and 631 ± 125 mm for ROW. Although a minimum of two AWD dry-down cycles were performed each year and runoff was the least from MIRI (5% runoff) and AWD (3% runoff), ROW (13% runoff) was the only system to receive less irrigation (p = 0.0314) than CASC (14% runoff). In terms of grain yield, only the ROW fields, with an average yield of 8890 ± 417 kg ha?1, differed (p = 0.0107) from CASC (9991 ± 751 kg ha?1). This reduction in ROW yield was due primarily to herbicide injury in 2018 and resulted in average irrigation water use efficiency (IWUE) values that were not different between irrigation treatments (p > 0.05). Taken together, ROW with end-blocking (a) proved to be a more consistent method of water conservation than MIRI and AWD under field conditions complicated by variable soil textures, and (b) lends itself to automation as the ROW fields were irrigated regularly, on a three-to-four-day schedule, rather than depending on human judgement to decide when to irrigate as was required for CASC, MIRI and AWD.
查看更多>>摘要：? 2022 Elsevier B.V.Improving irrigation systems to enhance irrigation efficiency is often considered an effective means of reducing water extraction. However, irrigation efficiency improvements do not always result in reductions in overall water extraction because of the irrigation water rebound effect (WRE). To better promote water conservation, it is necessary to clarify the drivers of the WRE. This study clarifies the drivers of the WRE by developing a 2 × 2 production model through a comparative static analysis. Then, a method for decomposing the WRE is constructed to quantify the drivers of the WRE with the logarithmic mean Divisia index (LMDI) approach. Finally, a case study of the WRE in the Hetao irrigation district in Yellow River basin of China is performed. The WRE can be divided into four effects: the product income effect, product substitution effect, factor income effect and factor substitution effect. These four effects illustrate the following four reasons why water extraction increases in response to irrigation efficiency improvements: sown area expansion, planting structure adjustment to include more water-intensive crops, irrigation proportion expansion and increase in irrigation intensity. In the case study, although the irrigation efficiency of the Hetao irrigation district improved from 1949 to 2017, the water extraction and consumption maintained an upward trend, leading to the WRE. The case study of Hetao irrigation district indicated that all the four effects increased the WRE, and the product income effect (expansion of the sown area) and the factor income effect (expansion of the irrigation proportion) were the main drivers of unrealized water savings in the Hetao irrigation district from 1949 to 2017. This study provides a framework for understanding the WRE and clearly identifies the locations where greater amounts of water are extracted despite irrigation efficiency improvements.
查看更多>>摘要：? 2022 Elsevier B.V.The authors regret. The study was designed and supervised by HY, FC, ZIK, and KA. JM, MIH, SN, and SA performed the experiments. IJ and AE, collected the data. Statistical analysis was carried out by HY, MS and MN. HY, MIH, SN, MHR and SA drafted the manuscript which was reviewed, improved and corrected by HY, YH and MHR. MS provided encouraging comments and valuable suggestions. The authors would like to apologise for any inconvenience caused.
查看更多>>摘要：? 2022 The AuthorsRegional-to-global studies of hydrology, water availability and water use, and the interaction with agricultural production and food security require accurate information on the location and extent of irrigated croplands. In this study, we derive a pan-European irrigation map – the European Irrigation Map for the year 2010 (EIM2010) - underpinned by the agricultural census conducted in the European Union in 2010. The map contains 14 irrigated crop classes as well as total irrigable and irrigated areas centred on the year 2010. The thematic resolution of the map was tailored specifically to European agriculture, and therefore contains most relevant staple crops (e.g. maize, rice, potato, cereals other than maize and rice) as well as essential permanent crops (e.g. irrigated olive orchards and vineyards). The map was created using a consistent methodology and data gathered across the European Union Member States and the UK, and therefore provides comparable and representative information across the continental domain. The input data used to construct the map consist of farm-level data on irrigated areas, total crop areas, collected during the census and aggregated to 10 km x 10 km grid, and regional-level statistics (at NUTS2 level) on irrigated areas by crop type. A custom-developed disaggregation algorithm was used to distribute regional statistical data into the 10 km x 10 km grid. Evaluation of the map against independent reference geospatial data indicated satisfactory agreement for both large-scale spatial patterns as well as grid-specific cell values for the main production regions. The EIM2010 (both crop-specific irrigation layers, and gap-filled TIA and IA layers) is publicly available.
查看更多>>摘要：? 2022Future climate change (FCC) and water scarcity significantly affect agricultural production in arid areas. Plastic film mulching (PM) combined with large irrigation amounts is popular for agricultural production in these areas. Crop model is an important tool for studying FCC's effect on crop production and its countermeasures. In this study, after calibration and validation using measured values from a two-year field experiment, the SPACSYS (v 6.0) and modified DSSAT-CERES-Maize (v 4.7.0.0) models were used to evaluate the implementation of six management systems (three mulching measures: transparent film, black film, no film; two fertilization levels: high, low) and to optimize management measures under FCC. Both models well simulated maize's anthesis and maturity dates, the final aboveground biomass, yield, and topsoil soil water content (SWC) compared with the measured values. SPACSYS simulated the maize growth and SWC under nitrogen stress better than DSSAT. Total 27 global climate models (GCMs) were used to drive DSSAT and SPACSYS models with different irrigation schemes, including three irrigation amounts (I1, I2, I3) and four irrigation ratios (the proportion of total irrigation amount in different growing stages: T1, T2, T3, T4) to simulate crop phenology and yield under FCC in future decades (2040s and 2080s). Both models advanced the anthesis date (by 8.1–16.2 d in the 2040s and 12.8–20.3 d in the 2080s), maturity date (by 12.7–18.9 d in the 2040s and 19.1–24.8 d in the 2080s), and length of reproductive growth period (by 3.6–6.1 d in the 2040s and 5.8–11.0 d in the 2080s). The I1T1 scenario under transparent film mulching produced the highest yields (12.14–16.07% in the 2040s and 5.36–6.07% in the 2080s higher than the average). The I3T4 scenario maintained stable yields in the 2040s, decreasing by nearly 20% in the 2080s. Consequently, the I3T4 scenario could be the optimal management practice for balancing yield and irrigation for maize production in this arid area in the future decades.
查看更多>>摘要：? 2022 Elsevier B.V.The objective of this study was to investigate and unravel the mechanisms for the impact of soil water regimes and N application rates on growth, physiological responses, phytohormone signaling, water use efficiency (WUE) and nitrogen recovery efficiency (NRE) of crassulacean acid metabolism (CAM) plant pineapple. The experimental treatments included three soil water regimes (90%, 70% and 50% of soil water holding capacity, representing well watered, mildly and moderately water stressed conditions) and N application rates (109, 218 and 473 mg kg-1 soil). Results showed that the well watered and mildly water stressed treatments increased the shoot dry biomass by 70.7–110.9% and the plant water use by 25.7–30.4%, consequently, the plant WUE was significantly improved compared to the moderately water stressed treatment. The specific leaf N content was significantly and positively correlated with plant carbon (C) accumulation that was increased by 66.9–89.9%, implying that the enhanced specific leaf N content in the well watered and mildly water stressed treatments could have facilitated the carbon fixation, thus increased the shoot biomass accumulation. Moreover, the well watered and mildly water stress treatments significantly increased leaf δ18O, indicating the significantly higher transpiration in line with the markedly increased plant water use due to both the large leaf water concentration and the characteristic diel pattern of stomatal conductance associated with CAM. The enhanced leaf δ13C and plant WUE in the well watered and mildly water stress treatments were ascribed to the enhanced specific leaf N content and the improved leaf relative water content. The moderately water stressed treatment decreased leaf and root water potential while significantly intensified root endogenous ABA due to water deficit. The [ZR], [IAA] and [GA3] in the leaves and roots interacted complicatedly with water and N rates. The well watered and mildly water stressed treatments enhanced ability of the roots to absorb water and nutrients from the soil, resulting in the significantly higher N and 15N accumulation. Conclusively, in the production of Ananas comosus maintaining high soil water supply is critical to achieve improved growth, water and fertilizer-N use efficiencies.
查看更多>>摘要：? 2022 Elsevier B.V.Drought is a natural hazard that may decrease agricultural production. To investigate crop growth and yield responses to drought conditions are vital for drought prevention during crop growth periods. This study aims to analyze the impacts of meteorological and agricultural droughts on wheat/maize yields from multiple perspectives and to select the key parameters which describe the best relationship between crop yield and drought indices. Using standardized precipitation evapotranspiration index (SPEI) and soil moisture deficit index (SMDI) at 1- to 9-month timescales, the drought characteristics of different crop growth periods at the selected 98 sites in different subregions were analyzed. DSSAT-CERES-Wheat/Maize models were used to simulate the leaf area index (LAI), biomass and yield of spring wheat, spring and summer maize over 1961 ? 2018. The relationships between yield related factors and SPEI/SMDI0–10 at different timescales were investigated using Pearson correlation. The key timescale and growth period which showed the best correlations between crop yield/growth and SPEI/SMDI were determined and used to obtain the yield/growth equations using multivariable linear regression. The results showed that: (1) The temporal variations of SPEI and SMDI0–10 differed with different timescales, months and subregions. DSSAT-CERES generally performed well in simulating growth and yields of wheat and maize over 1961–2018. (2) For spring wheat, the correlations of yield and SMDI were highest at 3-month timescale in July, at 5-month timescale in July and at 3-month timescale in June in subregions I, II and IV, respectively. For spring maize, in subregion I, yield correlated with 1-month SPEI in June best), while yield was correlated largest with 4-month SPEI in August in subregion III and IV. For summer maize, the best correlations occurred in August between yield and 4-month SPEI. Therefore, different crop had varying key parameters for drought prevention measures. (3) The multivariable linear equations described yield/growth vs. drought indices relationship well for different crops. The results are referable for providing measures for agricultural production practice under drought.
Carricondo-Anton J.M.Manzano Juarez J.Royuela Tomas A.Jimenez-Bello M.A....
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查看更多>>摘要：? 2022 Elsevier B.V.The modernization process in irrigation has generated a higher energy demand. Due to this problem, the ongoing increase in energy tariffs, and the reduction in manufacturing costs of photovoltaic (PV) panels, there has been an increased use of renewable energies, such as PV energy, to power the pumping equipment involved in pressurized irrigation. On direct pumping, the available solar power can be lower than that required by the pumping units. This fact can result in stoppages that can produce unwanted transient effects or even the emptying of the network. To avoid these phenomena and reduce the use of conventional energy, a methodology is proposed in this work, whereby meteorological predictions, corrected with a Kalman filter, are used to calculate the available PV power, irrigation needs, and maintaining soil moisture above desirable levels for the crop by minimizing deep percolation. This methodology is then compared to the traditional scheduling method that uses historical data and replaces the crop′s evapotranspiration that occurs in a given time period. The methodology was applied to a real case study during an irrigation campaign, which was simulated using a weekly operative period. It was found that the use of meteorological predictions allowed PV energy consumption estimates to be improved from 68.7% to 79.3%, while the use of available photovoltaic energy in the case study increased from 11.64% to 13.37%.
查看更多>>摘要：? 2022 Elsevier B.V.Special hydrological structures coupled with rainfall and agricultural activities have great impacts on water quality in karst areas. High-frequency hydro-chemical, dual nitrate isotopes and a Bayesian mixing model (SIAR) were employed to investigate the effect of heavy rainfall events on nitrogen patterns in surface and underground streams and explore the implications for nitrogen pollution prevention in a typical karst agricultural catchment in Southwest China. The results showed that [NO3--N] was relatively high in both surface and underground streams and the average value in surface stream was two times higher than in underground stream. The lowest [NO3--N] of underground stream was found in the falling limb of the hydrograph. According to source apportionment by SIAR, chemical fertilizer was the dominant nitrate source in the study area, which contributed 52–81% and 29–78% of nitrate in surface stream and underground stream, respectively. The highest dissolved inorganic nitrogen flux and [NO3--N] in surface stream was 5.7 times and 2.4 times higher, respectively, than in underground stream over the same period, which suggested that surface runoff rather than underground stream was the main route of rapid nitrogen loss in the karst catchment during heavy rainfall events. Reasonably planning the fertilization time and optimizing nitrogen fertilizer use should be considered to decrease nitrogen loss from farmland. Rational use of a widespread karst underground conduit system to reduce water nitrogen content may also be a potential method for achieving nitrogen removal.
查看更多>>摘要：? 2022 The AuthorsRising CO2 concentration ([CO2]) in the atmosphere may modulate the response of crop plants to drought stress. This study aimed to investigate the response of leaf gas exchange and plant growth of two C4 species representing both dicot (amaranth) and monocot (maize) to progressive drought under two different [CO2] (ambient (a[CO2], 400 ppm) and elevated (e[CO2], 800 ppm)). The soil water status in the pots was expressed as the fraction of transpirable soil water (FTSW). The results showed that as compared to a[CO2], e[CO2] significantly increased net photosynthetic rate (An) at non-stress condition (An max) for both species, while the increase was more pronounced in maize than in amaranth. Stomatal conductance (gs) at non-stress condition was significantly lower at e[CO2] in both species. The FTSW threshold, at which An starts to decrease, was higher in maize grown at e[CO2] than at a[CO2], whereas it was not affected in amaranth. In both species, gs decreased at higher FTSW threshold when grown at e[CO2] than at a[CO2]. e[CO2] decreased stomatal density (SD) in amaranth but increased it in maize; drought increased SD in amaranth but not in maize. Intrinsic water use efficiency (WUEi) was significantly enhanced by e[CO2] and drought stress at FTSW ranged from 0.0 to 0.6, particularly in maize. e[CO2] increased leaf area of well-watered plants in maize and decreased specific leaf area in amaranth. In amaranth, water consumption of well-watered plants was increased and plant WUE was decreased at e[CO2]. The varied responses of leaf gas exchange and WUE to soil water deficits and e[CO2] among the two C4 species imply their different mechanisms in stomatal control over carbon gain versus water loss in dicot and monocot plants, which is essentially important for selecting crop species and developing strategies to optimize crop WUE in a future drier and CO2-enriched climate. The more physiological and biochemical response from soil, stomatal to plant scale related to various environments would be considered in further investigation.
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