查看更多>>摘要：? 2022 The AuthorsCharacterizing soil heterogeneity helps to improve the management of the natural resources (mainly water, nutrients and soil itself) at the farm level and enhances crop growth and relative yield sustainability. In this context, the geophysical monitoring based on direct current methods (such as the Electrical Resistivity Tomography, ERT) can help to detect the soil heterogeneity by exploring the soil water variability. ERT time-lapse surveys were carried out in almond orchards characterized by different soil types in terms of structure (i.e. layered, light and heavy soil profiles) and texture features (i.e. prevalently clay loam versus sandy clay loam). Specifically, two-dimensional ERT surveys were combined with the monitoring of multiple soil-plant-atmosphere factors, including the components of the surface energy balance using an eddy covariance system, the soil moisture and the plant water status measured using a neutron probe and pressure chamber measurements, respectively. The interpretation of the ERT results together with the ancillary data has provided spatially and temporally distributed information about the soil water processes that occurred within the almond root-zone during irrigation, allowing us to identify where the most root-water uptake occurs and the delineation of the irrigation wet bulbs under micro-irrigations conditions.
查看更多>>摘要：? 2022 Elsevier B.V.Beef production is one of the largest water consumers of all food production systems, but there are substantial knowledge gaps about the accounting and interpretation of its freshwater consumption. Moreover, hardly any study has assessed the freshwater fluxes related to beef cattle in integrated crop-livestock (ICL) and crop-livestock-forestry (ICLF) systems. We aimed at quantifying the freshwater fluxes related to beef cattle raised on continuous permanent Brachiaria pastures (CON) or in ICL and ICLF systems in the Brazilian Cerrado in the rainy and dry seasons. Evapotranspiration of forage grass, Eucalyptus trees in ICLF, and from drinking water troughs were calculated from meteorological data collected in the field. Forage accumulation was measured in 11 paddocks over both seasons, and forage intake, drinking water intake, and bodyweight were quantified in 12 growing Nellore heifers per system during two months per season. Freshwater fluxes related to forage production and animals were estimated. Drinking water intake and water intake via forage did not differ (P ≥ 0.073) between the systems, and were greater (P ≤ 0.035) in the rainy than the dry season. Faecal and urinary water excretions were greater in the dry than the rainy season (P ≤ 0.005). The respiratory and cutaneous water losses were greater (P < 0.001) in the rainy than the dry season. In the rainy season, evapotranspiration related to forage accumulation and freshwater consumption for raising beef cattle were greatest in CON, whereas they were greatest in ICLF in the dry season. Although ICLF appeared to be less resilient to dry periods, both integrated systems offer the potential for reduced freshwater consumption for raising beef cattle under grazing conditions, by improving the efficiency of forage use and/or decreasing evapotranspiration of forage.
查看更多>>摘要：? 2022 Elsevier B.V.This paper investigates the impact of erratic rainfall and related water problems on agricultural productivity. The paper also aims to shed light on the conceptual importance of understanding the incidence and impacts of rainfall shocks for choosing feasible agricultural water risk management strategies both at household and policy levels. To achieve these goals we develop a conceptual framework, use national representative data from Zambia's crop estimates survey for 2017/2018 farming season, employ fixed effects regression approach, and find that dry spells, excessive floods, incidence of water logging are all detrimental to crop productivity. The crop-based equations also reveal the differential impacts of the rainfall shocks on different crops. Since the effect of water factors including dry spells, floods and water logging on agricultural productivity is dependent on the crop types, it is important for the Zambian government as well as other countries to take this into account when planning and implementing strategies for agricultural water risk management.
查看更多>>摘要：? 2022 Elsevier B.V.It is well-recognized that deep roots play a vital role in increasing soil water availability to crop water use, their ability in regulating the allocation of the crop water use during the growing season would also influence crop yield and water productivity. Experiments were conducted using tubes of 0.5, 1.0, 1.5 and 2.0 m in depth (with an inner diameter of 30.5 cm) and irrigation amounts varying from 90 to 500 mm for two seasons of winter wheat (2019–2020 and 2020–2021). The combinations of the different tube depth and irrigation created different situations in terms of maximum rooting depth and soil water availability to assess the functions of deep roots on regulation of soil water availability to crops, and if the deep root growth being economic or not in relating to crop production and water productivity (WP). The results showed that under the same seasonal evapotranspiration (ET), the shallower the root depth was, the lower the yield. Higher WP was achieved with deep root systems. Further analysis showed that higher proportion ET occurred during the reproductive stage for the treatments with deep roots, which increased the leaf photosynthetic rate and the duration of the greenness, resulting in higher harvest index and WP. Deep roots not only increased the soil water availability for crop water use, but also regulated the timing of the soil water use to favor an increased proportion of water use during the reproductive stage. The root: shoot ratio was slightly increased from the 0.5 m tube to 1.0 m tube, but under a sufficient water supply, root: shoot ratio gradually decreased in the 1.5 m and 2.0 m tubes, resulting in less root length corresponding to the unit grain production. The treatments with deep root systems increased the root efficiency. The results indicated that both the total available water and the allocation of the water consumption during the crop growing season influenced the yield and water productivity. Increasing rooting depth was an efficient regulation measure to optimize the allocation of water consumption and increase soil water availability to crops without increasing metabolic input in root growth.
查看更多>>摘要：? 2022 Elsevier B.V.Higher water efficiency and higher carbon efficiency are important goals of sustainable agricultural development. However, long-term rotary tillage has a negative impact on soil, resulting in a reduction of soil water availability, and an increasing severity of water shortage for crop production. In addition to which China faces a sharp increase in global carbon emissions (CE), which are likely to rise even further as a result of current global warming trends. Subsoiling is an effective measure to improve soil surface structure; further, appropriate irrigation management can improve grain yield (GY). We conducted field trials in the North China Plain (NCP) from 2019 to 2021 to investigate the combined effects of 35 cm subsoiling (S) and rotary tillage to a 15 cm depth (R), in combination with no irrigation (I0), 60 mm irrigation only at jointing (I1), or 60 mm at jointing and 60 mm at heading (I2), on crop water productivity (CWP) and CE during winter wheat production. Compared with R, S significantly increased soil water storage (SWS) (4.44%) and CWP (33.01%). Although S increased CE (17.94%), soil carbon storage (Cstock) (7.37%) and carbon accumulation rate (Cacc) (32.98%) were significantly higher than that R. The effect of irrigation was significant, and treatment effects on SWS, GY, and evapotranspiration (ET) were as follows: I2 >I1 >I0. The optimal treatment for GY in 2019–2021 was S-I2, but CE (2.92%) of S-I2 was higher than that of S-I1. Carbon emission efficiency (CEE) and Cacc of S-I2 and S-I1 were at a high level and no significant difference between them was observed. CWP under treatment S-I1 was significantly higher than for any other treatment. These results suggest that subsoiling to a depth of 35 cm in combination with 60 mm irrigation at jointing improved CEE and CWP of winter wheat in the NCP.
查看更多>>摘要：? 2022 Elsevier B.V.After an extreme rainy event agricultural fields can be submerged by water. Stagnant water can be generated by river’ flooding or by soil saturation causing different damage level to crops. In this work, the flood event occurred on 3rd October 2020 in NW Italy along the Sesia river was assessed with special concern about damages affecting rice crop fields. A method was proposed aimed at detecting flooded areas and giving an estimate of water depth (WD) based on free available Copernicus data (Sentinel-1 and Sentinel-2) and digital terrain model (DTM). In particular, Sentinel-1 pre- and post-event images were compared by differencing (ΔVV). ΔVV was processed at pixel level to detect submerged areas through the thresholding Otsu's method. A simplified morphological analysis was then performed by DTM tessellation to map WD. A further step aimed at classifying submerged areas was achieved based on DTM and a proximity analysis, making possible to separate areas where water was related to soil saturation from areas where water was coming from the river. Corine Land Cover 2018 level-3 and NDVI from a Sentinel-2 pre-event image were used to map crops that were still to be harvested at the time of flood. These were the ones that were considered while estimating the potential economic loss. A total of 255 ha of rice that still to be harvested were submerged but only 211 ha were affected by river overflow. Using local rice yield and price the resulting economic loss was about 2,200,000 €.
查看更多>>摘要：? 2022 Elsevier B.V.In arid and semi-arid regions, water scarcity and soil salinization are major factors impacting sustainable agricultural production. In this study, a macroscopic root-water-uptake model was used to adapt a plant water deficit index (PWDI) for irrigation scheduling under conditions of coexisting soil water and salinity stress-causing factors. The traditional approach, estimating PWDI with average root zone soil water and salt amounts, was improved by weighting the effects of soil water and salinity according to the normalized root length density profile. An experiment growing wheat (Triticum aestivum L.) in soil columns and an experiment growing cotton (Gossypium hirsutum L.) in a salinized field were implemented to explore and quantify the effects of soil water and salinity conditions on plant water status, and thus to validate the improvement and evaluate its application, by monitoring soil water and salinity dynamics and plant growth indexes (e.g., leaf area, dry weight, leaf water potential, transpiration and yield). The results indicate that, even under conditions with equal root zone averages of soil matric and osmotic potentials, plant water status might be significantly different. In general, plants were less stressed when more water and less salinity were allocated in the upper root zone with more roots while less water and more salinity occurred in the lower root zone with less roots. By referring to some information in the soil column experiment, a numerical experiment was conducted to further demonstrate the improvement. The root-weighted approach resulted in improved PWDI estimation and thus was more reliable for irrigation scheduling, leading to higher irrigation frequency and quantity, leaf area index, biomass, yield, and transpiration, without significant decrease in water productivity. However, further improvement could be possible by considering the effects of historical soil water and salinity stresses as well as meteorological conditions on plant water status.
查看更多>>摘要：? 2022 Elsevier B.V.In recent years, the impacts of climate change and socio-economic development on the water-energy-food nexus have been a hot topic. Forecasting future food and energy production and water withdrawal trends under a range of climate and socio-economic scenarios is a critical step for formulating agricultural, industrial, and environmental policy. However, published studies are imprecise due to the complexity of the changeable environment and nexus system. Here we conducted a systematic review and meta-analysis based on 97 studies (1253 observations) published before September 2021 to evaluate the effects of climate change factors on food yield and irrigation water, as well as the influence of socioeconomic development on energy production and water withdrawal. The study shows that the most serious impact of climate change on food yield occurred under the RCP8.5 scenario, with an average decrease of 1.73%, 4.17% and 4.56% in the 2020s, 2050s, and 2080s, respectively. Similar to the prediction of food yield, the irrigation water requirement of food production under the influence of climate change in the RCP8.5 scenario (12.22–18.01%) is higher than that in RCP4.5 and RCP2.6. Under the five socio-economic future scenarios, the average energy generation is projected to increase from 77.41 EJ (2010) to 334.11 EJ (2100). Water withdrawals for electricity generation range from 347 km3 (SSP1) to 1263 km3 (SSP5). Population and GDP were significantly and positively correlated with power generation and water withdrawal (P < 0.001). To some extent, increases in CO2 concentration and precipitation could compensate for the negative impact of rising temperatures on food yield. Climate change, as well as economic and social growth, will provide substantial challenges to the future water-energy-food nexus. In particular, the water resource risk at its core will create significant uncertainty in the future water-energy-food nexus. To ensure the security and stability of the nexus, we advocate for quick adoption of innovative technologies as well as a multi-sectoral, coordinated strategy for adaptation. We believe that the findings of this paper will provide effective and reliable data support for future policy formulation.
查看更多>>摘要：? 2022Climate change will increase the frequency and intensity of drought in water-scarce agricultural areas that rely on irrigation. The increased strain on finite water resources for irrigated agriculture will cause a shift from sprinkler and flood irrigation to micro-irrigation. Micro-irrigation results in complex 3-dimensional salinity patterns. Current field-scale apparent soil electrical conductivity (ECa) directed soil sampling protocols and guidelines are inadequate for mapping the complex local-scale 3-dimensional nature of salinity resulting from water applications by micro-irrigation systems (i.e., drip, buried drip, micro sprinklers, bubblers, etc.). A field study was conducted to develop additional ECa-directed soil sampling guidelines to map local- and field-scale variability in salinity under drip-irrigation systems within a commercial nut production orchard (i.e., pistachio orchard) using hard (i.e., salinity or ECe, electrical conductivity of the saturation extract) and soft data (i.e., geospatial ECa measurements), which required an accurate ECa – ECe calibration. The revised ECa-directed soil sampling guidelines for drip irrigation on a mature pistachio orchard indicate that a single soil core should be taken 0.9–1.2 m perpendicular to the drip line within the tree root system, rather than at the drip line, to improve the ECa – ECe calibration. Calibration of ECa to ECe, improved from R2 = 0.25 to R2 = 0.73 for site Flores D01, and from R2 = 0.17 to R2 = 0.72 for site Flores D05. The improved guidelines broaden the scope of application of ECa-directed soil sampling to map field-scale salinity on orchards under drip irrigation. The information presented is of value and benefit to producers, agriculture consultants, irrigation practitioners, cooperative extension specialists, Natural Resources Conservation Service field staff, and soil and water researchers.
查看更多>>摘要：? 2022 Elsevier B.V.The Gnangara groundwater system is Western Australia's most important groundwater resource, but it is being depleted. Although Australia has been at the forefront of establishing water markets, Western Australia has been slow to adopt legislation that would support trade in groundwater. This study explores the impact of introducing groundwater trading within the horticulture sector for farms that extract water from the Gnangara system. We use a simulation-optimization framework to evaluate market performance. The model is based on detailed water allocation data obtained from the relevant water agency. A farm optimization model was used to generate supply and demand functions for water at the individual farm level, and the market clearing price for water was established via a uniform price double-sided auction. The level of water available for extraction was also varied. The model considers unrestricted trading and trading within relatively small groundwater zones that limit the potential for local over-extraction externalities. The results show (1) substantial economic gains from allowing trading are possible, (2) most of the gains from establishing a groundwater market can be realized from within-zone trading only, (3) industry consolidation follows the introduction of trading, and (4) without zonal trading restrictions local over-extraction externalities are present. Also, with groundwater trading, we find that reallocating water to the most efficient producers could reduce horticulture sector water extraction by 14%, while maintaining the existing value of agricultural production in the area.
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