查看更多>>摘要：? 2021 Elsevier B.V.Economical fruit trees are a kind of forest with great economic and ecological benefits, which has become an important cash source of many rural household incomes. However, the shortage of water resources has limited their development. Deficit irrigation (DI) is a novel water-saving irrigation method, but there is a risk of yield reduction in practice. Therefore, a meta-analysis was conducted to quantitatively analyze the impact of DI on fruit yield and water use efficiency (WUE) to explore the most suitable DI strategy for fruit trees. Overall, compared to full irrigation, DI decreased the fruit yield by 6.05% and increased WUE by 5.05%. However, the effectiveness of DI depended on DI factors, fruit tree varieties and environmental factors. In order to achieve a win-win goal of water-saving and yield increasing, a Win-Win analysis was conducted on collected data. It was found that DI was suitable for drought-tolerant tree varieties in the arid region with medium-textured and large bulk density soil. Adopting subsurface irrigation methods for low or moderate deficit (Irrigation limit ＞55%θf) before the fruit growth stage (i.e., bud burst to leafing stage and flowering to fruit set stage) was recommended. Our findings can provide implications for applying DI to fruit trees.
查看更多>>摘要：? 2021 Elsevier B.V.Conventionally, canal water is distributed empirically regardless of soil water status at the time in irrigation districts of China, and the mismatch between the timing of water delivery and crop water demand often leads to the reduction in total production and irrigation water efficiency. In the study, an optimization model with minimizing both the difference between the time of water delivery and water demand, and fluctuation of discharge of the main canal as objectives was developefd for a two-stage canal system. The genetic algorithm was used to solve the problem. The irrigation time to meet the water demand in the optimization model was determined using a field water balance model for the command area of secondary canals. The optimization model was applied to the Xixun irrigation district located at Zhangye, Gansu Province, Northwest China. The performance of the model was evaluated by comparing crop water consumption and water productivity (WP) between optimized with conventional scheduling. The results showed that the optimized scheduling could achieve greater total production, less water loss, higher water use efficiency (WUE) and irrigation water productivity (IWP) under both full and reduced capacity conditions. Specifically, the optimized scheduling led to 20% greater total production, 33% less water loss, and more than 20% larger IWP than the conventional scheduling under both conditions. The optimization model could be a valuable tool in improving WP over the command area by adjusting water delivery and irrigation scheduling for irrigation districts.
查看更多>>摘要：? 2021 Elsevier B.V.Cover crops can increase crop water productivity (CWP) and succeeding crop yield. However, cover crops adoption in the Southern High Plains of USA is slow due to limited water available for crop production. This study evaluated the effects of winter cover crops on soil water dynamics, corn silage yield and nutritive values, and corn silage CWP in a semi-arid irrigated condition. Three winter cover crop mixtures: grasses + brassicas + legumes (GBL), grasses + brassicas (GB), grasses + legumes (GL), and control or no cover crop (NCC) were evaluated for soil water storage, cover crop biomass, corn silage yield, nutritive values, and crop evapotranspiration (ET), and the cover crop-corn silage system water productivity (SWP) under a no-till irrigated corn silage production system. All cover crop treatments reduced soil water storage before their termination in both years. However, water storage was higher for all cover crop treatments than for NCC during corn growth. Average CWP for corn was improved by 14–29% with cover crop mixtures over the NCC. Corn silage yield among cover crop treatments was 9–26% higher than NCC. Nutritive value components of cover crops such as non-fat carbohydrates, relative forage quality, and Ca and Mg were higher in the GBL and GL mixtures than the GB in one of the two years. This study demonstrated increased corn silage yield and water productivity with cover cropping. Cover crops mixtures with legumes could offer a high-quality alternative forage for crop-cattle integrated systems, including dairy producers in the Southern High Plains region.
查看更多>>摘要：? 2021 Elsevier B.V.Subsurface drainage systems have been widely used to help manage soil salinization worldwide. However, designing a subsurface drainage system requires predictions of regional groundwater and salt dynamics. While these dynamics can be obtained using MODFLOW's drain package (DRN), this package requires that the drain conductance be specified, which is difficult to determine for subsurface drainage systems with different layout parameters, including the pipe spacing, depth and radius. In this study, a new subsurface drainage (SDR) package based on the Hooghoudt equation was developed within the MODFLOW-LGR-MT3D framework to simulate the effects of subsurface drainage pipes on groundwater flow and salt dynamics. The accuracy and applicability of SDR were tested by a synthetic case, a published indoor experiment and two field experiments. Comparison with indoor experimental data shows that the RRMSE of cumulative drainage volume was 5.08% and the RRMSE of groundwater table depth was 3.69%. The simulation results of outdoor experiment show that the RRMSE of drainage volumes of a single pipe ranged from 3.14% to 4.69%, and the relative errors of cumulative drainage volumes were below 6% and the relative errors of drainage discharge were 3.1–16.3%. The results demonstrate that SDR can accurately simulate leaching water and solute transport under transient flow conditions. The model was then applied to the Yonglian irrigation area of Inner Mongolia, China, for subsurface drainage system design, and 3 different layout schemes of subsurface drainage systems were presented. The total salt discharge increased by 38–54% after the application of the subsurface drainage system, 36–45% of which was discharged by subsurface drainage pipes. This study provides a pilot example for regional subsurface drainage system design.
查看更多>>摘要：? 2021 Elsevier B.V.Agricultural policies and social change influence irrigation management decisions and their associated effects. The changes in the Common Agricultural Policy of the European Union have deeply affected irrigated agriculture in the Mediterranean region. In this region, hydrology is rather complex and the environment particularly vulnerable. We monitored cropping patterns and the water balance in a sprinkler-irrigated catchment in Central Portugal over thirteen irrigation seasons and twelve rainfall seasons. There was wide variation in annual rainfall (from 283 mm to 667 mm) and in the intensity of rainfall events from year to year. A monitoring station at the catchment outlet was installed to measure runoff which, together with field observations, allowed us to compute a water balance for both the rainfed and the irrigation seasons. Changes in cropping intensity led to changes in the depth of irrigation. Irrigation runoff followed irrigation depth and both followed the trend of cropping intensity. Less intensive cropping also reduced the off-site effects of agricultural activities. The runoff coefficient was 0.28 in the rainfed seasons and 0.02 in the irrigation seasons. The changes in the irrigation hydrology and in the off-site effects of agricultural activities in the catchment were caused by changes in cropping intensity induced by the European Union Common Agricultural Policy reforms, rather than by environmental or technical factors.
查看更多>>摘要：? 2021 Elsevier B.V.Intercropping planting pattern under plastic film mulching (PFM) has been widely adopted in the arid regions to reduce soil evaporation (E), improve land-use efficiency, and increase crop yield. However, water competition between intercropping components in the soil-plant-atmosphere continuum remains largely unexplored. The evaporation and radiation interception using the neighboring species model (ERIN) can effectively estimate evapotranspiration (ET) in a different intercropping ecosystem. However, the effects of soil surface resistance in the mulching area on ET are not considered in the ERIN model. Thus, the existing ET models do not accurately estimate ET in the intercropping ecosystem with PFM. In this study, we proposed a modified ERIN model (MERIN). In the MERIN model, soil surface resistance in the mulching area was taken into account, and its performance was compared to ERIN and Penman-Monteith (PM) models. These models were validated against observed ET and E using the water balance method and micro-lysimeters in a corn intercropped tomato experiment under high (HI: 30 mm for corn and 22.5 mm for tomato, a locally recommended irrigation depth), medium (MI: 22.5 mm for corn and 16.9 mm for tomato, 25% of HI), and low irrigation depth (LI: 15 mm for corn and 11.25 mm for tomato, 50% of HI) during 2018-2019, respectively. The outcomes of this study showed that the MERIN model could accurately estimate ET and E variation for a corn-tomato intercropping ecosystem under PFM during the entire crop growth season compared to the other examined models. The most intense water competition between corn and tomato was observed in stage II (the elongation and tasseling stages for corn; the flowering and fruiting stages for tomato). T of corn generally was higher than tomato, but an opposite result was also observed in stage II. Additionally, the variation of water competition under different irrigation levels was similar in the intercropping ecosystem. When irrigation depth decreased to 22.5 and 15 mm from 30 mm, average T for corn decreased by 10.7% and 16.3%, respectively, and by 12.9% and 22.4% for tomato, respectively, in both years.
查看更多>>摘要：? 2021Alternate wetting and drying irrigation (AWD) affects soil and plant K availability in the paddy field. However, it is unclear how zeolite amendment alters soil K fixation, K utilization, and K balance in the paddy rice systems under AWD compared with continuous flooding irrigation (CF). A two-year lysimeter experiment with a split-plot design was used to evaluate the effect of irrigation regime and fertilization management in paddy fields in Donggang, northern coastal China in 2018 and 2019. The field experiment included two irrigation regimes (CF and AWD) as the main plots, and three zeolite/K managements (Z0K0, no added zeolite or K; Z5K30, 5 t ha–1 zeolite and 30 kg ha–1 K; Z0K60, no added zeolite and 60 kg ha–1 K) as the subplots. The results showed that zeolite mitigated the reductions in grain yield and aboveground biomass caused by water stress in AWD. Zeolite addition also caused soil K fixation under AWD, which reduced K leaching losses and avoided excessive K absorption by rice plants, thus contributing to sustainable rice production by preventing soil K depletion. The Z5K30 treatment had lower total K leaching losses and higher K partial factor productivity (the ability of rice to use K to produce yield) than the commonly used practice (Z0K60). Compared with Z0K60 under CF, the Z5K30 treatment under AWD produced higher grain yield, economic benefit, water use efficiency, and total K balance. Therefore, appropriate zeolite and K amendments could be economically and environmentally feasible for rice production under AWD conditions.
查看更多>>摘要：? 2021 Elsevier B.V.Although the frequency and intensity of seasonal drought and wetness are increasing under climate change background, their effects on soil nitrate nitrogen (NO3--N) leaching have remained unclear. In this study, validated by the field data on a typical tea garden hillslope in Taihu basin, China, the Decomposition-Denitrification (DNDC) model was used to investigate these effects. The decennial drought, decennial wetness, and normal conditions of different seasons were combined to construct 31 scenarios. Results showed that seasonal drought decreased annual NO3--N leaching, with a reduction of 6.52%?18.70% (one-season drought), 18.62%?29.68% (two-season drought), 36.64%?43.99% (three-season drought) and 51.44% (all-season drought) relative to the normal scenario. Except the spring drought, drought in other seasons had legacy effects that increased NO3--N leaching in their succession seasons. The legacy effect of summer drought even continued till the summer of next year. Seasonal wetness increased annual NO3--N leaching, with an increase of 2.58%?11.39% (one-season wetness), 10.04%?22.31% (two-season wetness), 19.50%?29.39% (three-season wetness), and 29.66% (all-season wetness) relative to the normal scenario. Autumn and winter wetness decreased the NO3--N leaching in their succession seasons, while spring and summer wetness had no such effect. Soil NO3--N leaching had positive correlations with precipitation (drought scenarios: r = 0.74; wetness scenarios: r = 0.54) and soil water seepage (drought scenarios: r = 0.62; wetness scenarios: r = 0.56). Weak correlation coefficients between soil NO3--N content and NO3--N leaching were also observed especially under spring drought (r = 0.17) and summer drought (r = 0.14). However, NO3--N leaching was not limited by soil NO3--N content after the application of basal fertilizer. Fertilization plus drought or wetness increased the risk of soil NO3--N leaching. These findings will be benefit for controlling the non-point N loss of tea plantation under the background of climate change.
查看更多>>摘要：? 2021 Elsevier B.V.Sunflower (Helianthus annuus L.) is one of the most cultivated oil crops in the world. Given its high dependence on water availability, its cultivation in the Mediterranean area is severely threatened by climate change: very hot and dry weather conditions currently occurring in the Mediterranean area have a negative impact on sunflower yield. Many studies have pointed to earlier sowing dates as a promising strategy to prevent summer drought stress causing sunflower yield losses, but the literature on winter sowing dates is scarce. The aim of this research was to quantify the interplay between sowing date (winter time included) and water regime to sustain sunflower cultivation in the Mediterranean area. A field experiment and a modeling study were carried out to evaluate the effects of different sowing dates (00SD: ‘conventional sowing date’ in March/April and ‘earlier sowing dates’ in December-January-February, depending on years) under two different water regimes (irrigated vs. rainfed) on quantitative traits of high oleic cultivars of sunflower. Field experiments revealed that sowing in late February - mid March was the most effective strategy in terms of achene productivity. Achene production by sunflower was also simulated using EPIC under a baseline climatic scenario and for 4 hypothetical sowing dates (D1: 10th January, D2: 10th February, D3: 10th March, D4: 10th April) and different irrigation strategies. The most effective sowing date was D3 under rainfed conditions, confirming the results of the field study. Irrigation from 20 days before anthesis up to flowering significantly improved achene yield for the early sowing dates (D1 and D2), which almost reached their respective yield potentials. This confirms that an earlier sowing date could be a viable management strategy in Mediterranean areas with little water availability.
查看更多>>摘要：? 2021A deep understanding of root–soil–microbe interactions in response to drip irrigation can help optimize drip irrigation techniques and improve crop yield; however, relevant knowledge remains limited. In this study, field experiments were conducted for two consecutive years to investigate the effects of surface drip irrigation (DI), subsurface drip irrigation (SDI), and alternate drip irrigation (ADI) on root–soil–microbe interactions and tomato yield. The results showed that the soil moisture distribution uniformity in the root zone (0–60 cm depth) was reduced in the order SDI > DI > ADI. In the SDI treatment, the tomato root lengths were 4.83- and 3.94-fold higher than those in the DI and ADI treatments, respectively, and the relative abundances of Patescibacteria in the bacterial community and Blastocladiomycota in the fungal community were significantly elevated. In the ADI treatment, the root length was 1.23-fold higher than that in the DI treatment, and the relative abundance of Patescibacteria also increased significantly compared with that in the DI treatment. These changes led to distinct root–soil–microbe interactions. The most intensive positive root–soil–microbe interactions occurred in the SDI treatment, followed by the ADI and DI treatments. The differences in the root–soil–microbe interactions regulated tomato yield. The tomato yield in the SDI treatment was increased by 19.77% and 7.77% compared with that in the DI and ADI treatments, respectively. In the ADI treatment, the tomato yield was 24.09% higher than that in the DI treatment. Therefore, the different drip irrigation methods can regulate tomato yield by affecting root–soil–microbe interactions. The results provide a reference for the optimization of the drip irrigation mode to regulate root–soil–microbe interactions and increase tomato yield.
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