Explore the vast range of titles available.

This study aimed to improve water use efficiency at side deep fertilization paddy fields and reduce the direct discharge of tailwater from upstream dry-farming into Erhai Lake. Field experiments were conducted at Erhai Lake Basin in 2023 and 2024. In this study, paddies were used as storage basins. Two water managements were set with three replicates: flooding irrigation with deep storage and controlled drainage (CKCD), and water-saving irrigation with deep storage and controlled drainage (CCD). The rice growth indicators were observed. The results show that, in 2023, compared with CKCD, the root volume, root-to-shoot ratio, stem node spacing, stem diameter, plant height, tiller number, leaf area index and yield of CCD increased by 13.6, 19.6, 12.1, 4.1, 9.4, 3.0, 21.9, and 6.5%, respectively. For CCD, the total irrigation amount decreased by 27.3%, while irrigation productivity increased by 46.7%. In 2024, there were similar trends as in 2023. However, the tiller number and leaf area index of CCD decreased by 11 and 1.5%, respectively. Additionally, in CCD, the total irrigation amount decreased 52.5%, and the irrigation productivity increased by 1.4 kg/m3. There were similar regulars in soil temperature and its relationship with other growth indicates in 2023 and 2024. Soil temperature in CCD was generally higher than in CKCD. It positively correlated with stem diameter, but negatively with root volume. Additionally, root volume positively correlated with plant height and dry matter accumulation. Overall, the CCD approach could promote the indices of rice growth, increase the paddy capacity of tailwater storage, and reduce water consumption to further achieve water savings and increased yields.

Water table management through controlled tile drainage and subsurface irrigation (CDSI), retrofitting to conventional tile drainage, has been developed to abate the environmental impacts of irrigation and drainage meanwhile supporting agroecosystems and crop productivity. Since the environmental profile of new technologies is a prerequisite to understanding their socio-economic benefits, a life cycle assessment was conducted to assess the environmental impacts of CDSI on corn production for the 2014 and 2015 growing seasons at St-Emmanuel, south-western Quebec in eastern Canada, compared to the free drainage (FD). Inventory flows of corn production with CDSI and FD were developed using biophysical data from field experiments and public databases. Then, environmental impacts were compared for corn production with CDSI and FD, including climate change, eutrophication potential, acidification potential, and toxicity. The assessment results show the environmental benefits of implementing CDSI, particularly in improving water quality. However, potential synergy and trade-offs of climate change, eutrophication, and acidification impacts from the implementation of CDSI, especially under different climatic conditions, should be further monitored to improve the performance of the technology. Nevertheless, CDSI and associated practices can be adopted as adaptation measures in agricultural water management to support agroecosystems and address the challenges posed by environmental impacts.

The mixing layer theory is not suitable for predicting solute transfer from initially saturated soil to surface runoff water under controlled drainage conditions. By coupling the mixing layer theory model with the numerical model Hydrus-1D, a hybrid solute transfer model has been proposed to predict soil solute transfer from an initially saturated soil into surface water, under controlled drainage water conditions. The model can also consider the increasing ponding water conditions on soil surface before surface runoff. The data of solute concentration in surface runoff and drainage water from a sand experiment is used as the reference experiment. The parameters for the water flow and solute transfer model and mixing layer depth under controlled drainage water condition are identified. Based on these identified parameters, the model is applied to another initially saturated sand experiment with constant and time-increasing mixing layer depth after surface runoff, under the controlled drainage water condition with lower drainage height at the bottom. The simulation results agree well with the observed data. Study results suggest that the hybrid model can accurately simulate the solute transfer from initially saturated soil into surface runoff under controlled drainage water condition. And it has been found that the prediction with increasing mixing layer depth is better than that with the constant one in the experiment with lower drainage condition. Since lower drainage condition and deeper ponded water depth result in later runoff start time, more solute sources in the mixing layer are needed for the surface water, and larger change rate results in the increasing mixing layer depth.

Diffusive losses of nitrogen and phosphorus from agricultural areas have detrimental effects on freshwater and marine ecosystems. Mitigation measures treating drainage water before it enters streams hold a high potential for reducing nitrogen and phosphorus losses from agricultural areas. To achieve a better understanding of the opportunities and challenges characterising current and new drainage mitigation measures in oceanic and continental climates, we reviewed the nitrate and total phosphorus removal efficiency of: (i) free water surface constructed wetlands, (ii) denitrifying bioreactors, (iii) controlled drainage, (iv) saturated buffer zones and (v) integrated buffer zones. Our data analysis showed that the load of nitrate was substantially reduced by all five drainage mitigation measures, while they mainly acted as sinks of total phosphorus, but occasionally, also as sources. The various factors influencing performance, such as design, runoff characteristics and hydrology, differed in the studies, resulting in large variation in the reported removal efficiencies.

Rice is one of the major crops in China, and enhancing the rice yield and water use efficiency is critical to ensuring food security in China. Determining how to optimize a scientific and efficient irrigation and drainage scheme by combining existing technology is currently a hot topic. Crop growth models can be used to assess actual or proposed water management regimes intended to increase water use efficiency and mitigate water shortages. In this study, a CERES-Rice model was calibrated and validated using a two-year field experiment. Four irrigation and drainage treatments were designed for the experiment: alternate wetting and drying (AWD), controlled drainage (CD), controlled irrigation and drainage for a low water level (CID1), and controlled irrigation and drainage for a high water level (CID2). According to the indicators normalized root mean square error (NRMSE) and index of agreement (d), the calibrated CERES-Rice model accurately predicted grain yield (NRMSE=6.67%, d=0.77), , shoot biomass (NRMSE=3.37%, d=0.77), actual evapotranspiration (ETa) (NRMSE=3.83%, d=0.74), irrigation volume (NRMSE=15.56%, d=0.94), and leaf area index (NRMSE=9.69%, d=0.98) over 2 a. The calibrated model was subsequently used to evaluate rice production in response to the four treatments (AWD, CD, CID1, and CID2) under 60 meteorological scenarios which were divided into wet years (22 a), normal years (16 a), and dry years (22 a). Results showed that the yield of AWD was the largest among four treatments in different hydrological years. Relative to that of AWD, the yield of CD, CID1, and CID2 were respectively reduced by 5.7%, 2.6%, 8.7% in wet years, 9.2%, 2.3%, 8.6% in normal years, and 9.2%, 3.8%, 3.9% in dry years. However, rainwater use efficiency and irrigation water use efficiency were the greatest for CID2 in different hydrological years. The entropy-weighting TOPSIS model was used to optimize the four water-saving irrigation schemes in terms of water-saving, labor-saving and high-yield, based on the simulation results of the CERES-Rice model in the past 60 a. These results showed that CID1 and AWD were optimal in the wet years, CID1 and CID2 were optimal in the normal and dry years. These results may provide a strong scientific basis for the optimization of water-saving irrigation technology for rice.

【目的】阐明不同水分管理模式下土壤水氮素的赋存规律。【方法】在肥东灌溉实验站开展试验，观测L1处理（间歇时间3~4 d，蓄雨深度10 cm）、深蓄控排L2处理（间歇时间6~8 d，蓄雨深度14 cm）和L3处理（间歇时间6~8 d，蓄雨深度18 cm）地下埋深50、70、90、110、150 cm土壤水及稻田排水的氮素变化，分析干湿交替L1处理和深蓄控排L2、L3处理的灌水量、排水量以及水稻产量要素的响应规律。【结果】干湿交替灌溉L1处理和深蓄控排模式L2、L3处理较CK水稻灌溉水量分别降低725、1 703、2 304 m3/hm2，雨水利用率分别提高11.8%、19.0%、25.9%，稻田排水次数减少1~3次。NH4+-N、NO3--N和TN随土层深度增加而降低，深蓄控排L2、L3处理总氮峰值低于CK。L1、L2、L3处理TN污染负荷较CK减少21.3%、26.7%、31.5%。各处理间产量差异不显著。【结论】通过增加蓄雨上限至18 cm，延长间歇时间6~8 d，能够有效地减少灌溉定额，降低稻田排水量，提高雨水利用率，达到水稻节水、减排、控污、稳产的目的。

A review with meta-analysis of outflow and nitrate loss reduction in controlled drainage (CD) vs conventional, free drainage (FD) was carried out in the study. Since the results of experimental field studies usually cover short periods of data collection, hence in this paper, meta-analyses were based on model studies that usually cover a longer time range. The databases Web of Science and Scopus were searched for eligible English articles, published until December 2020, that describe the quantity and quality of drainage water. The meta-analysis of outflow and nitrate loss reduction in CD vs FD using the mean difference (MD) with a confidence interval (CI) of 95%. The influence of each study was measured through heterogeneity, sensitivity analyses and publication bias using STATISTICA (version 13.3) for all analyses. Of the 107 works identified, 18 were finally included in the analysis based on established criteria required for an appropriate meta-analysis. In general the results indicate a reduction in average drainage outflow of 30.5% (MD = -71.26 mm; 95% CI, -103.49 –-39.04; p = 0.000) in arable land with CD in comparison to FD practice. In the case of nitrate load the reduction was 33.61% and in the drainage water there was lower content in CD practice by an average of 8.36 kg NO 3 ha -1 year -1 (95% CI, -9.93 –-6.79; p = 0.000). Subgroup analysis of two meta-analyses indicates that the results concerning these associations may vary with the calculated weight for each article, in which the number of years of study had the most significant impact.

Controlled drainage (CRD) is an agricultural water management practice designed to adjust the capacity of a drainage system under varying hydrological conditions. This simulation study aimed to quantify the potential of combining a controlled subsurface drainage (CS) with open ditch damming (CD) to manage the water table depth (WTD) and field water balance in Nordic conditions. Simulations with and without controlled drainage were run using a hydrological model that had been set up for a flat loamy field in Northern Ostrobothnia, Finland, for the period 2010–2021. All CRD scenarios reduced the probability of deep WTDs during growing seasons (May–Sep). The impact of CS on WTDs was greater and more uniform than CD. The CRD effects on water balance were seen in water outflow pathways, as CS reduced drain discharge while CD had the opposite effect. When both methods were applied simultaneously, annual evapotranspiration increased 5–12% compared with the free drainage scenario. The effects of CRD on evapotranspiration were greatest during the dry years indicating that CRD has potential to reduce drought in food production areas. None of the CRD scenarios could maintain optimal WTDs during the entire growing season, highlighting the complexity of optimizing field water management using CRD alone.

Two‐phase flow displacement in rock fractures is crucial for various subsurface mass transfer processes and engineering applications. In fractures, the displacement of a less viscous fluid by a more viscous one (i.e., viscosity ratio M > 1) involves viscous forces help stabilizing the displacement front in presence of capillary pressure fluctuations. Although previous studies have reported displacement patterns in isotropic fractures, the impact of anisotropic fractures on displacement patterns has not been systematically examined. In this study, we conducted flow‐rate‐controlled drainage experiments to examine how anisotropic aperture fields affect displacement patterns. We observed the transition of displacement patterns from capillary fingering (CF) to crossover zone (CZ) to compact displacement pattern (CD) based on variations in transverse pore‐filling event (TPFE) frequency, which characterizes the competition between capillary and viscous forces. Increasing aperture correlation length in the transverse direction leads to increased TPFE frequency at a low flow rate, destabilizing displacement front. While the increasing aperture correlation length in longitudinal direction suppressed TPFE frequency, stabilizing displacement front. Therefore, the critical capillary number (CaCF‐CZ), which indicates the onset of the CF‐CZ transition, decreases as the aperture field varies from transversely to longitudinally correlated. At high flow rates, TPFEs almost disappeared, indicating that anisotropy did not affect CZ‐CD transition (CaCZ‐CD). Furthermore, we modified theoretical models of CaCF‐CZ and CaCZ‐CD by incorporating the aperture anisotropy factor, achieving a good fit with the experimental data. This study demonstrates the critical role of aperture field anisotropy in controlling two‐phase displacement patterns and provides a theoretical framework for predicting multiphase flow behavior in natural fractures. Plain Language Summary Understanding how a viscous fluid displaces a less viscous one in rock fractures is important for various underground processes and engineering applications. Previous studies on two‐phase flow have mainly focused on isotropic fractures. Natural fractures are often anisotropic, and the impact of fracture anisotropy on two‐phase flow patterns has not been thoroughly studied. Here we conducted laboratory experiments to examine how anisotropy affects displacement process. We found that more viscous injection fluid forms thin fingers that penetrate fractures and sometimes forms a compact displacement (CD) front. The movement of injection fluid depends on anisotropy and fluid velocity. At low and intermediate flow velocities, when the aperture correlation length in the main flow direction is much shorter than that in transverse direction, fingering of injection fluid is enhanced and the front tends to be unstable. When large‐aperture patches extend in main flow direction, fingering is suppressed and the front tends to be compact. Additionally, at high flow velocities, formation of thin fingers is restrained, and impacts of anisotropy on displacement process diminishes. We have conducted theoretical analyses on the interplay between capillary and viscous forces to better understand whether two‐phase flow through anisotropic fractures will exhibit fingering or a CD pattern. Key Points Aperture field anisotropy controls displacement pattern transitions by influencing the competition between viscous and capillary forces Theoretical analyses of the competition between viscous and capillary forces are conducted to predict displacement pattern transitions A phase diagram incorporating anisotropy, flow rate, and viscosity ratio has been developed to predict two‐phase displacement patterns in anisotropic fractures

Controlled drainage (CD) can improve crop yield by optimizing the soil water and nutrient environment. Nevertheless, the combined effects of reduced nitrogen fertilization and CD on crop leaf senescence characteristics is unclear. Thus, a two-year field experiment was conducted to address the effects of nitrogen fertilizer rates (280, 252, 224, and 196 kg N ha -1 , denoted as N1, N2, N3, and N4, respectively) on the leaf area index (LAI), SPAD value, net photosynthetic rate ( P n ), activities of superoxide dismutase (SOD), peroxidases (POD), catalase (CAT), and the contents of soluble protein (SP) and malondialdehyde (MDA) in plant leaves, and the seed yield of cotton under CD and free drainage (FD). CD resulted in greater LAI, SPAD value, P n , SOD, POD, and CAT activities, and SP content, and smaller MDA content at the three reduced nitrogen rates, and thus obtained a relatively high seed cotton yield. The delayed leaf senescence characteristics were due to greater soil moisture and NO 3 -- N content in the plough (0–40 cm) layer under CD. Notably, all reduced nitrogen rates significantly decreased the cottonseed yield under FD, but N2 and N3 had comparable cottonseed yields under CD. Therefore, we concluded that controlled drainage could stabilize seed cotton yield by improving photosynthesis, the antioxidant defenses and osmoregulation at 80%-90% of normal nitrogen fertilizer rate. The results also reveal the physiological mechanisms through which the drainage regime mediates crop yield under varying nitrogen rates.