ABSTRACT This study investigates farmers' willingness to pay for a reliable irrigation water supply in Zimbabwe's Tawona irrigation scheme, where intermittent water supply caused by funding shortages threatens irrigation sustainability. Using contingent valuation and logit regression analysis, data were collected from 313 farmers during the 2016/2017 farming season. The results show that 96% of farmers were willing to pay for improved irrigation water services, with an average willingness to pay of US$8.61 per acre per month. Key factors influencing willingness to pay included age, household income, irrigation conflicts, farming experience, membership in irrigation committees, and perceptions of water accountability. However, the amount farmers were willing to pay was significantly below the actual irrigation fee of US$15 per acre per month, highlighting an affordability gap. The study recommends irrigation water subsidies and water pricing models that consider farmers' socio‐economic conditions and governance challenges. It also emphasizes strengthening irrigation management, improving market access, and promoting agricultural value‐addition projects to enhance the sustainability of small‐scale irrigation schemes in Zimbabwe's drought‐prone areas.
ABSTRACT Rice is central to Tanzania's food security and economic development; however, persistent yield gaps, exacerbated by climate variability, threaten to undermine production targets. This study examines the role of irrigation in boosting rice productivity compared to traditional rainfed systems using nationally representative data from the 2019/2020 National Sample Census of Agriculture. A stochastic simulation approach assessed yields by water source across major agroecological zones (AEZs) under two productivity thresholds: (i) the national benchmark (≤ 1.5 and ≥ 3.0 t/ha) and (ii) the global high‐yield benchmark (≤ 2.0 and ≥ 4.5 t/ha). The results show that irrigation significantly improves yields and reduces downside risk. Nationally, irrigated farms were far more likely to exceed both benchmarks; for the ≥ 4.5 t/ha threshold, they had an over fivefold advantage compared to rainfed systems. Gains were evident across most AEZs, except the Western AEZ, which faces climatic and water constraints. These findings underscore irrigation's role in narrowing yield gaps, strengthening resilience and driving inclusive agricultural transformation. The evidence supports prioritizing irrigation expansion alongside inclusive water governance and complementary innovations such as improved seeds and extension services, contributing to SDGs 1, 2, 8 and 13. Targeted investment in underserved AEZs should be central to Tanzania's agricultural policy agenda.
ABSTRACT This study identifies determinants of farmers' water conservation behaviour in Iran by integrating the theory of planned behaviour (TPB) and protection motivation theory (PMT). Data were collected from 331 farmers in the Zohreh‐Jarrahi watershed and analysed using structural equation modelling (SEM). The integrated framework explained 36% of the variance in farmers' conservation behaviour. The findings reveal that perceived vulnerability is a significant direct predictor of intention, showing that farmers who feel personally at risk are more willing to act. Response efficacy and positive attitudes were significantly associated with intention, whereas response costs emerged as the primary barrier to engagement. Perceived severity influenced intention indirectly through attitude formation. Subjective norms played a crucial role, reflecting the collective nature of rural decision‐making. Conversely, perceived behavioural control had no significant effect on intention, suggesting that structural and institutional barriers limit farmers' ability to act despite perceived capability. Finally, behavioural intention was the strongest predictor of actual conservation behaviour. These results indicate that water conservation is driven by a complex interplay of cognitive, motivational and socio‐economic factors. Effective policies must move beyond individual training to address systemic barriers, reduce implementation costs and leverage social networks to foster sustainable water management.
ABSTRACT Drainage water recycling (DWR) is an emerging practice in tile‐drained agricultural landscapes that stores tile drainage in reservoirs and reapplies it as supplemental irrigation, jointly targeting agronomic and environmental objectives. A systematic search identified 27 peer‐reviewed records examining DWR, including 11 field‐based studies (two of which were field‐modelling hybrid analyses), eight modelling studies, seven review/synthesis papers and one dataset paper. Reported outcomes include reductions in nitrate–nitrogen losses of up to 37% and reactive phosphorus of up to 39%, together with yield increases of up to 61% for maize and 31% for soybean in dry years. These concurrent benefits, reduced pollutant loads, more reliable on‐farm irrigation supplies and improved crop yield distinguish DWR from most other edge‐of‐field practices. DWR systems may also provide aquatic and wetland habitats, attenuate runoff and generate aesthetic and recreational co‐benefits, especially when integrated with constructed wetlands or other best management practices. However, land requirements, potential salinity build‐up and microbial contamination in reservoirs, and uncertain net greenhouse gas balances highlight the need for careful design, adaptive operation and monitoring. A pronounced lack of independent long‐term field data on water quality, phosphorus dynamics, surface runoff, habitat services and greenhouse gas emissions remains a critical research bottleneck.
ABSTRACT Efficient irrigation management is essential for sustainable viticulture in hyperarid regions. This 3‐year study (2022–2024) in south‐eastern Iran employed a strip–split plot design to evaluate three irrigation regimes—full irrigation, moderate deficit (50% soil moisture depletion) and severe deficit (70% depletion)—across four critical phenological stages. Climatic variability, ranging from a mild 2023 season to extreme thermal shocks in 2024, significantly influenced absolute physiological traits. Despite these interannual fluctuations, irrigation regimes consistently modulated leaf architecture and water productivity (WP). Specifically, deficit irrigation applied between veraison and harvest enhanced WP by 19%–44% (moderate) and 11%–20% (severe) compared with full irrigation. These gains were closely coupled with adaptive morphological plasticity; moderate stress induced strategic reductions in leaf area index and specific leaf area, effectively minimising canopy transpiration without compromising yield. The findings further revealed that supraoptimal temperatures (> 40°C) necessitated these physiological adjustments, whereas severe water stress during early spring thermal peaks or late‐winter cold shocks induced detrimental declines in leaf development. Overall, targeted moderate deficit irrigation during late‐season stages represents a robust strategy for enhancing WP while maintaining canopy integrity under volatile climatic conditions.
ABSTRACT The theme for the 4th World Irrigation Forum was a question: ‘Is Irrigation a Sunset Industry’. The answer to that question was a resounding ‘No’ as irrigation is one of the main drivers for food security and will continue to be so for the foreseeable future. Nevertheless, irrigated agriculture is the largest user of freshwater, presently consuming some 72% of the total global withdrawal. With the world's population projected to grow from 8.2 billion to 8.9 billion by 2035, there will be greater competition for water from municipal use, industry and food production. In most countries, water for food production generally has the lowest priority. This paper will look at how the challenges faced by irrigated agriculture can be overcome through innovative policies, improved standards of service delivery and new financing mechanisms with special emphasis on Malaysia's journey to achieve food security.
ABSTRACT Biogas slurry can effectively replace chemical nitrogen fertilisers by drip irrigation, but its high ammonia nitrogen content leads to ammonia volatilisation. This study investigated the effects of drip irrigation methods (surface vs. subsurface) and biogas slurry substitution ratios (0%, 50%, 100%) on ammonia volatilisation using controlled indoor soil column experiments. Ammonia volatilisation was quantified by the ammonia absorption method, and the NH 3 ‐derived indirect global warming potential (GWP) resulting from ammonia volatilisation was evaluated. The results revealed that as the biogas slurry substitution ratio increased, the ammonia volatilisation also increased. Compared with surface drip irrigation with complete substitution, the 25‐ and 40‐cm subsurface drip irrigation treatments markedly reduced cumulative NH3 volatilisation, with the NH 3 ‐derived indirect GWP decreasing from 117 to approximately 59 kg CO 2 ‐eq ha −1 , corresponding to an approximately 50% reduction. However, different burial depth treatments resulted in similar total ammonia volatilisation amounts over time. Taking into account both gas emissions and biogas slurry utilisation, it is recommended to adopt a shallow burial depth of 25 cm in combination with complete substitution of biogas slurry for chemical fertilisers as an effective strategy for controlling ammonia gas volatilisation in biogas slurry drip irrigation systems.
ABSTRACT Efficient irrigation water management is vital in arid regions, where water scarcity and rising costs threaten farm profitability. This study evaluates how irrigation application efficiency ( E a ), applied water fraction (AWF) and irrigation water cost (IWC) affect the economic water productivity ratio (EWPR) and net income (NI) for grain maize (maize), fodder corn, cotton and tomato in the Ghareh‐Bolagh Plain, Iran. Using crop‐specific water‐yield functions and cubic regression analysis across wet, normal and dry conditions, the results show that E a and AWF positively influence EWPR and NI, while IWC has a consistent negative effect. Water cost is the dominant factor for EWPR in maize, fodder corn and cotton, whereas tomato EWPR is mainly controlled by the E a –AWF interaction. NI is most influenced by the E a –AWF interaction for maize and fodder corn, by the AWF linearly for cotton, and by the AWF cubically for tomato. Optimal outcomes occur under high efficiency and low water cost, with crop‐specific deficit levels. The study underscores the need to integrate efficiency improvements, deficit irrigation and water pricing to boost both water productivity and profitability in water‐scarce regions.
ABSTRACT This study evaluated daytime surface energy balance closure (EBC) in a summer maize field in Daxing, Beijing, during 2022–2024. Ordinary least squares (OLS) and standardised major axis (SMA) regression were used to assess the effects of horizontal thermal advection (A), additive damping (kB −1 ) and aerodynamic roughness length (Z 0m ) on EBC. A Bayesian network (BN) sensitivity analysis was then applied to explain interannual differences in correction performance and to identify the dominant controls and pathways under clear and cloudy/rainy conditions. The OLS and SMA results showed that the combined correction of Z 0m , kB −1 and A was the most effective, increasing EBC by more than 26% across the study period, with Z 0m contributing more strongly than the other single factors. The BN analysis further indicated that the effectiveness of EBC correction depended strongly on interannual meteorological variability. Correction performance was stronger under clear conditions than under cloudy/rainy conditions, and the dominant pathways differed markedly between the two weather regimes. These findings provide new insight into the weather‐dependent mechanisms of daytime surface energy balance closure in summer maize fields.
ABSTRACT Protected cultivation realizes efficient plant production via precise environmental control, with temperature, radiation and water being key factors affecting grape berry growth and quality. Thus, exploring their comprehensive impacts, constructing dynamic models and integrating these models with protected cultivation technologies can ensure efficient, stable grape production and enhanced berry quality. Based on four theoretical growth functions (Logistic, Gompertz, Richards and Weibull), we first established models for grape berry fresh weight (FW), water content (WC), total soluble solids (TSS) and titratable acid (TA) under 100% actual crop evapotranspiration (ETc), using photothermal products (PTP) and growing degree days (GDD) as driving variables. Water influence functions f(W) were then built as multipliers to modify these models, yielding 16 modified models for the four berry traits. Model calibration using 2021 data showed that GDD‐based models achieved higher simulation accuracy. However, during validation with 2022 data, PTP‐based models demonstrated better interannual stability and maintained reliable prediction performance, whereas GDD‐based models showed a substantial decline in accuracy. Among PTP‐based models, Mo‐L1 + L2 was optimal for FW, Mo‐O‐L for WC, Mo‐G1 + G2 for TSS and Mo‐L1‐L2 for TA. The simulation results indicated strong consistency with the measured data, confirming the models' high prediction accuracy.
ABSTRACT Autumn irrigation plays a crucial role in alleviating soil salinisation in the Hetao Irrigation District (HID), but its high water consumption and low efficiency require regional optimisation. An integrated eco‐hydrology simulation and optimisation framework was applied, where a distributed SWAP–WOFOST model was coupled with multi‐objective decision analysis. The distributed SWAP–WOFOST model reliably reproduces the coupled dynamics of crop growth and soil water, salinity and temperature. The average annual spring wheat yield was 5332–5517 kg/ha, and the WP (water productivity) was 1.25–1.27 kg/m 3 under different autumn irrigation patterns from 2000 to 2017. The optimal irrigation strategies were in Dengkou County, the autumn irrigation date was mainly after 20 October, and the average autumn irrigation quota was 189 mm; in Hangjinhouqi and Linhe District, mainly between 10 October and 20 October, the quotas were 171 and 172 mm, respectively; and in Wuyuan County and Wulateqianqi, mainly before 10 October, the quotas were 157 and 158 mm, respectively. The optimal autumn irrigation strategies maintain a stable average spring wheat yield of 5506 kg/ha and WP of 1.27 kg/m 3 . Compared with the baseline irrigation mode (150 mm on 15 October), economic returns were improved by about 5%.
ABSTRACT Irrigation can strongly influence agricultural productivity and sustainability. While sensor‐based irrigation has the potential to improve yield, reduce input costs and enhance resource‐use efficiency, its adoption in commercial agriculture remains limited. This study evaluated and demonstrated the performance of an IoT soil water monitoring system and the effects of sensor‐based irrigation on crop yield and economic returns in commercial farms in South Carolina. Field demonstrations were conducted across 18 site‐year observations (six farms annually from 2020–2022) under centre pivot systems. The centre pivot fields for each farm were divided into sensor fields and companion fields. The sensor fields used soil water potential (SWP) data from sensors installed at multiple depths to guide irrigation, while irrigation in the companion field followed farmers' preferred practices. Data collected from each site included irrigation applied, pumping characteristics, energy use, yield and economic returns. The IoT monitoring system reliably collected and transmitted data across all locations and years. Despite variability, the sensor fields achieved average increases of 11% in yield and 12% in net economic return compared with companion fields. These results indicate that sensor‐based irrigation improves water management and profitability under commercial conditions, supporting broader adoption of these technologies.
Small-scale irrigation (SSI) technologies are essential for boosting agricultural production, reducing drought risks, and enhancing climate resilience in the Sahel. This study examines vegetable growers' preferences for irrigation technology packages in Kadiogo Province, Burkina Faso, using a discrete choice experiment conducted with 208 farmers in the communes of Komsilga and Tanghin-Dassouri. Preferences and welfare effects were estimated through conditional logit and random parameter logit models. The results show strong and significant preferences for semi-Californian irrigation systems (a gravity-fed surface irrigation system combining canals and pipes), sprinkler systems, and motorized pumps, particularly solar-powered pumps. These choices reflect farmers' priorities for ease of use, energy independence, and expected productivity gains. In contrast, drip irrigation systems, extension services, and subsidies are not significantly valued. Cost remains a major barrier, with a strong negative effect on adoption decisions. Estimated willingness-to-pay values suggest marked differences in preference intensity across technologies. However, the monetary levels exceed typical household liquidity, indicating that they should be interpreted as measures of relative preference rather than actual purchasing capacity. Substantial preference heterogeneity points to diverse adoption pathways among farmers. Overall, the findings highlight the need to better align irrigation development strategies with farmers' technological priorities while easing financial constraints through adapted credit schemes, collective investments, and improved supply chains.
Land consolidation projects (LCPs) are widely implemented in irrigation areas to support irrigation infrastructure development and improve on-farm water management, yet evidence of their irrigation scheme-scale effects under actual operating conditions remains limited. This study evaluates how the period associated with LCP completion relates to irrigation method adoption, irrigation water use efficiency, managerial performance and water economic productivity. Selected indicators were compared between the pre-LCP period (2018-2020) and the post-LCP period (2021-2024). In the post-LCP period, drip irrigation became more prominent at the scheme scale, with the mean drip area share increasing from 9% to 20%. The water supply remained constrained throughout the study period (0.40-0.49). The delivered water per unit of irrigated area ranged from 3394 to 4310 m3 ha-1, while the highest observed economic water productivity values in the post-LCP period reached US$0.59 m-3 for income per unit of irrigation water delivered into the network and US$0.26 m-3 for income per unit of crop water consumption. Overall, the findings indicate that the post-LCP period was associated with a greater share of drip irrigation and higher economic water productivity in some years, while irrigation scheme performance remained strongly shaped by constrained water supply. Les projets de remembrement des terres agricoles (LCP) sont largement mis en oe uvre dans les zones d'irrigation afin de soutenir le d & eacute;veloppement des infrastructures d'irrigation et d'am & eacute;liorer la gestion de l'eau au niveau des exploitations agricoles; cependant, les donn & eacute;es concernant leurs effets & agrave; l'& eacute;chelle des r & eacute;seaux d'irrigation dans des conditions d'exploitation r & eacute;elles restent limit & eacute;es. Cette & eacute;tude & eacute;value la mani & egrave;re dont la p & eacute;riode suivant l'ach & egrave;vement du LCP est li & eacute;e & agrave; l'adoption des m & eacute;thodes d'irrigation, & agrave; l'efficacit & eacute; de l'utilisation de l'eau d'irrigation, & agrave; la performance de gestion et & agrave; la productivit & eacute; & eacute;conomique de l'eau. Des indicateurs retenus ont & eacute;t & eacute; compar & eacute;s avec les donn & eacute;es obtenues entre la p & eacute;riode pr & eacute;c & eacute;dant le LCP (2018-2020) et la p & eacute;riode suivant le LCP (2021-2024). Au cours de la p & eacute;riode suivant le LCP, l'irrigation goutte & agrave; goutte a pris de l'importance & agrave; l'& eacute;chelle du p & eacute;rim & egrave;tre, la part moyenne de la superficie irrigu & eacute;e goutte-& agrave;-goutte passant de 9% & agrave; 20%. L'approvisionnement en eau est. demeur & eacute; limit & eacute; tout au long de la p & eacute;riode & eacute;tudi & eacute;e (0,40-0,49). La quantit & eacute; d'eau fournie par unit & eacute; de surface irrigu & eacute;e variait de 3394 & agrave; 4310 m3 ha-1, tandis que les valeurs les plus & eacute;lev & eacute;es de productivit & eacute; & eacute;conomique de l'eau observ & eacute;es au cours de la p & eacute;riode suivant le LCP atteignaient 0,59 US$m-3 pour le revenu par unit & eacute; d'eau d'irrigation fournie au r & eacute;seau et 0,26 US$m-3 pour le revenu par unit & eacute; de consommation d'eau des cultures. Dans l'ensemble, les r & eacute;sultats montrent que la p & eacute;riode suivant le LCP a & eacute;t & eacute; associ & eacute;e & agrave; une part plus importante de l'irrigation goutte & agrave; goutte et & agrave; une productivit & eacute; & eacute;conomique de l'eau plus & eacute;lev & eacute;e certaines ann & eacute;es, tandis que les performances du p & eacute;rim & egrave;tre irrigu & eacute; sont rest & eacute;es fortement influenc & eacute;es par un approvisionnement en eau limit & eacute;.
Climate change poses increasing risks to wheat production in semiarid regions. This study examined long-term climate trends, wheat yield variability and farmers' perceptions and adaptation in District Rawalpindi, Pakistan. Wheat-season (November-April) climate data (1989-2019) were analysed alongside a survey of 175 farmers. The results showed a significant increase in T min (0.05 degrees C year-1, p = 0.03), whereas T max increased slightly but nonsignificantly. Rainfall showed a declining, nonsignificant trend. Wheat yield exhibited high interannual variability with a weak increasing trend. Regression analysis identified rainfall as a significant predictor of yield (beta = 0.002, p = 0.011), explaining 46% of yield variation, with a 1% increase in rainfall increasing yield by 0.34%. Farmers' perceptions aligned with observed trends, with most reporting declining rainfall (78%) and increasing drought frequency (70%). Perception was significantly associated with education and farming experience. Adaptation practices included improved varieties, line sowing and minimum tillage, whereas the adoption of advanced technologies remained limited. Key barriers included knowledge gaps (86%), limited access to technology, financial constraints and weak institutional support. The findings highlight rainfall variability as the primary driver of yield instability and emphasize the need for strengthened advisory services, technology access and institutional support to enhance adaptive capacity. Le changement climatique pose des risques les plus graves en ce qui concerne la production de bl & eacute; dans les r & eacute;gions semi-arides. Cette & eacute;tude a examin & eacute; les tendances climatiques & agrave; long terme, la variabilit & eacute; des rendements de bl & eacute;, ainsi que les perceptions et les strat & eacute;gies d'adaptation des agriculteurs dans le district de Rawalpindi, au Pakistan. Les donn & eacute;es climatiques concernant la saison du bl & eacute; (novembre-avril) (1989-2019) ont & eacute;t & eacute; analys & eacute;es parall & egrave;lement & agrave; une enqu & ecirc;te men & eacute;e aupr & egrave;s de 175 agriculteurs. Les r & eacute;sultats ont constat & eacute; une augmentation significative de Tmin (0,05 degrees C par an-1, p = 0,03), tandis que Tmax a l & eacute;g & egrave;rement augment & eacute;, mais de mani & egrave;re non significative. Les pr & eacute;cipitations ont d & eacute;montr & eacute; une tendance de la baisse, non significative. Le rendement du bl & eacute; a pr & eacute;sent & eacute; une forte variabilit & eacute; interannuelle avec une faible tendance & agrave; la hausse. L'analyse de r & eacute;gression a identifi & eacute; les pr & eacute;cipitations comme un indice significatif du rendement (beta = 0,002, p = 0,011), expliquant 46% de la variation du rendement, une augmentation de 1% des pr & eacute;cipitations entra & icirc;nant une augmentation du rendement de 0,34%. Les perceptions des agriculteurs s'harmonisaient avec les tendances observ & eacute;es, la plupart d'entre eux signalant une baisse des pr & eacute;cipitations (78%) et une augmentation de la fr & eacute;quence des s & eacute;cheresses (70%). Ces perceptions & eacute;taient fortement associ & eacute;es au niveau d'& eacute;ducation et & agrave; l'exp & eacute;rience agricole. Les pratiques d'adaptation comprenaient l'utilisation de vari & eacute;t & eacute;s am & eacute;lior & eacute;es, la ligne de semis et le travail minimal du sol, tandis que l'adoption de technologies de pointe restait limit & eacute;e. Les principaux obstacles comprenaient des lacunes dans les connaissances (86%), un acc & egrave;s limit & eacute; & agrave; la technologie, des contraintes financi & egrave;res et un faible soutien institutionnel. Les r & eacute;sultats mettent en & eacute;vidence la variabilit & eacute; des pr & eacute;cipitations comme principal facteur d'instabilit & eacute; des rendements et soulignent la n & eacute;cessit & eacute; de renforcer les services de conseil, l'acc & egrave;s & agrave; la technologie et le soutien institutionnel afin d'am & eacute;liorer la capacit & eacute; d'adaptation.
Located in Tengliaukeng Ravine catchment river basin, the Zhanghe Wetland (ZW) represents the constructed wetlands (CWs). Its function includes wastewater treatment, ecological conservation, irrigation, environmental education, flood regulation and climate change adaptation. Moreover, it collaborates with nearby schools to integrate ecological curricula into their educational programmes. Students' appreciation for wetland ecosystems is enhanced. This study involved the sampling and analysis of water quality in both inflow and outflow of the wetlands. The primary objective of this project was to conduct long-term sampling and testing of water quality in CW sites. Specifically, the focus was on inflow points, treatment units within the CWs and outflow water quality. The results of the survey provided the valuable data and played a vital role in wetland stewardship partnership. The survey was organized according to the distinct requirements of different species within each zone of the ZW. Its emphasis was on terrestrial ecology, covering aspects such as flora, avifauna, amphibians and reptiles, butterflies and Odonata. The calculated pollution reduction results demonstrated improvements in the outflow concentrations of ammonia nitrogen. The results of water quality analysis and the pollution removal effects of wetland water purification are presented, respectively. Situ & eacute;e dans le bassin versant du ravin de Tengliaukeng, la zone humide de Zhanghe (ZW) est un exemple de zone humide artificielle (CW). Ses missions comprennent: traitement des eaux us & eacute;es, conservation & eacute;cologique, irrigation, & eacute;ducation en mati & egrave;re d'environnement, r & eacute;gulation des inondations et adaptation au changement climatique. De plus, elle collabore avec les & eacute;coles voisines afin d'int & eacute;grer des programmes scolaires & eacute;cologiques. Cela permet de sensibiliser davantage les & eacute;l & egrave;ves aux & eacute;cosyst & egrave;mes des zones humides. Cette & eacute;tude a impliqu & eacute; un & eacute;chantillonnage et une analyse de la qualit & eacute; de l'eau & agrave; la fois & agrave; l'arriv & eacute;e et & agrave; la sortie des zones humides. Ce projet visait & agrave; mener un & eacute;chantillonnage et des analyses & agrave; long terme de la qualit & eacute; de l'eau dans les sites de zones humides artificielles. En particulier, l'accent a & eacute;t & eacute; mis sur les points d'arriv & eacute;e, les unit & eacute;s de traitement au sein des zones humides artificielles (CW) et la qualit & eacute; de l'eau & agrave; la sortie. Les r & eacute;sultats de l'& eacute;tude ont fourni des donn & eacute;es pr & eacute;cieuses et ont jou & eacute; un r & ocirc;le essentiel dans le partenariat de la gestion des zones humides. L'& eacute;tude a & eacute;t & eacute; organis & eacute;e en fonction des besoins sp & eacute;cifiques des diff & eacute;rentes esp & egrave;ces pr & eacute;sentes dans chaque zone humide de Zhanghe (ZW). L'accent & eacute;tait mis sur l'& eacute;cologie terrestre, couvrant des aspects tels que la flore, l'avifaune, les amphibiens et les reptiles, les papillons et les odonates. Les r & eacute;sultats calcul & eacute;s en ce qui concerne la r & eacute;duction de la pollution ont d & eacute;montr & eacute; une am & eacute;lioration des concentrations d'azote ammoniacal dans les effluents. Les r & eacute;sultats de l'analyse de la qualit & eacute; de l'eau et les effets de l'& eacute;puration des zones humides sur l'& eacute;limination de la pollution sont pr & eacute;sent & eacute;s respectivement.
ABSTRACT As an emerging irrigation technology, variable rate irrigation (VRI) has gained increasing global research attention. The WatSave team at the China Institute of Water Resources and Hydropower Research initiated VRI research in 2011 and established China's first VRI system in 2013. In its initial phase, the focus was on static zoning VRI management based on available water capacity (AWC). Through five consecutive seasons of field experiments, VRI management strategies were developed for winter wheat in semi‐arid climates and summer maize in humid climates. Since 2019, research priorities have shifted towards dynamic zoning approaches for VRI and variable rate fertilization (VRF), utilizing multi‐source data such as canopy temperature from infrared thermometers (IRTs) installed on the moving machine and in the field, UAV‐based thermal imagery and multispectral data. Compared to conventional uniform rate irrigation (URI), the integration of VRI and VRF has demonstrated significant benefits, including a 13% increase in crop yield, a 31% reduction in irrigation water use, a 24% improvement in water productivity and an 18% reduction in fertilizer application. Over the past 15 years, studies have also addressed ammonium volatilization during fertigation and greenhouse gas emissions during crop seasons, leading to the establishment of best management practices for grain crops in the North China Plain.
Long-term economic analyses of variable rate irrigation (VRI) strategies were performed compared with uniform irrigation management (UIM) in a reference production field using the AquaCrop model. Five strategies to trigger irrigation were as follows: (Field Capacity-VRI, Driest Soil Trigger-VRI, Water Mining-VRI, Conventional Uniform Irrigation Management (CUIM) and field-averaged uniform method (Aggregated Uniform Irrigation Method, AUIM). Thirteen field distribution models were developed by varying the reference field's soil textures (the reference field had four different soil textures) to model field variability. Analyses were based on three cost factors (100%, 75%, and 50% of the current costs of VRI). Costs, feasibility, and profits were calculated considering irrigation strategies and field soil distributions. VRI was not feasible at present costs because an average annual irrigation reduction of 2.4% was not able to justify the 4% yearly loss as compared with CUIM, considering capital and operational costs. AUIM is a feasible strategy and showed $2907 annual savings with CUIM. VRI was effective in the field areas where water mining is practical, that is, fields with variability in high water holding capacity soils covering at least 60% of the field. A reduction of at least 25% in the initial costs was considered essential for VRI to be economically beneficial. Des analyses & eacute;conomiques & agrave; long terme des strat & eacute;gies d'irrigation & agrave; d & eacute;bit variable (VRI) ont & eacute;t & eacute; r & eacute;alis & eacute;es par comparaison avec la gestion d'irrigation uniforme (UIM) sur une parcelle de production de r & eacute;f & eacute;rence, en utilisant le mod & egrave;le AquaCrop. Les cinq strat & eacute;gies de d & eacute;clenchement de l'irrigation & eacute;taient les suivantes: (capacit & eacute; au champ-VRI, seuil de sol le plus sec-VRI, extraction d'eau-VRI, gestion conventionnelle uniforme de l'irrigation (CUIM) et m & eacute;thode uniforme moyenn & eacute;e sur le champ (m & eacute;thode d'irrigation uniforme agr & eacute;g & eacute;e, AUIM). Treize mod & egrave;les de distribution de la parcelle ont & eacute;t & eacute; d & eacute;velopp & eacute;s en faisant varier les textures du sol de la parcelle de r & eacute;f & eacute;rence (la parcelle de r & eacute;f & eacute;rence pr & eacute;sentait quatre textures de sol diff & eacute;rentes) afin de mod & eacute;liser la variabilit & eacute; de la parcelle. Les analyses se sont appuy & eacute;es sur trois facteurs de co & ucirc;t (100, 75 et 50% des co & ucirc;ts actuels de la VRI). Les co & ucirc;ts, la faisabilit & eacute; et les b & eacute;n & eacute;fices ont & eacute;t & eacute; calcul & eacute;s en tenant compte des strat & eacute;gies d'irrigation et des distributions du sol au sein de la parcelle. La VRI n'& eacute;tait pas faisable aux co & ucirc;ts actuels, en raison d'une r & eacute;duction moyenne annuelle de l'irrigation de 2,4% qui ne pouvait pas justifier la perte annuelle de 4% par rapport & agrave; la CUIM, compte tenu des co & ucirc;ts d'investissement et d'exploitation. L'AUIM est. consid & eacute;r & eacute; une strat & eacute;gie faisable et permet de r & eacute;aliser des & eacute;conomies annuelles de 2907 $ par rapport au CUIM. La VRI s'est. montr & eacute;e efficace dans les zones o & ugrave; l'extraction d'eau est. pratique, c'est-& agrave;-dire dans les parcelles pr & eacute;sentant une variabilit & eacute; de sols & agrave; forte capacit & eacute; de r & eacute;tention d'eau couvrant au moins 60% de la superficie. Une r & eacute;duction d'au moins 25% des co & ucirc;ts initiaux a & eacute;t & eacute; estim & eacute;e indispensable pour que la VRI soit b & eacute;n & eacute;fique du point de vue & eacute;conomique.
Soil salinisation under saline irrigation is a major constraint to agricultural productivity in semiarid regions. This study evaluated how legume-based green manure systems influence soil chemistry, microbial biomass and maize nutrition under increasing irrigation salinity. A two-cycle field experiment combined four legume species with three irrigation salinity levels (1.5, 3.0 and 4.5 dS m-1). Soil fertility, exchangeable cations, microbial biomass and respiration, leaf nutrients and maize dry matter were assessed. Structural equation modelling (SEM) was used to evaluate soil-plant-microbe interactions. Increasing salinity elevated soil electrical conductivity and sodium accumulation while reducing organic carbon, available phosphorus and exchangeable potassium. Cumulative stress decreased microbial biomass and respiration, particularly in the second cycle. Leaf potassium decreased and sodium increased, causing ionic imbalances that reduced maize dry matter. However, green manures improved soil fertility and supported microbial biomass, promoting better plant nutritional balance. SEM revealed that salinity primarily affected maize indirectly via soil chemical changes, with green manure partially buffering these effects. Thus, organic management enhances system resilience against soil-mediated salinity impacts, although it does not fully offset saline stress. La salinisation des sols sous l'irrigation saline est. une contrainte majeure pour la productivit & eacute; agricole en zones semiarides. Cette & eacute;tude a & eacute;valu & eacute; l'influence d'engrais verts & agrave; base de l & eacute;gumineuses sur la chimie du sol, la biomasse microbienne et la nutrition du ma & iuml;s face & agrave; l'augmentation de la salinit & eacute; de l'eau. Une exp & eacute;rience de terrain men & eacute;e sur deux cycles a combin & eacute; quatre esp & egrave;ces de l & eacute;gumineuses avec trois niveaux de salinit & eacute; de l'eau d'irrigation (1,5, 3,0 et 4,5 dS m-1). La fertilit & eacute; du sol, les cations & eacute;changeables, la biomasse microbienne et la respiration, les nutriments foliaires et la mati & egrave;re s & egrave;che du ma & iuml;s ont & eacute;t & eacute; analys & eacute;s via une mod & eacute;lisation par & eacute;quations structurelles (SEM). L'augmentation de la salinit & eacute; a accru la conductivit & eacute; & eacute;lectrique et l'accumulation de sodium, tout en r & eacute;duisant le carbone organique, le phosphore disponible et le potassium & eacute;changeable. Le stress cumulatif a diminu & eacute; la biomasse microbienne, surtout au second cycle. Le d & eacute;s & eacute;quilibre ionique r & eacute;sultant de la diminution du potassium foliaire et l'augmentation du sodium a r & eacute;duit la mati & egrave;re s & egrave;che du ma & iuml;s. Cependant, les engrais verts ont am & eacute;lior & eacute; la fertilit & eacute; et soutenu la biomasse microbienne, favorisant un meilleur & eacute;quilibre nutritionnel. La mod & eacute;lisation par & eacute;quations structurelles (SEM) a r & eacute;v & eacute;l & eacute; que la salinit & eacute; affecte le ma & iuml;s principalement de mani & egrave;re indirecte, l'engrais vert agissant partiellement comme un tampon. Ces pratiques organiques de la gestion biologique renforcent la r & eacute;silience du syst & egrave;me contre impacts de la salinit & eacute; induits par le sol, sans toutefois compenser totalement le stress salin.
