Toward climate-smart irrigation: evaluating the sustainability of negative pressure systems through carbon-nitrogen footprint and cost-benefit analysis
0 
Abstract
In protected agriculture, irrigation methods and input structures play a critical role in shaping carbon and nitrogen footprints as well as ecological-economic performance. Using a life cycle assessment (LCA) approach, this study systematically evaluated the carbon footprint (CF), nitrogen footprint (NF), environmental damage cost (EDC), and net ecosystem economic benefit (NEEB) under conventional surface irrigation (CK) and three negative-pressure irrigation (NPI) treatments (N1, N2, N3). Compared with CK, NPI significantly reduced CF and NF by up to 74.09% and 76.45%, respectively, primarily due to reduced N2O emissions and fertilizer inputs. NPI also alleviated soil organic carbon loss by 78.85%, underscoring its strong potential for environmental sustainability. However, the high cost of ceramic emitters (accounting for 88.36%~89.80% of Costagricultural input) and their substantial upstream emissions resulted in a significantly lower net economic benefit (NEB) for NPI compared with CK. Despite this drawback, NPI treatments demonstrated superior ecological-economic efficiency: EDC was reduced by over 85%, and the N1 treatment achieved a NEEB of -10.37 CNY ha-1, nearly reaching break-even. These results highlight a clear trade-off between environmental benefits and economic feasibility. Policy support (e.g., subsidies, carbon credits) and innovations in emitter materials (e.g., low-carbon or biodegradable alternatives) are essential to improve the overall sustainability and scalability of NPI systems.
Keywords
INTRODUCTION
With the intensification of agriculture and the growing threat of climate change, enhancing resource-use efficiency while reducing agricultural greenhouse gas (GHG) emissions and reactive nitrogen (Nr) losses has become essential for the green and low-carbon agricultural transformation[1-4]. In protected vegetable production systems, in particular, high demands for water and fertilizers, intensive input requirements, and environmental sensitivity make traditional irrigation methods, such as furrow and sprinkler irrigation, not only inefficient in water and nutrient use but also major contributors to nitrogen leaching, ammonia volatilization, and N2O emissions[5-7]. Together, these processes create substantial carbon (CF) and nitrogen footprints (NF)[8]. Consequently, the development of efficient and intelligent water-fertilizer management technologies is central to ensuring the sustainability of protected agriculture[9].
Negative pressure irrigation (NPI) is a precision irrigation technique driven by crop root-zone water demand. Using porous ceramic emitters, it establishes a stable negative pressure that enables self-regulated uptake of water and nutrients[10-14]. This method significantly reduces unnecessary water and fertilizer application while improving the synchronization of nutrient absorption by crops[15,16]. Previous studies have demonstrated that NPI can reduce irrigation water use by more than 30%[13], decrease nitrogen losses by 20%-40%[17,18], and effectively suppress GHG emissions such as N2O, all while maintaining crop yields[19,20]. However, most existing research has focused on the field-level agronomic and environmental benefits of NPI, whereas the upstream environmental costs - particularly those associated with the production and deployment of irrigation infrastructure (e.g., ceramic emitters, pipelines, and control devices) - remain largely underexplored[21]. Because these components are often manufactured through energy-intensive processes (e.g., high-temperature sintering), their environmental footprints may offset gains achieved during the operation phase. Assessing these upstream impacts is therefore critical to evaluating the overall sustainability of NPI systems, yet they have received limited quantitative attention. This gap hinders a full understanding of the life cycle trade-offs involved in adopting NPI technologies.
Furthermore, current evaluation metrics are often narrow, focusing only on yield[19], water-use efficiency[17], or GHG emissions[20], without integrating upstream resource consumption or accounting for environmental externalities in economic terms. A comprehensive assessment framework that combines CF and NF with economic performance is lacking, hindering evidence-based decision making for policy design and technology adoption.
To address these gaps, this study evaluates the environmental and economic sustainability of NPI in a protected Chinese chive production system. By combining field experiments with a life cycle assessment (LCA) approach, we construct a system boundary encompassing “resource input-production
MATERIALS AND METHODS
Study site and experimental design
The experiment was carried out in a rain shelter at the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering in Nanjing, China (32.06º N, 118.77º E) from April to June 2019. The experimental soil was silty loam (31.41% sand, 53.8% silt, and 14.8% clay) with a bulk density of 1.35 g cm-3. A self-designed NPI device was used, consisting of four components: a water supply tank, a negative pressure generating unit, an electronic control unit, and a ceramic emitter. This system enabled automatic pressure regulation[22].
The experimental design included three negative pressure irrigation treatments: -2 kPa (N1), -4 kPa (N2), and -6 kPa (N3). Surface irrigation was used as the conventional surface irrigation (CK). For NPI treatments, ceramic emitters
System boundary
The system boundary considered both GHG emissions and Nr losses, and was divided into two stages [Figure 1]. The first stage included upstream processes such as the production and transportation of agricultural inputs (fertilizers, irrigation equipment, labor, and electricity). The second stage covered field processes during Chinese chive cultivation, including soil organic carbon (SOC) sequestration, N2O emissions, NOx emissions, nitrogen leaching, nitrogen runoff, and NH3 volatilization. The CF accounted for GHG emissions from upstream processes, SOC sequestration, and N2O emissions. The NF included Nr losses from upstream processes as well as field losses from N2O and NOx emissions, nitrogen leaching, runoff, and NH3 volatilization.
Figure 1. System boundaries for the life cycle assessment of the carbon footprint and nitrogen footprint in Chinese chive production.
Calculations of carbon and nitrogen footprints
Carbon footprint
GHG emissions during Chinese chive production under NPI include both upstream processes (production and transportation of inputs) and field application processes. The CF was calculated as follows[23]:
where AIi represents agricultural production input type i, and EFi is the corresponding CO2 emission coefficient [Supplementary Table 1]. N2Ototal denote total N2O emissions (kg CO2-eq ha-1), and N2Odirect is direct cumulative N2O emission (kg CO2-eq ha-1). FN-input the applied nitrogen fertilizer (kg ha-1). FRACGASF and FRACLEACH represent the fractions of inorganic N fertilizer lost as NH3-N/NOx-N volatilization and nitrate leaching, respectively (0.1 kg NH3-N + NOX-N volatilized kg-1 N input, and 0.3 kg N leached kg-1
Nitrogen footprint
NF was assessed by quantifying nitrogen losses from field inputs, including N2O emissions, NH3 volatilization, and nitrogen leaching. NF (kg N-eq kg-1) was calculated as follows[25]:
where NFinput represents nitrogen from farm inputs, AIi and NFi denote agricultural input type i and its emission factor (kg N-eq ha-1), respectively [Supplementary Table 1].
Calculation of net economic benefit, environmental damage cost, and NEEB
The Net Economic Benefit (NEB), (CNY ha-1 yr-1) was calculated as follows:
where Revenueyield represents the income from leek production [Supplementary Table 2]. Costagricultural input is the sum of expenditures on agricultural materials, energy, and labor for vegetable cultivation, as summarized in Supplementary Table 3. All infrastructure components were assigned a specific service life based on field practice or manufacturer specifications: 15 years for ceramic emitters, 2 years for soft Polyvinyl chloride (PVC) tubing, and 5 years for control units. The costs and associated environmental burdens of equipment (e.g., the carbon and nitrogen footprints of ceramic emitters) were amortized over their respective service lives to reflect contributions across multiple growing seasons. A straight-line depreciation method was used to annualize both costs and environmental impacts. Given the prototype nature of the system, no reuse potential was assumed for any component. Detailed calculations and amortization assumptions are provided in Supplementary Text 2.
The Environmental Damage Cost (EDC) (CNY ha-1 yr-1), the sum of climate warming impacts from GHG emissions, soil acidification from NH3 and NOX emissions, and eutrophication from nitrogen leaching/runoff, was calculated as follows:
where k is the total number of Nr loss types, and i denotes a specific type of Nr loss. Nri (kg N) is the amount of nitrogen lost in form i, and UNr,i is the corresponding damage cost to human health and ecosystems per unit of nitrogen lost. The damage costs of NH3, NOX, and nitrogen leaching/runoff were 37.5, 29.6, and 9.3 CNY kg-1 N, respectively[29].
The NEEB (CNY ha-1 yr-1) was then calculated as:
RESULTS
Carbon and nitrogen footprints
The CF and NF varied significantly among treatments [Figure 2]. The CK treatment exhibited the highest CF value (4,519.60 kg CO2 ha-1), while all NPI treatments (N1, N2, N3) resulted in markedly lower CF values (1,148.21~1,383.37 kg CO2 ha-1). In the CK treatment, CF was primarily driven by N2Ototal emissions and agricultural inputs, accounting for 62.36% and 43.34%, respectively, while ∆SOC contributed only 5.12%. In contrast, CF under NPI treatments was dominated by agricultural inputs, contributing over 95%, whereas N2Ototal emissions accounted for only 2.57%~7.36%. The substantial CF reduction in NPI treatments was mainly attributed to significantly lower N2Ototal emissions compared with CK (by 95.97%~98.83%). Within agricultural inputs, N fertilizer emissions constituted 99.63% of CF in the CK treatment, while labor contributed only 0.37%. For NPI treatments, the main contributors were N fertilizer (42.78%-50.95%) and ceramic pipes (45.34%~52.90%). Other components, including labor, acrylic materials, sensors, pumps, single-chip microcontrollers, PVC water pipes, and electricity for irrigation, contributed less than 5% and were relatively minor [Supplementary Table 1 and Supplementary Table 3].
Figure 2. Changes in carbon footprints and nitrogen footprints during Chinese chives cultivation.
The inclusion of ΔSOC indicated net carbon losses across all treatments, with CK showing the greatest SOC depletion (-231.21 kg C ha-1). Although ΔSOC remained negative under N1, N2, and N3 (-48.91, -65.38, and -62.21 kg C ha-1, respectively), these losses were much smaller than those observed in CK. This suggests that while NPI did not achieve net SOC sequestration, it substantially reduced soil carbon loss compared with CK.
NF showed a similar trend. CK had the highest NF, with 75.99% attributed to N fertilizer input. In contrast, N1, N2, and N3 had much lower NF values, 67.76%~76.45% lower than CK. Under NPI treatments, NF primarily originated from N fertilizer emissions (93.15%~94.55%), with ceramic pipes contributing 3.95%~5.41%. As shown in Table 1, the reduced NF in NPI treatments was largely due to lower N fertilizer application rates, with N emissions from fertilizer 64.15%-74.20% lower than in CK. Among NPI treatments, N1 had the highest NF, followed by N2 and N3, suggesting a potential trade-off between irrigation innovation and reactive nitrogen losses.
Emission inventory by component of agricultural inputs
| Items | Emissions from agricultural inputs (kg CO2 ha-1) | NFinput (kg N-eq ha-1) | |||||||
| CK | N1 | N2 | N3 | CK | N1 | N2 | N3 | ||
| Labor | 6.45 | 0.69 | 0.69 | 0.69 | / | / | / | / | |
| N fertilizer | 1,751.83 | 628.08 | 521.27 | 451.97 | 1,492.92 | 535.25 | 444.23 | 385.17 | |
| NPI control unit | Acrylic | 8.44 | 8.44 | 8.44 | 8.44 | / | / | / | / |
| Air pressure sensor | 0.00 | 0.002 | 0.002 | 0.002 | / | / | / | / | |
| Liquid level sensor | 0.00 | 0.002 | 0.002 | 0.002 | / | / | / | / | |
| Vacuum pump | 0.02 | 0.02 | 0.02 | 0.02 | / | / | / | / | |
| Single-chip microcomputer | 0.02 | 0.02 | 0.02 | 0.02 | / | / | / | / | |
| Peristaltic pump | 0.02 | 0.02 | 0.02 | 0.02 | / | / | / | / | |
| PVC water pipe | 0.00 | 1.02 | 1.02 | 1.02 | / | / | / | / | |
| Ceramic pipe | 0.00 | 558.91 | 558.91 | 558.91 | 0.00 | 22.36 | 22.36 | 22.36 | |
| Irrigation electricity consumption | 0.00 | 35.42 | 35.42 | 35.42 | 0.00 | 0.00144 | 0.00144 | 0.00144 | |
NEB
The Costagricultural input was shown in Table 2. The Costagricultural input under NPI treatments was 0.99-2.01 times higher than that in CK. Compared with CK, labor costs in the N1, N2, and N3 treatments were reduced by 89.33%, and nitrogen fertilizer costs were reduced by 64.15%~74.20%. However, the use of negative-pressure irrigation equipment incurred additional expenditures for components such as acrylic materials, sensors, pumps, single-chip microcomputers, and PVC pipes. These items accounted for 1.35%~1.37% of Costagricultural input. The most significant cost under NPI was for ceramic pipes, which amounted to
Agricultural Input Inventory and total cost per treatment (CNY ha-1)
| Item | Costagricultural input | |||
| CK | N1 | N2 | N3 | |
| Labor | 795 | 84.80 | 84.80 | 84.80 |
| N fertilizer | 375.84 | 134.75 | 111.83 | 96.99 |
| NPI control unit | 0 | 25.32 | 25.32 | 25.32 |
| PVC water pipe | 0 | 6.47 | 6.47 | 6.47 |
| Ceramic pipe | 0 | 2,078.90 | 2,078.90 | 2,078.90 |
| Irrigation electricity consumption | 0 | 22.46 | 22.46 | 22.46 |
| Total | 1,170.84 | 2,352.71 | 2,329.80 | 2,314.93 |
The Revenueyield for CK, N1, N2, and N3 was 2,950.46, 2,905.59, 2,391.23, and 2,097.04 CNY ha-1, respectively. There was no significant difference in Revenueyield between N1 and CK. However, Revenueyield under N2 and N3 were 18.95% and 28.92% lower than CK, respectively. The NEB was highest in CK at
Figure 3. Changes in Net Economic Benefit (NEB) during Chinese chives cultivation.
EDC and NEEB
As shown in Figure 4, the EDC under the CK treatment were significantly higher than those under NPI. Specifically, the EDC values for N1, N2, and N3 were 558, 479, and 423 CNY ha-1, respectively, whereas CK reached approximately 3,908 CNY ha-1. This reduction in EDC under NPI was attributed to its improved environmental performance through lower reactive nitrogen emissions and a reduced carbon footprint.
Figure 4. Changes in environmental damage costs (EDC) and net ecosystem economic benefit (NEEB) during Chinese chives cultivation.
All treatments exhibited substantially negative NEEB. In the NPI treatments, although the NEB was significantly lower than that of CK, the EDC was also markedly reduced. However, this reduction in EDC was insufficient to offset the decline in NEB, resulting in significantly lower NEEB values compared with CK. In contrast, the N1 treatment yielded a near-zero NEEB (-10 CNY ha-1), suggesting a relatively better ecological-economic balance under conventional management.
DISCUSSION
Upstream contributions to carbon and nitrogen footprints
When accounting for the embedded emissions of NPI equipment, NPI still exhibited lower CF, NF, CFy, and NFy compared with conventional irrigation [Figure 2 and Supplementary Figure 1]. The reduction in CF under NPI was primarily driven by a significant decrease in N2Ototal emissions, which resulted from both reduced N2Odirect emissions under NPI and lower N fertilizer application rates, which in turn led to decreased NH3-N and NOX-N emissions. Although the adoption of NPI increased emissions from agricultural inputs due to additional equipment requirements, this increase was outweighed by the larger reductions associated with decreased N fertilizer use. Consequently, input-related emissions were ultimately lower under NPI, contributing to a significantly reduced CF and, in turn, a lower CFy. The NF under NPI was also significantly lower than under CK. This reduction was mainly due to the decreased N fertilizer application rate, with fertilizer-related N emissions in the NPI treatment being 64.15%-74.20% lower than in the CK treatment.
We initially assumed a service lifespan of 15 years for the ceramic pipes. However, under actual soil environments, porous ceramics are prone to clogging and functional failure, which could bias estimates of carbon and nitrogen emissions. Because empirical data and industry standards on service life are lacking, we also examined shorter assumed lifespans of 10 and 5 years. The results showed that at a 10-year lifespan, CFs were 1,694.35, 1,558.46, and 1,450.35 kg CO2-eq ha-1, and NFs were 577.31, 484.75, and
Figure 5. Carbon and nitrogen footprints under different service lifespans of ceramic emitters.
These results highlight a well-documented concern in LCA: advanced technologies that improve field-level efficiency can simultaneously introduce substantial upstream environmental burdens[30,31]. Specifically, the use of high-temperature sintered ceramics and PVC infrastructure entails considerable embodied carbon, which can offset reductions achieved in field emissions. This trade-off underscores the importance of integrated assessment frameworks that move beyond operational performance metrics (e.g., water or fertilizer use efficiency) to fully capture the cradle-to-grave environmental costs of agricultural innovations. To enhance the sustainability of NPI systems, future efforts should focus on optimizing material choices (e.g., adopting low-carbon or recycled inputs), extending the lifespan and reusability of emitters, and exploring alternative emitter designs such as biodegradable polymers or composite materials. Incorporating these scenarios into future LCA models will be critical for guiding sustainable engineering practices and informing relevant policy frameworks.
From cost burden to environmental compensation: reframing NPI viability
The NEB analysis showed that although the NPI system significantly reduced operational costs - particularly labor (by ~89%) and nitrogen fertilizer inputs (by 64%~75%) - the high cost of system components, especially the ceramic irrigation devices, led to a substantial increase in total investment. Ceramic components alone accounted for approximately 88%~90% of total costs (2,078.90 CNY ha-1), far outweighing the savings from reduced fertilizer and labor. This finding aligns with previous studies that identified high initial capital requirements as a primary barrier to adopting precision or novel irrigation systems in smallholder and resource-limited settings[31-33].
Crop yield revenue did not significantly increase under NPI, and in some cases, even declined slightly under treatments N2 and N3. The slight yield reduction observed under these treatments may be attributed to suboptimal soil moisture conditions. Specifically, excessively low soil water potential likely restricted crop water uptake and growth, thereby reducing yield performance[15]. Due to the mismatch between input costs and revenue, the NEB under all NPI treatments was lower than under the CK treatment, turning negative under the N3 treatment. This indicates that, although the system is agronomically efficient (e.g., in water and fertilizer savings), its short-term economic feasibility is limited unless substantial financial support mechanisms -such as subsidies or carbon market incentives-are introduced to offset the cost gap.
Although the NEEB under the NPI system remained negative, it was consistently higher than that of the CK treatment. This suggests that despite the lower NEB resulting from high equipment costs and limited yield improvements, the NPI system provided notable environmental advantages. Specifically, EDC values were significantly lower under NPI, primarily due to marked reductions in greenhouse gas emissions and nitrogen losses. Since NEEB integrates both economic performance and environmental externalities, the relatively higher NEEB under NPI indicates a more favorable overall sustainability profile. In other words, while NPI may not currently offer short-term economic returns, its environmental co-benefits can partially offset economic drawbacks, highlighting its potential as a more sustainable irrigation strategy in the long term-particularly if policy instruments such as subsidies or carbon credits are introduced to internalize these environmental gains. It should be noted, however, that the EDC estimation relied on average unit damage costs for pollutants, without adjustments for regional characteristics (e.g., ecological sensitivity or population density). While this approach enables meaningful relative comparisons, it introduces uncertainty into the absolute values. Future assessments should incorporate region-specific damage cost parameters to enhance accuracy and policy relevance.
This finding aligns with results from integrated assessment models, which show that even technologies with high ecosystem service value may face adoption barriers without appropriate policy support[34]. In this study, the monetized value of environmental benefits (e.g., reduced emissions and pollution) failed to offset the substantial investment costs. This underscores the need for mechanisms such as carbon credit markets, ecological compensation, or green subsidies to internalize external environmental gains.
In this study, a 15-year lifespan for ceramic emitters was assumed based on design specifications. However, in real soil environments, issues such as clogging may shorten their actual service life, thereby affecting cost allocation calculations. When the lifespan was assumed to be 10 years, the NEB under NPI treatments remained negative, ranging from -485.57 CNY ha-1 to -1,257.34 CNY ha-1, which were 127.34% to 170.65% lower than those of the CK treatment. Under the same conditions, NEEB ranged from -1,733.14 CNY ha-1 to -1,098.53 CNY ha-1, representing an 18.57% to 48.39% improvement over CK [Figure 6]. However, assuming a lifespan of only 5 years, NEB values dropped sharply to -4,375.69 to -3,604.93 CNY ha-1, or 2.03 to 2.46 times lower than CK, while NEEB ranged from -4,997.63 to -4,363.01 CNY ha-1, or 1.05 to 1.35 times lower than CK [Figure 6]. These results demonstrate that the assumed service life of ceramic emitters significantly influences evaluations of both NEB and NEEB. Therefore, future research involving accelerated aging tests or in-situ durability assessments would be valuable for more accurately estimating their actual lifespan and corresponding economic performance. Additionally, this life cycle assessment did not account for emissions associated with equipment transportation and disposal. Although these stages may contribute some environmental impacts, the dominance of manufacturing emissions suggests their omission does not significantly alter the overall environmental assessment.
Figure 6. Changes in Net Economic Benefit (NEB) and net ecosystem economic benefit (NEEB) under different service lifespans of ceramic emitters.
This study demonstrates that NPI systems impose a considerable upstream environmental burden, primarily due to ceramic emitters, which dominate the system’s carbon footprint. By contrast, conventional irrigation technologies-such as plastic drip irrigation-typically have lower embodied carbon due to material and manufacturing differences, though they may pose challenges related to durability and recyclability. Although a detailed life cycle comparison was beyond the scope of this study, future research should investigate the environmental and economic trade-offs among different irrigation technologies to inform more sustainable infrastructure choices. Furthermore, NPI systems may provide additional long-term ecological benefits, such as improved soil structure, reduced salinity, and enhanced microbial resilience. However, these potential advantages were not captured in this short-term analysis due to its limited duration. Future research should incorporate such long-term ecological contributions into life cycle assessments to enable a more comprehensive evaluation of the environmental-economic synergies and sustainability potential of NPI systems.
CONCLUSION
This study applied an LCA framework to comprehensively evaluate the environmental and economic performance of a NPI system in protected agriculture. Compared with conventional irrigation, NPI reduced CF and NF by up to 75% and 76%, respectively, primarily through reduced N2O emissions and fertilizer inputs. It also mitigated soil carbon losses, demonstrating strong potential to enhance environmental sustainability. However, the high upstream cost and emissions associated with ceramic emitters (accounting for nearly 90% of input costs) resulted in lower NEB under NPI treatments, with some scenarios even producing negative returns. While all treatments showed negative NEEB, NPI treatments-especially
DECLARATIONS
Author’s contributions
Conceptualization, formal analysis, funding acquisition, investigation, methodology, writing - original draft: Wang, K.
Conceptualization, methodology, writing - review and editing: Chen, P.
Formal analysis, investigation: Min, Z.
Investigation, writing - review and editing: Chen, S.
Validation, writing - review and editing: Zhou, Z.
Availability of data and materials
The data that support the findings of this study are available from the corresponding author upon reasonable request.
Financial support and sponsorship
This research was funded by the Chinese Universities Scientific Fund (2452025045).
Conflicts of interest
Min, Z. is an employee of Powerchina Zhongnan Engineering Corporation Limited and contributed to this work through formal analysis and investigation. The other authors declared that there are no conflicts of interest.
Ethical approval and consent to participate
Not applicable
Consent for publication
Not applicable.
Copyright
© The Author(s) 2025.
Supplementary Materials
REFERENCES
1. Anderson, R.; Bayer, P. E.; Edwards, D. Climate change and the need for agricultural adaptation. Curr. Opin. Plant. Biol. 2020, 56, 197-202.
2. Denning, G. Sustainable intensification of agriculture: the foundation for universal food security. npj. Sustain. Agric. 2025, 3, 47.
3. Fan, C.; Li, B.; Xiong, Z. Nitrification inhibitors mitigated reactive gaseous nitrogen intensity in intensive vegetable soils from China. Sci. Total. Environ. 2018, 612, 480-9.
4. Kopittke, P. M.; Menzies, N. W.; Wang, P.; Mckenna, B. A.; Lombi, E. Soil and the intensification of agriculture for global food security. Environ. Int. 2019, 132, 105078.
5. Cheng, K.; Yan, M.; Nayak, D.; et al. Carbon footprint of crop production in China: an analysis of National Statistics data. J. Agric. Sci. 2015, 153, 422-31.
6. Zhang, W. F.; Dou, Z. X.; He, P.; et al. New technologies reduce greenhouse gas emissions from nitrogenous fertilizer in China. Proc. Natl. Acad. Sci. U. S. A. 2013, 110, 8375-80.
7. Zhou, J.; Li, B.; Xia, L.; Fan, C.; Xiong, Z. Organic-substitute strategies reduced carbon and reactive nitrogen footprints and gained net ecosystem economic benefit for intensive vegetable production. J. Clean. Prod. 2019, 225, 984-94.
8. Yu, Z.; Yang, Y. Carbon footprint of global cotton production. Resour. Environ. Sustain. 2025, 20, 100214.
9. Abdo, A. I.; Sun, D.; Yang, K.; et al. Carbon footprint of synthetic nitrogen under staple crops: a first cradle-to-grave analysis. Glob. Change. Biol. 2024, 30, e17277.
10. Bian, Y.; Yang, P.; Long, H.; Ding, Y.; Li, D. Water use efficiency and nutrient absorption of spinach (Spinacia oleracea L.)under two material emitters and negative water supply pressures. J. Plant. Nutr. Fertil. 2018, 24, 507-18. https://www.plantnutrifert.org/article/doi/10.11674/zwyf.17171 (accessed 2025-08-27).
11. Long, H.; Zhang, H.; Yue, X.; Zhang, R. Design and experiment of heavy liquid-type negative pressure valve used for negative pressure irrigation. Trans. Chin. Soc. Agric. Eng. , 2018, 34:85-92. https://iarrp.caas.cn/en/docs/2021-07/20210716104554533416.pdf (accessed 2025-08-27).
12. Nalliah, V.; Ranjan, R. S. Evaluation of a capillary-irrigation system for better yield and quality of hot pepper (Capsicum annuum). Appl. Eng. Agric. 2010, 26, 807-16.
13. Yang, P.; Bai, J.; Yang, M.; et al. Negative pressure irrigation for greenhouse crops in China: a review. Agric. Water. Manag. 2022, 264, 107497.
14. Yang, P.; Bian, Y.; Long, H.; Drohan, P. J. Comparison of emitters of ceramic tube and polyvinyl formal under negative pressure irrigation on soil water use efficiency and nutrient uptake of crown daisy. Agric. Water. Manag. 2020, 228, 105830.
15. Wang, K.; Wei, Q.; Xu, J.; et al. Matching water requirements of Chinese chives planted at different distances apart from the line emitter under negative pressure irrigation subsurface system. Agric. Water. Manag. 2022, 274, 107928.
16. Zhang, Z.; Liu, S.; Jia, S.; et al. Precise soil water control using a negative pressure irrigation system to improve the water productivity of greenhouse watermelon. Agric. Water. Manag. 2021, 258, 107144.
17. Li, S.; Tan, D.; Wu, X.; et al. Negative pressure irrigation increases vegetable water productivity and nitrogen use efficiency by improving soil water and NO3--N distributions. Agric. Water. Manag. 2021, 251, 106853.
18. Li, Y.; Xue, X.; Xu, F.; et al. Negative-pressure irrigation improves water and fertilizer use efficiencies and fruit yield of greenhouse tomato on the North China Plain*. Irrig. Drain. 2021, 70, 1027-38.
19. Li, S.; Jiao, L.; Wu, X.; et al. Negative pressure irrigation as a potential technique for increasing vegetable yields and decreasing nitrous oxide emissions. Sci. Hortic. 2023, 318, 112125.
20. Wang, K.; Xu, J.; Wei, Q.; Chen, P.; Min, Z.; Wang, H. The potential for mitigating greenhouse gas emissions and minimizing yield losses using the negative pressure irrigation system. Sci. Hortic. 2024, 324, 112621.
21. Xiang, G.; Yu, F.; Xu, Y.; Fang, Y.; Xie, S. Prediction for swelling deformation of fractal-textured bentonite and its sand mixtures in salt solution. Clays. Miner. 2019, 54, 161-7.
22. Wang, K.; Wang, H.; Xu, J.; et al. An automatic control device for negative pressure irrigation for continuous low-rate water supply at constant soil wetting. Biosyst. Eng. 2022, 213, 175-81.
23. Zhang, Z.; Wang, J.; Huang, W.; et al. Growing cover crop mixtures are more sustainable than single cover crop in continuous cotton cropping: Comprehensive assessment from 3-year field experiment. J. Clean. Prod. 2023, 420, 138350.
24. EFDB emission factor database. https://www.ipcc-nggip.iges.or.jp/EFDB/main.php (accessed 2025-08-29).
25. Wang, L.; Li, L.; Cheng, K.; Pan, G. Comprehensive evaluation of environmental footprints of regional crop production: a case study of Chizhou City, China. Ecol. Econ. 2019, 164, 106360.
26. Wang, C.; Sun, H.; Zhang, J.; et al. Effects of different fertilization methods on ammonia volatilization from rice paddies. J. Clean. Prod. 2021, 295, 126299.
27. Xue, J.; Pu, C.; Liu, S.; et al. Carbon and nitrogen footprint of double rice production in Southern China. Ecol. Indic. 2016, 64, 249-57.
28. Guinée, J. B.; Gorrée, M.; Heijungs, R.; et al. 2001. Life cycle assessment an operational guide to the ISO standards. https://scispace.com/papers/life-cycle-assessment-an-operational-guide-to-the-iso-3jmg2699qy (accessed 2025-08-29).
29. Xia, L.; Ti, C.; Li, B.; Xia, Y.; Yan, X. Greenhouse gas emissions and reactive nitrogen releases during the life-cycles of staple food production in China and their mitigation potential. Sci. Total. Environ. 2016, 556, 116-25.
30. Firoozi, A. A.; Firoozi, A. A.; Maghami, M. R. Harnessing photovoltaic innovation: advancements, challenges, and strategic pathways for sustainable global development. Energy. Convers. Manag. X. 2025, 27, 101058.
31. Pelletier, N.; Klinger, D. H.; Sims, N. A.; Yoshioka, J.; Kittinger, J. N. Nutritional attributes, substitutability, scalability, and environmental intensity of an illustrative subset of current and future protein sources for aquaculture feeds: joint consideration of potential synergies and trade-offs. Environ. Sci. Technol. 2018, 52, 5532-44.
32. Van de Zande, G. D.; Amrose, S.; Donlon, E.; Shamshery, P.; Winter, A. G. Identifying opportunities for irrigation systems to meet the specific needs of farmers in East Africa. Water 2024, 16, 75.
33. Van de Zande, G. D.; Grant, F.; Sheline, C.; et al. Design and evaluation of a precision irrigation tool’s human-machine interaction to bring water- and energy-efficient irrigation to resource-constrained farmers. Sustainability 2024, 16, 8402.
Cite This Article
Open AccessHow to Cite
Download Citation
Export Citation File:
Type of Import
Tips on Downloading Citation
Citation Manager File Format
Type of Import
Direct Import: When the Direct Import option is selected (the default state), a dialogue box will give you the option to Save or Open the downloaded citation data. Choosing Open will either launch your citation manager or give you a choice of applications with which to use the metadata. The Save option saves the file locally for later use.
Indirect Import: When the Indirect Import option is selected, the metadata is displayed and may be copied and pasted as needed.
About This Article
Copyright
Data & Comments
Data
0
Comments
Comments must be written in English. Spam, offensive content, impersonation, and private information will not be permitted. If any comment is reported and identified as inappropriate content by OAE staff, the comment will be removed without notice. If you have any queries or need any help, please contact us at [email protected].