Introduction

Rice cultivation in the desert and semi-arid zones also holds in-built opportunities and challenges to the progress and improvement in the long-term rate in agriculture, under water-scarce and fragile ecologies1. Existing research by Shahhoseini and Kazemi2 and by Fartout Enayat et al.3 also alludes to the intensification in the need to consider the ecological processes in the regionalised agro-ecosystems, under the increase in demand in the climate-altered and water-scarce affected zones. The Sistan and Baluchistan province, with its geography and climatic variations, has been considered a primary agricultural frontier where new approaches to rice cultivation on a sustainable scale are needed for regional food security and economic stability.

Despite its function of assuring food security, widespread agricultural use of chemicals has led to extensive environment-related problems, including degradation of soils, degradation of plants, and biodiversity loss4. Harmonising development with the surroundings has therefore been a great difficulty5. Ecological security then refers to preserving the sustainability and health of ecosystems6. It means maintaining ecosystems’ natural processes, ecosystems’ provision of services for sustainable growth, and harmonious human-nature relationships7. Ecological security estimation has been very critical for understanding the status and environment-related issues of a territory or a system8. An example of such estimation techniques for ecological security has been emergy footprint estimation, combining ecological footprint and emergy concepts, discussed by Zhao et al.9.

Emergy theory and methodology, devised in the 1980s by Odum, reconcile ecological, thermodynamic, and general systems concepts. Emergy values natural and economic assets and ecosystems and quantifies them and can be used for assessments of systems’ sustainability10. Emergy values natural and economic assets with precise accuracy, normalising heterogeneous input flows into a single solar emjoule (sej) value, and therefore their comparability2. The methodology has been extensively applied, including in agriculture, for systems’ sustainability assessments, for example, for the cultivation of Yaghout vine3for aquaculture11for canola for commerce and for sustenance12for vegetables under glass13for shallots14for wheat15and for dates and pistachios15 in Iran’s different regions.

The ecological footprint, coined by Wackernagel and Rees in 1996, measures the amount of biocapacity necessary for a way of life of a society16. Serving as a link between humans and nature, an ecological footprint describes the ecological consequences of human action17. The measurement, in global hectares, recognises the impact humans put on the environment18. The ecological footprint has also remained significant in environmental research, and research in the same19 has been conducted. Some research has been conducted in the domain of the sustainability of saffron in the rainfed crop-growing systems in the South Khorasan20 and rainfed barley and wheat crop-growing in Iran21 and rice crop-growing in Indonesia22 and in Taiwan23.

Emergy footprint analysis, a holistic methodology created by Zhao et al.9brings the best of ecological footprint and emergy concepts for a more insightful understanding of ecological sustainability. The novel methodology addresses the limitation of the use of individual techniques independently by combining ecological footprint’s ability to measure environmental impacts with emergy’s ability to measure the quality of resources and the performance of systems24. The technique transforms other input forms into normalised sej/global hectares, allowing for a more precise assessment of environmental impacts and ecological capacity of systems6. Measuring the sustainability of agricultural systems has benefitted much from recent studies using a comprehensive approach. Zhang et al.8 used the emergy footprint approach for measuring rice cultivation systems in Southeast Asia and identified key factors for water use of water resources and systems’ performance. Peng et al.25 used this approach for measuring the ecological security of agricultural systems of desert regions, identifying its importance for water-scarce regions of Iranshahr and Saravan. The approach’s ability to measure the quality of resources and environmental impacts jointly best accommodates measuring the ecological security of agricultural systems for regions with complex environmental problems26.

While ecological footprint and emergy approaches are useful, they also have inherent shortcomings. The ecological footprint does not take into account regional ecological variations, and emergy does not take into account the lack of availability of the resources and the capacity of a system for provision of services27. Scholars suggest integrating these methods for their limitation25. Various research works offer examples of the employment of emergy footprint for quantification of the ecological status and sustainability of regions and systems of production28,29. Research on Sistan suggests systems of cultivation of Yaghouti grapes present ecological surpluses and security3, and fish farming systems of concrete and galvanised present ecological deficits and insecurity11. Research on Baluchistan and on China also suggests vulnerability of single systems of production due to the large gap between capacity for emergy and emergy footprint28,29.

This study plans on closing research gaps with a holistic ecological examination of rice cultivation in the regions of Iranshahr and Saravan with the goal of meeting the need for agricultural productivity with ecological sustainability. There has also been research in other crop cultures in terms of ecological footprint and emergy, and also limited research in rice crop culture in southeastern Iran. The study sought to establish the ecological input and output of rice crop culture through emergy footprint, establish the ecological capacity and burden to the environment of rice crop culture in Iranshahr and Saravan, and establish the rice crop culture’s sustainability and potential ecological security in the two counties. The study unites emergy theory and ecological footprint calculation for the purposes of explaining environmental impacts of rice cultivation, with the vision of developing knowledge for the purposes of agricultural management and contributing towards ecological security discourse of agricultural systems.

Results and discussion

Emergy biocapacity

Emergy biocapacity determines the capacity of natural renewable sources of the environment. The research has identified solar radiation, rainfall (chemical and potential energy), wind power, and water of traditional irrigation systems (qanat and rivers) as the primary renewable input for rice cultivation in Iranshahr and Saravan counties. The primary renewable input for both counties has been identified as rivers’ water, with the highest percentage of the overall environment’s renewable emergy. The biocapacity of both counties has been determined after integrating the rivers’ water with solar and terrestrial cycle emergies. The 12% correction for biodiversity has been performed after determining the emergy biocapacity, and the value has been 2.29E+07 global hectares/year for Iranshahr and 7.36E+06 global hectares/year for Saravan (Fig. 3). The greater enhanced capacity of Iranshahr mostly originates from its larger cultivated field compared with Saravan.

A plethora of research has been performed on the systems’ biocapacities. Fartout Enayat et al.3 indicated Sistan’s systems of Yaghouti grapes had an annual biocapacity of 3.93E+08 global hectares. Fartout Enayat and Asgharipour19 also established that Sistan’s semi-natural, concrete, and galvanised ponds of aquaculture had 4.32E+05, 3.97E+04, and 1.51E+04 global hectares of biocapacities. The determinants of systems’ biocapacities are the duration of the cycle of production, geographical space of the system, and inherent characteristics. Liu et al.6 quantified the emergy biocapacities of megacities of the Yangtze River basin of China in different research. Chengdu and Chongqing had the highest, and Shanghai and Suzhou had the lowest, due to factors such as precipitation, geopotential, urban boundaries, and regional climatic factors.

Emergy footprint

The estimation of the environmental effects of rice farming in Iranshahr and Saravan has made use of the emergy footprint method. The method calculates, including direct and indirect energy consumption, the total amount of consumed energy in a system. The two areas had different economic input and management techniques, including machinery, seedlings, animal manure, pesticides, fertilisers, electricity, and human labour. The footprint of Iranshahr was 4.23E+04 global hectares, and for Saravan, 3.89E+04 global hectares (Fig. 3). Seedlings were the largest input, significantly in Iranshahr, where higher seedling numbers and higher plant density contributed more. The second largest contributor was the use of nitrogen fertiliser, with 6.03E+17 and 1.76E+17 sej for Iranshahr and Saravan, respectively. The differences in the footprint of the two regions can be explained mainly on the basis of differences in cultivated space and individual contributions of different economic inputs.

Fartout Enayat and Asgharipour19 quantified the emergy footprint of Sistan’s different environments’ aquacultures. The research established significant variations, from 375,000 up to 2,490,000 global hectares for a single cultivation period and 50,300 global hectares for a single habitat. Regional Yaghouti grape cultivation’s emergy footprint has been quantified at 1.25E+08 global hectares every year. The sustainability of the cultivation of four counties of Sistan and Baluchestan, i.e., banana, mango, papaya, and guava, has been compared and analysed by Adl et al.29. The highest emergy footprint of these fruits has been identified in Dashtyari, Qasr Qand, Sarbaz, and Chabahar, for banana, mango, papaya, and guava, respectively. The two research works established the significant contribution of the location of cultivation and economic input towards the emergy footprint. Liu et al.6 compared the different Chinese cities’ emergy footprint between 2007 and 2016. Chongqing, Shanghai, Nanjing, and Hefei had their emergy footprint enhanced, and there has been a drop in the footprint of Wuhan, Chengdu, and Suzhou. The authors associated the trends with demographic and economic growth.

Resource depletion index

The resource depletion index, reflective of the volume of consumed non-renewable environmental input in the process of production, for Iranshahr and Saravan rice fields was determined. The study showed 3.17E+18 and 1.09E+18 global hectares of non-renewable input were consumed for every cycle of production for these provinces, respectively (Fig. 3). Soil erosion has been identified as the only non-renewable environmental input in this study. To decrease this burden, use of lightweight, up-to-date machinery, wider tires for reducing compaction, and higher organic matter of the soils can be recommended. Besides, more enhanced water transportation and irrigation systems can decrease the amount of soil erosion and lower the resource depletion index significantly.

Research on Sistan cultivation of Yaghouti grapes has established a significant 1.35E+09 global hectares every year3 resource depletion index. Regional aquaculture systems’ resource depletion indexes were 8.80E+07, 1.02E+07, and 6.68E+05 global hectares for each cycle of semi-natural, concrete, and galvanised ponds, respectively19.

Ecological security assessment indicators

Emergy ecological surplus/deficit (EED/EES)

The emergy ecological deficit/surplus (EED/EES) metric, measured from the gap between the emergy footprint and emergy biocapacity, defines the environment’s capacity for maintaining a production system6. A value of higher than zero denotes ecological excess, in which case human demand exceeds supply; a value of lower than zero denotes ecological deficit30.

For Iranshahr and Saravan’s rice systems, respectively, the analysis produced EES values of 2.29E+07 and 7.32E+06 global hectares (Table 4). This indicates that locally, the ecosystems can fully support these systems of production. The smaller cultivated area and lower amount of renewable environmental input of Saravan can explain its lower surplus compared with Iranshahr.

Previous studies on the emergy footprint had established that marine farms in China had ecological sustainability, with their biocapacity (9.63E+05 global hectares) being greater compared with their emergy footprint (3.84E+05 global hectares). The same had been observed for the systems of cultivation of Yaghouti grapes and Sistan’s semi-natural ponds. But concrete and galvanised ponds for aquaculture and tropical fruits for cultivation in south Iran went under EED, where their demand for resources had been greater compared with available biocapacity. The study suggests the significant contribution of the environment and the type of production system towards ecological deficit or surplus.

Ecological pressure index (EPI)

This index looks into the regional ecological assets’ impacts of systems of production. The findings present dramatic contrasts between agricultural practices and regions. Rice cultivation in the regions of Iranshahr and Saravan had very low levels of regional ecological footprint, with EPI values of 0.00184 and 0.00526, respectively. The values imply that such practices operate very efficiently with the inherent capacity of the environment. The needs for the cultivation of tropical fruits, however, are quite different between regions. The systems of Dashtyari, Qasr-e-Qand, Sarbaz, and Chabahar had greater levels of use beyond regional environmental capacity, with heavy ecological burdens on regional assets29. The varying consequences point towards a dramatic pattern of this region’s agricultural practices: some systems of production maintain ecological stability with limited use of assets up to levels of sustainability, and others heavily transgress such boundaries, with a risk of destabilising the environment in the future.

Ecological footprint intensity (EFI)

For quantification of environmental sustainability of agricultural areas, researchers used ecological footprint intensity (EFI) measuring6. The measurement gauges how much agricultural activities affect nearby ecosystems. The study has taken into account the favourable effects of rice farming for the areas of Iranshahr and Saravan. The region’s natural environment capacity (biocapacity) suggested little environmental burden since it exceeded their agricultural ecological footprint. For Saravan, the EFI values were 0.00529; for Iranshahr, they were 0.00185. The values lie between 0 and 1, implying that these agricultural systems are on levels of sustainability for the surroundings. Studies on aquaculture systems show another trend. Studies done in China and the Sistan region have established a basic truth. Such activities are considered as being ecologically unsustainable where the emergy footprint of aquacultures exceeds the natural capacity for sustainability of the surroundings. The finding implies the necessity of a balanced relationship between environmental preservation and production19,28.

Ecosystem resilience index (ERI)

The examination of the Ecosystem Resilience Index (ERI) also confirmed substantial differences between the two regions under study. The ERI for Iranshahr was 86.45, and for Saravan, 318.98, a considerably higher value. The result demonstrates substantial differences between the ecological resilience capacities of the two agricultural systems. The much higher ERI value for Saravan suggests the rice cultivation system of this region has greater adaptive capacity and greater capacity for maintaining its major functions under environmental stress compared with Iranshahr.

The observed greater resilience can be accounted for by several key factors31. The greater efficiency of the renewable compared with the non-renewable input, represented by the greater ratio of R/N in the ERI calculation, significantly contributes towards this resilience. A greater buffer capacity of the system translates into greater capacity for absorbing and resisting various forms of disturbance and therefore greater resilience. A smaller emergy footprint for every square unit of area translates into greater optimal utilisation of the resources, with a lesser burden on the environment and overall resilience and sustainability of the system. The ERI of 86.45 for Iranshahr indicates a moderately resilient system with probable points of vulnerability for improvement. A lower value of ERI generally indicates greater utilisation of non-renewable input, lower resilience against environmental shocks, and greater ecological footprint relative to the amount of available renewable input.

The notable regional discrepancy in ERI values (approximately a ratio of 3.7) suggests the substantial contribution of regional practices and ecosystems’ properties towards agricultural resilience. The higher ERI value of Saravan relates to its complementary ecological indicators, such as its lower value of the resource depletion index and higher value of the ecological-economic coordination index, suggesting a more harmonious and more sustainable agricultural system overall.

The results suggest that Saravan’s practices of management can be replicated for greater resilience of ecosystems for other similar agricultural systems in arid environments. The value of ERI for Saravan being very high suggests greater capacity for maintaining productivity and ecosystems under the forces of climate and other environment-related stresses, suggesting a more resilient system in the longterm.

Water resource sustainability index (WRSI)

The evaluation of the water resource sustainability index (WRSI) also confirmed solid water sustainability indicators for both study regions, with Saravan showing a higher value of 176.47 compared with 147.06 for Iranshahr. The two regions also had values of WRSI significantly higher than 1, implying effective water use practices for their rice cultivation systems.

Saravan’s elevated value of 176.47 for its WRSI suggests improved water resource management and higher conformity between water demand and supply trends. Optimised water resource management, more water-efficient irrigation practices, and lower water stress accounted for this improved performance. The factors mentioned earlier, coupled with higher water accessibility due to improved infrastructure or supportive natural factors, led to measured values32. The value of 147.06 for Iranshahr’s WRSI suggests water utilisation on a sustainable scale, with its lower value compared with Saravan suggesting improvement space. The approximate 20% differential between the two regions’ values of their WRSI can be accounted for on the basis of a range of factors, including different irrigation practices, differences in regional water infrastructure, different regional hydrogeological factors influencing water availability, and different crop water demand management practices33.

The high values of the two regions’ WRSI are noteworthy because they fall in the climatic zone of the arid and semi-arid, where water resources are generally limited. The study demonstrates that water use of the two regions has been optimised and water availability has been balanced with agricultural needs. The findings are significant in light of water-intensive rice paddy cultivation. The water sustainability indicators in the above-mentioned regions are extremely high, despite the realisation that the support required to maintain such WRSI values calls for keen observation. The most essential items to monitor are future recharge in the ground, the expected impacts from water availability under various climatic circumstances, water demand fluctuations, rehabilitation and improvement needs in infrastructure, and general applications in water-conserving technologies34. The study supports the utilisation of ecological indicators and demonstrates that water use in the two regions has a positive contribution towards the overall ecological security of their agricultural systems. The Saravan’s value of the WRSI being very high supports the enhanced performance of a range of ecological indicators, substantiating the hypothesis of its agricultural practices being more environment-sustained.

Soil quality degradation index (SQDI)

The analysis of the Soil quality degradation index (SQDI) also showed moderately low quality of soils in both study areas, with a relatively lower value for Iranshahr (0.842) compared with Saravan (0.886). The lower values of SQDI suggest higher quality soils, and therefore, the result suggests both study regions suffer from major challenges of maintaining optimal soils for rice cultivation, with different intensities.

The lower value of SQDI for Iranshahr (0.842) indicates relatively better quality of the soil, even with significant improvement needed. The higher quality of the soil is a result of a range of factors, including improved soil management, improved maintenance of the soil organic matter, balanced utilisation of the nutrients, and optimal use of irrigation, and these factors, in sum, lead to lower degradation of the soil35. The higher value of SQDI for Saravan (0.886) indicates more critical soil quality issues. The small difference between the two regions’ soils (approximately 5%) can be attributed to variations in practices of soil management, historical utilisation of the land, regional environment influencing the quality of the soil, and density and forms of agricultural practices being conducted36.

The SQDI values for both regions, both of which are around 1.0, imply there exists substantial worry with regard to quality of soils and its improvement. The study’s findings lean towards several points of note. The two regions experience substantial degradation of their soils, possibly compounded by extensive rice cultivation and possibly unsustainable agricultural practices. This indicates the need for more stringent approaches towards soil management, such as improved practices of soil conservation, optimal organic matter management, adoption of crop rotation systems, and utilisation of improved methods of erosion control37. The issues transcend the immediacy of agricultural output, impacting the future sustainability and functioning of ecosystems, and demand adaptive methods towards its management and possible remediative interventions38. The two regions both host functioning agricultural systems; however, the relatively higher quality of soils in Iranshahr offers valuable lessons towards possibly enhancing practices for Saravan. Recommendations from this study include the adoption of improved methods of soil conservation, utilisation of more organic amendments, adoption of reduced tillage where possible, improvement of the quality of soils, establishment of regional-specific methods towards soil management, and adoption of traditional and improved methods of soil conservation39.

The findings also concur with other ecological indicators in the study, with quality of soils being a noteworthy point40. The study suggests, however, even with the presence of viable agricultural systems in both regions, there is a call for more improved soil’ management practices for future sustainability. The relatively better quality of soils in Iranshahr provides hints on more viable practices for adoption in Saravan.

It is advised to implement more enhanced techniques of soil conservation, more organic amendment, and reduced tillage where possible. Besides, more vigilant observation of indicators of soil quality, setting regional-specific methods of soil management, and utilising traditional and conventional techniques of soil conservation are critical for sustaining soils41. The study indicates the need for holistic practices for soils for both regions, with an emphasis on prevention of future degradation and restoration of soils in the present.

Agricultural system stability index (ASSI)

The assessment of the agricultural system stability index (ASSI) also measured levels of stability in both study regions, with Saravan registering a higher value (1.51) compared with Iranshahr (1.37). The research provides valuable insights into the stability and sustainability of rice cultivation systems in both regions. The higher Aggregate ASSI of 1.51 for Saravan suggests a more stable agricultural system. This can be associated with a range of factors, such as greater yield stability with the passage of years, more efficient use of ecosystem services, lower emergy footprint with regard to output, and more stable levels of output measured with a lower coefficient of variation42. Whilst Iranshahr has a moderately stable system, measured with its ASSI value of 1.37, holistic examination suggests improvement avenues. Iranshahr has greater levels of variations of output compared with other regions, lower use of ecosystem services, greater levels of emergy footprint for every output unit, and greater levels of fluctuations of yield stability.

The ASSI values for the two regions present useful lessons43,44. both regions experience similar levels of moderate resilience of the systems, defined in terms of enough resistance of the systems against drivers of the environment, maintaining the functioning of the ecosystem services, and optimal use of the resources, and this could be optimised. second, there are signs of sustainability of the production, indicated by stable yields under extreme environments, use of resources favouring sustained use, and impacts on the environment being under control. these findings present useful lessons for management, such as the need for constant observation of indicators of stability of the systems, the need for maintaining the functioning of the ecosystem services, the possibility of maximising use of the resources, and the identification of avenues for reducing the variability of the production.

The comparable values of ASSI for the two regions mean that, with different approaches and system characteristics, both regions had relatively stable agricultural systems. There still exists, however, room for improvement in both cases, in particular for maximising ecosystem services, reducing emergy footprint, stabilising yields, and limiting production variability.

The findings are in accordance with other ecological indicators in the research, suggesting that the two regions have achieved moderate stability in their agricultural systems, with room for improvement. The relatively better performance in Saravan has lessons on practices, whose improvement can be achieved with a vision of stabilising Iranshahr. We suggest utilising enhanced agricultural practices for reducing the variability of productions, enhancing the use of ecosystem services, maximising the utilisation of the use of resources, developing effective stress management, combining traditional and conventional farming practices, and measuring and evaluating systematically indicators of systems’ stability45. The findings affirm the necessity of maintaining and developing agricultural systems’ stability with holistic methods involving the utilisation of production efficiency and ecological sustainability.

Socio-Ecological coupling index (SECI)

The examination of the Socio-Ecological Coupling Index (SECI) also showed significant variations between the two study regions, with Iranshahr showing a much higher value (147.67) compared with Saravan (66.86). The finding provides significant insight into the coupling between ecological processes and social systems of the two regions’ agricultural landscapes.

Iranshahr exhibits a very high value of 147.67 for its SECI, suggesting a greater linkage between its ecological and socio-economic systems. This can be because of a range of factors such as a more balanced relationship between socio-economic capacity and ecological capacity, greater use of emergy biocapacity, greater management of the burden of the population with regard to the provision of resources, and greater coupling of ecological and social factors of the region46,47.

Saravan’s significantly lower value of SECI, i.e., approximately 45% of Iranshahr’s, indicates low synchronisation of ecological and social systems. This indicates greater relative human pressure on resources, lower use of emergy biocapacity, and more difficulty in socioeconomic growth and ecological conservation.

The notable regional differences in SECI values yield a variety of significant insights48. It indicates variations in the integration of systems, where regions share higher levels of ecological and social integration, more optimal utilisation of ecological capacity, and more optimal utilisation of available ecological capacity, accompanied by a balanced strategy towards socio-economic growth. Secondly, such variations signify different trends of use of resources, different levels of performance of addressing the problem of population pressure, and different ways of balancing growth and conservation between regions. This indicates different capacities for maintaining natural use of resources. such findings also imply policy implications, highlighting the significance of region-specific strategies towards socio-ecological governance, the need for giving regard towards regional trends of populations, the possibility of knowledge transfer between regions with best practices, and the need for interventions towards addressing region-specific gaps.

The significant values gap of SECI between Saravan and Iranshahr indicates that, even if both regions share functional agricultural systems, there remains a stark contrast between them with regard to their socio-ecological coupling capacity. Iranshahr depicts more effective coupling of ecological capacity with development, and Saravan depicts avenues for improvement of socio-ecological coupling. Each of the regions has its specific challenge of achieving long-term sustainability. To overcome such disparities, there exists a need for developing specific interventions for greater socio-ecological coupling in both regions49. This can be achieved via implementing mechanisms for addressing the problem of population pressure, greater utilisation of resources, and greater capacity of the locality. Saravan means developing harmonious methods for resource management, implementing greater mechanisms for population pressure, greater socio-economic capacity building, and greater ecological conservation. There exists a need for Iranshahr to strengthen and maintain present coupling mechanisms, record and share best practices, continue observation of socio-ecological coupling, and construct plans for achieving long-term sustainability.

The analysis underlines the importance of incorporating ecological and societal drivers into agricultural systems’ management, with a call for regional solutions for more socio-ecological coupling.

Ecological-Economic coordination index (EECI)

The ecological-economic coordination index (EECI) determines whether economic growth occurs within the ecological capacity of a location50. The EECI indexes for rice cultivation in Iranshahr and Saravan were 1.001 and 1.005, respectively. The indexes signify a negligible discrepancy, with economic growth in the two regions surpassing their ecological capacities. The finding is in accordance with previous studies on tropical fruits’ cultivation systems of Baluchestan29 and aquaculture systems of semi-natural, galvanised, and concrete ponds19 where such inconsistencies between ecological capacities and economic growth were confirmed.

Conclusion

This analysis of rice cultivation agricultural systems in Iranshahr and Saravan, southeastern Iran, provides insight into the ecological sustainability and security of agriculture in the region. The research had significant findings with major consequences for agricultural sustainability in desert environments. The emergy footprint calculation identified ecological surpluses for both regions, 2.92E+09 hectares for Iranshahr and 3.27E+08 hectares for Saravan. This suggests that the current rice cultivation methods are viable under the environment’s capacity for these regions. The low values of the Ecological Pressure Index (EPI) for Iranshahr (0.00184) and Saravan (0.00526) and values of Ecological Footprint Intensity (EFI) for Iranshahr (0.00185) and Saravan (0.00529) suggest minimal environmental degradation from current agricultural methods.

The research also identified substantial regional differences in socio-ecological coupling and resilience of ecosystems. Saravan had a much higher capacity for adaptation, with its Ecosystem Resilience Index (ERI) of 318.97 compared with 86.45 for Iranshahr. Iranshahr had higher socio-ecological coupling, with its Socio-Ecological Coupling Index (SECI) of 147.67 compared with 66.86 for Saravan. The two regions had optimal use of water resources, with their values of the Water Resource Sustainability Index (WRSI) being 176.47 for Saravan and 147.06 for Iranshahr. Soil quality still remains a big issue, with their Soil Quality Degradation Index (SQDI) values being quite high for both regions (Iranshahr: 0.842, Saravan: 0.886).

The marginally unbalanced values of the Ecological-Economic Coordination Index (EECI) of 1.001 for Iranshahr and 1.005 for Saravan imply that present-day economic processes are on the precipice of ecological thresholds. This indicates the need for watchful observation and possible adjustments for continued sustainability. The Agricultural System Stability Index (ASSI) values of 1.51 for Saravan and 1.37 for Iranshahr imply the need for enhanced stability of the system on holistic terms.

To improve the sustainability of rice cultivation in such regions, a variety of recommendations are needed. To decrease the Soil Quality Degradation Index (SQDI), adoption of more improved methods of soil conservation, such as greater organic amendment and, where possible, reduced tillage, must be implemented. Regional-specific plans of management must be conceived with the utilisation of Saravan’s enhanced resilience of ecosystems and Iranshahr’s resilient socio-ecological integration. Sustained observation and improvement of water resource practice must be achieved for maintaining a beneficial Water Resource Index (WRSI). Improvement of the Ecological Economic Capacity Index (EECI) must be achieved with a balanced proportion of economic growth and ecological capacity. Traditional and conventional agricultural practices must be harmonised for the overall stability of the system.

To further contextualize the ecological security assessment of rice cultivation systems in Iranshahr and Saravan, a comparison with previous research reveals both consistencies and divergences. For instance, our findings of ecological surpluses (Iranshahr: 2.92E+09 ha, Saravan: 3.27E+08 ha) align with those of Fartout Enayat et al. (2023), who reported ecological surpluses in Yaghouti grape production systems in Sistan, Iran, using a similar emergy footprint approach. However, unlike Zhang et al. (2022), who identified significant water resource stress in rice systems of Southeast Asia, our study indicates effective water management, with WRSI values of 176.47 (Saravan) and 147.06 (Iranshahr), reflecting arid-adapted practices. Additionally, Peng et al. (2018) reported higher ecological pressure (EPI > 0.05) in Qingdao’s agricultural systems, contrasting with the low EPI values (0.00184 and 0.00526) in our study, suggesting minimal environmental stress in these arid regions. These comparisons underscore that, while our systems exhibit sustainability akin to other Iranian arid agroecosystems, their resilience and low ecological footprint distinguish them from more stressed systems elsewhere, offering insights for sustainable agriculture in water-scarce environments.

The study finds rice cultivation in Saravan and Iranshahr to be environment-friendly today, and for this status, efforts need to be made on a sustained basis towards sustaining the quality of water, earth, and the relationship between economic growth and ecological conservation. The future research must be on framing concrete plans for solving these issues, sustaining the positive factors of the current agricultural practices.

The findings reinforce our knowledge of desert agriculture and offer useful lessons for agricultural managers and policymakers striving for agriculture-environmental balancing with the goal of achieving agricultural security. The research process and its findings offer a template for quantification and enhancement of the ecological security of agricultural systems for other climatic regions of the world.

Materials and methods

Study area

This study has been performed in Iranshahr and Saravan counties, southeastern Sistan and Baluchistan Province, Iran. Figure 1 demonstrates the map of positions of Iranshahr and Saravan. Iranshahr has been located between 60°29’ and 60°51’ E longitude and 27°03’ and 27°20’ N latitude, and Saravan between 61°30’ and 62°50’ E longitude and 27°20’ and 28°20’ N latitude. The climatic regions are arid and semi-arid, with temperate winters and very hot summers. The mean annual temperature ranges from 26 °C to 32 °C, with a maximum temperature up to 50 °C in summer. The annual rainfall of these regions has been very low, with an average of 95–110 mm, and with very extreme spatial and temporal variations51.

Fig. 1
figure 1

Map of Iranshahr and Saravan Counties Showing Research Locations in Sistan and Baluchistan Province, Iran. The map was generated using ArcGIS software (version 10.8, Esri, Redlands, CA, USA; URL: https://www.esri.com) by overlaying geographical coordinates of the study areas (Iranshahr: 60°29’–60°51’ E, 27°03’–27°20’ N; Saravan: 61°30’–62°50’ E, 27°20’–28°20’ N) onto a base map of Sistan and Baluchistan Province sourced from the Iranian National Cartographic Center. Administrative boundaries and research locations were digitized and visualized using vector layers created by the authors.

Full size image

The agricultural topography of the two counties is composed of intermountain valleys and alluvial plains. The soils range from sandy loam to clay loam with low to moderate organic matter, mostly under 1%. The agriculture depends mostly on groundwater from deep wells and qanats, supplemented with seasonal surface water from the Bampur River in Iranshahr and from small streams in Saravan on rainfall events52,53.

Rice cultivation in the two districts occurs mostly between the period of April and September, with single-cropping systems being implemented on a big scale by the farmers due to water limitation. The cultivated field of rice in 2023 occupied approximately 212.5 hectares of Iranshahr and 57.6 hectares of Saravan and represented 12.5% of the cultivated field of the two districts. Traditional environment-resistant rice cultivars are planted on a big scale, with some of the farmers recently developing enhanced, drought-resistant cultivars.

Data collection

The primary data collection captured extensive data on varying parameters of cultivation practices of rice. The field measurements, soils, and topography were captured, and extensive data on input factors, i.e., the amount and variety of seeds, fertilisers, pesticides, and machinery, were captured. We also took into account the human and hired labour needs, separating family from hired workers in terms of assigned tasks and working periods. Considered as watering frequencies, watering event durations, and total water use for the cultivation period are the water use data. Considered was the use of energy, including fossil fuels for machinery and electricity for pumps. The economic data considered overall cultivation expenditure, yields achieved, and output and input market prices. The agricultural practices were considered systematically, including field preparation, plantation practices, and varying crop management practices for the cultivation period.

Primary data collection included structured interviews with farmers to gather information on cultivation practices, input use, and water management. A stratified random sampling method was employed, targeting 50 farmers from Iranshahr and 30 from Saravan, proportional to the cultivated rice area (212.5 ha and 57.6 ha, respectively). Farmers were selected from lists provided by the Sistan and Baluchistan Agricultural Organisation, ensuring representation across farm sizes and irrigation types (qanats, wells, and rivers). Interviews were conducted in person during April–September 2023, with responses recorded and cross-verified against field observations for accuracy.

Environmental parameters were measured and monitored systematically with varying techniques. Soil samples were also gathered and analysed from varying points of every field for measuring the soils’ physical and chemical properties. Daily weather data were also acquired from regional weather observation points, such as temperature, precipitation, relative humidity, and wind speed. The groundwater levels were also monitored from regional water authority wells for measuring water table variations. Water quality tests of irrigation sources were also conducted to determine their usability for rice cultivation and their probable environmental impacts.

Secondary data were also acquired from other institutional sources for the purpose of complementing primary data. The Sistan and Baluchistan Agricultural Organisation provided historical statistics for output and provincial agricultural data. The Regional Water Authority provided extensive water use and water use trends. The regional department of extension provided agricultural practice data and regional barriers. The databases of the Meteorological Organisation provided extensive climatic data, and research studies and research articles published earlier supplied extensive contextual data and recommendations on methodology.

A stringent quality check process has been conducted to assure data reliability. The submitted field data were screened for completeness and for internal coherence. Where inconsistencies and suspicious values were encountered, repeat field trips were undertaken for data confirmation and correction. Local agricultural experts were also consulted for data confirmation, technical issues of rice cultivation being of utmost importance. Multiple sources of data were utilised for data confirmation and corroboration, therefore assuring overall reliability of the dataset.

The data preparation process utilised a systematic approach for preparing the data for analysis. The data were, for the very first time, converted into computer-readable format and organised into Excel spreadsheets in a standardised format. The data were checked for errors and inconsistencies and corrected after field checks. All measurements were converted into international conventional standardised units for purposes of easy comparisons and for analysis. The standardised data were then converted into sej utilising applicable conversion factors from published sources for use in the ensuing emergy footprint calculation (Tables 1 and 2).

Table 1 Emergy analysis of rice production systems in Iranshahr.
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Table 2 Emergy analysis of rice production systems in Saravan.
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Emergy biocapacity

Emergy biocapacity, as defined by Liu et al.6refers to ecological renewable resources’ regenerative capacity. The ecological renewable resources are solar radiation, wind, precipitation, rivers’ water, and Earth’s cycling processes.

The emergy biocapacity of these resources is determined using Eq. 1:

$${\text{EBC}} = \left( {1 - 12\% } \right) \times R/P_{{\text{1}}}$$
(1)

EBC represents global hectares of emergy of renewable resources, and R stands for maximum environmental renewable emergy. The global emergy density is represented by P1. To avoid doublecounting, the sum of the input of renewable resources is synchronised with the maximum input of the system’s renewable. According to the recommendation of the WCED, 12% of the biocapacity can be allocated for biodiversity30.

The global emergy density (P1) can be determined from global emergy and Earth’s surface area, for example, from Eq. 2:

$${\text{P}}_{1} = \frac{{Total\;emergy\;of\;the\;earth}}{{Area\;of\;the\;earth}} = \frac{{1.20{\text{E}} + 25\;{\text{sej}}}}{{5.1E + 14\;{\text{m}}^{2} }} = 2.35E + 10\;{\text{sej}}\;{\text{m}}^{{ - 2}}$$
(2)

Emergy footprint

The emergy footprint symbolises human-initiated contributions towards systems of production6. The emergy footprint can be determined from the conversion of overall economic input, such as machinery, seedlings, fertilisers, and pesticides, into solar emjoules (sej) and then dividing this amount by regional emergy density (Eq. 3).

$${\text{EFP}} = {\text{E}}_{{\text{w}}} /{\text{P}}_{2}$$
(3)

EFP signifies quantification of the emergy footprint in terms of local hectares, EW stands for the sum of acquired renewable inputs, and P2 denotes regional emergy density. The regional emergy density, measured in sej/m2/yr, is calculated using Eqs. 4 and 5.

$${\text{P}}_{2} = \frac{{Total\;emergy\;in\;Iranshahr}}{{Areas\;of\;the\;Iranshahr}} = \frac{{1.12756E + 24\;{\text{sej}}}}{{1.84E + 10\;{\text{m}}^{2} }} = 6.12853E + 13\;{\text{sej}}\;{\text{m}}^{{ - 2}}$$
(4)
$${\text{P}}_{2} = \frac{{Total\;emergy\;in\;Saravan}}{{Areas\;of\;the\;Saravan}} = \frac{{3.14429E + 23\;{\text{sej}}}}{{1.60E + 10\;{\text{m}}^{2} }} = 1.96518E + 13\;{\text{sej}}\;{\text{m}}^{{ - 2}}$$
(5)

Resource depletion index

The resource depletion index quantifies the utilisation of non-sustainable natural resources for a specific process of production3. The calculation is made with the use of Eq. 6:

$${\text{RDI}} = {\text{N}}/{\text{P}}_{1}$$
(6)

The resource depletion index (RDI) can be quantified in global hectares with this formula. It can be derived from the emergy of the non-renewable environment inputs (N) and global emergy density (P1).

Ecological security assessment indicators

This study employs a broad variety of ecological security indicators for quantification of the sustainability of rice cultivation systems in regions under study. Table 3 depicts that such indicators embrace varying factors of ecological security, including utilisation of resources, stability of systems, and ecological-socio interactions. The study employs a variety of novel indicators specific for quantifying the sustainability of agricultural systems in arid regions, supplemented with widely used indicators such as Emergy Ecological Deficit/Surplus (EED/EES) and Ecological Pressure Index (EPI) from previous research6,25.

Table 3 Comprehensive overview of ecological security assessment Indicators.
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The newly created indicators are the Ecosystem Resilience Index (ERI) for quantification of the resilience of systems under stressed conditions, the Water Resource Sustainability Index (WRSI) for quantification of water use efficiency, and the Soil Quality Degradation Index (SQDI) for quantification of the status of soils. The Agricultural System Stability Index (ASSI) and Socio-Ecological Coupling Index (SECI) were also created for quantification of stability of systems and coupling of society and environment, respectively. The newly created indicators, such as the Ecosystem Resilience Index (ERI), Water Resource Sustainability Index (WRSI), and Soil Quality Degradation Index (SQDI), are designed to address arid-specific agricultural sustainability issues, as illustrated in Fig. 2 (Fig. 3).

Fig. 2
figure 2

Conceptual framework for ecological security assessment of rice production systems integrating emergy analysis and sustainability indicators.

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Fig. 3
figure 3

Comparison of emergy footprint components in Iranshahr and Saravan Regions in Gha (Logarithmic Scale).

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The amalgamation of traditional and new indicators (Table 3) forms a holistic approach for ecological security, and this can be analysed in detail for its impacts on the environment and the sustainability of the systems. The approach can facilitate a complete examination of the complex relationship between agricultural practices, natural resource use, and the health of ecosystems in the regions under study. The appendix has supplementary data and complete analyses that underpin the outcomes of this research (Table 4).

Table 4 Comparison of ecological indicators between Iranshahr and Saravan rice production systems.
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