The European Commission’s Communication on the European Green Deal announced the development of a new, more ambitious EU climate-change strategy to enhance endeavors related to climate resilience, prevention and preparedness. Several regulatory and technical approaches have been undertaken to increase water and energy use efficiency and reduce CO2
emissions in terms of irrigated agriculture; for example, pressure networks have replaced outdated open distribution systems, and irrigation systems have been improved by utilizing more efficient water delivery equipment, such as drippers and sprinklers. Government regulators have responded by requiring abstraction permits, setting abstraction limits and establishing a minimum practice for irrigation water use efficiency; despite this, poor irrigation scheduling practice remains a major challenge because of scheduling technique complexity, the cost and inaccessibility of soil-water monitoring tools and lack of local climate data and soil-water parameters [1
Research indicates that irrigation scheduling using soil-moisture sensors reduces water requirements while improving yield, irrigation efficiency and net yield [3
]. Examples show that total irrigation volume can be reduced by up to 25–40% without affecting crop yield by reducing the current irrigation surplus when there is above-average or near-average seasonal precipitation [5
]. Achieving high productivity using less irrigation and better matching irrigation volumes to crop water requirements are compatible goals [5
]. It is possible to reduce energy costs while improving water use efficiency through comprehensive irrigation management; energy cost savings of nearly 15% are achievable without significant yield reduction [6
]. Improved farm irrigation management enables a 40% reduction in CO2
]; to do so comprehensive irrigation-decision support systems (IDSSs) tools are required to optimize water consumption and plant production based on regional climate conditions and farming systems [8
Even so, IDSS implementation faces several challenges. A lack of consistency between environmental variability and irrigation system design, insufficient information on plant water demand and spatial variability within farms and low control of the water distribution network limits IDSSs’ contribution to efficient water use and agricultural climate-change resilience [14
]. The use of IDSSs by farmers is far below what is possible [15
]. Some researchers [16
] consider linear, technology-supported approaches to be the main reason for this. In contrast, co-innovation, including inter alia close cooperation among experts, farmers and other stakeholders, supposedly improves IDSS uptake.
The introduction of IDSS requires careful consideration of farmer motivation, need and expectation [17
]. The adoption of technology to mitigate climate change depends on a number of psychological and socioeconomic preconditions [16
], as well as cultural and symbolic capital factors [18
]. It requires the involvement of farmers [16
], experts from different disciplines [16
], as well as non-academic stakeholders [21
] at all phases of the innovation process. The farmers’ extension service, traditionally the main actor in this system, is now only one of the services tasked with this role additionally challenged by taking over this role due to lacking appropriate competencies [29
IDSS implementation is most often a process beginning with an evaluation of farm practice, followed by the creation of an accurate irrigation plan that may include exact plant water requirements and installation of soil moisture sensors, smart water meters, programmers, electrovalves and weather stations. This process is usually followed by development of an application to provide farmers with irrigation advice for optimal irrigation planning [33
]. However, farmers use a range of options to meet their specific need, some use fully functional irrigation controllers, others will gradually start using IDSSs—initially only an individual component—particularly the web-based graphic interface for farmer-controlled irrigation scheduling [4
This article offers insight into improving farm irrigation scheduling and provides policy lessons to optimize water and energy consumption and reduce irrigated agriculture CO2
emissions. The research highlights IDSS adoption in sub-Mediterranean Vipava Valley, a region vulnerable to climate change. There are 2,518 agricultural holdings in Slovenia’s Vipava Valley, amounting to 11,337 ha of agricultural land in use. The development of intensive agriculture in the area is threatened by natural disasters, which are becoming more frequent because of climate change: drought, flooding and strong winds caused damage worth more than €15 million damage between 2012 and 2014 [2
]. The latest climate change projections for the 21st century indicate high exposure to climate change and further deterioration of existing agricultural conditions. Based on EUROCORDEX climate simulation [34
], using the moderately optimistic RCP4.5 scenario, that assumes significant measures to reduce future greenhouse gas releases, an increase in average annual temperature (+1.8 °C), a decrease in summer precipitation (−4%), and an increase in summer evapotranspiration (+6%) are predicted [35
]. Additionally, an increase of warm (maximum temperature exceeds 25 °C) and hot days (maximum temperature exceeds 30 °C), and an increase of number of days with precipitation above 20 mm are expected in the area by the end of the 21st century [36
Our aim is to detect, analyze and present challenges and provide solutions to introducing the IDSS at the case study in Slovenia to be able to draw policy lessons from experience gained when involving farmers in setting up IDSS. The hypothesis was that farmers would gradually start using daily irrigation advice and increase water and energy consumption efficiency and reduce CO2 emissions. Different regulatory instruments, such as standards and recommendations, education, institutional support and information and economic instruments, including incentives, are discussed as standalone or combined instruments to provide alternative policy options for achieving better irrigation efficiency and greater agricultural resilience to climate change in the area. The experience gained from the introduction of different tools to improve irrigation planning on farms that is brought together in a discussion based on our findings and findings from the international scientific community support the development of the new EU strategy for adaptation to climate change.
In 2017, before IDSS implementation, most farmers’ irrigation based on previous experience (74%) and experience and daily weather forecasts (23%), while only one used a soil moisture sensor. The majority had no water consumption records (74%) and only 26% used water meters. Water consumption on-farm was rarely recorded. Most farmers (69%) were able to report water use in dry years (m3/ha, m3/year), while 31% were unable to report annual water consumption. None of the farmers reported water use in wet years, indicating that irrigation is unnecessary in such years and that irrigation requirements vary considerably from year-to-year. Initial irrigation diaries proved too detailed for the farmers’ level of knowledge and were simplified to include only records of irrigation events; even so, 91% of our farmers failed to regularly record their actions. It suggests that some farmers were not appropriately motivated to fully participate in the project (reasons given were a lack of time, lost questionnaires) while others were unable to irrigate due to force majeure (spring frost).
Simulation highlights the difference between the two irrigation strategies: (i) replenishing soil water content to FC; and (ii) replenishing reservoirs (FC-WP) to 85% to allow a 25% average reduction in total irrigation-volume consumption. It is also possible to reduce energy requirements by 24% by improving water use efficiency; moreover, it has been evidenced that improved farm irrigation management can help reduce CO2
emissions by 24% (Figure 3
), in line with the findings of [5
]. For more detail see Appendix C
, Table A4
, Table A5
, Table A6
, Table A7
, Table A8
, Table A9
, Table A10
, Table A11
and Table A12
In 2019, 66% of our farmers shared their first experience of IDSS on their farms. Forty-six farmers use the irrigation advice they receive by e-mail, 20% also use the IDSS website. ‘Soil moisture’ is the most commonly used tab on the IDSS website at 37%, a combination of ‘soil moisture’ and ‘net irrigation requirements’ accounted for 11% and ‘net irrigation requirements’ accounting for 9%, with only one farmer reporting use of all of the tabs. This indicates a significant change in the way farmers make irrigation decisions. Bearing in mind that those farmers initially only irrigated in terms of experience, they now report using a web platform that supports irrigation decisions. Discussion with farmers at the third workshop evidenced that using the web platform makes them feel better informed about plant water requirements and that their knowledge has increased significantly in this regard.
In 2019, 40% of our farmers used irrigation recommendations more than five times per year, 9% used them at least three times, with 6% only using them once. Although 11% did not use irrigation recommendations, they reported that they regularly checked soil moisture measurements. Even so, the provided IDSS information only marginally affected farmer irrigation practice in terms of water consumption, in all probability due to insufficient farmer knowledge on how to convert soil water volume content into irrigation duration. This signifying the importance of establishing a detailed inventory of farm irrigation systems prior to IDSS implementation. However, low utilization of IDSS could also be related to the overly technical approach adopted, which emphasizes the technical functioning of the system and not farmer benefit, which better motivates them.
Manual phenological phase adjustment is crucial when formulating relevant irrigation advice. Farmers are responsible for IDSS phenophase updating. Merely 5 users changed phenological stages in 2019, which is why the irrigation advice for most farmers had larger error than if users had more frequently updated phenophases.
Farmers shared their opinion on how their user-experience could be improved by means of the questionnaire and during discussion at the third workshop. In some cases, farmers stated that soil-moisture sensors location could be optimized to better respond to irrigation (closer to drippers) or installed deeper to better capture main root depth. Individual farmers reported that they think that irrigation advice overestimates their on-field water requirements. Based on our analysis of on-farm irrigation practice before IDSS, farmers irrigated rarely, but when they did, they usually used too much water. We assume that when farmers were presented with their justified daily irrigation requirements, they automatically believed them to be excessive. Nevertheless, the mid-term evaluation of IDSS indicates that farmers are able to adapt and follow IDSS irrigation advice. The process indicates that change in farmer behavior will take several years and require consistent on-farm presence. Farmers have taken a first step towards using the IDSS, mainly to provide them with information on when to start irrigation (close to or at critical point) and when to stop irrigation (at FC or 85% of soil water reservoir). We expect that as the IDSS becomes more common, farmers will also start to use it to provide them with information on how much water to apply.
suggests that higher irrigation efficiency, achieved by changing farmer behavior by introducing the IDSS, will only contribute to better agricultural resilience to climate change after the initial period of IDSS implementation, in about five years. Farmers have in first three years made an enormous shift from irrigation decisions based on experience and assumptions to irrigation scheduling based on real-time soil-water monitoring, including the partial uptake of irrigation based on the IDSS. In doing so, they have improved irrigation scheduling accuracy and slowly begun to use more technologically advanced methods for irrigation planning. The simulation of justified water requirements shows that when farmers would use the IDSS more regularly, they would also significantly contribute to increased water and energy efficiency and CO2
emission reduction, thereby gradually increasing farms resilience to climate change in Vipava Valley (Figure 4
All farmers provided feedback on their experience of using the IDSS during their three-weekly telephone conversations in 2020; 83% report using the IDSS and 71% report regularly viewing soil-moisture status; 49% claim irrigation duration remained unchanged, while 40% report irrigating more often for a shorter period of time. Eleven percent of the participating farmers reported that they did not use the IDSS, but that they followed the IDSS reports (no irrigation system installed), while only 6% (2 farmers) were dissatisfied with the IDSS due to inconsistent soil-water measurements and lacked trust in the IDSS. Seventeen percent were partly satisfied, reporting occasional inconsistencies in soil-water measurements or reported irrigation advice overestimating water requirements. A number of factors influence the accuracy, functioning and acceptance of IDSS. The farmers’ previous practice was to irrigate once every few days and to apply plant water requirements for several days. It is therefore understandable that for some farmers, daily water recovery appears to be an exaggeration of the water requirement. Nevertheless, most users state that they are very satisfied with the IDSS (66%); their confidence in the system is high, the irrigation recommendations are compatible with their observations in the field and the soil water content fits well with irrigation practice.
There are various approaches to increase water and energy use efficiency and reduce CO2
emissions in irrigated agriculture (Table 2
), however their contribution to climate change adaptation varies in different environments and social settings. Regulatory approaches such as requiring abstraction permits designed to regulate water abstractions (Table 2
) have a limited impact on achieving higher irrigation efficiency and improved irrigation [8
]. Closing open irrigation channels [1
] must be accompanied by the installation of flow meters and regular maintenance [2
]. At the case study area, the investments in modernization of large irrigation systems were identified as a priority in adapting to climate change [2
]. However, they showed to be particularly difficult to implement, as they require formation of large network of actors that are not easily established [2
]. Purchasing individual irrigation equipment requires a smaller network of actors, which is why it was likely more successful in the past [2
]. The two measures enable purchase of soil-water monitoring equipment. However, this option has not yet been fully exploited by farmers, partly due to the inefficient communication of the option to potential users. This suggests that policy options should be better communicated in rural development programs [1
]. Particular attention should be directed to finding suitable, low-cost, low-power soil moisture sensors, with factory calibration functions covering a wide range of soil types and automatic temperature correction for reliable measurements [47
Another reason soil-moisture sensors have not yet been introduced on a larger scale is current inaccessibility of IDSS to a wider range of users. Farmers need to be supported with integrated tools (Table 2
), such as IDSS in order to improve decision making in the application of individual regulatory and technical approaches and gain greater competence in irrigation planning. Implementation of IDSSs face similar challenges [8
]. The Vipava Valley process indicates poor data on irrigation system capacity and an irregular control of water delivery on the farm. The latter indicates that while farmers are willing to implement the IDSS, they may not be able to do so if their water supply is limited.
Vipava Valley’s approach to implementing IDSS is similar to that of [33
], where the development of IDSS closely involved farmers, as suggested by [16
]. Workshops are necessary to provide farmers with relevant knowledge on how IDSS works. In addition, a detailed technical inventory was developed in collaboration with the farmers to convert net irrigation demand into irrigation duration in order to provide farmers with practical advice on irrigation planning. However, this proved to be particularly difficult during the implementation of IDSS, as farmers had little knowledge of the technical characteristics of their irrigation equipment. The evaluation of agricultural practices was followed by the determination of the plant water requirements, soil analysis and the installation of soil moisture sensors. The IDSS processes field data and produces graphs and diagrams that allow users to access daily irrigation needs via electronic devices on a daily basis [13
]. Farmers gradually started to use IDSS, in line with the results of [4
], suggesting that increased irrigation efficiency by changing farmers’ behavior through the introduction of IDSS will improve the resilience of agriculture to climate change only after the initial IDSS implementation phase of about five years. The process also shows that optimized irrigation scheduling using IDSS to further reduce water and energy consumption and CO2 emissions is only possible if systemic support is offered on the farm [1
]. To evaluate the success of the IDSS introduced, future research should extend its focus to yield and compare irrigation planning practices of farmers with and without irrigation advice. The IDSS evaluation could be improved by the integration of water meters but would still have to include individual consultation with farmers, as their practice will change over the years. Some of the more technical factors that influence the accuracy, functioning and acceptance of IDSS are the accuracy of the soil moisture measurement; errors caused by the way the soil moisture probe is installed (air pocket); the degree to which the position and depth of the soil moisture probe is able to capture general soil-water retention properties for a larger area of operation (e.g., orchard); the accuracy of the phenophase at the time of calculating daily irrigation requirements and the precipitation and ET0 forecast. Apart from the more technical factors that influence IDSS acceptance, the perception of farmers plays an important role. Sometimes only installation of additional soil-moisture sensors (and in some cases rain gauges) will increase the trust in measurements.
Financial incentives for the technical modernization of farms are likely to fail unless a sufficient innovation support system is in place to enable farmers to use these advanced tools. Greater emphasis should be placed on farmers’ motivations, needs and expectations including professional support beyond technical information and assistance [17
]. Willingness of farmers to innovate depends on a number of conditions. The process of putting innovation into practice in agriculture shows that psychological and socioeconomic factors related to communication between different stakeholders often present greater barriers than those related to technological issues [16
]. Aspects such as farmers’ motivation, attitudes, cultural capital including knowledge, skills and access to information play a role in the introduction of new technologies to mitigate climate change [18
]. Farmers are motivated by the expectation of lower input costs, higher crop productivity and financial benefits and discouraged from using this type of technology by the perception of risks and uncertainties [56
]. Their involvement in all phases of the innovation process is therefore necessary to better address the complexities of introducing innovation in agriculture [16
Farmers must be treated as co-creators of project knowledge, not just as implementers. It is also suggested that discussion with farmers should take place through personal contact and farm visits, which is a necessary condition for creating and maintaining trust between farmers and experts. All this diversifies and increases the expert workload, not only those in agriculture and irrigation, but also social researchers and marketing specialists [16
]. The extension service, that traditionally was the main actor in transferring innovation into practice, is now among many [21
]. Consequently, future agricultural innovation policy should extend its actions beyond financial measures to those related to facilitating the establishment of multidisciplinary agricultural innovation teams and the development of transparent institutional frameworks that define responsibilities at the different stages of the innovation process (Table 2