Boots on the ground: construction management of urbanizing irrigated farm land

Since its inception, in 1885 the Buckeye Irrigation Canal has delivered irrigation water in the Buckeye Valley, southwest of Phoenix, Arizona. Throughout its tenure the owners of the canal have consulted design professionals for its engineering needs. Early engineering in 1885 established canal alignments, delivery points and channel capacity. Until recently, the Buckeye Valley was a rural area relying on agricultural revenues to drive the local economy. Now, due to the recent housing market boom new homes started springing up like corn in September driving the existing open-channel laterals below grade into a patch work redesigned pipeline system. Because of these changes, professional construction managers are an enormous benefit to the Buckeye Water Conservation and Drainage District (BWCDD), the owner of the canal.As a result of this urbanization, contractors working for home developers are installing irrigation pipelines and systems with the focus of completing the project as quickly and economically as possible. Irrigation providers, on the other hand, focus on meeting the agricultural needs of their clients with consistent and uninterrupted water delivery. The services of a professional construction manager help both entities achieve their respective goals, shield BWCDD from construction of sub-par systems and risk, maintain uninterrupted service to growers and providing the technical expertise to communicate with both BWCDD and contractors.Construction managers provide a number of services to rural irrigation districts under-going urbanization. They team with an irrigation district by:

• Understanding irrigation design concepts;
• Understanding agricultural demands;
• Providing a thorough knowledge of construction practices and standards;
• Creating long-term design functionality;
• Reducing stress on and increasing productivity of personnel;
• Coordinating construction activities with water deliveries;
• Verifying constructed facilities perform as designed, which reduces maintenance costs.

Construction managers represent an irrigation district in the field by:

• Reviewing development plans for adherence to current construction standards and practices and coordinates construction schedules with water delivery needs;
• Observing construction for proper installation;
• Clarifying installers understanding of plans and specifications;
• Coordinating interruptions in service;
• Tracking multiple construction projects;
• Explaining agricultural practices to contractor personnel;
• Providing a single point of contact for construction related correspondence.

These “boots on the ground” create a local presence with a focus on the specific needs unique to an irrigation district. They provide a liaison while minimizing the impact to its growers.This paper will discuss the strain of urbanization on an irrigation district and the benefits of an engineering consulting firm to manage construction projects. The benefits include expertise, technical resources, design capability, coordination and inspection. Construction managers can help protect an irrigation district from being overwhelmed by rapid urbanization.     

User charges in irrigation: Potentials and limitations

Interest in systems of user charges for irrigation projects serving large numbers of small farmers has grown in recent years in response to concerns about

-the need to provide more adequate funding of O&M,

-distortions and inefficiencies induced by subsidies, and

-inadequate accountability of irrigation system managers to water users.

The effects that can be expected from a system of user charges depend on

-whether the charges are assessed as water prices or as area-based fees,

-whether the irrigation agency has a significant degree of financial autonomy, and

-the nature of the linkages between irrigation charges and investment decisions.

Other important considerations in establishing user charges are the ability of the users to pay irrigation fees; the cost-effectiveness of O&M activities; the costs of implementing the user charges; and whether charges are project-specific or uniform throughout a region or a nation.     

The potential for farmer participation in irrigation system management

The management of most irrigation systems involves shared responsibility between one or more government agencies and farmers. Finding the optimal level of farmer management participation is an essential part of achieving optimal system performance. Two cases are discussed where farmers have been encouraged to play a more active management role with promising results. In the Gal Oya system in Sri Lanka, farmers manage the tertiary channels and also have a voice in managing the main system. In the Philippines, small systems have been turned over entirely to farmer management, while on large systems farmers manage the tertiary or secondary levels. A number of factors appear to be important in the management success of these irrigation systems including:

-the social environment,

-a manageable main system,

-a strong commitment by the irrigation agency,

-the use of community organizers, and

-construction tasks around which farmers can organize.

Greater farmer involvement in irrigation management can have both economic and social benefits. Economically there is evidence that farmers perform certain functions better than outside agencies can, and that both farmers and agencies perform their management tasks better when they feel a mutual responsibility for a common objective. Social benefits include the organizational skills that farmers learn and which may be useful in other activities, and a sense of self-respect and self-reliance. Though farmer participation requires a deliberate effort on the part of international and government agencies, as well as farmers, the benefits can be substantial.     

Computerised irrigation scheduling using spreadsheet models

Microcomputers are increasingly being used to help in the management of smallholder irrigation schemes in Third World countries. In many cases, commercially available spreadsheet packages offer advantages over established scientific programming languages. The paper starts with a review of computer models which have been developed for irrigation scheduling. Two criteria are identified which must be considered when developing computer models for this purpose: realistic data requirements and programs which are easy to understand. Spreadsheet packages provide a good introduction to computing and macro programming techniques can be used to customise spreadsheet models to create refined yet simple management tools. Two practical examples are presented from current research projects:

-a small scale scheme in Zimbabwe, where a spreadsheet model is used to produce irrigation schedules for smallholder farmers;

-a 20,000 ha project in Thailand, where a spreadsheet model makes use of feedback to improve main system scheduling.

     

The Viejo Retamo secondary canal

The intended operation of the Rio Tunuyan irrigation scheme in the province of Mendoza, Argentina, is to divide flow proportionately over the entire area in accordance with registered water-rights. The main division of flow is by regulators at the heads of the lateral canals, which serve areas of appr. 15,000 ha. Taking the sub-lateral or secondary canal Viejo Retamo as an example, this paper discusses the flow division downstream of these regulators. The operation of the canal is evaluated with two performance indicators:

-the ratio of volume of water intended to be supplied to the tertiary units over the volume of water actually supplied, and

-the misallocation of water in volume.

In the Rio Tunuyan scheme, there is also a relation between the evapotranspiration of crops and the groundwater level: if less than 60% of the supplied canal water evapotranspires, the groundwater level rises.     

A review of slurry aeration 3. Performance of aerators

The two previous papers in this series have examined the factors affecting the aeration, mixing and foam control aspects of aerator performance. In this final paper, existing designs are reviewed to provide some guidance for the selection of aerators for farm use.The various types are classified as follows:

• 1.(a) compressed air,
• 2.(b) mechanical surface,
• 3.(c) mechanical subsurface,
• 4.(d) combined compressed air/mechanical, and
• 5.(e) pumped liquid.

Each group is assessed in terms of its principles of operation, the main factors influencing performance, and reported effectiveness in various liquids (including agricultural slurries wherever possible).     

The yield,quality and profitability of annual forage,perennial pasture and perennial forage systems under irrigation

Intensive fodder production systems were compared under irrigation in western New South Wales. The three basic systems studied were:

• 1.(1) Annual forages (Sorghum bicolor × S. sudanense plus Avena sativa).
• 2.(2) Perennial pasture (Paspalum dilatatum).
• 3.(3) Perennial forage (Medicago sativa).

The first two systems included nitrogen fertilizer or legume options, while the last had the option of including a perennial sorghum.Dry matter production was highest in the annual forage system (maximum of 30·5 tonnes ha⁻¹ year⁻¹), although annual establishment costs were higher than for perennial systems. The perennial pasture yielded 21·5 tonnes ha⁻¹ year⁻¹ but, like the annual forage system, 250 kg N ha⁻¹ year⁻¹ was required to obtain this yield. The perennial forage yielded 19·8 tonnes ha⁻¹ year⁻¹ without nitrogen fertilizer. Furthermore, it yielded more digestible dry matter and nitrogen than any other system.Although the annual forage system was the most profitable when based upon a set price for hay, the best system for grazing was difficult to determine; factors relating to grazing management are discussed.     

Hydraulic model investigation of downstream erosion of large regulators: a case study

Flow conditions, which could not be explained, occurred in the stilling basin and outfall channel of the Feni Regulator sited at the western end of the Feni River closure dam. This regulator controls outflows from the upstream reservoir which supplies irrigation water to Muhuri Project in Bangladesh. Analysis of flood discharge data revealed that the design discharge for the structure was not exceeded; yet abnormal scour occurred in the outfall channel and the brick block rip-rap placed thereon was damaged. A model study was conducted to understand the causes of such unusual local erosion downstream of the stilling basin and to provide answers to two main questions:

-Is potential scour serious in terms of the stability of the structure?

-What protection measures could be taken to stabilize the scour at a safe level?

Using a 1:30 scale model, the probable maximum scour was simulated, and the performance of alternative rip-rap designs including that of the existing one were examined. The results of this study supplemented by field scour data collected during subsequent flood seasons indicated that even if the flow rate through the regulator approaches the design flood discharge, the downstream scour is not likely to extend up to an elevation of ? 10.7 m, a scour level observed in the previous year at a lower discharge. It also showed that the existing rip-rap blocks were marginally undersized and consequently the rip-rap was prone to failure if flow conditions departed from uniform. A suitable method of scour protection downstream of the stilling basin at the regulator exit also evolved from the study.     

Salt tolerance analysis of chickpea,faba bean and durum wheat varieties: II. Durum wheat

Seven varieties of durum wheat (Triticum turgidum), provided by ICARDA, were tested in a greenhouse experiment for their salt tolerance. Afterwards two varieties, differing in salt tolerance, were irrigated with waters of three different salinity levels in a lysimeter experiment to analyse their salt tolerance.The characteristics of the salt tolerant variety compared to the salt sensitive variety are:

• -a shorter growing season and earlier senescence;
• -a higher pre-dawn leaf water potential;
• -a stronger osmotic adjustment;
• -a better maintenance of the number of productive stems per plant.

Salt tolerance of durum wheat corresponds with drought tolerance because the tolerance is caused by earlier senescence and stronger osmotic adjustment, both reducing the transpiration of the plant.     

Analysis of several discharge rate–spacing–duration combinations in drip irrigation system

In order to study the use of water irrigation in a rational way, several combinations of discharge rate, irrigation duration and inter-emitter distances were tested. For instance, three dripper spacings of 30, 50 and 70 cm which delivered water volumes of 4, 8 and 16 l per dripper, respectively, and three discharge rates of 2, 4 and 8 l/h for each spacing, were applied.An overlapping of the wetted bulbs was observed at the end of the different irrigation experiments. The inter-dripper root-zone had an average water content of 45% and a coefficient of uniformity of 90%.The discharge rate of 2 l/h applied to a 70 cm dripper spacing was characterised by water losses of 15% due to the significant irrigation duration (8 h).From this study, we reach the following conclusions, specific to the soil type and practical culture.

• 1.The maximum irrigation duration does not exceed 4 h.
• 2.Two hours durations can be used for the different spacings, each of which was characterised by its own discharge rate.

     

Salt tolerance analysis of chickpea,faba bean and durum wheat varieties: I. Chickpea and faba bean

Two varieties of chickpea (Cicer arietinum L.) and faba bean (Vicia faba), differing in drought tolerance according to the classification of the International Center for Agronomic Research in Dry Areas (ICARDA), were irrigated with waters of three different salinity levels in a lysimeter experiment to analyse their salt tolerance.The drought-sensitive varieties are more salt tolerant than the drought-tolerant varieties. Under saline conditions, the drought-sensitive varieties show a much higher yield up to a salinity threshold, corresponding with an electrical conductivity (EC_e) between 2.5 and 3 dS/m for chickpea and between 5.5 and 6 dS/m for faba bean.The drought-sensitive varieties are able to improve or maintain the water-use efficiency when irrigated with saline water. This ability can be ascribed to

• •the larger biomass production owing to the later senescence, which allows a better utilization of the irrigation water;
• •the late flowering of chickpea.

     

Optimization of groundwater abstraction system and distribution pipe in pressurized irrigation systems for minimum cost

A tool named DOPIR (Dimensioning Of Pressurized IRrigation) was developed to optimize the process of water abstraction from an aquifer for pressurized irrigation systems. This tool integrates the main factors throughout the irrigation process, from the water source to the emitter. The objective is to minimize the total cost of water abstraction and application (C _T) (investment (C _a) + operation (C _op) per unit of irrigated area according to the type of aquifer, crop water requirement and electricity rate periods. To highlight the usefulness of this tool, DOPIR has been applied to a corn crop in Spain with a permanent sprinkler irrigation system, considering two types of aquifer: confined and unconfined. The effects of parameters such as the static water table in the aquifer (SWT), irrigated area (S), number of subunits in the plot (NS), sprinkler and lateral pipe spacing, and average application rate (ARa) on C _T have been analyzed. Results show that energy cost (C _e) is the most important component of C _T (50–72 % in the case studies). Thus, it is very important to adapt the design and management of the irrigation and pumping system throughout the irrigation season to the energy rate periods.     

Potential farmer contributions to the design process: Indications from Indonesia

The paper argues that conventional irrigation design processes rely heavily on predetermined design criteria, often without allowing for interactions with farmers and revising of criteria during implementation. Six cases from a tertiary development project in North Sulawesi, Indonesia are described, where farmers altered what had been designed and constructed by contracting and agency engineers. Through field inspections and farmer interviews, the farmers' alternative set of design criteria was elicited to explain why the farmers changed what had been constructed. A total of 27 cases are analyzed to show the relative importance of:

Modeling soil water dynamics in a drip-irrigated intercropping field under plastic mulch

Intercropping, drip irrigation, and the use of plastic mulch are important management practices, which can, when utilized simultaneously, increase crop production and save irrigation water. Investigating soil water dynamics in the root zone of the intercropping field under such conditions is essential in order to understand the combined effects of these practices and to promote their wider use. However, not much work has been done to investigate soil water dynamics in the root zone of drip-irrigated, strip intercropping fields under plastic mulch. Three field experiments with different irrigation treatments (high T1, moderate T2, and low T3) were conducted to evaluate soil water contents (SWC) at different locations, for different irrigation treatments, and with respect to dripper lines and plants (corn and tomatoes). Experimental data were then used to calibrate the HYDRUS (2D/3D) model. Comparison between experimental data and model simulations showed that HYDRUS (2D/3D) described different irrigation events and SWC in the root zone well, with average relative errors of 10.8, 9.5, and 11.6 % for irrigation treatments T1, T2, and T3, respectively, and with corresponding root mean square errors of 0.043, 0.035, and 0.040 cm³ cm^?3, respectively. The results showed that the SWC in the shallow root zone (0–40 cm) was lower under non-mulched locations than under mulched locations, irrespective of the irrigation treatment, while no significant differences in the SWC were observed in the deeper root zone (40–100 cm). The SWC in the shallow root zone was significantly higher for the high irrigation treatment (T1) than for the low irrigation treatment, while, again, no differences were observed in the deeper root zone. Simulations of two-dimensional SWC distributions revealed that the low irrigation treatment (T3) produced serious severe water stress (with SWCs near the wilting point) in the 30–40 cm part of the root zone, and that using separate drip emitter lines for each crop is well suited for producing the optimal soil water distribution pattern in the root zone of the intercropping field. The results of this study can be very useful in designing an optimal irrigation plan for intercropped fields.     

Assessing water stress in a hedgerow olive orchard from sap flow and trunk diameter measurements

We used sap flow and trunk diameter measurements for assessing water stress in a high-density ‘Arbequina’ olive orchard with control trees irrigated to replace 100 % of the crop water needs, and 60RDI and 30RDI trees, in which irrigation replaced ca. 60 and 30 % of the control, respectively. We calculated the daily difference for both tree water consumption ( $ D_{{E_{\text{p}} }} $ ) and maximum trunk diameter (D _MXTD) between RDI trees and control trees. The seasonal dynamics of $ D_{{E_{\text{p}} }} $ agreed reasonably well with that of the stem water potential. We identified peculiarities on the response $ D_{{E_{\text{p}} }} $ to changes in water stressing conditions, which must be taken into account when using the index. An analysis of the water stress variability in the orchard is required for choosing the instrumented trees. The reliability of the D _MXTD index was poorer than that of $ D_{{E_{\text{p}} }} $ . The maximum daily shrinkage (MDS) was not a reliable water stress indicator.     

Land and water rights and the design of small scale irrigation projects: The case of Baluchistan

In countries around the world where small-scale irrigation systems are being improved, the design and functioning of these upgraded systems will be greatly enhanced if pre-existing patterns of land and water rights and established procedures for system operation are taken into account. An appreciation of these rights and procedures can greatly influence the layout of the water distribution network, water management practices, anticipated cropping patterns, and the related incidence of project benefits. Failure to do so will almost certainly have an adverse effect upon the functioning of the irrigation system, and can often result in serious conflicts. This is illustrated by the case of small-scale irrigation development in Baluchistan Province, Pakistan, where limited analysis of property rights and management practices and lack of consultation with intended beneficiaries caused major delays during the initial stages of project implementation. However, by introducing a methodology for social action that included an assessment of property rights and extensive consultation with affected households during the design and construction phases, the physical features and operating procedures for the upgraded irrigation system were crafted in a manner which maximized economic returns within the range of options acceptable to the local community.     

Constructional aspects of some heated concrete floors for greenhouses

The paper gives particular attention to the constructional aspects of concrete floors in greenhouses.In 1979 preliminary research was started in IMAG into the cultivation of vegetable seedlings on several floor materials, namely on ordinary concrete, porous concrete and asphalt. Overhead watering was provided, and the heating system was in the soil below the floor.These experiments revealed two problems. Uneven water distribution caused uneven growth and the mass of soil around and the concrete above the heating tubes caused a long response time for warming up and cooling down the concrete surface. For strength and wear resistance the ordinary concrete turned out to be the only suitable material.In 1981 IMAG made further trials with floors where heating and (flooded) watering system were integrated in the floor. These floors were made of reinforced concrete cast in situ, of asbestos cement and of concrete tiles. The 100 mm thick concrete floor cast in situ, turned out to be the most suitable because of the loading capacity and the good drainage of water. A standard specification was prepared for this floor type. At the end of 1985, applications of concrete floors in greenhouse, extended to 150 ha in the Netherlands for the production of vegetable seedlings, pot plants and cut flowers in pots or mats. If this trend continues there will be about 600 ha by 1990.Further development of the concrete floor has the objectives of improving thermal behaviour and easier removal or restoration of a floor. For that purpose two types of floor are under trial.

• 1.(1) An insulated concrete floor cast in situ that contains less concrete per square meter.
• 2.(2) A concrete floor built from removable concrete elements combined with a system for air movement between the plants.

     

Improving estimates of <Emphasis Type="Italic">N</Emphasis> and <Emphasis Type="Italic">P</Emphasis> loads in irrigation water from swine manure lagoons

The implementation of nutrient management plans for confined animal feeding operations requires recording N and P loads from land-applied manure, including nutrients applied in irrigation water from manure treatment lagoons. By regulation, lagoon irrigation water nutrient records in Mississippi must be based on at least one lagoon water nutrient analysis annually. Research in Mississippi has shown that N and P levels in lagoon water, and the N:P ratio, vary significantly through the year. Nutrient estimates based on one annual analysis do not account for this variability and may overestimate or underestimate N and P loads. The present study reports an improved method to more precisely estimate N and P loads in irrigation water from swine manure lagoons. The method is based on predictable annual cycles of N and P levels in lagoon water and employs simple curve-fitting of lagoon-specific formulas derived by analyses of historical data. Similarity of curves from analyses of Mississippi lagoons and other lagoon studies suggests that the method can be applied using the often limited nutrient data for a lagoon to more precisely estimate seasonal shifts of N and P and to improve the precision of estimates for N and P in irrigation water. Although the present study focused on swine manure lagoons in the southern US, recognition that the annual N cycle in lagoon water is temperature driven, suggests that additional research incorporating temperature into future models could extend these models to other types of waste treatment lagoons and climates.     

Evaluation of the Watermark sensor for use with drip irrigated vegetable crops

The Watermark 200SS sensor was evaluated for the measurement of soil matric potential (SMP) with drip-irrigated vegetable crops. Pepper and melon crops were grown sequentially during autumn-winter and spring-summer, in a sandy loam soil in a greenhouse. Ranges of SMP were generated by applying three different irrigation treatments — 100, 50 and 0% of crop water requirements, during two treatment periods (16 December 2002–7 January 2003; 20 January–10 February 2003) in pepper and one treatment period (26 May–6 June 2003) in melon. Watermark sensors and tensiometers were positioned, at identical distances from irrigation emitters, at 10 cm soil depth, with four replicate sensors for each measurement. Electrical resistance from Watermark sensors and SMP from tensiometers were recorded at 30-min intervals. An in-situ calibration equation was derived using data from the first pepper treatment period. For data in the three treatment periods, SMP was calculated from Watermark electrical resistance using the in-situ, Thomson and Armstrong (in Appl Eng Agric 3:186–189 1987), Shock et al. (1998) and Allen (2000) calibration equations. Additionally, the Thomson and Armstrong (in Appl Eng Agric 3:186–189 1987) and Shock et al. (1998) equations were re-parameterised with the SOLVER^® function of Microsoft Excel 2000^® using data from the first pepper treatment period. Watermark-derived SMP, for each equation, were compared with tensiometer-measured SMP, for <-10, ?10 to ?30, ?30 to ?50 and ?50 to ?80 kPa ranges, using visual analysis, and relative root mean square error (RRMSE) and mean difference (Md) values. In rapidly drying soil, the Watermark-derived SMP responded considerably more slowly to continual drying and to drying between irrigations, regardless of the calibration equation used. Otherwise, the Watermark sensor was able to provide an accurate indication of SMP, depending on the calibration equation. The in-situ and re-parameterised equations were accurate for the conditions in which they were derived/re-parameterised. However, as the growing conditions increasingly differed from those original conditions, these equations lost their advantage compared to the two published equations, suggesting that they are not robust approaches. The Thomson and Armstrong (in Appl Eng Agric 3:186–189 1987) equation generally provided an accurate indication of SMP at >?30 kPa, measuring to ?2.5 kPa. Where the soil was not drying rapidly, the Shock et al. (1998) equation generally provided an accurate indication of SMP at ?30 to ?80 kPa. The use of dynamic data (collected every 30 min) compared to static data (collected only at 6 a.m.) did not influence the evaluation of calibration equations. This study suggested that the Watermark sensor can provide an accurate indication of SMP provided that a suitable calibration equation is derived/verified for the specific cropping conditions, and that the performance characteristics of the sensor are considered.     

Deficit irrigation based on drought tolerance and root signalling in potatoes and tomatoes

Agriculture is a big consumer of fresh water in competition with other sectors of the society. Within the EU-project SAFIR new water-saving irrigation strategies were developed based on pot, semi-field and field experiments with potatoes (Solanum tuberosum L.), fresh tomatoes (Lycopersicon esculentum Mill.) and processing tomatoes as model plants. From the pot and semi-field experiments an ABA production model was developed for potatoes to optimize the ABA signalling; this was obtained by modelling the optimal level of soil drying for ABA production before re-irrigation in a crop growth model. The field irrigation guidelines were developed under temperate (Denmark), Mediterranean (Greece, Italy) and continental (Serbia, China) climatic conditions during summer. The field investigations on processing tomatoes were undertaken only in the Po valley (North Italy) on fine, textured soil. The investigations from several studies showed that gradual soil drying imposed by deficit irrigation (DI) or partial root zone drying irrigation (PRD) induced hydraulic and chemical signals from the root system resulting in partial stomatal closure, an increase in photosynthetic water use efficiency, and a slight reduction in top vegetative growth. Further PRD increased N-mineralization significantly beyond that from DI, causing a stay-green effect late in the growing season. In field potato and tomato experiments the water-saving irrigation strategies DI and PRD were able to save about 20-30% of the water used in fully irrigated plants. PRD increased marketable yield in potatoes significantly by 15% due to improved tuber size distribution. PRD increased antioxidant content significantly by approximately 10% in both potatoes and fresh tomatoes. Under a high temperature regime, full irrigation (FI) should be undertaken, as was clear from field observations in tomatoes. For tomatoes full irrigation should be undertaken for cooling effects when the night/day average temperature >26.5 °C or when air temperature >40 °C to avoid flower-dropping. The temperature threshold for potatoes is not clear. From three-year field drip irrigation experiments we found that under the establishment phase, both potatoes and tomatoes should be fully irrigated; however, during the later phases deficit irrigation might be applied as outlined below without causing significant yield reduction:

•

Potatoes

°

After the end of tuber initiation, DI or PRD is applied at 70% of FI. During the last 14 days of the growth period, DI or PRD is applied at 50% of FI.

•

Fresh tomatoes

°

From the moment the 1st truce is developed, DI is applied at 85-80% of FI for two weeks. In the middle period, DI or PRD is applied at 70% of FI. During the last 14 days of the growth period, DI or PRD is applied at 50% of FI.

•

Processing tomatoes

°

From transplanting to fruit setting at 4th-5th cluster, the PRD and DI threshold for re-irrigation is when the plant-available soil water content (ASWC) equals 0.7 (soil water potential, Ψ_soil = −90 kPa). During the late fruit development/ripening stage, 10% of red fruits, the threshold for re-irrigation for DI is when ASWC = 0.5 (Ψ_soil = −185 kPa) and for PRD when ASWC (dry side) = 0.4 (Ψ_{soil, dry side} = −270 kPa).

The findings during the SAFIR project might be used as a framework for implementing water-saving deficit irrigation under different local soil and climatic conditions.