A review of strategies, methods and technologies to reduce non-beneficial consumptive water use on farms considering the FAO56 methods

doi:10.1016/j.agwat.2020.106267

Agricultural Water Management

Volume 239, 1 September 2020, 106267

https://doi.org/10.1016/j.agwat.2020.106267 Get rights and content

Highlights

•
Techniques for minimizing consumptive water use on farms were reviewed: they result in limited water saving (usually <20%).
•
Directions for adjustment of FAO56 crop coefficients under water-saving practices were recommended qualitatively in tabular format.
•
Data collection needs to be standardized internationally to aid comparison of water-saving practices and transferability of the FAO56 methodology.
•
Remote sensing, plant and soil conditioners provide opportunities for future research and implementation.

Abstract

In the past few decades, research has developed a multitude of strategies, methods and technologies to reduce consumptive water use on farms for adaptation to the increasing incidence of water scarcity, agricultural droughts and multi-sectoral competition for water. The adoption of these water-saving practices implies accurate quantification of crop water requirements with the FAO56 crop coefficient approach, under diverse water availability and management practices. This paper critically reviews notions and means for maintaining high levels of water consumed through transpiration, land and water productivity, and for minimizing non-beneficial water consumption at farm level. Literature published on sound and quantified experimentation was used to evaluate water-saving practices related to irrigation methods, irrigation management and scheduling, crop management, remote sensing, plant conditioners, mulching, soil management and micro-climate regulation. Summary tables were developed on the benefits of these practices, their effects on non-beneficial water consumption, crop yields and crop water productivity, and the directions for adjustment of FAO56 crop coefficients when they are adopted. The main message is that on-farm application of these practices can result in water savings to a limited extent (usually <20%) compared to sound conventional practices, however this may translate into large volumes of water at catchment scale. The need to streamline data collection internationally was identified due to the insufficient number of sound field experiments and modelling work on the FAO56 crop water requirements that would allow an improved use of crop coefficients for different field conditions and practices. Optimization is required for the application of some practices that involve a large number of possible combinations (e.g. wetted area in micro-irrigation, row spacing and orientation, plant density, different types of mulching, in-field water harvesting) and for strategies such as deficit irrigation that aim at balancing water productivity, the economics of production, infrastructural and irrigation system requirements. Further research is required on promising technologies such as plant and soil conditioners, and remote sensing applications.

Section snippets

Introduction and concepts of water use and water consumption

In the last few decades, population growth and pressures for economic development have put much strain on water resources. This has resulted in competition and over-allocation of water resources, deterioration of water quality, increased vulnerability to extreme weather conditions and water scarcity in many regions of the world. Water scarcity is exacerbated during dry spells and droughts, which frequency and severity is expected to increase in many areas due to the impacts of climate change (

Irrigation methods

Irrigation methods can be broadly classified as surface, sprinkler and micro-irrigation. A consolidated description of irrigation methods and related performance issues was provided by Merriam and Keller (1978), Pereira (1999) and Pereira and Trout (1999a). The basis for field assessment of irrigation performance is provided by Merriam and Keller (1978). Design and management are included in various manuals such as those by Tiercelin and Vidal (2006), Hoffman et al. (2007) and Stetson and

Irrigation management and irrigation scheduling

The goal of irrigation management and scheduling may differ depending on the purpose. The goal of the farmers is to maximize the economic benefit by increasing yield and/or reducing costs. This can be achieved by maximizing beneficial water consumption and Y_a. As there is a strong relation between T_c and CO₂ assimilation (gas exchange through stomata), higher Y_a is achieved at the expense of more water transpired. Under conditions of water scarcity, the goal of irrigation management may be to

Crop management

Crop management covers a variety of practices, which benefits and effects on non-beneficial crop water consumption, WP_ET, K_{c act} values and ET_{c act} are summarized in Table 4. Beneficial and non-beneficial crop water consumption can be manipulated to cope with conditions of water scarcity by choosing crops with short biological cycles that have inherent abilities to develop and reproduce fast (drought escape), crops that have reduced T_c (small K_{cb act}), better developed root systems or the

Remote sensing uses in irrigation management

Remote sensing (RS) data and methodologies have been increasingly used for estimating parameters related to crop water requirements, e.g. ET and K_cb (D’Urso et al., 2010; Melton et al., 2012; Vuolo et al., 2015a; Calera et al., 2017). By providing the spatially distributed representation of data, RS allows understanding the within- and among fields variability, which is important to support irrigation management ranging from local farmers up to water-scheme managers (Table 4). The increased

Plant conditioners

Plant conditioners include anti-transpirants, bio-stimulants and plant growth regulators. They are applied to plants to regulate crop growth and yields, and to mitigate the effects of environmental stresses. Although plant conditioners do not directly reduce non-beneficial crop water consumption, they affect T_c or the T_c/ET ratio and therefore they need to be considered when defining irrigation scheduling. The use of plant conditioners do not change the standard K_c and K_cb coefficients but may

Mulching materials and practices

Mulching is an old practice of covering the soil surface to reduce surface runoff and soil evaporation, improve crop growth, regulate soil temperature, suppress weeds and improve soil health. Different material can be used for mulching, such as bark chips, straw, grass or other plant material, stones or plastic sheets, and humic substances (Rose et al., 2014). A wide variety of environmental and management factors were reported to be involved in the complex crop growth response to humic

Soil management, soil additives and conditioners

Soil management practices that may modify the volume of water infiltrated and stored in the soil, thereby affecting the ratio of E_s and T_c, are usually related to tillage (deep, conservation or no-tillage), land preparation (levelling or ridge and furrows) or in-field rainwater harvesting. Soil additives and conditioners are materials used to increase the soil water and nutrients retention capacity or reduce E_s. Many of these practices affect particularly the top soil, which is the most dynamic

Micro-climate regulation

Different practices to condition micro-climate can be employed in order to reduce water losses and improve beneficial water consumption through T_c. Manipulation of micro-climatic variables such as solar radiation, temperature, wind, humidity and CO₂ concentration could result in a modified micro-climate and improved conditions for crop growth. This may affect crop development, evapotranspiration and growth, and improve crop water use efficiency (Table 6).

Main outcomes and conclusions

Two general considerations emanated from this review. Firstly, there is a need to streamline data collection internationally, however following well-defined scientific approaches, and secondly there is a need for optimization of strategies, methods and technologies to reduce non-beneficial water consumption on farms. A more focused collaboration between researchers and equipment manufacturers may help developing guidance issues for the irrigation practiced.

The literature review indicated that

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The support of the Fundação para a Ciência e a Tecnologia (FCT), Portugal granted to the research unit LEAF (UID/AGR/04129/2013) and to the third author (DL 57/2016/CP1382/CT0022) is acknowledged. Isabel Pôças acknowledges the Post-Doctoral grant supported by the Research Infrastructure Enabling Green E-science for the SKA (ENGAGE SKA), reference POCI-01-0145-FEDER-022217, funded by COMPETE 2020 and FCT, Portugal. This research did not receive other specific grants from funding agencies in the

References (223)

A.M. AbdAllah et al.
Reduction of plant water consumption through anti-transpirants foliar application in tomato plants (Solanum lycopersicum L.)
Sci. Hortic.
(2018)
A.M. AbdAllah et al.
Physiological basis for controlling water consumption by two snap beans genotypes using different anti-transpirants
Agric. Water Manage.
(2019)
R. Adhikari et al.
Preformed and sprayable polymeric mulch film to improve agricultural water use efficiency
Agric. Water Manage.
(2016)
M.O. Adu et al.
Meta-analysis of crop yields of full, deficit, and partial root-zone drying irrigation
Agric. Water Manage.
(2018)
M.C.R. Alberto et al.
Actual evapotranspiration and dual crop coefficients for dry-seeded rice and hybrid maize grown with overhead sprinkler irrigation
Agric. Water Manage.
(2014)
M.C.R. Alberto et al.
Comparisons of energy balance and evapotranspiration between flooded and aerobic rice fields in the Philippines
Agric. Water Manage.
(2011)
R.G. Allen et al.
Evapotranspiration information reporting: I. Factors governing measurement accuracy
Agric. Water Manage.
(2011)
M.C. Anderson et al.
Use of Landsat thermal imagery in monitoring evapotranspiration and managing water resources
Remote Sens. Environ.
(2012)
M.C. Andrenelli et al.
Field application of pelletized biochar: Short term effect on the hydrological properties of a silty clay loam soil
Agric. Water Manage.
(2016)
M. Bittelli et al.
Reduction of transpiration through foliar application of chitosan
Agric. Forest Meteorol.
(2001)

Cited by (79)

An integrated strategy for improving water use efficiency by understanding physiological mechanisms of crops responding to water deficit: Present and prospect
2021, Agricultural Water Management
Artificial intelligence methods reliably predict crop evapotranspiration with different combinations of meteorological data for sugar beet in a semiarid area
2021, Agricultural Water Management
Prediction of crop coefficients from fraction of ground cover and height: Practical application to vegetable, field and fruit crops with focus on parameterization
2021, Agricultural Water Management
Citation Excerpt :
Special practices such as the use of plastic films and organic mulches or small plastic tunnels were not considered due to the lack of information on the reductions in Kc associated with these practices. Brief notes on their effects on Kc were recently provided by Jovanovic et al. (2020). Relative to the initial crop stage, there was a lack of base information for appropriate parameterization for tree and vine crops; therefore, related Kc ini values were not computed.
Updated single and dual crop coefficients for tree and vine fruit crops
2021, Agricultural Water Management
The present study reviews the research on the FAO56 crop coefficients of fruit trees and vines performed over the past twenty years. The main objective was to update information and extend tabulated single (K) and basal (K) standard crop coefficients. The selection and analysis of the literature for this review have been done to consider only studies that adhere to FAO56 method, computing the reference ET with the FAO Penman–Monteith ET equation and field measuring crop ET with proved accuracy. The crops considered refer to vine fruit crops, berries and hops, temperate climate evergreen fruit trees, temperate climate deciduous fruit trees and, tropical and subtropical fruit crops. Papers satisfying the conditions expressed above, and that studied the crops under pristine or appropriate eustress conditions, were selected to provide for standard K and K data. Preference was given to studies reporting on the fraction of ground cover (f), crop height (h), planting density, crop age and adopted training systems. The K and K values obtained from the selected literature generally show coherence relative to the crop biophysical characteristics and reflect those characteristics, mainly f, h and training systems. The ranges of reported K and K values were grouped according to crop density, particularly f and h, and were compared with FAO56 (Allen et al., 1998) previously tabulated K and K values, as well as by Allen and Pereira (2009) and Jensen and Allen (2016), which lead to define update indicative standard K and K values. These values are aimed for use in crop water requirement computations and modeling for irrigation planning and scheduling, thus also aimed at supporting improved water use and saving in orchards and vines.
Standard single and basal crop coefficients for field crops. Updates and advances to the FAO56 crop water requirements method
2021, Agricultural Water Management
This study reviews the abundant research on FAO56 crop coefficients, published following introduction of the FAO56 paper in 1998. The primary goal was to evaluate, update, and consolidate the mid-season and end-season single () and basal () crop coefficients, tabulated for many field crops in FAO56. The review found that the prevalent approach for estimating crop evapotranspiration (ET) is the FAO56 -ET approach, i.e., the product of the and reference evapotranspiration (ET). The FAO56 -ET approach requires use of the FAO56 PM-ET grass reference equation with appropriate crop-specific and/or . Reviewed research provided various approaches to determine and and used a variety of actual crop ET (ET) measurements. Significant attention was placed on accessing the accuracy of the field measurements and models used in these studies. Accuracy requirements, upper limits for values, and related causal errors are discussed. Conceptual approaches relative to transferability requirements are provided with focus on standard crop conditions and use of the FAO56 segmented curve. Papers selected to update used the FAO56 PM-ET, provided accurate measurements to determine and partition ET, and satisfied transferability requirements. Selected observed and values were converted to standard, sub-humid climate as adopted in FAO56. Observed values, with respect to tabulated FAO56 and , were used in consolidating updated values for crops within general categories of grain legumes, fiber crops, oil crops, sugar crops, small grain cereals, maize and sorghum, and rice. Ancillary data, e.g., maximum root depth and crop height, were also collected from selected literature and tabulated. Results showed good agreement between updated and original tabulated FAO56 and , confirming the reliability of the FAO56 values. This indicates change in the (ET/ET ratio) of crops has not occurred due to climate change during the past sixty years. New data for crops, not included in FAO56, are also now presented for several oil crops and pseudo-cereals. The approach adopted for rice differs from FAO56 because consideration was given to the numerous rice water management practices currently used and, thus, values for the initial season of rice were also presented. The review also observed that many research papers did not satisfy the adopted requirements in terms of ET method and/or the accuracy of ET determinations and, therefore, could not be used. Thus, emphasis is placed on adopting improved accuracy and quality control in future research aimed at determining data comparable to presented values. The transferability of standard and has been assured for the values tabulated herein. Improved future applications of the FAO56 -ET method should consider remote sensing observations when available, particularly in defining crop growth stages at given locations.
Soil water balance models for determining crop water and irrigation requirements and irrigation scheduling focusing on the FAO56 method and the dual Kc approach
2020, Agricultural Water Management

View all citing articles on Scopus

View full text

A review of strategies, methods and technologies to reduce non-beneficial consumptive water use on farms considering the FAO56 methods

Highlights

Abstract

Section snippets

Introduction and concepts of water use and water consumption

Irrigation methods

Irrigation management and irrigation scheduling

Crop management

Remote sensing uses in irrigation management

Plant conditioners

Mulching materials and practices

Soil management, soil additives and conditioners

Micro-climate regulation

Main outcomes and conclusions

Declaration of Competing Interest

Acknowledgments

Sci. Hortic.

Agric. Water Manage.

Agric. Water Manage.

Agric. Water Manage.

Agric. Water Manage.

Agric. Water Manage.

Agric. Water Manage.

Remote Sens. Environ.

Agric. Water Manage.

Agric. Forest Meteorol.