Understanding and applying drip irrigation for sustainable agriculture

IWA 20:2017 reviews drip irrigation in comparison to major irrigation methods available and practiced today by farmers worldwide. IWA 20:2017 reviews the benefits of drip irrigation, such as increased yield, reduced water consumption, reduced energy consumption, lower environmental impact, reduced contamination of groundwater and surface water, reduced greenhouse gas emissions and reduced labour. IWA 20:2017 also reviews some of the limitations of drip irrigation. IWA 20:2017 does not provide a technical specification for the implementation of drip irrigation. The qualities of drip irrigation referred to in IWA 20:2017 apply to systems manufactured in accordance with ISO 9261 or equivalent standard. IWA 20:2017 is intended to be used by agricultural policymakers, infrastructure providers, water supply regulatory bodies and authorities, and food chain and farmer cooperatives interested in developing agricultural policies to preserve natural resources and funds. IWA 20:2017 is also intended to be used by farmers and smallholders interested in applying an economic agricultural method.

Compréhension et application de l'irrigation goutte à goutte pour l'agriculture durable

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Status
Withdrawn
Publication Date
26-Feb-2017
Current Stage
6060 - International Standard published
Completion Date
27-Feb-2017
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INTERNATIONAL IWA
WORKSHOP 20
AGREEMENT
First edition
2017-03
Understanding and applying drip
irrigation for sustainable agriculture
Compréhension et application de l’irrigation goutte à goutte pour
l’agriculture durable
Reference number
IWA 20:2017(E)
©
ISO 2017

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IWA 20:2017(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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ii © ISO 2017 – All rights reserved

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IWA 20:2017(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Global environmental changes . 2
4.1 Water scarcity . 2
4.2 Food scarcity and prices . 4
4.3 Land degradation . 4
5 Irrigation . 5
5.1 General . 5
5.2 Common irrigation methods . 5
6 Advantages of drip irrigation . 6
6.1 Crop production . 6
6.2 Water distribution in the field and irrigation efficiency . 8
6.3 Water evaporation from soil surface . 9
6.4 Dry harvest .10
6.5 Irrigation as a delivery system .10
6.6 Water infiltration, water budget and the environment.11
6.7 Soil and water salinity .12
6.8 Soil and land conservation .13
6.9 Energy saving .14
6.10 Treated wastewater irrigation . .15
6.11 Labour savings .15
7 Drip irrigation limitations .16
Annex A (informative) Role of governments: National investment as a driver of growth .17
Annex B (informative) Drip Irrigation implementation .19
Annex C (informative) Used material disposal and recycling .21
Annex D (informative) Impact of drip irrigation on sustainability .22
Annex E (informative) Subjects for which detailed standards could be prepared .26
Annex F (informative) Workshop contributors .27
Bibliography .28
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IWA 20:2017(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
International Workshop Agreement IWA 20 was approved at a workshop hosted by the Swedish
Standards Institute (SIS), in association with the Standards Institution of Israel (SII), held in Stockholm,
Sweden, in August/September 2016.
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IWA 20:2017(E)

Introduction
Dwindling vital natural resources, such as land and water, and rising world population pose a constant
threat that could develop into a future food and water crisis. Given the limited availability of water
and land resources, the amount of food grown today needs to be increased to meet the demands of
tomorrow. Reduction of available water for human consumption needs be addressed. As direct
consumption of fresh water by populations cannot be decreased, the amount of water consumed by
agricultural uses needs to be reduced and allocated for domestic or industrial use.
Drip irrigation addresses water scarcity and other environmental considerations. Its use can save large
amounts of water (over 50 % of water can be saved for certain crop types), and can increase yields.
Drip irrigation not only addresses the need to reduce water consumption and increase yield, but also
requires less labour and energy for operation, leading to lower costs to farmers due to reduced usage of
labour, fertilizers and other chemicals.
Drip irrigation relates to sustainability agriculture issues, and can be used in dry areas, in saline
soil with saline water, and in steep-sloped topographies, where other irrigation methods cannot be
practiced.
Drip irrigation is easy to handle and operate once installed. It is suited for automation and remote
operation by computer or mobile phone. The system’s simplicity makes it easy to install, operate,
maintain and repair.
Other than irrigation, the drip irrigation method is used as a delivery system for fertilizers and other
agrochemicals. Drip’s advantage as a delivery system is its ability to optimize fertilizer usage, and
distribute it exactly where needed, in the root zone, while minimizing its release to the environment.
Adoption of drip irrigation can help achieve sufficient fresh water availability for domestic use and
sufficient food quantity and quality for reasonable pricing, while increasing farmers’ income with yield
increment and cost reduction, and ensuring food security.
The purpose of this document is to review the benefits of the drip irrigation method in relation to other
practiced irrigation methods, and to outline a future standardization roadmap.
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International Workshop Agreement IWA 20:2017(E)
Understanding and applying drip irrigation for sustainable
agriculture
1 Scope
This document reviews drip irrigation in comparison to major irrigation methods available and
practiced today by farmers worldwide. This document reviews the benefits of drip irrigation, such
as increased yield, reduced water consumption, reduced energy consumption, lower environmental
impact, reduced contamination of groundwater and surface water, reduced greenhouse gas emissions
and reduced labour.
This document also reviews some of the limitations of drip irrigation.
This document does not provide a technical specification for the implementation of drip irrigation.
The qualities of drip irrigation referred to in this document apply to systems manufactured in
accordance with ISO 9261 or equivalent standard.
This document is intended to be used by agricultural policymakers, infrastructure providers, water
supply regulatory bodies and authorities, and food chain and farmer cooperatives interested in
developing agricultural policies to preserve natural resources and funds. This document is also intended
to be used by farmers and smallholders interested in applying an economic agricultural method.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
application efficiency
ratio between the amount of water consumed by the plant and the amount of water applied in the field
Note 1 to entry: Application efficiency units are normally presented as the percentage of water consumed by the
plant in relation to the amount of water applied.
3.2
chemigation
injection of agrochemicals, such as pesticides, herbicides or other growth-enhancement products, to
the irrigation system, together with irrigated water
3.3
drip irrigation
irrigation method whereby drippers are installed along a polyethylene (PE) pipe of between 10 cm and
1 m, from which water is released at a given capacity (e.g. 1 l/h)
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IWA 20:2017(E)

3.4
evaporation
type of vaporization of a liquid that occurs at its surface and goes into a gaseous phase that is not
saturated with the evaporating substance
3.5
evapotranspiration
combination of the water transpirated through the plant and the water evaporated through the soil
surface
3.6
fertigation
injection of soluble fertilizers into the irrigation system together with water
3.7
irrigation efficiency
amount of productivity (yield) in relation to the amount of water applied
Note 1 to entry: Irrigation efficiency units are normally presented as the weight of yield per volume of water
applied.
3.8
sprinkler irrigation
method of applying irrigation water that is similar to natural rainfall
Note 1 to entry: In sprinkler irrigation, water is distributed through a system of pipes, usually by pumping, and
then sprayed into the air through sprinklers so that it breaks up into small water drops that fall to the ground.
Note 2 to entry: Sprinkler irrigation is also referred to as overhead irrigation.
3.9
surface irrigation
group of application techniques, such as flood irrigation and furrow irrigation, in which water is applied
and distributed over the soil surface by gravity
Note 1 to entry: Surface irrigation is the most common form of irrigation throughout the world. It has been
practiced in many areas, and has remained virtually unchanged for thousands of years.
3.10
transpiration
process of water movement through a plant and its evaporation (3.4) from aerial parts such as leaves,
stems and flowers
Note 1 to entry: In transpiration, water is necessary for plants, but only a small amount of water is taken up by
the roots used for growth and metabolism.
4 Global environmental changes
4.1 Water scarcity
Climate changes on a global scale over the past years have led to extreme conditions such as strong
storms with heavy precipitation on the one hand and long and dry periods of elevated temperatures on
the other. One major consequence of these changes is the constant reduction of available fresh water
worldwide. Water scarcity already affects every continent around the world. Approximately 1,2 billion
people, almost one-fifth of the world’s population, live in areas with physical water scarcity, and 500
million people are approaching this situation. Another 1,6 billion people, almost one quarter of the
world’s population, face economic water shortages (where countries lack the necessary infrastructure
to take water from rivers and aquifers). Water scarcity is among the main problems that many societies
and the world will be facing throughout this century. Water use has been growing at more than twice
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IWA 20:2017(E)

the rate of the population in the last century and although there is no global water scarcity as such, an
increasing number of regions are chronically short of water.
Water scarcity is both a natural and human-made phenomenon. There is enough freshwater on the
planet for seven billion people, but it is distributed unevenly and too much of it is wasted, polluted
or unsustainably managed. While 1,6 billion people are currently subjected to severe water scarcity,
it is projected that that this figure will reach 2,4 billion by 2030. Figure 1 shows the projected water
scarcity worldwide in 2030. According to this, most of Europe and Asia, as well as the US, will suffer
severe water stress.
NOTE 1 The different colours stand for water stress, percent of total renewable water withdrawn.
[18]
NOTE 2 Source: IFPRI and VEOLIA water project .
Figure 1 — Projected water scarcity in 2030
As illustrated in Figure 2, most available water is consumed by agriculture. For this reason, the most
significant moves to save water should be carried out in this sector. A more efficient irrigation system
can have a positive impact on global water availability. In developing countries where there is water
scarcity, such as in Africa, more than 80 % of the freshwater is used for agriculture to provide basic
food for the population. An efficient use of water in agriculture can drastically increase freshwater
availability for domestic use in these countries.
[14]
NOTE Source: UN water (2013) .
Figure 2 — Global water consumption by sector
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IWA 20:2017(E)

4.2 Food scarcity and prices
By the middle of the 21st century, as the world’s population reaches around 9 billion, global demand for
food, feed and fibre will nearly double while crops may be increasingly used for bioenergy and other
industrial purposes. New and traditional demand for agricultural produce will, as a result, put growing
pressure on already scarce agricultural resources. While agriculture will be forced to compete for
land and water with sprawling urban settlements and increasing industry demands, it will also need
to serve across other major fronts: adapting and contributing to climate change mitigation, helping to
preserve natural habitats, protecting endangered species, and maintaining a high level of biodiversity.
Furthermore, in most regions, fewer people will be living in rural areas and even fewer will be farmers.
As such, they will need new technologies to grow more on less land and with less manpower.
The productivity of rice is projected to dip by 17 %, and the productivity of maize is projected to drop
by 6 % by the middle of the 21st century. A report by the International Food Policy Research Institute
(IFPRI) has stated that food prices will rise even without climate change, but that global warming will
aggravate matters. It concludes that prices are a useful single indicator of the effect of climate change
on agriculture.
Wheat prices are projected to grow by almost 40 % without climate change, but could rise as steeply
as 194 % with climate change, according to the IFPRI report. Rice prices are projected to rise by 60 %
without climate change, and by up to 121 % with climate change. Maize prices are expected to surge
60 % without climate change, and by up to 153 % with climate change. Figure 3 shows projected prices
of some commodity crops in the US.
[13]
NOTE Source: USDA website .
Figure 3 — US farm level prices of corn, wheat and soybean
4.3 Land degradation
Land degradation is the result of a combination of several processes such as soil erosion, soil salinity,
chemical contamination, desertification, nutrient depletion, and water scarcity.
Land degradation has been occurring for a long time, and continues to affect soil worldwide, particularly
in sensitive and vulnerable areas such as tropical and South Africa, Southeast Asia, South China, North-
central Australia, Central America, Southeast Brazil, Alaska, Canada and Eastern Siberia. Some of the
causes of land degradation are man-made or natural processes with human inputs as an accelerator.
Due to recent climate changes, the world has experienced longer drought periods and stronger rain
and storm events. These cause a gradual reduction in natural vegetation that helps stabilize soil during
water runoff. But with the absence of vegetation and stronger water runoff, soil is subjected to erosion
forces by water and wind. Afforestation, toxic chemical soil contamination, mining activities, and soil
salinity are examples of man-made causes of soil degradation that reduce available cropland for food
production. Currently, 18 % of the degraded land is cropland, 25 % central forests, and 17 % north
forests.
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IWA 20:2017(E)

[19]
A paper published by the Food and Agriculture Organization of the United Nations (FAO) in 2014
recommends several methods to achieve sustainable agriculture, while increasing food quality and
quantity and reducing water consumption. One key element suggested is to use water more efficiently
in order to grow more food with fewer resources.
5 Irrigation
5.1 General
Fresh water and fresh healthy food are basic human resources that should be provided everywhere, at
all times, for everyone. In today’s world, large dry regions suffer from water shortages, others suffer
from food scarcity, and others suffer from both. Food and water scarcity are two of the main concerns
for developed and developing countries and global organizations, as well as for many individuals
experiencing drought and hunger.
Agriculture is the clear connection between water and food supply. Food production requires crops,
crop production requires water, and water is related to increased crop production. The relationship
between water supply and crop production, however, is not one-dimensional. A given crop production
can be achieved through less irrigated water; that is, higher yields can be achieved with the same
amount of water applied (i.e. water use efficiency). Increased water use efficiency can be achieved by
simple, efficient irrigation practices.
For all irrigation methods, water applied in the field is not 100 % transferred into plant biomass. Some
of it spreads into the soil by deep percolation or runoff. Some of it evaporates from the soil surface or
wetted leaves, while the remaining water captured in the root zone (“effective water”, as illustrated in
Figure 4) is used by the plant for biomass production. The rate of transpiration is related to the plant
canopy cover and air evaporation conditions. When less water is lost as runoff, deep percolation and
evaporation, the relative portion of effective water is increased and higher effective use of water is
achieved.
Figure 4 — Water evaporation and transpiration in the field
5.2 Common irrigation methods
Rain-fed agriculture covers 80 % of the world’s cultivated land and accounts for about 60 % of crop
production. Today, irrigated agriculture covers 275 million hectares (about 20 % of all cultivated land)
and accounts for 40 % of global food production. This shows the relative importance of irrigation in the
worldwide global food balance. Current irrigation methods are surface irrigation, sprinkler irrigation
(which includes irrigation machines and centre pivots), and micro-irrigation methods such as drip
irrigation.
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Crop irrigation goes back thousands of years. Ancient Egyptians flooded their fields from the Nile, and
the Persians built a network of tunnels for irrigation water delivered to the field by gravity. Gravity
flood irrigation remains the most popular irrigation method in developed and developing countries
today. The major improvement for this method was the invention of pumps that could deliver water
further and higher than the water source. Much research was conducted in surface irrigation (i.e.
flood irrigation, furrow irrigation) since the beginning of the industrial revolution and in agro
science to improve efficient use of water. Formulae to calculate irrigation periods, field slopes and
furrow structure were developed to design and plan furrow irrigated fields. Surface irrigation offers
advantages of simplicity, visibility (i.e. the farmer can see water along the field), and easy control, and
when excluding pumping costs, it can be a low-cost irrigation system.
The next step in irrigated farmlands was the development of sprinklers and similar products such
as rain guns and pivots. In these methods, the water is delivered via buried or surface pipes at high
pressure and high flow rates. Sprinkler irrigation can be easily installed, used and then relocated at the
next field. Sprinkler irrigation not only maintains uniform water distribution on the soil surface, which
can be advantageous for some crops, but also irrigates bare soil not containing plants (i.e. in row crops),
which reduces efficient use of water.
Drip irrigation was invented in the mid-1960 by an Israeli water engineer who developed a method for
delivering a small amount of water directly to where it is needed, i.e. the root zone. In drip irrigation,
only a small portion of the soil that is needed for the plant’s water supply is wetted while the rest of
the soil remains dry. Major progress was made in drip irrigation products and know-how, including
the introduction of better raw materials and new solutions for all crop types. The emitter discharge
rate in drip irrigation systems has dropped over the years. While the first emitters had a flow rate of
8 l/h or more, today, agricultural irrigation emitters produced according to ISO 9261 specifications
have flow rates of less than 1 l/h with a low probability of clogging. Flow rate reduction leads to less
required energy for system operation, which means that a larger area can be irrigated simultaneously.
The flow rate should be adjusted to the plant’s needs, power availability, water availability, and other
local conditions.
6 Advantages of drip irrigation
6.1 Crop production
Drip irrigation used at optimal scheduling in a given field can increase yields by tens to hundreds of
percent compared to other irrigation methods. Reports show that drip irrigation has led to an increase
in sugar cane yield of 133 % in India with a 50 % reduction in water usage compared to flooded plots.
They also show an increase of 16 % in potato yield in China with a 33 % reduction in water usage
compared to sprinkler irrigation. Results like these are due to improved water management by
supplying the exact quantity of water at the right time and at the right place.
Drip irrigation enables not only water delivery to the plant’s roots, but also fertilizer and other
supportive nutrient delivery (see 6.5). To achieve high yields, the right amount of water and nutrients
need to be applied to the plant at the right time and at the right place, according to the plant’s needs. In
surface irrigation, water quantity applied by each irrigation event is high, and the time between two
applications may be long (i.e. days to weeks).
In surface irrigation, the plant can be subjected to oxygen stress for a few hours at the beginning of
irrigation due to soil flooding. On the other hand, it can suffer from water stress just before the next
irrigation due to large time intervals between irrigation application and available water depletion.
In sprinkler irrigation, yields can be relatively high, since water can be applied in much shorter intervals,
depending on the farmer’s ability to reinstall sprinklers in the field or the centre pivots. With sprinkler
irrigation methods, time intervals are a matter of days, which enables effective irrigation scheduling.
Drip irrigation scheduling enables short intervals between irrigation events, i.e. irrigation can be
applied once every few minutes, several times a day, once a day, or every few days. Irrigating in short
intervals enables maintaining relatively constant water content at the root zone, and preventing over-
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irrigation or water stress for the plant. In drip irrigation, farmers can apply the right amount of water at
the right time according to the plant’s needs, and can immediately react to sudden extreme conditions
such as heat, which requires additional water.
Figure 5 shows the amount of water required for drip irrigation compared to flood irrigation in order
to meet the plant’s water demand during the growing season. A large portion of the w
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