Waterlogging and salinity

Waterlogging and Salinity The downward mov ement of residue irrigation water below the root zone is restricted by a barrier. This leads to
accumulation and rise of saline water that reduces productiv ity . This problem can be solv ed by drainage effort. Drainage canals are expensiv e.
Waterlogging can be slowed by adoption of higher efficiency irrigation technologies. They can be induced by incentiv es. Waterlogging and salinity cost
$11 billion annually . 20% of the irrigated land worldwide is affected by salinity . 1.5 million hectares are taken out of production each y ear as a result
of high salinity lev els in the soil.
"Waterlogging" is defined as the state of land in whichthe subsoil water table is located at or nearthe surface with the result that the yield of
crops commonly grownon it is reduced well bellow for the land, or, if the land is not cultivated, it cannot be put to its normal use because of
the high subsoil water table.
"Salinity control" is defined as the physical control, management, and use of water and related land resources in such a way as to maintainor
reduce salt loading and concentrations of salt inwater supplies.
Drainage of irrigated land is required to reduce waterlogging and soil salinizationthat inevitably accompanies waterlogging inarid zones. At
present, about 20-30 million hectares of irrigated land are seriously affected by salinity.
WATERLOGGING AND SALINITY
* Basic Concepts in Waterlogging and Salinity
* Control of Waterlogging and Salinity Problems
* Irrigation Water Quality
BASIC CONCEPTS IN WATERLOGGING AND SALINITY
Excess water in the plant root zone restricts the aeration required for optimum plant
growth. It may affect the availability of several nutrients by changing the environment
around the roots.
Excess salts in the root zone inhibit water uptake by plants, affect nutrient uptake and
may result in toxicities due to individual salts in the soil solution. Excess
exchangeable sodium in the soil may destroy the soil structure to a point where water
penetration and aeration of the roots become impossible. Sodium is also toxic to many
plants.
Waterlogging and salinity in the soil profile are most often the result of high water
tables resulting from inadequate drainage or poor quality irrigation water. Adequate
surface drainage allows excess irrigation and rain water to be evacuated before excess
soil saturation occurs or before the water is added to the water table. Adequate
subsurface drainage insures that water tables are maintained at a sufficient depth
below the soil surface to prevent waterlogging and salt accumulation in the root zone.
Salinization of the soil profile is prevented because upward capillary movement of

water and salts from the water table does not reach the root zone. Adequate subsurface
drainage also allows salts to be removed from the soil profile through the application
of excess irrigation water (leaching).
To understand how we may prevent, eliminate or otherwise deal with a waterlogging
or salinity problem, we must first understand how crops and soils respond to excess
water and salts.
Waterlogging and High Groundwater Tables
The growth of most crops is affected when groundwater is shallow enough to
maintain the soil profile in the root zone wetter than field capacity. This excess water
and the resulting continuously wet root zone can lead to some serious and fatal
diseases of the root and stem. Working the soil when overly wet can destroy soil
structure and thus restrict root growth and drainage further. The chemistry and
microbiology of waterlogged soils is changed due to the absence of oxygen. This can
result in changes which affect the availability of many nutrients. For example,
nitrogen can undergo denitrification more readily and be lost to the atmosphere as a
gas. The anaerobic (reducing) environment results in changes to metals and other
cations that can result in deficiencies or toxicities. For example, sulfide, ferrous and
manganese ions will accumulate in waterlogged soils.
Crops vary in their tolerances to waterlogging and a high water table. Some crops,
such as rice, are adapted to these conditions and can thrive. The table below presents
the different tolerances of some crops.
Tolerance Levels of Crops to High Groundwater Tables and Waterlogging
GROUNDWATER AT 50 CM WATERLOGGING
HIGH TOLERANCE sugarcane, potatoes, rice, willow, plum, broad beans
strawberries, some grasses
MEDIUM TOLERANCE sugarbeet, wheat, oats, citrus, bananas, apple, barley, peas,
cotton pears, blackberries,
onion
SENSITIVE maize, tobacco, peaches, cherries, olives, peas, beans, date palm
The capillary fringe is a saturated zone that extends some distance above the water
table. Water moves into this zone by capillary movement. The roots on many crops do

not generally penetrate closer than 30 cm above the water table. The capillary fringe is
thinner in sandy soils than in loam or clay soils. Thus the following depths to
groundwater are suggested as a minimum for most crops:
Sandy Soils ----------- Rooting Depth + 20 cm
Clay Soils ------------ Rooting Depth + 40 cm
Loam Soils ------------ Rooting Depth + 80 cm
Soil and Water Salinity
Crop yields decrease linearly with increasing salt levels above a given threshold level.
This threshold level will vary according to the tolerance of the crop. Yield decreases
in the absence of toxic salts such as boron are mainly due to the difficulties the crop
has in taking up water due to the high concentration of salt in the soil solution. Often
crops present a droughty or dry appearance in high salt soils.
The table below presents the tolerance of different crops to soil and water salinity
levels, and the effect that increasing salinity levels has on yield. In this table, the ECe
(Electrical Conductivity of the Saturated Paste Extract) is a measure of soil salinity,
ECw (Electrical conductivity of the Irrigation Water) a measure of water salinity. The
Max ECe is the highest ECe that the plant can tolerate. The Yield Potential is the
percent of an optimum yield that can be attained under given growing conditions.
Crop Salt Tolerance Levels for Different Crops as Influenced by Irrigation
Water or Soil Salinity
YIELD POTENTIAL
FIELD CROPS 100 90 % 75 % 50% 0%
ECw ECe ECw ECe ECw ECe ECw ECe ECw ECe
Barley 8 5.3 10 6.7 13 8.7 18 12 28 19
Cotton 7.7 5.1 9.6 6.4 13 8.4 17 12 27 18
Sugarbeet 7 4.7 8.7 5.8 11 7.5 15 10 24 16
Sorghum 6.8 4.5 7.4 5 8.4 5.6 9.9 6.7 13 8.7
Wheat 6 4 7.4 4.9 9.5 6.3 13 8.7 20 13
Wheat, Durum 3.8 7.6 5 10 6.9 15 10 24 16
Soybean 5 3.3 5.5 3.7 6.3 4.2 7.5 5 10 6.7
Cowpea 4.9 3.3 5.7 3.8 7 4.7 9.1 6 13 8.8
Peanut 3.2 2.1 3.5 2.4 4.1 2.7 4.9 3.3 6.6 4.4

Paddy Rice 2 3.8 2.6 5.1 3.4 7.2 4.8 11 7.6
Sugarcane 1.7 1.1 3.4 2.3 5.9 4 10 6.8 19 12
Corn(Maize) 1.1 3.4 2.3 5.9 4 10 6.8 19 12
Flax 1.7 1.1 3.4 2.3 5.9 4 10 6.8 19
Broadbean 1.5 1.1 2.6 1.8 4.2 2 6.8 4.5 12 8
Bean 1 0.7 1.5 1 2.3 1.5 3.6 2.4 6.3
VEGETABLE CROPS
Zucchini Squash 3.1 5.8 3.8 7.4 4.9 10 6.7 15 10
Beet, Red 4 2.7 5.1 3.4 6.8 4.5 9.6 6.4 15 10
Squash 3.2 2.1 3.8 2.6 4.8 3.2 6.3 4.2 9.4 6.3
Broccoli 2.8 1.9 3.9 2.6 5.5 3.7 8.2 5.5 14 9.1
Tomato 2.5 1.7 3.5 2.3 5 3.4 7.6 5 13 8.4
Cucumber 2.5 1.7 3.3 2.2 4.4 2.9 6.3 4.2 10 6.8
Spinach 2 1.3 3.3 2.2 5.3 3.5 8.6 5.7 15 10
Celery 1.8 1.2 3.4 2.3 5.8 3.9 9.9 6.6 18 12
Cabbage 1.8 1.2 2.8 1.9 4.4 2.9 7 4.6 12 8.1
Potato 1.7 1.1 2.5 1.7 3.8 2.5 5.9 3.9 10 6.7
Sweet Potato 1 2.4 1.6 3.8 2.5 6 4 11 7.1
Pepper 1.5 1 2.2 1.5 3.3 2.2 5.1 3.4 8.6 5.8
Lettuce 1.3 0.9 2.1 1.4 3.2 2.1 5.1 3.4 9 6
Radish 1.2 0.8 2 1.3 3.1 2.1 5 3.4 8.9 5.9
Onion 1.2 0.8 1.8 1.2 2.8 1.8 4.3 2.9 7.4 5
Carrot 1 0.7 1.7 1.1 2.8 1.9 4.6 3 8.1 5.4
Turnip 0.9 0.6 2 1.3 3.7 2.5 6.5 4.3 12 8
FORAGE CROPS
Ryegrass,per. 3.7 6.9 4.6 8.9 5.9 12 8.1 19 13
Vetch,Common 2 3.9 2.6 5.3 3.5 7.6 5 12 8.1
Sudan Grass 1.9 5.1 3.4 8.6 5.7 14 9.6 26 17
Forage Cowpea 1.7 3.4 2.3 4.8 3.2 7.1 4.8 12 7.8
Alfalfa 2 1.3 3.4 2.2 5.4 3.6 8.8 5.9 16 10
Clover,Berseem 1 3.2 2.2 5.9 3.9 10 6.8 19 13
Other Clover 1 2.3 1.6 3.6 2.4 5.7 3.8 9.8 6.6
FRUIT CROPS
Date Palm 4 2.7 6.8 4.5 11 7.3 18 12 32 21
Grapefruit 1.2 2.4 1.6 3.4 2.2 4.9 3.3 8 5.4

Orange 1.7 1.1 2.3 1.6 3.3 2.2 4.8 3.2 8 5.3
Peach 1.7 1.1 2.2 1.5 2.9 1.9 4.1 2.7 6.5 4.3
Apricot 1.6 1.1 2 1.3 2.6 1.8 3.7 2.5 5.8 3.8
Grape 1.5 1 2.5 1.7 4.1 2.7 6.7 4.5 12 7.9
Almond 1.5 1 2 1.4 2.8 1.9 4.1 2.8 6.8 4.5
Plum, Prune 1 2.1 1.4 2.9 1.9 4.3 2.9 7.1 4.7
Blackberry 1 2 1.3 2.6 1.8 3.8 2.5 6 4
Strawberry 0.7 1.3 0.9 1.8 1.2 2.5 1.7 4 2.7
An example of how to use this table is as follows: A farmer can produce 50 Kg per
Hectare of corn on good soil. The farmer has a field with an ECe of 3.8 which gives
him or her many problems. Using the table, an estimate can be made of an expected
yield of roughly 37 Kg per Hectare (i.e. a 75% Yield Potential) for this field.
This table represents general information about relative tolerances to salt, but varietal
differences are also very important. Much effort has been put into developing salt
tolerant varieties of many crops because of the worldwide salinity problem. In some
cases, minor problems can be alleviated by selecting the correct variety.
Electrical Conductivity (EC) is the reciprocal of Resistance (1/ohms), and is
measured in mmhos/cm or in dS/m (dS/m = mmhos/cm). EC is measured with a
salinity or conductivity meter, which is a standard piece of equipment in all soil labs
and can often be purchased at a reasonable price for field use. ECw (salinity of the
water) is measured by simply inserting the conductivity meter in the irrigation water,
with adjustment made for temperature. ECe (soil salinity) is a little more complicated,
requiring a saturated paste of the soil from which the water is then extracted and the
salts measured.
Exchangeable sodium in the soil becomes a problem when the predominant salts in
irrigation water or in the soil solution are sodium salts. Soil constituents which
determine soil structure, such as clays and organic matter (soil colloids), have
negative charges (exchange sites) on their outer surface which loosely attach to
positive ions and molecules (cations) such as Calcium (Ca++), Ammonium (NH4+),
and Sodium (Na+) (see Figure 7.1). These cations can readily be replaced by other
cations (they are exchangeable). If there is excessive sodium in the soil solution, it
will take over most of the exchange sites. Sodium is a small cation, so when present in
large quantities on the exchange sites, it destroys the separation between soil particles.
What happens then is that the clay or organic matter collapses on itself leaving no air
spaces or pores (deflocculation). In some cases, the structureless organic matter is

dispersed and can be lost in the drainage water, hence the old-fashioned term for these
soils is Black alkali soils.
Sodium is measured as the Exchangeable Sodium Percent (ESP) or as the Sodium
Absorption Ratio (SAR ). The ESP is simply the percent of all the exchange sites in
the soil which are holding sodium on them. The SAR is more complicated, and is
merely an index of the extent of the problem.
Very high sodium levels not only affect soil structure, but are toxic to many crops.
Classification of Salt Affected Soils
Saline Soils
These soils contain sufficient amounts of soluble salts to interfere with germination,
growth and yield of most crop plants. They do not contain enough exchangeable
sodium to alter soil characteristics. Technically, a saline soil is defined as a soil with
an ECe greater than or equal to 4 mmhos/cm and an Exchangeable Sodium Percent
(ESP) less than 15. The soil pH is usually less than 8.5. These soils may have a white
crust or white salt crystal accumulation on the surface (salt blooms) so they are
sometimes called "white alkali soils". Excess soluble salts can be removed by
leaching if drainage permits as will be discussed.
Saline-Sodic Soils
These soils contain soluble salts and exchangeable sodium in sufficient quantities to
interfere with the growth of most crops. Technically, a saline-sodic soil is defined as a
soil having an ESP greater than 15 and an ECe greater than or equal to 4 mmhos/cm.
The soil colloids (charged particles) are collapsed (deflocculated), and drainage and
aeration are very poor. pH is usually in the range of 8-10.
Sodic Soils
These soils contain sufficient exchangeable sodium to interfere with the growth of
most crops, but do not contain appreciable quantities of soluble salts. Technically,
they are soils with an ESP greater than 15 and an ECe of less than 4 mmhos/cm.
Drainage and aeration are very poor because soil colloids are very dispersed. The pH
is generally above 8.5. These soils are sometimes called "black alkali soils". High pH
values generally can be used as a indicator of possible sodium problems, but this is
not always true.
Evaluating Waterlogging and Salinity Problems

The evaluation of the extent of waterlogging and salinity problems can usually be
conducted through simple observation, communication and possibly some soil
analysis. The following steps can be followed:
1) Interview local agronomists, agricultural technicians, and agribusiness personnel.
Ask them questions about water table depths, salinity problems etc. If such problems
exist, how are local farmers taking care of them?
2) Conduct a field reconnaissance to find out if the problem exists in your area. Wells,
gravel pits and deep channels which show the depth to groundwater should be
observed. If there are few of these, then install pits or auger small observation wells
into the soil to depths of 30 to 80 cm below the expected rooting depths (30 cm for
sandy soils, 80 cm for loams and fine textured soils). If soil horizons are reached
which are grey, wet and may contain black or red mottles, you have hit "gleyed" or
waterlogged horizons. You can assume at this point that soils are poorly drained at
this level.
As part of the reconnaissance, observe fields for signs of excess water or salinity such
as:
a) White crusts on the soil surface. There may be a problem even when these are not
present.
b) Plants which are stunted, appear droughty or irregular even though the soil is fairly
moist. In cases of high salinity, the leaves may be curled up and yellow. The margins
of the leaves may burn, a reddish color is often seen and in some cases the plant may
actually die during or shortly after germination and emergence.
c) Use of drainage water, tailwater or water which has been used extensively for
washing, irrigation or industrial purposes before reaching the field. This may be a
problem when the farmer is a tail-end user on a major irrigation system. This water
can accumulate salts.
d) Soils with poor structure, which appear sticky and plastic when wet and which do
not grow a crop. Hard, structureless soil pans can develop at different depths in sodic
soils.
e) Standing water or wet spots in parts of the field where crops grow poorly. Standing
water in spots after a prolonged drying period are also useful indicators.

f) When soil is dry and smooth or has slicked over areas without vegetation,
sometimes with a thin peeled up skin, it can indicate infiltration and sodic soil
problems
g) Absence of field drains for removing excess water.
h) Condition of field drains: Are surface drains full of vegetation or plugged up? Are
surface and subsurface drains operating properly?
i) If the opportunity presents itself, take soil samples and have them analyzed if you
suspect a salinity problem, or look at past samples if any are available.
CONTROL OF WATERLOGGING AND SALINITY PROBLEMS
Surface and Subsurface Drains
The first requisite in the prevention or elimination of waterlogging and salinity
problems is an adequate drainage system. Very often, the natural drainage in an area
along with good water management is sufficient to eliminate excess water and to
preclude the need for expensive subsurface drainage systems. However, almost every
farmer who applies water by surface irrigation or who deals with significant rainfall
should have adequate surface drainage facilities to remove excess water. This will
allow the farmer to avoid waterlogging and possible salinity problems at the tail end
of borders, furrows or basins after irrigation or intense rainstorms. It will also allow
the prevention of erosion associated with natural movement of the excess water over
the soil surface.
Surface drains are open channels which collect water as it runs off of, or into irrigated
fields. These drains convey water to a stream or channel where it can be carried
safely. The design procedures for these drains are the same as for any open channel
(see Chapter 5). The main requirement is that they are able to convey the maximum
expected flow rate without erosion. At the tail-end of irrigated fields, these drains are
often broad and shallow to allow farm machinery to operate efficiently.
Subsurface drainage may be accomplished either through the construction of open
trenches or through buried clay or concrete tiles or perforated pipe. Subsurface
drainage systems can be classified as Natural, Herringbone,GridironorInterceptor
(Cutoff) types.
The Natural systems are used in fields where there are small and isolated wet areas.
The buried drain lines follow natural draws or depressions.

The Herringbone systems are useful in situations where the land slopes toward a
draw on either side. The main line follows the draw, and the laterals empty into this
from both sides.
The Gridiron systems are similar to the Herringbone except that they enter the main
drain from only one side.
Interceptor drains are installed across a slope to intercept the passage from higher
ground. These drains can prevent the waterlogging of soils below irrigation ditches,
springs or at the foot of a hill. They can be useful in collecting water for recycling into
the irrigation system.
The design, drain size, spacing and depth are a function of the water table depth
desired, the soil permeability (hydraulic conductivity), amount of water to be drained,
economics of construction, etc. Generally, the deeper the drains are
installed, the wider the spacing between drains can be. In humid regions, drain
spacings of 10 to 50 meters (30 to 150 feet) are common. The closer spacing is used in
heavier soils with higher value crops and greater rainfall. In more arid irrigated areas,
spacings of 50 to 200 meters (150 to 600 feet) are common.
Tile drain is common in 10, 13 and 15 cm (4, 5 and 6 inch) sizes, but can be obtained
in greater sizes as can corrugated drainage pipe. Minimum grades are sometimes
based on a minimum velocity of 0.45 m/s (1.5 feet per second) at full flow. Surface
inlets, outlets and cleanouts, envelope filters and other structures must be properly
designed if the drain system is to operate correctly.
The design of subsurface drains is generally more complex than for surface drains and
requires significant knowledge of groundwater hydrology. Thus the reader should
seek the assistance of a drainage engineer before undertaking the design of expensive
subsurface drains. The one possible exception is the Interceptor drain which can be
installed as an open channel below the level of an irrigation canal to provide drainage
to land which would otherwise be waterlogged by the canal.
Reclamation of Salt Affected Soils
The chemical and physical analysis of soils provides a basis for the diagnosis,
treatment and management of salt affected soils. After diagnosing the problem but
before actual reclamation, two steps must be observed.
1. Establishing adequate drainage in the area. The water table should be lowered if it
is high and water should be at least 3 to 4 meters below the surface.

2. The land should be level or contour farmed so that the surface of the soil will be
covered uniformly by water.
Saline Soil
If the soil is only saline, it can be reclaimed simply by leaching the excess salts below
the root zone. The quantity of water depends on the texture of the soils, the
concentration of salts in the soil and in the leaching water (the higher, the more water
needed) and the amount of salts to be leached. On the average, 0.5 to 1.25 meters of
water are required.
Saline Sodic Soil and Sodic soil
If leaching is conducted on a saline-sodic soil, the soil will become sodic and could
present more problems than it would have originally. Saline-sodic soils require the
leaching process to be accompanied by the application of amendments. The
amendments that are used are the same ones that would be utilized on a sodic soil.
Sodic soils are generally very poor in infiltration, so amendments are slow to enter
soil. For this reason, both compacted saline-sodic soils and sodic soils should undergo
deep cultivation such as deep ripping to break up hardpans which prevent infiltration.
Correcting Sodium Problems with Amendments:
The presence of lime (free calcium carbonate) in soil allows for the widest choice of
amendments. To test for this, a spoonful or clod of soil is treated with a few drops of
sulfuric acid or hydrochloric acid. If bubbling or fizzing occurs where the acid drops
fall, then lime is present. The greater the fizzing, the more lime is present. If the soil
contains lime, any of the amendments listed in Table 7.3 can be used. If no lime is
present, then only amendments containing soluble calcium are recommended.
Commonly UsedAmendment Materials and Their Equivalent Amendment Values
Tons of Amendment Material Equivalent
to:
Amendment Chemical Formula 1 Ton of 1 Ton of
(100% Basis) Pure Gypsum Soil Sulfur
Gypsum CaSO4.2H20 5.38
Soil Sulfur S 0.19 1
Sulfuric Acid H2SO4 0.61 3.2
Ferrous Sulfate Fe2(SO4).9H2O 1.09 5.85
Lime Sulfur CaSx 0.78 4.17

Calcium Chloride CaCl2.H2O 0.86 ---
Calcium Nitrate Ca(NO3)2.H2O 1.065 ---
Aluminum Sulfate Al2(SO4)3 --- 6.34
The percent purity is generally given on the bag.
Types of Amendments
Calcium containing amendments such as gypsum react in the soil as follows:
GYPSUM + SODIUM-SOIL _ CALCIUM SOIL + SODIUM SULFATE
Leaching is then undertaken to wash out the sodium sulfate. Repeated applications are
necessary in many cases. The amount of gypsum used is substantial, often 1.5 or more
tons of material per hectare, because it is not highly water soluble, and in many cases,
the reaction described above takes a long period of time. It needs to be incorporated to
speed up reaction. A more precise measurement of the "gypsum requirement" is
available from most soil labs, assuming a material of 100% purity.
Acids such as sulfuric acid undergo a two step process:
1. SULFURIC ACID + SOIL LIME _ GYPSUM + CO2 + WATER
2. GYPSUM + SODIUM-SOIL _ CALCIUM SOIL + SODIUM SULFATE
Acids are dangerous and corrosive, so handling can be a problem. The volume applied
has to be controlled because of excessive frothing. Occasionally, cheap industrial
sources are available but must be used with caution because of the potential for heavy
metal contamination. An analysis of spent acids is recommended. They are much
faster than other reclamation procedures because the reaction is instantaneous.
Acid forming materials such as sulfur are much slower because they undergo a three
step process, the first step requiring microbial intervention in the oxidation reaction:
1. SULFUR + OXYGEN + WATER _ SULFURIC ACID
2. SULFURIC ACID + SOIL LIME _ GYPSUM + CO2 + WATER
3. GYPSUM + SODIUM-SOIL _ CALCIUM SOIL + SODIUM SULFATE
These steps can take years.

Effectiveness and Amount of Amendments:
In the absence of a soil analysis for gypsum requirement, a rule of thumb is that
something is better than nothing. Gypsum is usually used in large quantities, so 0.5 to
2 metric ton applications per hectare are not unusual. To convert the gypsum
requirement to an amount of some other amendment, Table 7.3 offers a simple
guideline. Simply multiply the gypsum ton equivalent by the gypsum requirement.
If the material being considered is not 100% pure, a simple calculation will indicate
the amount needed to be equivalent to 1 metric ton of pure material:
100 % / % purity = m Tons per 1 m ton of pure material.
For example: If gypsum is 60 percent pure, the calculation would be 100/60 = 1.67 m
tons. In other words, 1.67 tons of 60 percent pure gypsum is equivalent to 1 m ton of
100% material.
Sulfur presents an additional challenge, since not only purity but the fineness of the
granules must be accounted for. The finer the material, the faster microbial oxidation
will occur. Coarse grade materials are highly insoluble and may take years to be
active.
Management of Saline and Sodic Soils
Often, it is too expensive or impractical to reclaim saline or sodic soils, or even to
maintain them at low salinity levels. It may be impossible to adequately drain an area,
amendments may not be available or may be too expensive, or the water used for
irrigation may be of poor quality.
In these situations, there are various management practices that will aid in controlling
or reducing the impact of salts or sodium:
1. Selection of crops or crop varieties that have higher tolerances for salt or sodium
(See Table 7.2)
2. Use of special planting procedure that will minimize salt accumulation around the
seed. (See Figure 7.2)
3. Use of the appropriate irrigation method for the root characteristics of the crop (See
Figure 7.3).

4. Use of sloping beds and other special land preparation procedures and tillage
methods to provide a low salt environment
5. Use of irrigation water to maintain a high water content to dilute the salts or to
leach the salts out for germination or from the root zone.
6. Use of physical amendments such as manure, compost, etc. for improving soil
structure and tilth. Conservation tillage to incorporate crop residues will help create
drainage.
7. Deep ripping of soil to break up sodic and other hardpans or other impervious
layers to provide internal drainage.
8. Use of chemical amendments as described.
9. Good, sound farming practices and careful fertilizer management.
IRRIGATION WATER QUALITY
An understanding of the quality of the irrigation water is essential in any salinity or
sodium control program. Often, poor quality water is the source of the salinity or
sodium problem. Table 7.4 presents some quality guidelines for evaluating the
riskiness of the water. If water is of poor quality, tactics such as dilution with other
water sources, or applications of larger leaching amounts can be implemented.
Effect of Irrigation Water Quality on Soil Salinity, Permeability, Toxicity
None Moderate Severe
Effect on:
Salinity ECw (mmhos/cm) < 0.75 0.75 - 3.0 > 3.0
Permeability ECw (mmhos/cm) > 0.50 0.50 - 0.20 < 0.2
adj. SAR
Montmorillonite 1 < 6.0 6.0 - 9.0 > 9.0
Illite 2 < 8.0 8.0 - 16.0 > 16.0
Kaolinite 3 < 16.0 16.0 - 24.0 > 24.0
Toxicity (most tree crops)
Sodium (adj. SAR) 4 < 3.0 3.0 - 9.0 > 9.0
Chloride (meq/l) 5 < 4.0 4.0 - 10.0 > 10.0
Boron (mg/l) < 0.75 0.75 - 2.0 > 2.0

Miscellaneous
Nitrogen (mg/l) 6 < 5.0 5.0 - 30.0 > 30.0
Bicarbonate (HCO3) < 1.5 1.5 - 8.5 > 8.5
pH Normal Range: 6.5 - 8.4
1 Temperate clay soils, highly expandable, not suited for ceramics or clay tiles.
2 Temperate clay soils or tropical soils in low rainfall or wet/dry climates. Not highly
expandable. Can be used for ceramics.
3 Tropical clay soils in high rainfall areas. Usually have a distinct red or yellow color.
4 For most field crops
5 Sprinkler irrigation may cause leaf burn when >3 meq/l.
6 Excess nitrogen causes excessive vegetative growth, lodging, and delayed crop
maturity.
Salinity problems can occur due to saline water being used in irrigation. Decreased
soil infiltration rates can be the result of irrigation water which is low in salts but high
in sodium, or water which has a high sodium to calcium ratio. If infiltration problems
are due to high sodium water, the effect will be noticed in the surface few centimeters
of the soil.
Other water quality problems to be on the look-out for include:
1. Water high in iron, bicarbonate or gypsum which can result in unsightly deposits on
cash crops.
2. Highly acid (low pH) or corrosive water which can result in severe corrosion of
irrigation hardware such as pipelines and wells.
3. Other pH abnormalities (high or low) which can result in encrustation or other
effects on crops.
4. Risks from diseases such as Bilharzia (schistosomiasis), malaria and lymphatic
filariasis; or risks from vectors of diseases such as mosquitoes. Vector breeding can
often originate in situations where there is low water infiltration rates, use of
wastewater for irrigation or poor drainage.

5. Sediments which can clog up irrigation structures, build films on leafy cash crops
which make them unacceptable for marketing and seal-off soils due to the depositing
of structureless silt on soil surfaces.
WealthfromWater factsheetWaterlogginginsoil SymptomsandcausesWaterloggingoccurswhenthe
soil profile orthe rootzone of a plantbecomessaturated.Inrain-fedsituations,thishappenswhen
more rain fallsthanthe soil can absorbor the atmosphere canevaporate.Lackof oxygeninthe root
zone of plantscausestheirroot tissuestodecompose.Usuallythisoccursfromthe tipsof roots,and this
causesroots to appearas if theyhave beenpruned.The consequence isthatthe plant’sgrowthand
developmentisstalled.If the anaerobiccircumstancescontinue foraconsiderable timethe plant
eventuallydies.Mostoften,waterloggedconditionsdonotlastlongenoughforthe plantto die.Once a
waterloggingeventhaspassed,plantsrecommence respiring.Aslongassoil conditionsare moist,the
olderrootsclose to the surface allowthe planttosurvive.However,furtherwaterlogging-inducedroot
pruningand/ordry conditionsmayweakenthe planttothe extentthatitwill be verypoorlyproductive
and mayeventuallydie.Manyfarmersdonot realise thatasite is waterloggeduntil waterappearson
the soil surface (see picture above).However,bythisstage,plantrootsmayalreadybe damagedand
yieldpotential severelyaffected.Keypoints Waterloggingoccurswhenrootscannotbreathe due to
excesswaterinthe soil profile. Waterdoesnothave to be on the soil surfacefor waterloggingtobe a
potential problem. Improvingdrainage candecrease the time thatthe crop rootsare subjectedto
anaerobicconditions. Opentrenchesare the simplestdrainsandarethe firstrequirementof a
drainage systemwithmore intensivedrainage suchasundergroundpipes,raisedbedsorhumpand
hollow,providingmore effectivedrainage.BackgroundWaterloggingcanlimitagricultural productivity
inmany areasof Tasmaniaas the State enjoysrelativelyhighrainfall whichnormallyoccurswithan
excessof rainfall overevaporationinwinterandspring.Manysoilsexperiencepartsof the yearwhen
theyare saturateddue tohighregional watertables,low ratesof waterconductivity,perchedwater
tablesor seepage.Waterloggingoccurswheneverthe soil issowetthatthere isinsufficientoxygenin
the pore space (anaerobic) forplantrootstobe able toadequatelybreathe.Othergasesdetrimentalto
root growth,suchas carbon dioxide andethylene,alsoaccumulate inthe rootzone andaffectthe
plants.Plantsdifferintheirdemandforoxygenandaplant’sdemandforoxygeninitsrootzone will
vary withitsstage of growth.WealthfromWaterfactsheetContact:Ph1300 368 550 Email:
wfwp@dpipwe.tas.gov.auWealthfromWaterLocal call on1300 368 550 email
wfwp@dpipwe.tas.gov.auwww.dpipwe.tas.gov.au/wealthfromwaterProducedbyDrBill Cotching,TIA
Last updatedMarch 2012 IdentifyingproblemareasDiagnosing yourwaterloggingproblemisthe keyto
achievingsuccesswithanydrainage.Youneedtoknow the source of the water andwhere itis moving
inthe soil.Thiswill ensurecorrectselectionof draintype toinstall anddepthof installation.Inwinterit
iseasierto identifythe limitsof wetareas,particularlyseepage areas,andtoidentifysoil horizonson
whicha perchedwatertable occurs.Forthe initial investigation,digaseriesof holesuptoone metre
deepinandaround wetareas.A numberof pegsare useful tomarkout drainage linesandpotential
drainlocations.Signsof waterloggingtolookforon the soil surface include ponding,puggingbystock
and ruts frommachinery,poorcropestablishmentandgrowth,andpatchesof excessiveweedgrowth.
Benefitsof improveddrainage Reducingthe lengthof time soilsremainwaterloggedbythe installation
of appropriate drainage systems,resultsingreaterease of soil management,increasedplantgrowthby
improvingaerationandsoil temperature,pluscontrol of plantdiseases.Improvingdrainageresultsin
the soil becomingfriableratherthanplastic,andlesslikelytobe compactedor pugged.A more aerated
soil encouragesorganismswhichmetaboliseorganicmatterandstabilise soil aggregates.Improved

drainage increasesthe depthof aeratedsoil allowingplantrootstoexplore agreatersoil volume.This
increasesthe pool of nutrientsavailable,andwithagreatervolume of soil todraw on for water,plants
are able tocontinue growingforlongerduringdrysummerperiods,whichisoftenone of the
unexpectedbenefitsof improveddrainage.Drainage canlessenthe incidence of fusariumand
phytophthorarootrots whichcan occur whenplantsare stressedbywaterloggedconditionsandpoor
aeration.Poorsoil drainage maybe limitingplantgrowthtothe extentthatnoresponsesare gained
fromincreasedfertiliseruse.Drainage isalsoanimportantwayof improvingworkingconditionsby
removingthe unpleasantnessof muddy,wetsoil.DisclaimerInformation inthispublicationisintended
for general informationonlyanddoesnotconstitute professional advice andshouldnotbe reliedupon
as such.No representationorwarrantyismade as to the accuracy, reliabilityorcompletenessof any
informationinthispublication.Readersshouldmake theirownenquiriesandseekindependent
professionaladvice before actingorrelyingonanyof the informationprovided.The Crownand
TasmanianInstitute of Agriculture,theirofficers,employeesandagentsdonot acceptliabilityhowever
arising,includingliabilityfornegligence,foranylossresultingfromthe use of or reliance upon
informationinthispublication.Typesof drainage Drainage iscarriedouteitheronthe surface or
undergrounddependingonthe diagnosisof the problem.Surfacedrainscanbe openarterial ditches,
grassedwaterwaysorhumpand hollow.Undergrounddrainscanbe pipe drains,mole drains,ordeep
ripping.Surface drainsare a minimal investment,lastalongtime providedstockare excluded,andcan
alwaysbe deepenedormoved.Differentsoil typesrequire differentsolutionstodrainage problems.
Planyour drainage inthe winter,butinstall drainsinthe summer.
20.02.16
Waterlogging is happened when the soil is so f illed or soaked with water that caused the roots of the plant to rot.
Waterlogging is 100% when water table rises to the surf ace. Howev er the process of waterlogging starts ev en when the water table is quite below the
surf ace. In this case thereexists a capillary f ringe. For example presence of water due to capillary action abov e the saturation line. Capillary f ringe
depth depends upon the ty pe of soil. If the soil is coarse and sandy , then its depth is low. Depth of capillary f ringe is large f or f ine grained soil. The
other important f actor is the depth of root-zone which v aries f rom crops to crops. In case of wheat, the depth of root zone is about 2 f eet, and if there is
a height of capillary f ringe is 4f t. Then water logging process will start if the water table is at 6 meter f rom the surf ace.
Harmf ul ef f ects of waterlogging and salinity are caused by unthoughtf ul planning of irrigation sy stem.
With respect to water logging and salinity , there are f ollowing harmf ul ef f ects:
1. Waterlogged soil prov ides excellent breeding grounds f or misquitoes, and cause malaria.
2. It causes loss in crop y ield.
3. When waterlogged soil are f ully saturated, plant roots can not absorb water. Theref ore, they are depriv ed of aeration. Due to absence of
aeration, anaerobic conditions exist killing the aerobic bacteria present in the root-zone of the plant. This aerobic bacteria helps to make f ood f or the
plant. This aerobic bacteria transf orm chemical compounds into nitrogen and phosphorus and prov ides f ood to the plant. Due to waterlogging, killing
of this bacteria occured and ultimately causes the death of the plant.

4. In rainf all or irrigation, water af ter saturating the root-zone trav els downward washing down excess salts. When the unsaturated conditions begin,
plant start taking up water. In waterlogged soil, water mov es upwards due to capillary . It bring up salts more and more in the root-zone. Thus making
soil solution excessiv ely saline. The plant then f aces hindrences in taking up moisture. This results in permanent wilting of the plant.
5. Where land is totally waterlogged, salinity causes destruction of v egetation and crops. Waterlogging causes depostion of salt s in the root zone. If the
salts are alkaline, then soil pH increases. If the soil pH increases to 8.5, it ef f ects the plant and if increases to 11.0 then plant becomes inf ertile. If the
salts are acidic, then its lower the pH. For acidic salts with pH low than 4, plants cannot absorb nutrients and die.
6. Destruction of roads occured due to reduced bearing capacity of waterlogged soil.
7. Rise of water through capillary in the buildings, causes dampness and theref ore causes diseases. This also causes peeling of f plasters and
appearance of salt patched on the walls of the buildings.
8. Certain weeds grow v ery f ast in the waterlogged area and normal crops cannot compete with them. Thus suppressing the usef ul crops to grow.
9. Due to reduced bearing capacity , agricultural machinery cannot operate well in the f ields.
10. Saline soil being unf it f or agriculture is used f or making bricks. The salts f rom these bricks appear on the surf ace whenev er they get dry .
Definition:
When the conditions are so created that the crop root-zone gets deprived of proper aeration due
to the presence of excessive moisture or water content, the tract is said to be waterlogged. To
create such conditions it is not always necessary that under groundwater table should enter the
crop root-zone. Sometimes even if water table is below the root-zone depth the capillary water
zone may extend in the root-zone depth and makes the air circulation impossible by filling the
pores in the soil.
The waterlogging may be defined as rendering the soil unproductive and infertile due to
excessive moisture and creation of anaerobic conditions. The phenomenon of waterlogging can
be best understood with the help of a hydrologic equation, which states that
Inflow = Outflow -I- Storage
Here inflow represents that amount of water which enters the subsoil in various processes. It
includes seepage from the canals, infiltration of rainwater, percolation from irrigated fields and
subsoil flow. Thus although it is loss or us, it represents the amount of water flowing into the
soil.

The term outflow represents mainly evaporation from soil, transpiration from plants and
underground drainage of the tract. The term storage represents the change in the groundwater
reservoir.
Causes of Waterlogging:
After studying the phenomenon of waterlogging in the light of hydrologic equation main factors
which help in raising the water-table may be recognised correctly.
Theyare:
i. Inadequate drainage of over-land run-off increases the rate of percolation and in turn helps in
raising the water table.
ii. The water from rivers may infiltrate into the soil.
iii. Seepage of water from earthen canals also adds significant quantity of water to the
underground reservoir continuously.
iv. Sometimes subsoil does not permit free flow of subsoil water which may accentuate the
process of raising the water table.
v. Irrigation water is used to flood the fields. If it is used in excess it may help appreciably in
raising the water table. Good drainage facility is very essential.
Effects of Waterlogging:
The waterlogging affects the land in various ways. The various after effects are the
following:
1. Creation of Anaerobic Condition in the Crop Root-Zone:
When the aeration of the soil is satisfactory bacteriological activities produce the required
nitrates from the nitrogenous compounds present in the soil. It helps the crop growth. Excessive
moisture content creates anaerobic condition in the soil. The plant roots do not get the required
nourishing food or nutrients. As a result crop growth is badly affected.
2. Growth of Water Loving Wild Plants:
When the soil is waterlogged water loving wild plant life grows abundantly. The growth of wild
plants totally prevent the growth of useful crops.

3. Impossibility of Tillage Operations:
Waterlogged fields cannot be tilled properly. The reason is that the soil contains excessive
moisture content and it does not give proper tilth.
4. Accumulation of Harmful Salts:
The upward water movement brings the toxic salts in the crop root-zone. Excess accumulation
of these salts may turn the soil alkaline. It may hamper the crop growth.
5. Lowering of Soil Temperature:
The presence of excessive moisture content lowers the temperature of the soil. In low
temperature the bacteriological activities are retarded which affects the crop growth badly.
6. Reduction in Time of Maturity:
Untimely maturity of the crops is the characteristic of waterlogged lands. Due to this shortening
of crop period the crop yield is reduced considerably.
Detection of Waterlogging:
From the subject matter discussed above it is clear that the waterlogging is indicated when the
ground water reservoir goes on building up continuously. When the storage starts building up in
the initial stages the crop growth is actually increased because more water is made available for
the crop growth. But after some time the waters table rises very high and the land gets
waterlogged. Finally the land is rendered unproductive and infertile.
The problem of waterlogging develops in its full form slowly. Therefore its early detection is
possible by keeping a close watch over the yields and also on the variations in the groundwater
level. A comparative reduction in crop yields in spite of irrigation and fertilisation and early
maturity of crops indicate the symptoms of waterlogging. Also when harmful salts start
appearing on the fields as white incrustation or deposit it indicates that waterlogging is likely to
follow. In worst cases the water-table rises so high and close to the ground surface that the
fields turn into swamps and marshes.
The best way of keeping watch over the problem of waterlogging is by observing variations in
the groundwater level. It can be done by measuring the depth of water levels at regular interval
in the wells dug in the area. Continuous high water levels indicate that the groundwater storage
is building up which may create waterlogging in the area.

Solution to the Problem of Waterlogging:
The problem of waterlogging may be attacked on two fronts. First is preventive measures, which
keep the land free from waterlogging. Secondly curative measures may be adopted to reclaim
the waterlogged area. But in principle both measures aim at reducing the inflow and augmenting
the outflow from the underground reservoir.
Preventive Measures:
Preventive measures include the following:
(a) Controlling the loss of water due to seepage from the canals:
The seepage loss may be reduced by adopting various measures for example
i. By lowering the FSL of the canal:
Loss may be due to percolation or absorption but when FSL is lowered the loss is reduced to
sufficient extent. It is course essential to see that while lowering the FSL command is not
sacrificed.
ii. By lining the canal section:
When the canal section is made fairly watertight by providing lining the seepage loss is reduced
to quite a good extent.
iii. By introducing intercepting drains:
They are generally constructed parallel to the canal. They give exceptionally good results for the
reach where the canal runs in high embankments.
(b) Preventing the loss of water due to percolation from field channels and fields:
The percolation loss can be removed by using water more economically. It may also be affected
by keeping intensity of irrigation low. Then only small portion of the irrigable tract is flooded and
consequently the percolation loss takes place only on the limited area. It keeps the water-table
sufficiently low.
(c) Augmentation of outflow and prevention of inflow:
It may be accomplished by introducing artificial open and underground drainage grid. It may
also be achieved by improving the flow conditions of existing natural drainages.
(d) Quick disposal of rainwater:

Quick removal of rainwater by surface or open drains is a very effective method of preventing
the rise in water table and consequent waterlogging of the tract. It is needless to state that the
rainwater removed is net reduction in inflow.
Curative Measures:
Curative measures include the following:
(a) Installation of lift irrigation systems:
When a lift irrigation project in the form of a tube well irrigation system is introduced in the
waterlogged area the water table gets lowered sufficiently. It is found to be very successful
method of reclaiming waterlogged land. Thus a combination of a canal system and a
supplementary tube well irrigation system may be considered to be most successful and
efficient irrigation scheme.
Of course it is true that it will create some complications while assessing the charges for
irrigation water. (The canal water being cheaper than tube well water). Implementation of
drainage schemes: The waterlogged area may be reclaimed by introducing overland and
underground drainage schemes.
(b) Implementation od Drainage Schemes:
The waterlogged area may be reclaimed by introducing overland and underground drainage
schemes.
Extent or Waterlogged Area:
In our country water-logging is a problem of great concern. It is estimated that total area of
waterlogged land is 86.92 lakh hectares. It includes area in irrigation commands as well as other
area outside the command.
While the areas in the irrigation command get waterlogged due to rise in water table as a direct
consequence of inadequate drainage, other areas get waterlogged due to inundation, as
consequence of flooding for long durations. The States mainly affected and the extent of area
rendered infertile and unproductive are given in Table 11.1.

About 48 lakh ha are estimated to be affected by salinity and 25 lakh ha by alkalinity. Saline
soils include 10 lakh ha in arid and semi-arid regions of Rajasthan and Gujarat and 14 lakh ha in
black cotton soils. The alkali problem is mainly in Punjab, Haryana and Uttar Pradesh.
Steps are being taken to reclaim the waterlogged land in the country. The steps taken to reclaim
such areas include implementation of drainage schemes, provision of deep drains, excavation
of new channels and improvement of existing ones, construction of sluices with marginal
embankment and installation of tube wells.
The spread of conjunctive use of groundwater with that of surface water especially in Punjab,
Haryana and parts of Uttar Pradesh has substantially lowered the groundwater table and helped
in containing water-logging/salinity.
Summarising the most effective and efficient anti-water-logging measures are:
i. Lining of channels (main canal, branches and field channels).
ii. Provision of surface drains for drainage of rainwater; and
iii. Implementation of tube well projects both extensive and local.

Water-Logging
Key Points
 Waterlogging occurs w hen roots cannot respire due to excess w ater in the soil profile.
 Water does not have to appear on the surface for w aterlogging to be a potential problem.
 Improving drainage from the inundated paddock can decrease the period at w hich the crop roots are subjected to
anaerobic conditions.
 While raised beds (see Raised Bed Cropping fact sheet) are the most intensive management strategy, they are
also the most effective at improving drainage.
 Waterlogged soils release increased amounts of nitrous oxide (N2O), a particularly damaging greenhouse gas.
Background
Waterlogging occurs w henever the soil is so w et that there is insufficient oxygen in the pore space for plant roots to be able
to adequately respire. Other gases detrimental to root grow th, such as carbon dioxide and ethylene, also accumulate in the
root zone and affect the plants.
Plants differ in their demand for oxygen. There is no universal level of soil oxygen that can identify w aterlogged conditions
for all plants. In addition, a plant’s demand for oxygen in its root zone w illvary w ith its stage of grow th.
Symptoms and causes
Lack of oxygen in the root zone of plants causes their root tissues to decompose. Usually this occurs from the tips of roots,
and this causes roots to appear as if they have been pruned. The consequence is that the plant’s grow th and development
is stalled. If the anaerobic circumstances continue for a considerable time the plant eventually dies.
Most often, w aterlogged conditions do not last long enough for the plant to die. Once a w aterlogging event has passed,
plants recommence respiring. As long as soil conditions are moist, the older roots close to the surface allow the plant to
survive. How ever, further w aterlogging-induced root pruning and/or dry conditions may w eaken the plant to the extent that it
w ill be very poorly productive and may eventually die.
Many farmers do not realise that a site is w aterlogged until w ater appears on the soil surface (figure 1). How ever, by this
stage, plant roots may already be damaged and yield potential severely affected.

Figure 1: Waterlogging in a crop grown on a duplex soil in early winter, 1997, along the Esperance South Coast, Western
Australia.
Waterlogging occurs w hen the soil profile or the root zone of a plant becomes saturated. In rain-fed situations, this happens
w hen more rain falls than the soil can absorb or the atmosphere can evaporate.
Western Australia’s ‘Mediterranean’ climate of cool and w et w inters and hot dry summers produces more rain than the
atmosphere can evaporate every w inter. The amount of ‘excess’ rain is particularly large in the higher rainfall areas of the
south-w est.
Cost of waterlogging and inundation
Most data on the cost of w aterlogging and inundation are from the Upper Great Southern (see McFarlane et al., 1992),
although the problems are w idespread. Cereal crop yields decrease by about 150 kg/ha for every 10 mm of rainfall in excess
of the decile 5 rainfall during August in the Upper Great Southern. In the same study it w as calculated that over a 10 year
period in eight shires from that region, excess rainfall costs farmers about 14 % in lost w heat production each year.
Waterlogging and inundation slow pasture grow th in w inter and delay the spring flush. Pasture grow th in w inter is at least
five times more valuable than extra production in late spring. Waterlogged legumes grow more slow ly than w aterlogged
grasses, so w aterlogged pastures become grassy and w eedy.
In w et years, w aterlogging reduces the area that can be cropped. When paddocks are w aterlogged shortly after seeding,
germination and emergence are often reduced; and crops may have to be re-sow n w hen the soil is firm enough to support
machinery.
Waterlogged and inundated areas contribute recharge to saline aquifers, are very susceptible to w ater erosion and are
prone to soil structure decline if cultivated or stocked w hen too w et.

Identifying problem areas
The best w ay to identify problem areas is to dig holes about 40 cm deep in w inter and see if w ater flow s into them (figure 2).
If it does, the soil is w aterlogged. Digging holes for fence posts often reveals w aterlogging.
Some farmers put slotted PVC pipe into augered holes. They can then monitor the w ater levels in their paddocks.
Symptoms in the crop of w aterlogging include:
 Yellow ing of crops and pastures.
 Presence of w eeds such as toad rush, cotula, dock and Yorkshire fog grass.
Figure 2: Waterlogged duplex soil – sandy loam topsoil overlying a sandy clay subsoil at 30 cm. Seepage is entering the
hole above the clay base.
Effects on plant growth
Low levels of oxygen in the root zone trigger the adverse effects of w aterlogging on plant grow th. Waterlogging of the
seedbed mostly affects germinating seeds and young seedlings. Established plants are most affected w hen they are
grow ing rapidly. Therefore, if a soil becomes w aterlogged in July, final yields may not be greatly reduced; soils are cold, the
demand for oxygen is low and plant grow th is slow at this time of year. Prolonged w aterlogging during the w armer spring
period could be more detrimental, how ever the probability for this to occur is much low er than w aterlogging in July.
When plants are grow ing actively, root tips begin to die w ithin a few days of w aterlogging. The shallow root systems that
then develop limit the uptake of nutrients (particularly nitrogen) and w ater, particularly w hen the soil profile starts to dry in

spring. As a result plants may ripen early and grains may not fill properly.
Nitrogen is lost from w aterlogged soils by leaching and denitrification (degassing). Denitrification leads to the gaseous los s
of nitrous oxide (N2O) into the atmosphere, w hich is a major greenhouse gas. These losses, together w ith the low ered ability
of plants to absorb nutrients from w aterlogged soil, cause the older leaves to yellow . Waterlogging also directly reduces
nitrogen fixation by the nodules of legume crops and pastures.
Solving waterlogging
Drainage can be improved on many sites and is the first thing to consider once a w aterlogging problem has been identified.
Options might vary from shallow surface drains (ie. Spoon- and ‘W’-drains) to more intensive drainage using w ide-spaced
furrow s, to the intensive drainage form of raised beds (see Raised Bed Cropping fact sheet). The efficiency of surface
drainage increases in that order as does the degree of management. Consult your local adviser for further advice.
Adverse effects.
In the irrigated areas ofsemi-aridregions, especially in northwest India, a considerable rechargeto the
groundwater leads to waterlogging and secondary salinization. In several sub-areas groundwater is
mined, water tables fall, and salts are added to the root zonebecause a high proportion ofirrigation water
is derived from pumped groundwaterofpoor quality. Out of1 million hectares ofirrigation induced
waterlogged saline area in northwest India, approximately halfa million hectares are in the state of
Haryana. Taking a homogenousphysical environment as a starting point, the way and the extent to which
farmers’ activities will affect the salinity and sodicity situation dependon farming and irrigation pra ctices.
In the past, soil salinity was mainly associated with high groundwatertables, which bring salts into the
root zone through capillary rise when water is pumped.But nowadays, increasing exploitation of
groundwater for irrigation purposes has led to declining groundwater tables and a threat ofsodification
and salinization due to use ofpoor quality groundwater. Farmers in northwest India are facing a situation
in which they have to deal with salt volumes that are harmful for water uptake ofcrops. They are also
facing the problem ofsodicity, which has an adverseeffect on the physical structure ofthe soil, causing
problems ofwater intake, transferand aeration.To mitigate the adverseeffect ofsoil salinity on crop
yield, the farmers irrigate frequently,eithermixing canal waterand groundwater, or alternately using
canal water and groundwater. Due to differences in environmental parameters in the farming systems,
such as groundwater quality, soil types and uneven distribution ofirrigation water ,income losses to the
farming community are notuniform.This paper highlights the economic loss due to environmental
degradation through the twin problems ofwaterlogging and soil salinity, which threaten the sustainability
of agricultural production in Haryana state. Our analysis shows that the net present value ofthe damage
due to waterlogging and salinity in Haryana is about Rs. 23,900/ha (in 1998–1999constantprices). The
estimated potential annual loss is about Rs. 1669 million (aboutUS$ 37 million) from the waterlogged
saline area. The major finding ofthe paper is that intensification per se is not the root cause ofland
degradation, but rather the policy environment that encouraged inappropriate land use and injudicious
input use, especially excessiveirrigation. Trade policies,output price policies and input subsidies all have
contributed to the degradation ofagricultural land.

How do I manage waterlogging?
Key Points
Understanding the problem
 Why is it important to me as a f armer?
 How and why it occurs
 How to recognise it in the paddock
Managing the problem
 What is the best practice?
 How can y ou achiev e this?
Case Study
Other related questions in the Brown Book
Resources
References Source: DEPI Victoria
Key Points
 Signif icant problem f or dairy f armers during wet winter
and early spring
 Manage water running onto the paddock bef ore
considering subsurf ace options
 Water does not hav e to appear on the surf ace f or
waterlogging to be a potential problem
 Bef ore considering draining a wet area y ou should
contact y our local Catchment Management Authority f or
adv ice, as a permit may be required
Understanding the problem
Why is it important to me as a farmer?
 Waterlogging is currently a signif icant land degradation
threat across much of south-west Victoria
 Vast areas including the Hey tesbury Soldier Settlement
and the Victorian Volcanic Plains represent landscapes
signif icantly affected by waterlogging
 Is a signif icant problem f or dairy f armers during winter
and early spring where soils can remain waterlogged f or
considerable periods
 Causes poorer pastures, both in growth and quality
 Makes it harder and more unpleasant to f arm,
particularly f or dairy f armers:
o those jobs with critical timing (such as silage
making and crop sowing) can be upset
o tractors leav e deep f urrows in paddocks
when f eeding out
o cows pugging pasture to the point where
they require a f ull renov ation
 Waterlogging is also a major constraint to grain
production in the region
Top of Page
How and why it occurs

 Waterlogging may be a natural condition of the soil, but can worsen with
deterioration in soil structure
 It occurs when rainf all exceeds the ability of some soils to drain surplus
water away
 It is of ten perceiv ed that waterlogging is a surf ace water problem that
surf ace drains
will ov ercome. Howev er, in many situations waterlogging is due to the
soil prof ile (soil below the ground surf ace) being saturated and some
ty pe of subsurf ace drainage may be necessary to ov ercome this problem
 Unf ortunately , some soils and areas, due to their location, cannot be
economically or f easibly drained by any means
 Susceptibility maps indicate that waterlogging is high to v ery high ov er
more than 50% of the Corangamite region and is:
o usually a seasonal problem
o caused by a relativ ely impermeable lay er through which
water mov es only v ery slowly
o due to soil compaction, sodic soils, high rainf all
o ‘perched’ water-tables in topsoil
Figure 1 - Waterlogging susceptibility in the Corangamite region
(DEPI FFSR). – Source: CCMA
[View larger image]
o Generally located on low-ly ing
heav y duplex soils in higher
rainf all areas
o High to v ery high susceptibility
to soil structure decline cov ers
similar areas to that of
waterlogging, predominant in
the south-west section of the
region
o Waterlogging is common in
the higher rainf all pastures of
the region particularly those
on the clay soils of the
Gellibrand Marl (Hey tesbury )
and Basalt
For detailed inf ormation about the
phy sical extent of waterlogging in the
Corangamite region, see f ollowing report -
A terrain analy sis assessment of
waterlogging susceptibility
For detailed inf ormation about regional
soils, ref er toSoils of the Corangamite
Region online
Top of Page
How to recognise it in the paddock

 Ty pically , waterlolgging can be easily observ ed on the soil
surf ace, by the puddles as a result of perched watertables
o It is commonly associated with compaction,
pugging, and sodic soils
Figure 2a – Waterlogging in the paddock. – Source: Soil
Ty pes and Structures Module, DEPI Victoria
Figure 2b – Waterlogging in the paddock. – Source: Soil
Ty pes and Structures Module, DEPI Victoria
 The ef f ects on plants include:
o Reduced growth and y ellowing or chlorosis of
older leav es
o Damaged plant roots, resulting in restricted
water and nutrient uptake by the plant
o Chlorosis of older leav es is observ ed due to
poor root dev elopment and the consequential
slow uptake of N by crop roots f rom the
anaerobic soil
o Nitrogen def iciency symptoms (figure 3)
o Poor pasture utilisation by cattle
o The presence of weeds
Figure 3 – Loss of colour in older leaves of wheat
indicating nitrogen deficiency. – Source: DAFWA
Figure 4 – Waterlogging can be detrimental to crop
germination. – Source: Soil Ty pes and Structures Module,
DEPI Victoria
 If surf ace waterlogging is not clearly ev ident, the best way
to identif y waterlogged problem areas:
o Dig holes about 40 cm deep in winter and see if
water f lows into them. If it does, the soil is
waterlogged
o Digging holes f or f ence posts of ten rev eals
waterlogging
o Some f armers put slotted PVC pipe
(piezometers) into augered holes. They can
then monitor the water lev els in their paddocks
Top of Page

Managing the problem
What is the best practice?
Proper installation and maintenance of surf ace drainage (including
raised beds) is critical in minimising of f -site impacts, especially
where sediments and nutrients may enter waterway s and threaten
water quality
1. Remov e excess water (drainage options)
o Surf ace drainage – start with the perimeter
o Subsurf ace drainage
o Raised beds (cropping areas) - to reduce
soil compaction and improv e soil structure
2. Minimise compaction (non-drainage options)
o Controlled traf f ic flat beds (cropping areas) -
to reduce soil compaction and improv e soil
structure
o Stock management - graze and spell
(rotation) based on understanding of plant
and soil needs
o Land class f encing
3. Improv e water storage in prof ile
Top of Page
How can you achieve this?
1. Removal of excess water through drainage
options
 Surf ace and sub-surf ace drainage is
commonly used to rehabilitate
waterlogged land and improv e soil
structure
 Currently , ov er 80% of dairy land has
some f orm of surf ace drainage and up
to 20% has sub-surf ace drainage
(MacEwan 1998)
Questions to ask y ourself when
planning f arm drainage:
1. What is causing the
waterlogging problem?
2. Does this happen each
y ear or is it only a problem
in v ery wet y ears?
3. Is there a suf f icient outlet
av ailable?
4. What are the likely
benef its of draining this
area?
5. Which areas should be
drained f irst?
6. What ty pe of drainage
sy stem is required?
- Surface
drains
- Subsurface
drains
Figure 5. - Humps and hollows in newly sown pasture. – Source:
DEPI Victoria

7. What are the non-
drainage options?
8. Rev iew the Water Act
(1989)
Surface drainage - Is v ery usef ul in
remov ing excess water f rom land in a
controlled manner and as quickly as
possible, to an artif icial drainage
sy stem or a natural watercourse. This
should be done with no damage to the
env ironment.
Ty pes of surf ace drainage include:
Ditches or open drains:
o These v ary in size and
length and can be f ormed
by spinner cuts or
excav ators
o Must be v ery wary of
constructing open drains in
dispersiv e soil as they are
highly prone to erosion
Grassed Waterways:
o These are usually shallow,
v ary ing in width f rom
narrow to meters wide, but
are constructed such that
they are of ten grazed as
part of the paddock
o They are sometimes used
to bring drain outf lows
down slopes to prev ent
erosion without
considerable expense
Humps and hollows
(bedding):
o Hump and hollowing is the
practice of f orming (usually
while renov ating pastures)
the ground surf ace into
parallel conv ex (humps)
surf aces separated by
hollows. The humped
shape sheds excess
moisture relativ ely quickly
while the hollows act as
shallow surf ace drains
o Humps and hollows are
usef ul in areas or on soil
ty pes that are not suitable
f or tile or mole drainage
Figure 6 – Good water management. – Source: Soil Ty pes and
Structures Module DEPI, Victoria
[View larger image]
Figure 7 – Poor water management. – Source: Soil Ty pes and
Structures Module DPI, Victoria
[View larger image]

Subsurface drainage - Once y ou hav e taken care of the surf ace
drainage, y ou may need to look at improv ing the drainage through
the soil prof ile. Subsurf ace drainage aims to take away only the
surplus water in the soil. Theref ore, y ou need to know what the
soil ty pe is bef ore any works start.
Ty pes of Subsurf ace drainage include:
Mole Drains:
o Mole drains are unlined channels f ormed in clay
subsoil by pulling a ripper blade (or leg) with a
cy lindrical f oot (or torpedo) attached on the bottom
through the subsoil. A plug (or expander) is of ten used
to help compact the channel wall. The f oot is usually
chisel pointed
o Mole drains are used in heav y soils where a clay
subsoil near moling depth (400 to 600 cm) prev ents
downward mov ement of ground water. Mole drains do
not drain groundwater but remov es water as it enters
f rom the ground surf ace
Figure 8 - Mole drains over a collector pipe
system. – Source: Managing Wet Soils: Mole
Drainage DEPI Victoria
Gravel mole ploughs:
o Grav el mole ploughs incorporate a hopper to allow
f inely graded grav el to f all into the mole channel.
These ploughs hav e been used successf ully in the UK
in heav y soils that cannot hold “normal” mole drains
o Experimental results f rom north east Victoria and
Gippsland show they hav e promise on unstable clay
soils, but are expensiv e because of the amount of
grav el and close spacing needed. Unf ortunately v ery
f ew of these machines exist in southern Australia
Raised bed cropping:
o Ov er the past decade, extensiv e research ef f orts hav e
been directed towards the f actors that contribute to
waterlogging and soil structure decline under broadacre
cropping regimes. The biggest dev elopment has been with
raised bed techniques, which currently cov er about 10% of
the annual crop area in the Corangamite region
o Raised beds aim to reduce machinery compaction by using
controlled traf f ic and to reduce waterlogging by lif ting the
soil abov e the saturated zone. Where used, raised beds
hav e signif icantly improv ed soil structure and reduced
waterlogging on cropping land, while signif icantly
increasing agricultural productiv ity in high rainf all areas
Case Study
Soil structure differences under raised beds in the
Corangamite region
Figure 9 – Raised beds and a well planned grassed
waterway. – Source: DEPI Victoria
The Water Act
o The Water Act (1989) prov ides guidance f or the
management of waterway s and swamps. Bef ore
considering draining a wet area y ou should contact y our
local Catchment Management Authority f or adv ice, as a
permit may be required
2. Minimise compaction - non-drainage options
 Controlled Traf f ic
o to reduce soil compaction and improv e soil structure
 Stock Management
o Change land use (dedicate as a hay or silage paddock and graze only in summer, or remov e f rom the grazing rotation)

o Remov e stock as soon as pugging is imminent
o Allocate short grazing periods on restricted area to allow optimal f eed intake prior to onset of pasture damage – use 'on-
of f ' grazing techniques:
 This ref ers to remov ing cows f rom the pasture af ter a short period of grazing
 It has been identif ied as an ef f ective method of reducing hoof compaction on broadacre grazing land as it
maintains good ground cov er and higher organic carbon lev els
 This practice is currently being adopted ov er 30% of broadacre grazing land in the Corangamite region
(MacEwan 1998)
o Designate “sacrif ice area” to which cows are mov ed in any wet weather
o Construct or designate “loaf ing area” (pad, laneway , barn or woodlot) to which stock can be mov ed in wet conditions
o Construct f eed pad f or all supplementary f eeding in wet weather
We have had some flooding in vegetable crops due to heavy rains already this year and soils in some areas have remained water logged
for extended periods. The majority of watermelons and other fresh market vegetables have been planted, peas are being harvested, lima
bean plantinghas startedand significant acres of pickles, snap beans, and sweet corn are in the field. Growers may be concerned.
Of course, low lying areas of fields are most affectedby excess rainfall. However, croppingpractices can also increase water ponding.
Field compaction will reduce water infiltration andincrease ponding. In plasticulture, water can accumulate and persist between rows of
plastic mulch. Because much of the rainfall runs off of the plastic, water pooling can be more of a problem in plastic mulched fields,
especially where row middles have become compacted. Vining crops that fruit into the rowmiddles can have vines and fruits sittingin
water and this produces an ideal environment for diseases of wet conditions such as Phytophthora capsici to infect plants.
When water overflows the bed tops of plastic mulched crops, whole beds become saturated as water enters the plantingholes. T his often
leads to plant losses as beds take a long time to dry once saturatedin this way and oxygen is very limited in the root zone.
To avoidwater accumulation between beds, tilling with a deep shank or a subsoiler in row middles can help improve drainage. Cut
drainage channels at row ends to reduce blockage that can back up water. Where practical, sectioningfields to go into plastic beds and
installing cross drains to remove extra water can reduce water damage potential. Growers may also choose not to plant lower areas in the
field prone to water damage where plastic is laid.
In flooded soils, the oxygen concentration drops to near zero within 24 hours because water replaces most of air in the soil pore space.
Oxygen diffuses much more slowly in water filled pores than in open pores. Roots need oxygen to respire and have normal cell activity.
When any remaining oxygen is used up by the roots in flooded or waterlogged soils, they will cease to function normally. Ther efore,
mineral nutrient uptake and water uptake are reduced or stoppedin flooded conditions (plants will often wilt in flooded conditions
because roots have shut down). There is also a buildup of ethylene in flooded soils; an excess of this plant hormone can cause leaf drop
and premature senescence.
In general, if flooding or waterlogging lasts for less than 48 hours, most vegetable crops can recover. Longer periods will lead to high
amounts of root death andlower chances of recovery.
While there has not been much research on flooding effects on vegetables, the following are some physiological effects that have been
documented:
 Oxygen starvation in root crops such as potatoes will lead to cell death in tubers and storage roots. This will appear as dark or
discolored areas in the tubers or roots. In carrots and other crops where the tap root is harvested, the tap root will often die
leading to the formation of unmarketable fibrous roots.

 Lack of root function andmovement of water and calcium in the plant will lead to calcium related disorders in plants; most
notably you will have a higher incidence of blossom end rot in tomatoes, peppers, watermelons, andseveral other susceptible
crops.
 Leaching and denitrification losses of nitrogen and limited nitrogen uptake in flooded soils will lead to nitrogen deficiencies
across most vegetable crops.
 In bean crops, flooding or waterlogging has shown to decrease flower production and increase flower and young fruit
abscission or abortion.
 Ethylene buildup in saturated soil conditions can cause leaf drop, flower drop, fruit drop, or early plant decline in many
vegetable crops.
Recovering from Floodingor Waterlogging
The most important thingthat youcan do to aid in vegetable crop recovery after floods or waterlogging is to open up the soil by
cultivating(in crops that still small enough to be cultivated) as soon as you can get back into the field. This allows for oxygen to enter
the soil more rapidly. To address nitrogen leaching, sidedress with 40-50 lbs of N where possible.
In fields that are still wet, consider foliar applications of nutrients. Since nitrogen is the key nutrient to supply, sprayingwith urea
ammonium nitrate (28% N solution) alone can be helpful. These can be sprayed by aerial or ground application. Use 5 to 20 gallons of
water per acre. The higher gallons per acre generally provide better coverage. As with all foliar applications, keep total salt
concentrations to less than 3% solutions to avoidfoliage burn. Research in on flooded vegetables in Florida showed the best response to
foliar applications of potassium nitrate.

Waterlogging and salinity

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Waterlogging and salinity