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Recent techniques in fertigation of horticultural crops in
Israel
Patricia Imas (1)
(1) International Potash Institute Coordinator India c/o ICL
Fertilizers
Paper presented at the IPI-PRII-KKV workshop on Recent trends in
nutrition management in horticultural crops, 11-12 February 1999,
Dapoli, Maharashtra, India
Abstract
Israel is a small country with a total land area of 21,000 km2,
from which 20% is arable land. More than half of Israel
has an arid to semi-arid climate. Approximately half of the
cultivated area (200,000 hectares) has to be irrigated due to
lack of rainfall and other water resources. Approximately 80% of
the irrigated land in Israel uses the fertigation method,
combining the application of water and fertilizers through the
drip irrigation system.
The Israeli production of vegetables, flowers, ornamental plants
and spices in greenhouses has been experiencing
accelerated growth in recent years, reaching 3,000 hectares
today. Most of the greenhouses are computerized, allowing
automatic control of water, fertilizers and climate systems.
The direct delivery of fertilizers through drip irrigation
demands the use of soluble fertilizers and pumping and
injection
systems for introducing the fertilizers directly into the
irrigation system. Many Israeli companies specialize in
manufacturing fertigation systems and in producing fertilizers
and mixtures for their application through the drip
irrigation system.
Fertigation allows an accurate and uniform application of
nutrients to the wetted area, where the active roots are
concentrated. Therefore, it is possible to adequate the
nutrients quantity and concentration to their demand through
the
growing season of the crop. Consequently, recommendations have
been developed for the most suitable fertilizer
formulation (including the basic nutrients NPK and
microelements) according to the type of soil, physiological
stage,
climate and other factors. Special attention should be given to
the pH and NO3/NH4 ratio, nutrient mobility in soil and
salinity conditions.
Planning the irrigation system and nutrient supply to the crops
according to their physiological stage of development,
and consideration of the soil and climate characteristics,
result in high yields and high quality crops with minimum
pollution.
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1.- Introduction
Israel is a small country with a total area of 21.000 km2, from
which 20% is arable land. More than half of the area of Israel has
an arid to semi-arid climate. Near half of the cultivable area
(200.000 hectares) must be irrigated due to the lack of rain and
other water resources. Approximately 80% of the irrigated area in
Israel uses the method of "fertigation", that combines the
application of irrigation water with fertilizers. This practice
contributes to the achievement of higher yields and better quality
by increasing remarkably the efficiency of the fertilizer
application. Greenhouse crops in Israel are fertilized exclusively
through the irrigation system. The Israeli production of
vegetables, ornamental flowers, plants and spices under greenhouses
has experienced an accelerated growth in the last years, with more
than 3.000 hectares of greenhouses nowadays. Most of these
greenhouses are computerized, allowing the automatic control of the
irrigation, the fertilization and the climate. Hydroponics in
Israel reaches a total area of 700 Has, being the main crops
tomatoes, cucumbers, strawberries and flowers (roses, crisantemum,
gerbera and gypsophylla). The most common growing medium is tuff
(volcanic stone) which is a reactive substrate with high power of
adsorption and high indigenous phosphorus content. Inert substrates
as rockwool and vermiculite are also used. At the moment most of
the greenhouses have an open system. The aim is to change them by
closed systems in which the farmer must collect the leached
solution and reuse it thus avoiding contamination.
Israel is an unequaled example of the use of fertilizers by
fertigation. In 1996, the Israeli farmer used an average of 115 kg
N/Ha, 46 kg P2O5/Ha and 57.5 kg K2O/Ha. Over 50% of the N and P2O5,
and 65% of the K2O is applied by fertigation (Tarchitzky and Magen,
1997). 2.- Advantages of fertigation
The fertigation allows to apply the nutrients exactly and
uniformly only to the wetted root volume, where the active roots
are concentrated. This remarkably increases the efficiency in the
application of the fertilizer, which allows reducing the amount of
applied fertilizer. This not only reduces the production costs but
also lessens the potential of groundwater pollution caused by the
fertilizer leaching. Fertigation allows to adapt the amount and
concentration of the applied nutrients in order to meet the actual
nutritional requirement of the crop throughout the growing season.
In order to make a correct planning of the nutrients supply to the
crop according to its physiological stage, we must know the optimal
daily nutrient consumption rate during the growing cycle that
results in maximum yield and production quality. These functions
are specific for each crop and climate, and were determined in
different experiments for the main crops in Israel like tomatoes,
cucumbers, melons, maize, etc. (Table 1). The optimal curve of
consumption of nutrients defines the minimal application rate of a
certain nutrient that is required to maintain a constant nutrient
concentration in the soil solution. These data constitute the base
of the recommendations given by the Israeli Soil Extension Service
for the farmers regarding the fertigation regime for the different
crops.
Other advantages of the fertigation are: (1) the saving of
energy and labor, (2) the flexibility of the moment of the
application (nutrients can be applied to the soil when crop or soil
conditions would otherwise prohibit entry into the field with
conventional equipment), (3) convenient use of compound and
ready-mix nutrient solutions containing also small concentrations
of micronutrients which are otherwise very difficult to apply
accurately to the soil, and (4) the supply of nutrients can be more
carefully regulated and monitored. When fertigation is applied
through the drip irrigation system, crop foliage can be kept dry
thus avoiding leaf burn and delaying the development of plant
pathogens.
Drip and microirrigation have a characteristic not shared by
other irrigation methods: fertigation is not optional, but is
actually necessary. Fertigation provides the only good way to apply
fertilizers physically to the crop root zone. On high value drip
irrigated crops, such as lettuce, tomatoes, and peppers, the level
of fertigation management for achieving high yields and crop
qualities exceeds to what is found with other irrigation methods
and crops.
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3.- Chemical and biological guidelines for a sound
fertigation
Effective fertigation requires an understanding of plant growth
behavior including nutrient requirements and rooting patterns, soil
chemistry such as solubility and mobility of the nutrients,
fertilizers chemistry (mixing compatibility, precipitation,
clogging and corrosion) and water quality factors including pH,
salt and sodium hazards, and toxic ions. 3.1.- Fertilizers
solubility
An essential pre-requisite for the solid fertilizer use in
fertigation is its complete dissolution in the irrigation water.
Examples of highly soluble fertilizers appropriate for their use in
fertigation are: ammonium nitrate, potassium chloride, potassium
nitrate, urea, ammonium monophosphate and potassium
monophosphate.
The solubility of fertilizers depends on the temperature. The
fertilizer solutions stored during the summer form precipitates
when the temperatures decrease in the autumn, due to the diminution
of the solubility with low temperatures. Therefore it is
recommended to dilute the solutions stored at the end of the
summer. Fertilizer solutions of smaller degree specially formulated
by the manufacturers are used during the winter.
Table 2: Fertilizers solubility and temperatures (g/100 g water)
(Wolf et al., 1985).
Temperature KCl K2SO4 KNO3 NH4NO3 Urea 10C 31 9 21 158 84 20C 34
11 31 195 105 30C 37 13 46 242 133
3.2.- Interaction between the fertilizers and irrigation
water
3.2.2.- Water quality: Many water sources in Israel have high
contents of calcium, magnesium and bicarbonates (hard waters), the
reaction of the water is alkaline with pH values between 7.2 and
8.5. The interaction of these waters with fertilizers can cause
diverse problems, such as formation of precipitates in the
fertilization tank and clogging of the drippers and filters. In
waters with high calcium content and bicarbonates, use of sulphate
fertilizers causes the precipitation of CaSO4 obtruding drippers
and filters. The use of urea induces the precipitation of CaCO3
because the urea increases pH.
The main problem concerns phosphorus application: the presence
of high concentrations of calcium and magnesium and high pH values
lead to the precipitation of calcium and magnesium phosphates.
Recycled waters are particularly susceptible to precipitation due
to its high bicarbonate and organic matter content. The resultant
precipitates are deposited on pipe walls and in orifices of
drippers and can completely plug the irrigation system. At the same
time, P supply to the roots is impaired. When choosing P
fertilizers for fertigation with high calcium and magnesium
concentrations, acid P fertilizers (phosphoric acid or monoammonium
phosphate) are recommended.
3.2.3.- Clogging: This is specially critical for drip systems
that must be kept free from suspended solids and microorganisms
that plug the small orifices in the emitters. In the case of
clogging of the drip system by bicarbonate precipitation, the use
of fertilizers with acid reaction partially corrects this problem.
However, acid fertilizers cause corrosion of the metallic
components of the irrigation system and damage the cement and
asbest pipes. Therefore, the
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periodic injection of acid in the fertigation system is
recommended in order to dissolve the precipitates and to unclog the
drippers. The following acids can be used: phosphoric, nitric,
sulfuric and chlorhydric. In Israel, HCl is widely used due to its
low cost. Acid injection through the system will also remove
bacteria, algae and slime. The irrigation and injection system
should be carefully washed after the injection of acid.
3.2.4.- Fertigation under saline conditions: Crops vary widely
in their tolerance to plants, reference tables are available
defining individual crop sensitivity to total soluble salts and
individual toxic ions (Maas and Hoffman, 1977). When brackish
waters are used for irrigation, we must bear in mind that
fertilizers are salts and therefore they contribute to the increase
of the EC of the irrigation water. Nonetheless, calculation of the
contribution of chloride from KCl to the overall load of chloride
from irrigation water shows its relative by low share (Tarchitzky
and Magen, 1997).
When irrigation water has an EC > 2 dS/m (with high
salinization hazard), and crop is sensitive to salinity, we must
decrease the amount of accompanying ions added with the N or K. For
example, in avocado - a very sensitive crop to chloride - KNO3 is
preferred on KCl to avoid Cl accumulation in the soil solution.
This practice diminishes leaf burning caused by Cl excess. Also in
greenhouse crops grown in containers with a very restricted root
volume we must choose fertilizers with low salt index. Sodium
fertilizers as NaNO3 or NaH2PO4 are unsuitable due to the adverse
effect of sodium on the hydraulic conductivity and the performance
of the plant.
A correct irrigation management under saline conditions includes
water application over the evaporation needs of the crop, so that
there is excess water to pass through and beyond the root zone and
to carry away salts with it. This leaching prevents excessive salt
accumulation in the root zone and is referred to as leaching
requirement (Rhoades and Loveday, 1990).
3.2.5.- Fertilizers compatibility: when preparing fertilizer
solutions for fertigation, some fertilizers must not be mixed
together. For example, the mixture of (NH4)2SO4 and KCl in the tank
considerably reduce the solubility of the mixture due to the K2SO4
formation. Other forbidden mixtures are:
Calcium nitrate with any phosphates or sulfates Magnesium
sulfate with di- or mono- ammonium phosphate Phosphoric acid with
iron, zinc, copper and manganese sulfates
The use of two fertilization tanks allows to separate the
fertilizers that interact and cause precipitation, placing in one
tank the calcium, magnesium and microelements, and in the other
tank the phosphorus and the sulfate.
3.3.- Soil pH:
pH values for optimal availability of all the nutrients is in
the rank of 6-6.5. The main factor affecting pH in the rhizosphere
is NH4/NO3 ratio in the irrigation water, specially in sandy soils
and inert substrates with low buffer capacity such as rockwool.
Rhizospheric pH determines the phosphorus availability since it
affects the processes of precipitation/solubilization and
adsorption/desorption of phosphates. pH also influences the
availability of micronutrients (Fe, Zn, Mn) and the toxicity of
some of them (Al, Mn).
The nitrogen form absorbed by the plant affects the production
of carboxylates and the cation-anion balance in the plant. When NH4
absorption is predominant, the plant absorbs more cations than
anions, H+ are excreted by the roots and rhizosphere pH decreases.
Fluctuations of pH of the ground around the roots of the order of
1,5 units of pH due
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to ammonium or nitric nutrition have been reported in the
literature (Barber, 1984). According to Ganmore-Neumann and Kafkafi
(1980, 1983), NH4 is an undesirable source of nitrogen for tomato
and strawberries when the temperature in the root zone is greater
than 30oC, due to its adverse effect on root growth and pant
development. The pattern of cationic uptake due to an ammonium
nutrition decreases the uptake of other cations like Ca2+, Mg2+ and
K+.
When NO3- anions are absorbed, the plant takes up more anions
than cations and the excess of anions is palliated by a greater
synthesis of carboxylates. During the carboxylation process
dicarboxylic acids (citric, malic, etc.) and OH- are produced. Both
the carboxylates and the hydroxyls can be exuded by the roots to
the soil. The exuded OH- increase the pH of the rhizosphere. The
organic acids exuded by the roots increase the availability of
phosphorus since the carboxylates are specifically adsorbed to iron
oxides and clays of the ground, releasing therefore adsorbed
phosphorus to the soil solution. The carboxylates can also increase
to the availability of iron and phosphorus by chelation: for
example, citrate forms a chelate with calcium, thus releasing
phosphorus that is under the calcium phosphate form (Imas et al.,
1997).
According to this, NO3 nutrition is recommended due to the
greater organic acid synthesis and enhanced cations uptake, whereas
the ammonium nutrition is detrimental. However, nutrition with 100%
nitrates would increase rhizospheric pH up to undesirable values -
values of more than 8 have been registered - and this would
decrease the availability of P and micronutrients by precipitation.
Therefore it is recommended to use a nitrogen mixture with 80% of
nitrates and 20% of ammonium to regulate pH.
3.4.- Physiological effects: antagonism and synergism:
When two or more ions are present in external medium,
antagonistic and synergetic effects can be observed. Synergism
means the increase of the absorption of an ion due to the presence
of another ion; antagonism refers to the competition between two
ions. There is a competitive antagonistic effect between NO3 and Cl
anions: the presence of Cl ion reduces the absorption of NO3 and
vice versa (Imas, 1991; Kafkafi, 1982). Therefore, under saline
conditions, the damage by salinity can be reduced fertilizing with
NO3. The nitrate ions will be more absorbed replacing the chloride
ions.
4.- Practices of fertigation
To capitalize on fertigation benefits, particular care should be
taken in selecting fertilizers and injection equipment as well in
the management and maintenance of the system.
4.1.- Fertilizer preparation
In Israel, application of fertilizers is executed by various
methods (Sneh, 1995):
Stock solution preparation: farmers mix solid fertilizers as
ammonium sulfate, urea, potassium chloride and nitrate, and liquid
phosphoric acid to prepare a "tailor made" stock solution. The
stock solution is then injected into the irrigation system, at
rates of 2-10 L/m3, depending on the desired concentrations of N, P
and K. Clear NK, PK and NPK fertilizer solutions with at least
9-10% nutrients (N, P2O5, K2O) based on cheap solid fertilizers
(urea, phosphoric acid and KCl) can be easily prepared on the farm
site with limited facilities under "grass roots" field conditions,
with minimal mixing (Lupin et al., 1996).
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Compound solid fertilizer mixtures: manufactured for use in
fertigation, with different ratios between the three major
elements. The first mixture used in fertigation was 20-20-20 and
was produced in the mid-sixties. Some compositions contain
microelements in the form of chelates.
Compound liquid fertilizer solutions: due to solubility, the
total nutrient concentration is much lower (5-3-8; 6-6-6; 9-2-8,
etc.). Specified for use in greenhouses. Some compositions contain
microelements in the form of chelates.
Generally two fertilizer tanks that contain the concentrated
fertilizer solutions are used to separate those fertilizers that
can interact. A possible combination is: a tank "A" containing
calcium nitrate, potassium nitrate, magnesium nitrate and
microelements, whereas tank "B" contains ammonium sulfate,
phosphoric acid and nitric acid; in this way P and Ca/Mg are in
different tanks to avoid their precipitation. A third tank "C"
contains an acid solution to control the pH of the fertilizer
solution and to wash the irrigation system to avoid drippers
clogging.
4.2.- Dosification
There are two types of fertigation, the type of fertigation
chosen depends on the crop grown, the soil type and the farm
management system.
Quantitative: is the application of the plant nutrients in
predetermined concentrations to the irrigation system. The
fertilizer is applied in a pulse after a certain water sheet
without fertilizer using a fertilizer tank. The advantages of this
method are the low cost and the low required maintenance. The
disadvantages are: the system is affected by water pressure
changes; the concentration of the fertilizer varies during its
application and it does not adapt to work with automation.
Proportional: the nutrients are is applied in a constant and
proportional ratio to the water sheet, so that the irrigation water
takes a fixed concentration of the applied fertilizer. In this case
the fertilizers are applied by direct injection through fertilizer
pumps. The advantages are: precise control of the dosification and
the injection moment, is not affected by the water pressure
changes, and it can be easily automated. The disadvantages are:
high cost and maintenance and complicated operation.
4.3.- Fertilizer injection methods
Modern fertigation equipment should be able to regulate:
quantity applied duration of applications proportion of
fertilizers starting and finishing time
It is important to select an injection method that best suits
the irrigation system and the crop to be grown. Incorrect selection
of the equipment can damage parts of the irrigation equipment,
affect the efficient operation of the irrigation system and reduce
the efficiency of the nutrients. Each fertilizer injector is
designed for a specified pressure and flow range.
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The majority of injectors available today can generally
incorporate automatic operation by fitting pulse transmitters that
convert injector pulses into electric signals. These signals then
control injection of preset quantities or proportions relative to
flow rate of the irrigation system. Injection rates can also be
controlled by flow regulators, chemically resistant ball valves or
by electronic or hydraulic control units and computers.
Suitable antisiphoning valves or non-return valves should be
installed to prevent backflow or siphoning of water and fertilizer
solution into fertilizer tanks, irrigation supply and household
supply.
The three methods of injection are:
Pressure differential (by-pass tank) A pressure differential
tank system is based on the principle of a pressure differential
created by a valve, pressure regulation, elbows or pipe friction in
the mainline. The pressure difference forces the water to enter
through a by-pass pipe into a pressure tank which contains the
fertilizer, and to go out again, carrying a varying amount of
dissolved fertilizer.
The application of nutrients is quantitative and inaccurate,
therefore is adapted for perennial crops like citrus, fruit trees
and/or crops grown on heavy soil.
Advantages:
Very simple to operate, the stock solution does have not to be
pre-mixed. Easy to install and requires very little maintenance.
Easy to change fertilizers Ideal for dry formulations No
electricity or fuel is needed
Disadvantages:
Concentration of solution decreases as fertilizer dissolves
Accuracy of application is limited Requires pressure loss in main
irrigation line or a booster pump Proportional fertigation is not
possible Limited capacity Not adapted for automation
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Inlet valve
Outletvalve
Drain valve
Inlet mixing hose
Main irrigation line Non returnvalve Choke valve
Pressure gauge
Fertilizer solution
Fertilizer tank
Pressure gauge
Vacuum injection (Venturi) This method uses a venturi device to
cause a reduced pressure (vacuum) that sucks the fertilizer
solution into the line.
Advantages:
Very simple to operate, no moving parts Easy to install and to
maintain Suitable for very low injection rates Injection can be
controlled with a metering valve Suitable for both proportional and
quantitative fertilization
Disadvantages:
Requires pressure loss in main irrigation line or a booster pump
Quantitative fertigation is difficult Automation is difficult
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Pressure regulator Non return
valveChoke valveVenturi
Valve
Fertilizer tank
Main irrigation line
Fertilizer solution
Pump injection Pumps are used to inject the fertilizer solution
from a supply tank into the line. Injection energy is provided by
electric motors, hydraulic motors (diaphragm and piston).
Advantages:
Very accurate, for proportional fertigation No pressure loss in
the line Easily adapted for automation
Disadvantages:
Expensive Complicated design, including a number of moving
parts, so wear and breakdown are more likely
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Fertilizer tank
Fertilizer solution
Valve
Main irrigation lineNon return valve
Valve
Waterexhaust
Hydraulic injector
4.4.- Monitoring
Plants: the determination of the nutrients content and dry
matter in the whole plant is tedious, destructive and needs
laboratory facilities. Therefore we monitor plant nutrient status
in the diagnostic organ, whose concentrations are correlated with
the total nutrients content in plant and is a good indicator of the
nutrition state of the crop. In Israel it was developed calibrated
methods of monitoring in diagnostic organs for roses and different
fruit trees.
Soil: soil sampling and the determination of the nutrients
concentrations in the extracts is a difficult and tedious method.
Instead, the soil solution can directly sampled by porous ceramic
cups permanently inserted in the soil at a certain depth. The
solution is collected periodically and sent to the lab for
analyzing the different nutrients concentrations. This method is
easy, cheap and widely used by the Israeli farmers.
Field quick test kits: allows a quick determination of pH and
approximate content of nitrates, potassium and chlorides in the
soil solution and in the plant sap without sending the samples to
the lab (usually by colorimetric strips).
4.5.- Fertigation management in greenhouse crops
The growth of vegetables and flowers in greenhouses built on
sandy dunes and/or with inert substrates requires a special and
precise control of the fertigation, because the CEC of these
growing media are very low and therefore they do not provide
nutrients. The only source of nutrients is through the fertigation
system. Growing plants in containers allows the collection of the
leaching water and its comparison with the irrigation water. The
measurement of pH, EC and nutrients concentration in the leached
solution indicates if fertilizers are being applied in excess or
deficiency, and therefore
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allows the consecutive correction of the fertigation regime. It
is recommended to collect the leached solution from the containers
and the solution that leaves the drippers, and to compare both
solutions on a daily basis. In Israel there are automatic
computerized devices that measure pH and EC of both solutions and
automatically corrects the next irrigation solution according to
optimal values entered beforehand.
Electric Conductivity: A higher value of EC in the leached
solution that in the applied solution indicates that the plant
absorbs more nutrients than water, therefore we must apply greater
amount of water to the plant. On the other hand, if the difference
between the EC of the leached solution and the incoming solution is
more than 0.4-0.5dS/m, we must apply a leaching irrigation in order
to wash the excess of salts.
Chlorides: An impaired management of the irrigation regime may
lead to an unwanted accumulation of Cl ions present in the
irrigation water. If the Cl concentration in the leachate is higher
than the Cl concentration in the incoming solution and surpasses
50mg/L, it indicates a chloride accumulation in the root zone. Then
it is recommended to apply an irrigation without fertilizers to
leach the chlorides.
pH: the optimal pH value of the irrigation solution must be
around 6 and the pH of the leaching solution should not exceed 8.5.
A more alkaline pH in the leaching water indicates that pH in the
root zone reaches a value that causes phosphorus precipitation and
decreases micronutrients availability. When pH in the leachate is
higher than 8.5, we must adjust the NH4/NO3 ratio of the irrigation
solution by increasing slightly the NH4 proportion. When pH in the
irrigation solution is higher than 6, we must inject acid to the
solution (from tank C) to lower the pH.
5. Example: recommendation of a fertigation program by the
Israeli Extension Service
For each crop there are many fertilizer programs. Fertigation
allows changing the program during the growing season, adjusting it
to suit fruit, flower, shoot and root development. A specific
fertigation program is developed on the basis of leaf and soil
analysis and tailored to suit the actual crop requirements.
The following is the recommendation of the fertigation program
for tomato offered by the Extension Service of the Ministry of
Agriculture of Israel. It is observed that the recommended doses of
each nutrient are different according to the physiological stage of
the crop. The recommendations are different for tomato crop grown
in open field or in greenhouse. Regarding the soil type, the doses
recommended for inert substrates are precise and expressed as
concentration in the irrigation water (proportional dosification).
On the other hand, in heavy clay soils recommendations are
expressed for quantitative dosification (in kg/ha); and recommended
doses for phosphorus and potassium are not provided since in this
type of soils these elements are adsorbed by clays and therefore is
very difficult to determine their concentrations in the soil
solution.
a.- Tomato in open field Soil sandy loam Plant density
11.000-12.500 plants/Ha Expected yield 100 ton/Ha (for
processing)
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Nutrient requirements:
Physiological Stage Days RATIO KG/HA/DAY N P2O5 K2O N P2O5 K2O
PLANTING- FLOWERING 25 1 1 1 1.6 1.6 1.6
FLOWERING - FRUIT SET 20 1 0.5 1.5 2.1 1.0 3.1
FRUIT SET- FRUIT RIPENING 25 1 0.3 2 2.8 0.6 5.6
FRUIT RIPENING-HARVEST 35 1 0.3 2 3.6 0.6 7.2
TOTAL 105 280 90 500
FERTIGATION PROGRAM
Physiological Stage Fertilizers * kg/ha/day ** PLANTING-
FLOWERING 20-20-20 8
FLOWERING - FRUIT SET 14-7-21 15
FRUIT SET- FRUIT RIPENING 14-3-28 20
FRUIT RIPENING-HARVEST 14-3-28 26
* This is one example using a commercial fertilizer solid
mixture. The fertilizer solution can be prepared also from
commercial liquid mixtures, or prepared by the farmer mixing
potassium chloride, urea ,ammonium monophosphate,
ammonium nitrate, potassium nitrate, phosphoric acid and other
soluble fertilizers ** Plants are irrigated every 3-5 days in heavy
soils, and every 2-3 days in light soils. To calculate the
fertilizer dose at
each irrigation, multiply the daily amount of fertilizer by the
days interval between irrigation cycles b.- Tomato in
greenhouse
Substrate - soilless culture
Concentration in the irrigation solution (dripper) Physiological
stage N* P K Ca Mg ppm Planting and establishment 120-150 40-50
180-220 100-120 40-50
Flowering 150-180 40-50 220-270 100-120 40-50
Ripening and harvest 180-200 40-50 270-300 100-120 50-80 *
NH4/NO3 ratio=0.1-0.2
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Sandy soil
Concentration in the irrigation solution
(dripper) Physiological stage N* P K ppm Planting and
establishment 120-150 40-50 180-220
Flowering 150-180 40-50 220-270
Ripening and harvest 180-200 40-50 270-300 * NH4/NO3
ratio=0.3
Clay soil
Physiological stage N P K Kg/Ha/day Flowering 2.0-2.5 ? 0-2.5
?
Ripening and harvest 4.0-4.5 ? 4-5.5 ? ? = Depends on P and K
levels in the soil
6. References
1. Barber, S.A. 1984. Soil Nutrient Availability: A Mechanistic
Approach. John Wiley and Sons, Inc., NY.
2. Bar-Yosef, B. 1996. Root excretions and their environmental
effects - Influence on the availability of phosphorus. In: Plant
Roots - The Hidden Half. Second Edition. Y. Waisel, A. Eshel and U.
Kafkafi (Eds). Marcel Dekker, Inc., New York. pp 529-557.
3. Feigin A., M. Zwibel, I. Rilski, N. Zamir and N. Levav. 1980.
The effect of ammonium/nitrate ratio in the nutrient solution on
tomato yield and quantity. Acta Hortic. 98: 149-160.
4. Ganmore-Neumann, R. and U. Kafkafi. 1980. Root temperature
and percentage NO3-/NH4+ effect on tomato plants. I Morphology and
growth. Agron. J. 72:758-761.
5. Ganmore-Neumann, R. and U. Kafkafi. 1983. Root temperature
and percentage NO3-/NH4+ effect on strawberry plants. I Growth,
flowering and root development. Agron. J. 75: 941-947.
6. Imas, P. 1991. Yield-Transpiration relationships under
different nutrition conditions. M.Sc. Thesis, presented to the
Hebrew University of Jerusalem.
7. Imas, P., B. Bar-Yosef, U. Kafkafi and R. Ganmore-Neumann.
1997. Release of carboxylic anions and protons by tomato roots in
response to ammonium nitrate ratio and pH in nutrient solution.
Plant and Soil 191: 27-34.
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8. Lupin, M., H. Magen and Z. Gambash. 1996. Fertiliser News,
The Fertilizer Association of India (FAI), 41:69-72.
9. Maas, E.V. and G.J. Hoffman. 1977. Crop salt tolerance -
current assessment. J. Irrig. Drainage Div. ASEC 103: 115-134.
10. Rhoades, J.D. and J. Loveday. 1990. Salinity in irrigated
agriculture. In: Irrigation of Agricultural Crops. B.A. Stewars and
D.R.Nielsen (Eds.). ASA-CSAA-SSSA, Madison, WI. pp 1089-1142.
11. Scaife, A. and B. Bar-Yosef. 1995. Nutrient and fertilizer
management in field grown vegetables. IPI Bulletin No. 13.
International Potash Institute, Basel, Switzerland.
12. Sneh, M. 1995. The history of fertigation in Israel. In:
Proc. Dhalia Greidinger Int. Symp. on Fertigation. Technion, Haifa,
Israel, 26 March - 1 April. pp 1-10.
13. Tarchitzky, J. and H. Magen. 1997. Status of potassium in
soils and crops in Israel, present K use indicating the need for
further research and improved recommendations. Presented at the IPI
Regional Workshop on Food Security in the WANA Region, May 1997,
Bornova, Turkey.
14. Wolf, B., J. Fleming and J. Batchelor. 1985. Fluid
Fertilizer Manual. Vol. 1. National Fertilizer Solutions
Association, Peoria, Il.
14
-
Table 1: Daily consumption rate of nitrogen, phosphorus and
potassium (kg ha-1 day-1) of different vegetables grown under drip
irrigation after emergence or planting (Scaife and Bar-Yosef,
1995).
Days planting / Tomato greenhouse Tomato industry Eggplant
Broccoli Melon emergence N P K N P K N P K N P K N P K1-10 1.00
0.10 2.00 0.10 0.02 0.10 0.05 0.01 0.00 0.02 0.00 0.01 0.15 0.03
0.1011-20 1.00 0.10 4.00 0.50 0.05 0.30 0.10 0.01 0.00 0.07 0.01
0.02 0.20 0.03 0.2521-30 1.00 0.10 3.50 1.00 0.16 2.00 0.20 0.01
0.30 1.08 0.12 0.74 0.35 0.07 0.6031-40 2.50 0.20 3.50 2.80 0.19
2.30 0.25 0.01 0.80 1.22 0.13 0.91 0.90 0.18 1.4541-50 2.50 0.40
5.50 4.50 0.75 8.00 3.20 0.02 4.90 1.75 0.20 1.35 1.30 0.25
3.0051-60 2.50 0.60 6.00 6.50 0.80 8.50 2.90 0.08 7.20 1.04 0.13
3.04 2.50 0.25 6.0061-70 2.50 0.30 4.00 7.50 1.80 9.00 0.25 0.09
1.30 3.02 0.36 4.34 4.30 0.35 7.0071-80 2.50 0.30 6.00 3.50 0.50
4.50 0.25 0.05 0.50 3.41 0.46 3.95 2.40 0.45 8.0081-90 1.50 0.30
0.10 5.00 0.50 9.20 0.25 0.05 0.50 2.79 0.38 4.09 1.20 0.43
7.5091-100 1.50 0.10 0.10 8.00 0.89 9.00 0.25 0.05 0.50 2.09 0.32
3.13 1.00 0.27 3.50101-110 1.00 0.10 0.10 - - - 0.25 0.09 2.00 0.93
0.18 2.74 0.50 0.13 1.00111-120 1.00 0.10 1.00 - - - 1.20 0.15 3.00
0.20 0.09 0.96 0.30 0.07 0.05121-130 1.50 0.20 1.00 - - - 2.40 0.27
3.00 0.18 0.09 0.48 - - - 131-150 1.50 0.35 1.30 - - - 2.60 0.31
3.00 0.15 0.04 - - - -151-180 4.00 0.50 3.80 - - - 2.30 0.38 1.60 -
- - - - -181-200 2.00 0.30 3.00 - - - 1.90 0.35 1.60 - - - - -
-TOTAL 450 65 710 393 59 520 290 33 380 202 26 165 151 25
385variety F-144 VFM82-1-2 Black Oval Woltam Galia Date em./pl. 25
Sep** 27 Mar* 10Sep** 30 Aug** 14 Jan Harvest selective 18 Jul
selective 17 Jan selective Plants/ha 23,000 50,000 12,500 33,000
25,000 Soil sandy clay sandy loam sandyYield (t/ha) 195 160 51 13
56
* emergence ** planting
15
Recent techniques in fertigation of horticultural crops in
Israel