Fertigation: Optimizing the Utilization of Water and Nutrients - SSWM

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Fertilizer delivery There are two main methods. 1 – Fertilizer dilution tanks, which are usually used in small plots, are connected to the head of the irrigation line, and deliver predetermined quantities of fertilizer during the irrigation cycle. 2 – External pumps, which are used to cover large areas, inject the fertilizer solution under positive pressure (usually that of the water supply) directly into the irrigation line. The latter method is supposed to deliver a constant concentration of fertilizer during the irrigation cycle. Filtration Filtration is a prerequisite in drip irrigation, to avoid clogging of drip lines and emitters, and to maintain the uniformity of water and fertilizer application. The type of filtration system depends on the quality and source of the water supply, and the water quality and composition must be taken into consideration at the planning stage of the fertigation systems, especially when a subsurface installation is considered. In the case of deep well water sources the system should remove gravel, sand or suspended materials. Open surface waters (ponds, rivers or lakes) may contain organic matter and algae that must be removed before entry to the lines. In fertigation systems a second filtration step after the fertilizer container is necessary, to remove any particulate matter or precipitates from the fertilizer mixtures. Deep well water sources may contain soluble divalent iron, which, on contact with phosphate, may produce a gel-‐like precipitate that can block the tricklers and filters. Distribution of water and nutrients in soil Water flow Two main forces – gravity and capillarity – govern the movement of water in the soil. In drip irrigation, water spreads from a dripper in three dimensions and creates a wetted front of various shapes (Bressler, 1977), depending on the soil type and the water discharge rate. When the trickle discharge rate is higher than the soil infiltration rate, lateral water movement dominates and shallower penetration is to be expected albeit with larger wetted soil surface area with a given amount of water. 14
Nutrient movement Strongly sorbed ions, such as phosphate, are less mobile in soils than non-‐ sorbed ions, such as nitrate or chloride (Kafkafi and Bar Yosef, 1980). During repeated fertigation cycles there is a balance between the lateral spread of water and evaporation, as a result of which soluble salts might accumulate at the border between the dry and the wet zones, especially in hot dry areas with no dry-‐season rainfall (Kafkafi and Bar Yosef, 1980). The salt accumulated at the wet zone periphery can reach very high levels and, a single flush of rain could wash this salt into the root zone and cause considerable damage. Plastic covers To avoid soluble salt accumulation on the soil surface because of evaporation, irrigation under a plastic cover is used, especially when saline water is the only source for irrigation. In an arid climate zone, where the evaporation rate is high, mobile nutrient anions (NO3-‐, Cl-‐, ), together with the cations Na+ and Ca2+ may accumulate around the wet zone periphery on the soil surface. This zone of highly concentrated soluble salts is detrimental to young seedlings, because their restricted root system might be exposed to high salt concentrations, even with good-‐quality water. Selection of fertilizers Most water-‐soluble and liquid fertilizers are suitable for fertigation. In selecting a fertilizer four main factors should be taken into consideration. 1. 2. 3. 4. Plant type and stage of growth. Soil conditions. Water quality. Fertilizer composition and price. Type of plant Plant sensitivity to the form of N increases during the fruiting stages (Xu et al., 2001). Some plants, such as tomato, are very sensitive to high ammonium concentration near the roots, therefore, nitrate-‐rich nutrient solutions should be selected (Kafkafi et al., 1971). Soil and water conditions At elevated root-‐zone temperatures ammonium might damage the roots by competing with the sugar needed to root respiration. Local high ammonium 15
Page 1 and 2: Fertigation Proceedings: Selected P
Page 3 and 4: © All rights held by: Internationa
Page 5: Yield and Fruit Quality of Tomato a
Page 8 and 9: Preface Irrigation is a crucial com
Page 10 and 11: Global Aspects of Fertigation Usage
Page 12 and 13: 5. 6. 7. Prevents salt injuries to
Page 14 and 15: Fertigation reduces the amount of h
Page 18 and 19: concentration can result in ammonia
Page 20 and 21: Scheduling fertigation Nutrient ele
Page 22: soil temperatures are high, i.e., u
Page 25: Kafkafi, U. 1994. Combined irrigati
Page 29 and 30: Introduction The rapid economic dev
Page 31 and 32: However, small changes in the assum
Page 34 and 35: and industrial feedstocks (Table 1)
Page 36: Environmentally sound nutrient mana
Page 39 and 40: fertilizers also show promise for i
Page 41: Matson, P., P. Loiseau, and S.J. Ha
Page 45: minimizing detrimental effects of e
Page 48 and 49: Fig. 2. Schematic representation of
Page 50: Deficiencies of K and/or Mg cause m
Page 53: nutritional status of the plants. T
Page 56 and 57: Conclusions The existing data indic
Page 59: Close, D.C., C.L. Beadle, and M.J.
Page 63: Wang, Y.J., M. Wisniewski, R. Melia
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strongly for potable water, but whi
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In Asia, 84% of the water is used f
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Discussion Value of nutrients in TW
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sources are presented in Table 3. T
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Fig. 4. P concentration in soil pro
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Cornel, P. ,and B. Weber. 2004. Wat
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Introduction “Fertigation” is a
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Young bearing trees Thompson et al.
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Fig.3. Effects of fertilizer source
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(TSS) yield was 16% greater with fe
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surficial aquifer underneath citrus
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Fig. 8. Comparison of the effects o
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Fig. 10. Fruit yield responses (6-
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Fertigation of Deciduous Fruit Tree
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demand more precisely than in syste
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In sandy soils, it is also possible
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supplied N at about 63 kg/ha, indic
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Phosphorus Fertigation is known to
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Conclusions Fertigation offers the
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Neilsen, D., P. Millard, L.C. Herbe
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consumed as table grapes, 16% are d
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Table 1. Estimates of approximate p
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affected by rootstock (Treeby et al
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The table grape fertigation decisio
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References Alexander, D. McE. 1957.
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Henschke, P.A., and V. Jiranek. 199
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Zerihun, A., and M.T. Treeby. 2002.
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integration of this knowledge into
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Table 1: Concentrations of macro-
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y moderate application rates (maxim
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Fig. 7. Outgrowth but not the numbe
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scarcity, micro-‐irrigation sys
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Conclusions The presented case stud
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Fertigation in Greenhouse Productio
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Table 2. Target values for nutrient
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Table 4. Water and nitrogen efficie
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quantity and quality is therefore s
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To control the model, the moisture
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(1) (2) Table 6. Results of a 3-
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References Adams, P. 1991. Effects
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Effects of Fertigation Regime on Bl
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incidence of BER in pepper fruits (
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eported an increase in the incidenc
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oth the fruits and the young leaves
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The use of the ECS reduced the inci
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Fig. 5. The effects of Mn on the Na
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Bar-‐Tal, A., and E. Pressman.
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Maynard, D.N., W.S. Barham, and C.L
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Fertigation in Micro-‐irrigated
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other irrigation systems. These hig
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secondary elements, and micro-‐
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supplied by applying part of the fe
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Locascio, S.J., and J.M. Myers. 197
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Yield and Fruit Quality of Tomato a
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Table 1. Effects of K:Ca ratios on
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Munson, R.D. 1985. Potassium in Agr
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nutrients, and certain species are
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via drip lines with a dripper for e
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Prior to the start of the greenhous
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Both Chlamydomonas spp. and Scenede
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Ravina, I., E. Paz, Z. Sofer, A. Ma
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common methods of irrigation includ
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then be used to describe crop water
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In aiming to optimize fertigation e
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Interactive Effects of Nutrients an
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nutrient levels, especially when th
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supply will not improve plant growt
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