Booklet Fertigation Management - Dimenstein - English - December 2017, Notas de estudo de Agronomia

Baixe Booklet Fertigation Management - Dimenstein - English - December 2017 e outras Notas de estudo em PDF para Agronomia, somente na Docsity! yes A Ta») o No RE Re) FT 8 Foi) E! [a] ) 2 Index Summary page. 3 Premises - concept peg. 6 Premise No. 1 – Salinity pag. 7 Premise No. 2 – pH pag. 15 Premise No. 3- ppm pag. 20 Premise No. 4- Soil Solution Extractors and fast kits pag. 21 Nitrite & nitrate pag. 23 Phosphate pag. 24 Potassium pag. 25 Calcium pag. 26 Chloride pag. 28 Sulfate pag. 29 Magnesium peg. 30 Interpretations peg. 30 Premise No. 5 – Quantity X Concentration pag. 33 Premise No. 6 - Golden Rule for Fertigation pag. 34 Parameters for the main crops pag. 37 Questions & Answers about Fertigation pag. 44 Summary CV of the author pag. 97 Bibliography pag. 99 5 Parameters for more than 100 different crops are suggested presenting the acceptable ranges for electrical conductivity (EC), pH, Chlorides, Nitrates, Phosphates, Potassium, Calcium, Magnesium and Sulfates. The suggested ranges for these nutrients in which the smaller values apply to young plants or vegetative phase and will increasing along the growing cycle until maturation to the larger values suggested. Most likely, the future research will adjust these values in some cases. Here we present the suggested values up to the present moment, considering values within physiological ranges for a viable performance without falling in "gross errors", which by definition would be unintentional mistakes that practice by simple ignorance of not knowing the nutritional status of that moment. Example: apply fertilizer acid trend i.e. Ammonium Sulfate or soluble Purified MAP, without knowing what is the current pH of soil solution, however if this pH is identified in soil solution already quite acid, assume for instance, about pH ~5, would be a "gross error" insist to continue applications via fertigations of that same acid fertilizers, while proper management would avoid these acids and choose other fertilizers to get more alkaline trend in the soil solution using for examples Nitrates of Potassium and/or Calcium, among others. Another example of a "gross error" would be unnecessarily apply some nutrient whose tests indicate high values, and therefore there would be no need for new applications at that time and could follow accompanying and monitoring these levels of several nutrients in soil solution for the settings on a case by case basis, avoiding both faults and excesses. The very practical tool of Soil Solution Extractors (ESS) are placed in 3 depths (15, 30 and 45 cm) and if the nutrients and the EC are well distributed between the 3 depths means that the volume of irrigation watering is adequate, however if the nutrients and the EC are higher 6 in the SSE tube deeper of 45 cm, indicating clear that the salts are leaching, than it would be a mistake following the same irrigation volume of irrigation, while the correct management would be an obvious reduction of the irrigation volume, since who decides about the irrigation management could get true information from the collection SSE tool and easy measurement by the quick kits. Then the management decisions are very logic and sometimes obvious. In the following, we present a series of Questions & Answers always so common in irrigated agriculture with controversial topics with a focus on management and thus presented in a very didactic way that may be useful. Let's go to the premises. Premises They are truths that serve as a basis to sustain an idea in a logical sequence, based on strong arguments and easy to understand. For the practical purpose of making the fertigation management something accessible and easy within the storyline that evolves throughout the premises, to reach all levels of farmers since the highest academics even those who had no access to studies in a typical rural extension work as the art of make less complex for a subject that until then was treated as "cake recipe". The easy way to achieve this target comes with the “golden rule of fertigation” which brings the popular level the day-to-day management of the fertigations making agriculture a science of coherent, practical and effective decisions via fertigation. The details with examples for the use of this golden rule of fertigation are presented here. 7 Premise No. 1 - Salinity: Most of soluble fertilizers are salts. On the solid phase salts are neutral, however, after dissolve in water, the components of salts dissociate into positive electrical charges, the cations and negative, the anions. So the salts dissolved in water conduct electricity and can be measured by a single use device called the conductivity meter which measures the electrical conductivity abbreviated as EC. Our luck is that the EC is proportional to the concentration of salts in a given volume of water and this facilitates our interpretation of salinity for use via fertigation that we will explain in the sequence of arguments. A fertilizer or salt or a cocktail of mixed fertilizers, to dissolve at a dose of 1 g/L have a salinity x, then we can say that this same fertilizer or fertilizer cocktail with double the dose in g/L have a salinity of 2x, if it is 3 g/L have salinity of 3x, and so on until the saturation which is already outside the agricultural scale which is above 7 g/L when the high salt concentration is not anymore proportional due saturation of the solution. The normal is working via fertigation in soft and frequent doses so we avoid getting the doses of greater than 7 g/L. In practice, we were usually below 2 g/L which is equivalent to 2 kg/m3. Means that applying 2 kg of soluble fertilizer in each m3 (1,000 L) of irrigation, we obtain the EC of twice the same fertilizer with 1 kg/m3. EC actual unit is Siemens as a tribute to this scientist. The official international unit is dS/m (deciSiemens per meter). The old unit used before the 90’s in the 20th century was used as mmho/cm. It is common to express the unit in centimeter instead of meter, mS/cm (milliSiemens per centimeter). There is also conductivity meter that 10 3 -0.9 4 -1.2 5 -1.5 6 -1.8 7 -2.1 As analogy between salinity measured by the EC and the tension of - 0.3 ATM for each EC unit, generating a counterforce to the roots for the absorption of the nutrient solution. If a tensiometer could measure this negative force caused by salinity, it would be like the diagram below, but of course tensiometers will inform only the water availability independent of the salinity: 11 The EC of 3.33 mS/cm would be equivalent to a full turn of the tensiometer scale that is for 1 ATM, indicating that salinity measure of EC = 3.33 mS/cm would cause a water retention in soil resisting absorption by roots similar to a tension meter worth of -1 ATM and the diagram is in the range usually of CentiBars (CBars). 100 CBars = 1 ATM. This confirms that water stress may occur for plants even with the soil wet, in case of high EC even in presence of humid soils, but the salinity would cause some difficult to the roots to absorb the soil solution. This scenario could be caused by natural soil salinity of irrigation water, or by excessive fertilizer applications. In this latter case, we would have management control by measuring the EC of the soil solution with certain frequency to adjust the doses of fertigations. The EC meter cannot identify the salt composition of every salt (fertilizer), but only the total salinity. The great challenge of fertigation management is handling the composition and proportions of fertilizer salts. Keep the total salinity measured by the EC within the physiological tolerance of each culture and change the doses of fertigations to get the best agronomic response for each stage of development of the crops. To better understand the relationship of the main nutrients present in soluble fertilizers, simply identify what we call in "equivalents", i.e. the molecular weight divided by electric charge of the ion (cation or anion). For Potassium K+ which is a monovalent cation and its molecular weight is divided 39 by 1 is equal to the same 39, so 1 equivalent of K+ is worth 39. For the chloride Cl- that is an anion whose molecular weight is about 35 and also divides it by 1 because it is a monovalent ion to get 35 which is 1 equivalent of chloride. For the bivalent ions like Calcium Ca++ with molecular weight 40 divided by the electric charge 2 to form 1 equivalent of 20. For 12 Magnesium Mg++ also bivalent, with molecular weight 24 divide by 2 to form 1 equivalent of 12. The next step for our best understanding must link the “equivalents” to the electric conductivity, stating that 1 equivalent of any ion has the power to increase the salinity in the EC meter by 0.1 mS/cm. So, for example 5 equivalents of K+ bring the EC to 0.5 mS/cm. Similarly 3 equivalents of Mg++ contribute to the total EC with the fraction of 0.3 mS/cm that we can read in the device conductivity meter. The conductivity meter measures the total salinity. EC = 1mS/cm means that there are 10 equivalents of cations and 10 equivalents of anions, so the total of 20 equivalent to always be half and half cations to anions. For an EC = 2.5mS/cm, the number of equivalents are 25 of cations and other 25 equivalents of anions, to get a total of 50 equivalents of both kind of ions, always being half and half cations to anions proportion. Any salt dissolved in water releases cations and anions so balanced in number of equivalents. The conductivity meter measures the power of only one of the charged ions, or cations or anions, and so the EC identified x 10 = number of equivalents of one of the charges. To the total number of cations and anions by adding equivalents will be double. Example for EC = 1.5 mS/cm, there are 15 equivalent of cations and other 15 equivalents of anions for a total of 30 equivalents of all ions. Below is a table with a summary: EC (mS/cm) Equivalents Cations Equivalents Anions 1 10 10 15 Important the pH colorimetric test strips kit to use once in a while only to confirm that the digital pH meter is calibrated. The illustration of the pH meter was presented above together with the EC meter. Calibration of pH meter using two solutions of pH 7 and 4 or 7 and 10 and can be performed where the difference between the digital and the colorimetric pH test strip is more than 0.5 is a good indicative that need calibration. Instructions on how to use colorimetric pH test strip tape – Insert the tape within the solution for at least 2 minutes before comparing with the scale on the container package. The choice of the soluble fertilizers for fertigation will have strong influence on pH of the soil solution into the wet soil bulb along the roots. This will influence also the solubility of nutrients, the compatibility between the nutrients and other no nutrients ions present in the soil and soil microbial flora. Note in the chart below, the solubility and availability of macro and micronutrients as a function of pH in soil solution. It is clear that the 16 range of balance lies between 5.7 to 7.5 and the midpoint of 6.5 as the average value desirable to keep all the nutrients available in the soluble phase. The choice of soluble fertilizers with tendencies of more acidic or more alkaline will surely influence the pH in the wet bulb along the many fertigations. The use of pH meter is the key to that decision in the choice of fertilizers which will put the pH of soil solution on track for better absorption by the roots. The choice of the Nitrogen source should always be based on the pH meter. Urea (OC(NH2)2), Ammonium (NH4+) or nitrate (NO3-). Roots of plants only recognize and absorb electric charges, i.e. cations and anions. The Urea releases (NH2) which is an amine and with two amines form an amide (NH2)2 , but no electrical charge for amine nor for amide. 17 In the soil the common enzyme called urease breaks the link between the C with N releasing on soil solution two NH2 amines that are unstable and seek the soil to combine and react with H-free. So when capturing the first H it forms NH3 that has the name of Ammonia and ammonia is a volatile gas, so if it will be close to the soil surface at high temperatures of a sunny day, it will surely evaporate. If however, ammonia is infiltrated into the soil, will win soon one more H-free and will turn finally one cation NH4+ called now as Ammonium and as a charged ion cationic, the roots can finally recognize and uptake it. Note that the first reaction of urea which began with NH2 gets 2 H-free from the soil solution to switch and form NH4+ and so the pH of soil solution with less H-free becomes more alkaline. However, the Ammonium (NH4+) normally found in soil, a rich microbial population that has great affinity for this form of nitrogen and is called nitrifying bacteria of the species Nitrosospiras and Nitrosomonas breaking chemical bonds between N and the 4H releasing all these 4H to the soil solution causing in this sequence its acidification. So the urea initially takes from the soil solution 2H and later returns 4H to get the final balance of acidification of the soil environment. After this stage where the N is again free but unstable the next sequence of reaction will be with Oxygen to form first NO and following NO2- (Nitrite). From this point another group of soil bacteria called Nitrobacter finally make the last stage of Nitrification forming NO3- (Nitrate). Both NO2- and NO3- are anions and the roots can recognize and can absorb them. NO2- is an intermediate and apparently under normal conditions the nitrifying bacteria complete the process quickly forming NO3- that within the plant induces internal production of the enzyme nitrate reductase that turns NO3- in NH2 (Amine) and hence form several kinds of amino acids and then proteins. Unfortunately the plants has low ability to synthesize the enzyme that would decompose 20 Keeping then the 4 zeros difference, we can say that the concentration of 1000 ppm = 0.1%. It is preferable to say for example that we have 500 ppm of K than 0.05% K, even if they are exactly the same, to avoid use fractional numbers at level of percentage %. The nutrient guarantees of commercial soluble fertilizers are all presented on their bags in %. The nutrients analysis of the fast kits for identifying concentrations in soil solution is all in ppm. This method presented here aims to bring understanding of fertigation management to be used in ppm, which is a form of dosing concentrations, as well as the numbers presented on the fertilizers bags also in concentrations, but appear in % and we need to do the conversion to use everything in ppm that brings an understanding simple and straight to the farmer that will be able to use the simple golden rule of fertigation described in detail later in this text. Premise No. 4 – Soil Solution Extractors (SSE) and fast kits: For irrigated crops the frequent collection of soil solution for fast analysis, replaces the traditional soil analysis by dynamic and ease in identifying only the available nutrients. It is very practical compare two sequence collections with time interval, for example weekly, identifies the DELTA (∆) between the two 21 collections and decide the doses via fertigation. Example: If the nitrate last week was identified at 200 ppm and in the current week went to 150 ppm, have a ∆ = 50 ppm that indicates we lost this nitrogen and have the option to compensate it via fertigation to that dose to fill only the ∆, if the goal is to maintain the previous week's original 200 ppm. It is a game of identifying the current status, comparing with the previous collected sample of soil solution and manipulates the doses of fertigation to the desired values that must consider the sum of all the nutrients for total salinity measured by the EC in the physiological range for each crop. The collection samples of soil solution can be done easily through the use of tubes called Soil Solution Extractors (SSE) (see pictures) which must be introduced into the soil in 3 depths, usually 15, 30 and 45 cm, and with the aid of a syringe is done extracting the air to form vacuum 22 and force the suction of soil solution by the porous ceramic tip of these tubes when the soil is wet, i.e. at the end of an irrigation when the soil is close to field capacity near the saturation level of water retention by soil that is the ideal time to trigger the vacuum, and while repeating the removal of air by at least 3 times one can realize that the syringe plunger comes with difficulty indicating that the suction tube is under vacuum. If the syringe plunger comes easily is a sign that there is no vacuum. In dry soil you can't do the vacuum. After about 2 hours of waiting under vacuum action to fill the tube with the soil nutrient solution and release the vacuum to collect the sample from the SSE. After release the vacuum in the SSE, use a syringe to collect the samples. The syringe of 60 ml with Luer-Lok tip to allows safe connection to SSE. Then we can start the fast measure the EC to know the level of salinity in each horizon deep where it distributes the nutrients into the wet soil around the root system. These tubes SSE do a mimic to imitate exactly what the roots are absorbing of only the available nutrients in the soil solution in each collected sample depth. Then the other kits complement the data of pH in soil solution and detail the concentration for each relevant nutrient like N, P, K, Ca, S, Cl to identify only available nutrients and their distribution in 3 depth of soil to ease see if there are leaching or good nutrient distribution around the roots. The main kits of nutrients of colorimetric titration, tape and turbidity and the step-by-step instructions: 25 This fast phosphate kit is in PO4-- and not in P2O5. To pass P2O5 for PO4- - multiply by 0.75. Example: NPK Formula 30-20-10, the 20 of P2O5 worth 15 of PO4--. Optimal levels of PO4-- in soil solution depend on soil texture. 25 ppm for heavy clay and 50 ppm for light sandy soils. Intermediary levels for soil textures moderate to be between 30 – 40 ppm. Above 50 ppm, only for hydroponics that can stay between 60 to 100 ppm of PO4--. Potassium – There are 2 small glass tubes that must be filled, one of them being with the sample solution collected in soil solution extractor while the other with 10 drops of reagent (Kalium/Potassium-1). Immerse the test strip that has the reagent in the solution sample collected from soil solution extractor for a brief period of 1 to 2 seconds, remove the strip, shake off excess liquid and immediately insert it the second vial and keep it immersed for 1 full minute, then remove it, shake off excess liquid and is ready to compare the color with the scale in tube packaging. 26 The scale of the Potassium kit starts at 200 ppm. It is normal in the early stages of growing, vegetative stage of crops keep the K+ below 200 ppm and in this case may have the false impression that the value would be zero, but remember that 200 ppm is about 5 K+ equivalents (39 x 5 = 195 ppm) and this implies that the K+ may be contributing to up to 0.5 mS/cm in the EC, even if this test strip doesn't show at least 200 ppm that is limiting the scale of this colorimetric kit. However in the following phases of the crops with greatest needs of K+ range caters well to the goal of monitoring between 200 and 700 ppm. The Potassium kit read the ion K+, while the commercial fertilizers present Potassium as K2O (as oxide). The conversion of K2O to K multiplies by 0.83. Example: KCl with 60%, K2O 60 x 0.83 = 49.8 and to get round number we can consider it as 50 K pure. 27 Calcium- Fill the container with 5 ml of the solution sample collected in soil solution extractors. Add 2 drops of reagent "NaOH 5-20%" and give a brief stirred and the sample may be turbid (when the solution is not fully transparent). Add 2 drops of the other reagent on the black small bottle that is an indicator solution "Indikator CA 20" and again give a brief stirred and the solution will turn red. However, if the solution turns blue means no calcium is present in the sample. If the color is red continue the test. Now fill the syringe with the solution of the larger bottle called "Calcium TL CA 20", is the bottle of 100 ml. Syringe has two scales in ºd or in mmol/L. The best suggestion is to use the scale in mmol/L, whereas 1 mmol/L = 40 mg/L (ppm) of calcium. On another scale would be conversion to 5.6°d = 40 mg/L (ppm). So let's drip enough solution with the syringe until the red color changes to blue in a simple titration. When the color flip from red to blue just watching in the syringe as you spent and for each 1 mmol/L x 40 = ppm calcium concentration in the sample. If you spend the entire volume of the syringe worth 3.5 mmol/L x 40 = 140 ppm and color not turn from red to blue, you must continue refill the syringe to continue the titration indicates that the sample must contain a greater concentration of calcium. 30 the beginning with only 10 ml of sample and make up to 20 ml with pure water. Magnesium – Fill the container with 1 ml of the solution sample collected in soil solution extractors + 4 ml of pure water or tap water with EC close to zero. Add 1 ml of reagent "MG-1" and a small spoon of the reagent “MG-2” that is a salt and will immediately dissolve after give a brief stirred and the sample will turn red or pink. Now start the titration drop by drop using a syringe of 1 ml with the reagent “MG-3” till the solution color changes to blue and check the volume used in the scale of the syringe. Observe that for the used volume of 0,01 ml = 3 ppm of Mg; at this same proportion, for a volume of 0,1 ml of this last reagent “MG-3” means = 30 ppm of Mg and for a full syringe using 1 ml = 300 ppm de Mg. 31 Interpretations In fertigation the relative interpretation is the most appropriate, identifying the DELTA (∆) between two analyses of the soil solution. Let's compare for each item, the current collection against the previous collection to identify the ∆. If for example the pH was 6 and for one new collection it was 5.5 implies that the ∆ was 0.5 more acidic and this indicates a tendency to acidify the soil solution which can be confirmed in the next collection of samples. If for example the Nitrate kit presented 300 ppm and 200 ppm in the next collection presented, implies that we lost 100 ppm and the management decision is apply or not this rate of lost Nitrogen, considering that the desired Nitrate level would be 300 ppm in this example. If the Phosphate was identified as 10 ppm and the next week we got some increase to 25 ppm, but the ideally desired level would be 50 ppm. Then we would still have to apply +25 ppm of Phosphate. Even with improved in relation to previous collection, was not enough to reach the desired concentration. This approach will inform the availability of nutrients and the grower must adjust the dose for the next fertigation and optimize the availability for the roots. Quick kits are easy and giving practical guidance on nutrient levels, salinity (EC) and pH are valued information to facilitate decision making by minimizing the mistakes in choices of fertilizers and in doses to be applied. The majority of management errors are due to lack of minimum information about the availability of the nutrients, total salinity (EC), pH and leaching nutrients by exaggerated irrigation, that 32 we can identify if the SSE at high depth (45 cm) get more nutrients and EC than the less depth SSE at 30 and 15 cm. Would be unlikely for one grower after identify the soil solution pH as acid and continue new applications of acid fertilizer via fertigation to increase the size of the problem such as ammonium sulfate, Urea, Phosphoric Acid, etc. The opposite decision is the coherent and logic to immediate avoids the use of acid sources and give preference for some alkaline fertilizers such as Calcium Nitrate and Potassium Nitrate among others. Would be unlikely also for one grower after identify in soil solution for example Calcium levels above 150 ppm when it would be sufficient between 60 and 100 ppm. The farmer that insists to apply more Calcium in this case get more than only a waste of fertilizer and money, but will cause more competition against other cations like K and Mg, beside the total salinity of excess of fertilizers. The interpretations are intuitive and according to clear parameters and always the decisions for any fertigation correction are making logic by avoiding management mistakes just by tweaking of dosages and choice of the sources of fertilizer without kick and without gross errors. The monitoring is an effective tool to alert to avoid many errors of management decisions of fertigation and errors that the "recipes of cake" are subject to occur and fleeing, but now is very easy and obvious to identify and correct. 35 formula already presented in ppm. The proportionality is applied also for reduction, for instance if we use half the starting dose would be 50g/m3 provides half the formula guarantee in ppm. Example with a very popular soluble NPK formula 16-08-32 to apply via fertigation in a volume of 5 mm = 50 m3 to irrigate 1 hectare. When using the “Golden Rule of Fertigation” in original proportion of 100g/m3 x 50 m3 would be a dose of 5kg per hectare of this formula during that irrigation day and each emitter (drip, micro sprinkler, other) would provide exactly 16 ppm N, 08 ppm of P2O5 and 32 ppm of K2O in that area. If we apply the default initial dose 5x, shall be 500g/m3 and the guarantee of the formula goes from % to ppm 5x more concentrated, going from 16-08-32 (5x) to get 80-40-160 all in ppm of N-P2O5-K2O. The fertilizer industry uses for phosphorus and potassium Oxides expressions since the years 1930’ because at that time the science believed that plants would absorb nutrients by roots in the oxide forms although we know nowadays that instead of P2O5 the correct absorption form is ionic as PO4-- (Phosphate) and Potassium instead of K2O the ionic form is the cation K+ pure, without Oxygen. The kits presented here measure PO4-- and not P2O5. The conversion from P2O5 to PO4-- is multiply by 0.75. Also the test kit for Potassium is K+ and converts K2O to K need to multiply by 0.83. In the example above which applied 500g/m3 reaching 80-40-160, the 40 ppm of P2O5 multiply by 0.75 = 30 ppm of PO4-- and 160 ppm of K2O multiply by 0.83 = 133 ppm of K+. The Oxides for other nutrients also need conversion: CaO to Ca multiply by 0.71. MgO to Mg multiply by 0.6. 36 For Sulfur the case is more curious because the oxide format used is SO3, but the ionic form of absorption by roots is SO4. The industry present the % guarantees as SO3 or as pure S. To convert SO3 to SO4 divide by 0.83. To convert SO3 to S multiply by 0.39. To convert SO4 to pure S multiply by 0.34. Example or the Golden Rule of Fertigation using Urea 45% N and applying the standard dose via fertigation of 100g/m3 provides exactly 45 ppm of N. If the volume is for instance 40 m3/hectare, there will be 100g x 40 m3 = 4 kg of Urea to apply in this fertigation day per hectare and from each emitter (drip or other irrigation equipment) this dose will give 45 ppm of N. As this rule is proportional, just decide the dose per m3 to get proportional dose in ppm. If we double the standard proportion to 200 g/m3 it will provide 2x the guarantee for Urea 45 x 2 = 90 ppm. Example using soluble white KCl with 60% K2O and we want to apply for instance, 300 ppm of K2O. If 100g/m3 provides the guarantee of 60, to achieve the level of 300 ppm would be 5x, then 500g/m3. If the watering volume desired for this irrigation would be 7 mm = 70 m3/hectare, then 500 g x 70 m3 = 35 kg of KCl and you apply in this hectare the 300 ppm of K2O. Convert 300 ppm of K2O to pure K multiplies by 0.83 = 249 ppm of K and we can consider the round number of 250 ppm of K applied. 37 Parameters - suggested for some crops using the fast kits for the soil solution analysis. The suggested range for the nutrients consider the larger values for advanced growth stages up to maturation and the lower values for vegetative and flowering stages. Consider for Chloride values as the tolerance limit above this value the yields tend to decrease. For the range of pH balance to the various nutrients are in soluble phase should be above and below 7.5 5.7. The actual values given as parameters are intended to serve as a reference for future adjustments that according to research that will make case-by-case basis. The experience we observe during several years in the irrigated fields alert us for the common and so-called "no intentional errors" that choose of wrong fertilizer as well wrong doses of application of certain fertilizers sometimes by excess or deficiency, due lack of data on which to base these decisions on the fertigations. The more important thing using this fertigation method is not to achieve 100% efficiency, but avoid wastes due feasible information that we can get ease access to minimize the “no intentional errors”. Why one farmer would apply an acid fertilizer like ammonium sulfate or purified MAP, or phosphoric acid, if the pH identified in the soil solution collected by the SSE was < 5? For those cases that are common to occur this monitoring of soil solution will be helpful and serve as a guideline for choose some alkaline fertilizer trend as Calcium Nitrate, Magnesium Nitrate or Potassium Nitrate and get higher pH to correct the pH level in the soil solution. If a farmer needs 150 ppm of Calcium and identified that there is already in the soil solution 200 ppm available, it doesn’t make sense to apply new fertigation to supply more calcium in this case 40 Crop EC mS/cm pH Cl - (ppm) NO3 - (ppm) PO4 -- (ppm) K + (ppm) Ca ++ (ppm) Mg ++ (ppm) SO4 -- (ppm) Pomegranate 1,5 - 3,5 5,7 - 7,5 < 500 200 - 300 25 - 50 300 - 600 80 - 150 40 - 75 80 - 120 Peach 1,5 - 3 5,7 - 7,5 < 400 200 - 350 25 - 50 200 - 500 80 - 150 40 - 75 60 - 100 Loquat 1,5 - 3 5,7 - 7,5 < 400 200 - 350 25 - 50 200 - 500 60 - 120 30 - 60 60 - 100 Plum 1,5 - 3,5 5,7 - 7,5 < 400 200 - 400 25 - 50 250 - 550 80 - 150 40 - 75 80 - 120 Apricot 1,5 - 3 5,7 - 7,5 < 400 200 - 350 25 - 50 200 - 500 60 - 120 30 - 60 60 - 100 Ciruela 1,5 - 2,5 5,7 - 7,5 < 400 150 - 300 25 - 50 250 - 500 60 - 120 30 - 60 80 - 120 Cherry 1,5 - 3,5 5,7 - 7,5 < 400 100 - 300 25 - 50 300 - 600 80 - 150 40 - 75 60 - 100 Fig 1,5 - 3,5 5,7 - 7,5 < 500 200 - 300 25 - 50 300 - 600 80 - 150 40 - 75 80 - 120 Almonds / Nuts 1,5 - 3,5 5,7 - 7,5 < 600 150 - 300 25 - 50 300 - 600 80 - 150 40 - 75 80 - 120 Pistachio 1,5 - 3,5 5,7 - 7,5 < 600 150 - 300 25 - 50 300 - 600 80 - 150 40 - 75 80 - 120 Macadamia 1,5 - 3,5 5,7 - 7,5 < 600 150 - 300 25 - 50 300 - 600 80 - 150 40 - 75 80 - 120 Carambola 1 - 2,5 5,7 - 7,5 < 300 100 - 300 25 - 50 150 - 500 50 - 150 25 - 75 60 - 100 Pitanga 1 - 2,5 5,7 - 7,5 < 300 100 - 300 25 - 50 200 - 500 50 - 150 25 - 75 60 - 100 West Indian Cherry 1,5 - 3 5,7 - 7,5 < 450 200 - 300 25 - 50 250 - 600 60 - 120 30 - 60 90 - 140 Casheu 1,5 - 3 5,7 - 7,5 < 500 200 - 300 25 - 50 250 - 600 80 - 150 40 - 75 80 - 120 Jackfruit 1 - 2,5 5,7 - 7,5 < 400 150 - 350 25 - 50 250 - 500 50 - 150 25 - 75 60 - 100 Spondias mombin 1 - 3 5,7 - 7,5 < 350 150 - 300 25 - 50 200 - 600 80 - 120 40 - 60 100 - 150 Sugar apple 1,5 - 3,5 5,7 - 7,5 < 400 150 - 300 25 - 50 200 - 500 80 - 150 40 - 75 80 - 120 Hancornia 1 - 3 5,7 - 7,5 < 350 150 - 300 25 - 50 200 - 600 80 - 120 40 - 60 100 - 150 Soursop 1,5 - 3,5 5,7 - 7,5 < 400 150 - 300 25 - 50 200 - 500 80 - 150 40 - 75 80 - 120 Guava 1 - 2,5 5,7 - 7,5 < 400 100 - 300 25 - 50 200 - 450 50 - 120 25 - 60 60 - 100 Raspberry 1,5 - 3 5,7 - 7,5 < 500 200 - 300 25 - 50 250 - 600 80 - 150 40 - 75 80 - 120 Blackberry 1,5 - 3 5,7 - 7,5 < 500 200 - 300 25 - 50 250 - 600 80 - 150 40 - 75 80 - 120 Pineapple 2 - 3,5 5,7 - 7,5 < 800 100 - 300 25 - 50 500 - 800 60 - 100 30 - 50 100 - 150 41 Crop EC mS/cm pH Cl - (ppm) NO3 - (ppm) PO4 -- (ppm) K + (ppm) Ca ++ (ppm) Mg ++ (ppm) SO4 -- (ppm) Tomato 1,5 - 3 5,7 - 7,5 < 500 150 - 300 25 - 50 200 - 600 60 - 150 30 - 75 70 - 120 Cherry Tomato 1,5 - 4 5,7 - 7,5 < 700 150 - 300 25 - 50 300 - 800 60 - 150 30 - 75 90 - 140 Melon / Watermelon 1 - 3 5,7 - 7,5 < 400 100 - 300 25 - 50 200 - 600 60 - 100 30 - 50 60 - 100 Onion / Garlic 1 - 1,8 5,7 - 7,5 < 300 150 - 300 25 - 50 200 - 400 60 - 100 30 - 50 70 - 120 Pepper 0,8 - 2 5,7 - 7,5 < 300 100 - 300 25 - 50 150 - 400 40 - 80 20- 40 60 - 100 Hot Pepper 0,8 - 1,5 5,7 - 7,5 < 300 100 - 200 25 - 50 150 - 300 40 - 80 20 - 40 50 - 80 Piper Nigrum 1,2 - 2,5 5,7 - 7,5 < 400 100 - 300 25 - 50 200 - 400 60 - 100 30 - 50 100 - 150 Potato 0,8 -2,2 5,5 - 6,5 < 300 100 - 300 25 - 50 100 - 600 40 - 60 20 - 30 60 - 100 Sweet Potato 1 - 2 5,7 - 7,5 < 300 100 - 300 25 - 50 200 - 400 50 - 100 25 - 50 40- 80 Lettuce 0,6 - 1,8 5,7 - 7,5 < 200 150 - 250 25 - 50 100 - 250 60 - 100 30 - 50 40- 80 Rucola 0,7 - 1,5 5,7 - 7,5 < 200 150 - 250 25 - 50 100 - 250 60 - 100 30 - 50 40- 80 Chard 1,2 - 1,8 5,7 - 7,5 < 300 150 - 300 25 - 50 150 - 300 60 - 100 30 - 50 50 - 100 Cress 0,7 - 1,5 5,7 - 7,5 < 200 150 - 250 25 - 50 100 - 250 60 - 100 30 - 50 40 - 80 Cabbage 1,2 - 1,8 5,7 - 7,5 < 300 150 - 300 25 - 50 150 - 300 60 - 100 30 - 50 50 - 100 Strawberry 0,8 - 2,2 5,7 - 7,5 < 300 150 - 300 25 - 50 150 - 550 60 - 80 30 - 40 60 - 100 Cucumber / Zucchini 1,2 - 2 5,7 - 7,5 < 300 150 - 300 25 - 50 150 - 300 60 - 100 30 - 50 40 - 80 Pumpkin 1,5 - 2,5 5,7 - 7,5 < 350 200 - 300 25 - 50 250 - 400 60 - 120 30 - 60 50 - 100 Eggplant 1,2 - 2 5,7 - 7,5 < 300 150 - 300 25 - 50 150 - 300 60 - 100 30 - 50 50 - 100 Beet / Sugar Beet 1,5 - 3 5,7 - 7,5 < 500 150 - 300 25 - 50 200 - 500 60 - 150 30 - 75 70 - 120 Carrot 0,8 - 1,8 5,7 - 7,5 < 300 100 - 200 25 - 50 100 - 300 50 - 100 25 - 50 40 - 80 42 Crop EC mS/cm pH Cl - (ppm) NO3 - (ppm) PO4 -- (ppm) K + (ppm) Ca ++ (ppm) Mg ++ (ppm) SO4 -- (ppm) Yam 1,2 - 1,8 5,7 - 7,5 < 400 100 - 300 25 - 50 200 - 400 60 - 100 30 - 50 40 - 80 Chayote 1,2 - 2 5,7 - 7,5 < 300 150 - 300 25 - 50 150 - 300 60 - 100 30 - 50 40 - 80 Gumbo 1 - 2 5,7 - 7,5 < 300 150 - 250 25 - 50 200 - 400 50 - 100 25 - 50 40- 80 Ginger 1 - 2 5,7 - 7,5 < 300 150 - 250 25 - 50 150 - 300 50 - 100 25 - 50 40 - 80 Spinach 1 - 2 5,7 - 7,5 < 300 100 - 300 25 - 50 150 - 300 50 - 100 25 - 50 40 - 80 Couve / Broccoli 1,2 - 1,8 5,7 - 7,5 < 300 150 - 300 25 - 50 150 - 300 40 - 80 20 - 40 50 - 100 Parsley / Coriander 0,7 - 1,5 5,7 - 7,5 < 250 150 - 250 25 - 50 100 - 250 60 - 100 30 - 50 40 - 80 West Indian Gourd 1 - 2 5,7 - 7,5 < 300 150 - 250 25 - 50 200 - 400 50 - 100 25 - 50 40 - 80 Mustard 1 - 2 5,7 - 7,5 < 300 100 - 300 25 - 50 150 - 300 50 - 100 25 -50 40 - 80 Turnip / Radish 0,8 - 1,8 5,7 - 7,5 < 300 100 - 200 25 - 50 100 - 300 50 - 100 25 - 50 40 - 80 Scarlet Eggplant 1 - 2,5 5,7 - 7,5 < 400 100 - 300 25 - 50 200 - 450 60 - 100 30 - 50 40 - 80 Peas 0,8 - 1,3 5,7 - 7,5 < 250 50 - 120 25 - 50 150 - 300 40 - 80 20 - 40 50 - 70 Peanut 1 - 2 5,7 - 7,5 < 350 50 - 120 25 - 50 150 - 300 60 - 100 30 - 50 40 - 80 Asparagus 2 - 4 5,7 - 7,5 < 800 150 - 350 25 - 50 300 - 500 60 - 120 30 - 60 90 - 140 Cassava 1,2 - 1,8 5,7 - 7,5 < 400 100 - 300 25 - 50 200 - 400 60 - 100 30 - 50 40 - 80 Arracacha 1 - 2 5,7 - 7,5 < 400 150 - 350 25 - 50 200 - 450 60 - 100 30 - 50 40 - 80 Mint 1 - 2 5,7 - 7,5 < 300 100 - 300 25 - 50 150 - 300 50 - 100 25 - 50 40 - 80 Basil 1 - 2 5,7 - 7,5 < 300 100 - 300 25 - 50 150 - 300 50 - 100 25 - 50 40 - 80 Crop EC mS/cm pH Cl - (ppm) NO3 - (ppm) PO4 -- (ppm) K + (ppm) Ca ++ (ppm) Mg ++ (ppm) SO4 -- (ppm) Eucalyptus 0,8 - 1,5 5,7 - 7,5 < 350 100 - 200 25 - 50 150 - 300 40 - 60 20 -30 40 - 80 Pinus 1 - 2 5,7 - 7,5 < 400 100 - 300 25 - 50 200 - 400 50 - 100 25 - 50 40 - 80 Rubber Tree 1 - 2 5,7 - 7,5 < 400 100 - 250 25 - 50 150 - 350 50 -80 25 - 40 40 - 80 45 However if the difference is greater than 0.5 mS/cm and the SSE tube of 45cm, indicating leaching by excess of irrigation water applied, or eventually due rain. See example below: EC to 15 cm = 1 mS/cm, EC to 30 cm = 1.8 mS/cm, EC to 45 cm = 2.5 mS/cm Note that in this example we have far greater salinity at 45 cm indicating strong leaching. The handling in this case would be to reduce watering and adjust the volume to get the objective of homogenous EC distribution inside the soil with difference of EC < 0.5 mS/cm between the 3 depths. Similarly the opposite interpretation for SSE tube at 15 cm has the higher EC indicates that the irrigation volume was insufficient to better distribute the fertilizer salts to the deeper horizons. Ideally, the 2 tubes of ESS of the depths of 15 and 30 cm should dominate the desired nutrition, while the third tube in the depth of 45 cm is our guarantee that there is no waste of nutrients out of the dominant active root system, if the deeper tube has EC higher, is a strong indication that even deeper will be with higher EC of presence of nutrients wasted. Deep nutrition is typical of dryland agriculture, whereas in irrigated, should induce the emission of roots and radicles in the upper soil horizons that improve the ability to absorb, while nurture deep roots or far apart laterally is far more expensive and inefficient because these roots are more for physical support and less for absorption because they suberized and woody when they pass a dry period. 46 2. How to choose the fertilizer for fertigation and how to choose the source of N among the options of Urea, Ammonium or nitrate? The answer lies with the pHmeter. Although many agriculturists choose fertilizers due the nutrient guarantees and prices, it would be prudent before identifying the pH of soil solution before deciding to apply fertilizers. Example: Let's choose a source of Nitrogen for the next fertigations after identify the soil solution pH is between 8 and 8.5. We know that ammonium sources are acidifying, as well as Urea tends to be acidifying at the end of process in spite of the first reaction of Urea is alkaline, but the second reaction in the sequence is more acid. On the other hand the sources of nitrate are alkalizing. If the soil solution has already acid pH between 5 and 5.5 we should minimize the use of Ammonium and urea to give preference to Nitrates. The choose of the best fertilizers is really a question to the device pHmeter and keep the soil solution pH in levels that all nutrients will be soluble and available to roots uptake. Soil solution pH between 5.7 to 7.5 is the range target and we must use different sources of fertilizers to maintain the pH into this range. If we use only one type of fertilizer throughout the crop growing cycle, the tendency is to get out of the proper range and frequent monitoring of soil solution would easily give us the necessary information about pH to direct the decisions about choose the correct fertilizers. It is clear that this pH manipulation is done with many other fertilizers in addition to the sources of nitrogen from the example above. 47 For many years believed that there was a relationship between Nitrate/Ammonium to recommend based on an old trial with melon that had given the best result in proportion of 80% Nitrate / 20% Ammonium, however some years later proved that this ratio was suitable for irrigation waters acidic with pH between originally 5 to 5.5 and that ratio of Nitrate and Ammonium arrived at an excellent level of pH in soil solution between 6 and 7. Certainly this ratio with dominant Nitrates will elevate the pH and if the original irrigated water is already alkaline this recommendation doesn’t make sense. So there is no proportion ready to recommend between Nitrate/Ammonium but, only the pH in soil solution obtained with that ratio. Of course there is no one best proportion previously defined, but in every case we must make the adjustments considering the original irrigation water pH and pH obtained in soil solution and after some adjustments of doses to reach the desired pH and the ratio of Nitrate/Ammonium will not be never a ready recommendation and must be frequently checked to possible new adjust. 3. Fertigation is a complement of the conventional fertilization or should be 100% of the nutrients applied via fertigation instead of part of the fertilizer applied as base and side dressing? Is possible eliminate the traditional soil fertilization to get total nutrition via fertigation? This is a natural evolution that will occur as the educational level of the farmer increases. The main limit factor is cultural due the tradition practiced during long periods since before modern irrigation arrived to the market. The reliability and trust in fertigation efficiency is the key to migrate to 100% of nutrition via fertigation and it will occurs gradually when the farmer confidence in the fertigations increases after 50 5. How should we act for fertigation during the rainy season that typically gives generous water during at least 3-4 months of the year? Conventional fertilizers for soil application and products for soluble via fertigation are easily leached during these months of abundant rain, besides that the farmer normally does not trigger the irrigation during this period. However we have some management options to discuss how applications of small irrigation just to have the sufficient time to apply concentrated nutrients whereas the soil is already wet, meaning it wouldn't be to give more water, but just to provide some nutrients via fertigation in runtime. This is feasible only in drip or micro sprinkler irrigation, but it would not be possible in pivot because time of watering for this type of equipment is too long, even at the highest speed that it can works. Another management alternative for the rainy season during these 3 to 4 months is applied in soil fertilizers protected by cover of polymers, known as controlled or slow release fertilizers. The term controlled release is more suitable because the nutrient release rate is practically constant in controlled doses over time of release, called longevity. So there are individual fertilizers based on Urea, or granulated soil MAP, or KCl, or other sources that have longevities between 2 to 6 months depending on the thickness of the cover layers of polymers which will involve the grain of fertilizer. Below is a diagram illustrating the latest polymer technology called E-Max developed by ICL for fertilizers of the family Agrocotes, and in the example below to coat and protect the Urea. Considering the pure traditional Urea between 45% - 46% N, to cover with a thin layer of polymers formed E-Max Agrocote N 44% with longevity up to 2 months. Increasing the thickness of polymers on Urea will also increase the longevity and decreases evidently N content, 51 forming E-Max Agrocote N 43%, or 42%, or 41% with longevities increasing to 3 up to 6 months when the N is released day by day at small and constant rhythm and minimize the leaching risk caused by the rains. There are different polymers for granular MAP and KCl and also different longevities. All of those fertilizers called COTES, protected by polymers can form different formulations called Agroblens and Agromaster and sure will certainly be very efficient to provide throughout the rainy season an interesting alternative when the fertigations nutrition would be less attractive. Infiltration very little water through the polymer, but mainly water steam goes well easily within the grain, which will be condensed and dissolve the nutrient internally to form a solution that tends to escape by diffusion at constant rate by spreading gradually and steadily over time scheduled. 6. How often you should do fertigations? 52 The ideal is always that if you irrigate do a fertigation. However this question is unanswered, due to wide variation of practice in the field. The higher the frequency of fertigation with small doses, we consider the better situation regarding less salinity (EC) variations. If we have daily irrigations, but weekly fertigations (example), we will have on the day of fertigation 7 days of accumulated dose at once and this will increase suddenly the salinity which will be diluted over the next 6 days when it will receive only water. So the EC strongly increases at the day of fertigation and is being diluted and washed in the rest of the week. The sequence of repetition of this practice at weekly base will cause ups and downs in the EC concentration of soil solution like accordion (music instrument) do causing the effect of frequent increase and decreases in soil solution salinity. This causes some physiologic stress to any plant. Evolution is controlling with automation via timers or small computers that open and close solenoids (electronic faucet) that meet the command via computer, tablet or even via mobile smartphone, to open and close the injection of dissolved fertilizer solutions from reservoirs with automation. There are no restrictions to prepare the fertilizer solutions previously. These solutions are stable and do not spoil. 7. How proceed the correction if the original irrigation water (River, Lake, pond, well) have pH outside of the ideal range, or too acid or too alkaline? 55 soil. Other situation is even at good quantity in soil, if other nutrient is present at exaggerated level and cause by competition deficiency in leaves and tissues. This kind of analysis is not enough to use them for fertigation management and decide the fertilizers sources and rates of application. Example: a grapes producer collected for every 4 months intervals leaves samples for foliar analysis and repeat them again and again every 4 months during 2 years, that sum the total of 6 times of these foliar analysis and always got Iron and Phosphorus deficiencies. During these 2 years he increased the fertigation rates for both Iron and Phosphates, every time he applied larger doses of iron and phosphorus, using different fertilizers sources including chelates for Iron and different soluble Phosphates available in the market. However after 2 years without resolving the problem of the lack of Iron and Phosphorus in foliar analysis, we identified that it was not a quantitative problem, since the farmer applied high doses of these missing elements in the leaves, but we have identified in soil solution the real problem was the high pH in the soil solution between 9 and 9.5 whereas the original water above pH 8 and improper choice of fertilizer alkaline trend with lots of Nitrate Nitrogen in addition to excess of Calcium. After some fertigations using several acid fertilizers like Ammonium Sulfate, SOP, Nitric Acid, among other acid options till get the soil solution the reduction of pH between 6.5 and 7, all nutrients appeared well on the following foliar analysis including iron and Phosphorus. In this specific case the foliar content for both Iron and Phosphorus were above the ideal because it became available and fully soluble in the soil solution at high concentration. We know that it's called soluble Iron Fe+2 which is stable up to pH 7.5 which passes for the reduced form insoluble Fe+3 above pH 7.5. In relation to the Phosphorus some precipitation starts above pH 7.5 and increase to full precipitate between pH 8 to 9 due reactions with Calcium to form insoluble Calcium Phosphate. 56 10. What to do if we identify that appears Nitrite (NO2-) which is toxic to plants? There are two typical situations to appear Nitrite (NO2-) in the fast test kit of colorimetric analysis: or lack of Oxygen in the soil either by compaction, excess water from the rain and/or the irrigation, that inhibiting the action and proliferation of nitrifying bacteria groups that are formed by aerobic Nitrosomonas, Nitrobacters and Nitrosospiras. Or alternative inhibition due the extreme pH range in the soil solution < 5 or 8 >, since these bacteria reproduce only in this pH range between 5 and 8. There is another factor that should be considered only for cold climate regions, outside the tropical areas, because the nitrifying bacteria need soil temperatures > 8°C and can reduce the population of these bacteria during the cold winter period extending the normal nitrification timing of normal soil temperatures between 15ºC to 25ºC the period of 2 – 3 weeks to longer periods if the Nitrogen source came from Urea 57 or Ammonium to form some Nitrite (NO2-) due the low bacteria population to fast convert the N to Nitrate (NO3-). 11. Why can't we mix in the same dissolution tank Calcium with Phosphates and Sulfates? Calcium reacts easily with Phosphates and Sulfates forming insoluble precipitates. Only in very acidic pH < 4, Calcium does not react with Phosphates. It is prudent not to mix in the same tank these elements. Calcium Phosphate and Calcium Sulfate (Gypsum) are at low solubility or even insoluble at all. Blends of fertilizers for fertigation must be compatibles and at high solubility. Note that there are no restrictions for example, for blends of Calcium sources with fertilizers free of Phosphates and Sulfates such as Urea, KCl, Potassium Nitrate, Ammonium Nitrate, Magnesium Nitrate, etc. 12. What is the best choice: use straight soluble fertilizers as individual products or ready mixes fertilizers that form blends of NPK + secondary Macros + Micros? The ready formulas NPK are always easier to use because of the difficulty of labor to make the mixes on the farms. Use some options of formulations and choose different proportions are always the best and most practical way to do fertigations. Some straight fertilizers always could be added as complementary sources if need. Only as explained before, avoid Calcium which is incompatible with Phosphates 60 14. Can we consider Chlorides harmful via fertigation? What is the tolerance level? The chlorides are very inexpensive sources of fertilizers as KCl and CaCl2, among others, and the needs of plants for Cl are at level of Micro for few ppm between 5 to 20 ppm of plant demand. The main point is identify a level of tolerance for the presence of Chlorides to allow the supply of the accompanies cations like K, Ca, Mg, others. The Cl level in soil solution can be measured by a fast titration kit and identified its concentration to help direct decisions of doses using cheap Chlorides fertilizers up to the crop tolerance. Most vegetables can tolerate between 200 to 300 ppm, for fruit-growing the tolerances are bigger up to about 400 ppm. It is manageable to handle the fertigation levels using Chlorides as long as you perform the tests regularly to avoid excesses and choose other sources of K and Ca when the presence of Chlorides is high in soil solution. Chlorides are easily leached by a good irrigation or rainfall, removing from the roots region the Cl excesses, since there is a good drainage. In compacted soils and drainage-impaired, the chlorides rise by capillary action, as well as other salts also could be harmful to the roots. Remembering that the molecular weight of Cl is 35 and as a monovalent, also its equivalent is 35 and we can say that that 35 ppm in soil solution has the power of salinity in the EC = 0.1 mS/cm. It is proportional, then the level of concentration of 70 ppm Chlorides will have an EC = 0.2 mS/cm. And follow this proportion. The important thing is that the total Chlorides in vegetables does not exceed 30% (~1/3) of the total EC and to fruit and grains up to 40% of the total EC which are reasonable tolerance levels, avoiding the 8 or 80, all or nothing. Zero Chlorides in the soil solution is not the best economic 61 choice, considering the tolerance of these cheap fertilizers based on Chlorides, the agronomic management is to handle the plant nutrition based on physiology optimum response and best relation of benefic/cost. Example: For vegetables with EC total 1.5 mS/cm, up to 5 equivalents (~ 175 ppm) Chlorides are within tolerance. If the EC increases to 2.5 mS/cm we can arrive without problems until 8 equivalents (~ 280 ppm). The hard part is to estimate doses without measure EC and without measure the Chlorides. The fast kits are easy tools for the best agronomic decision and to adjust the doses safely respecting the physiology of plants. 15. What is Salt Index we found on bags of fertilizers? The Salt Index expression was rather used in the past between the 40’s and 60’s of the 20th century, to compare the saltiness against a default standard salt Sodium Nitrate, which was chosen to be the index 100. Any salt dissolved in water in the same concentration was compared against the standard in your osmotic pressure. However, without consider de application dose in fields, it would be only a chemical data not relevant for irrigated agriculture. With the evolution of soluble fertilizers from the years 60’s, the use of Salt Index lost practical function because it is an absolute value and does not represent the risk of salinity for the crops because it depends on the application rate. So interpreting salinity became far more 62 important from the dissolved concentrations in water and much better expressed by electrical conductivity (EC). The use of fertilizers at low Salt Index at high quantities per area will cause of course, high EC and the use of only the Salt Index to classify risk of salinity is not enough, but would need the dose used to identify the salt concentration in soil solution. For no irrigation crops the salinity risk depends on the solubility of the fertilizers, the amount of rain to dissolve these fertilizers to identify the EC formed in the soil solution. This is contrary to the irrigation crops due the advantage of injection manipulation of soluble fertilizers by fertigation and easy control the salinity according to the EC of the sum of all fertilizers applied. In Brazil, a curiosity was adopted few years ago a “New Salt Index” that also has no practical purpose of use. It is an adaptation of measure the EC of fertilizer at a fix dose of 10 g/L and the EC of Sodium Nitrate in the same concentration. Then divide the value of EC of the first by the second and the result is multiplied by 100. This is the New Salt Index method and it is used only in Brazil. No one adopts in the world, but the Brazilian legislation adopted and requires that this new index must be presented on bags of fertilizers. It has no practical purpose for farmers, which do not use that information for anything. It seems that is just another bureaucratic requirement unnecessary. 16. How important is the degree of accuracy of the fast test kits? Will we really need tests more accurately? These fast kits are quite useful even with approximate values that are enough to give a guideline in doses via fertigation for the farmer level. The main objective is getting an indicative level for the nutrients availability and also identifies the DELTA (∆) between two sequences of samples tested and then the tendencies for loss or accumulation of 65 The impulse to treat all day-to-day problems with computer facilities through applications and software strong attract the new generations that use this for several activities as routine for fast and easy 66 handlings. It is clear that this tool works with mathematical logic and restricted to a sequence of questions that only admit two answers: yes or no. First premise: "Biology is not Mathematics". We split the Fertigation in two steps: the mathematical and biological phases. Mathematics stage it is also the hydraulic phase, i.e. the access to water source, pumping and transport of water that occurs inside the pipes till the exit of the solution at the trickle, micro sprinkler, sprinkler... At this stage we have the possibility to control mathematically the various components that are open or close a valve, to inject doses of fertilizers, irrigation, set if you're going to inject a more alkaline or acid solution, more saline fertilizers or less saline, with more of the nutrient, A, B or C. Program the system to work based on time or volume, respond to temperature range or humidity sensors, etc... These many facilities are an illusion that the agronomic management "would be restricted to the mathematical phase and so outsource for software some complex technical interpretations that are not mathematics. The biologic phase starts from the output of the irrigation/fertigation solution that leaves the dripper or sprinkler and infiltrates into the soil/substrate. Now we don't have answers type yes or no. The miscellany of factors is complex and heterogeneous based on multi- factors with dynamic interactions with the environment, microbiology, other participants of biology, root systems, phenology crops phases, different soils types, water-holding capacity, nutrient fertilization base dressing and side dressing, influence on pH and soluble salinity EC, soil depth variations of soil layers, rainy season, heterogeneous and a very wide range of biotic and abiotic stresses that together form a dynamic ecosystem in which the agronomist's role is to interpret and take 67 responsibility for management whereas the fertigation is only a tool for handling through small and frequent adjustments, respect the physiology of the plant and provide optimal conditions for obtain the best benefit/cost to overcome the limiting factors first and then for the nutritional plants grown do maximum photosynthesis that agronomic management could achieve. How handle these incognita using the system of single answers of yes or no based on algorithm. The actual level of this technology is not ready for this target and maybe it will never be fully automatic. How beautiful is the difference in fields where every plant is unique while the statistic methods try to get uniformity data or at least get the average to bring to mathematical level what will never be homogeneous. Second premise: "Agronomy is an intervention in nature". Third premise: "Statistic used in biology phase considering the average variations is dangerous". Mathematic, physics and chemistry applied in biology loses the proportionality. Statistics on agronomy is an attempt through some samples to apply the logical reasoning on the diversity of the biology, but the beauty of physiology response is the diversity. Fourth premise: "Software and applications to biological phase will come a day in the future, perhaps, when programmers studying deeply plant physiology and all interactions with nature environment and the day that a machine can understand the word management". Summary: Use of pH, EC and humidity sensors to inform the software to decide the handling of fertigation is a source of mistakes by negligence. It would be nice if the automation with a program could consider the several factors and their interactions that occur within the soil where the roots and all of biology and abiotic react differently with the variables. 70 orchard planted at rhythm of 20 hectare per year to for the total of 200 hectares after 10 years and get plants at different age’s very heterogeneous situation. Also in this example the grower start with variety of mango Tommy Atkins of 100 hectares + 60 hectares with variety Haden and other 40 hectares with variety Palmer. Also we have 80% of the area flat topography and 20% of the area with slopes of up to 15%. Note that variables make the scenario heterogeneous. The grower must choose some stations which are representative of dominant situations because it's not practical exaggerate the number of several SSE stations, but decide for few stations to be representative of dominant situations. Each one must check his situation with good sense and choose the number of SSE stations. 21. How to treat the Soil Solution Extractors (ESS) in soils with extreme textures, or high sandy content or high clay content? In dominant sandy soils, the time to trigger the vacuum in the suction pipes SSE is very important because we will only be able to make vacuum in wet soil and this is easier at the end of the irrigation and until 1 hour before the end of the watering. After the soil dries, no vacuum is possible and we have to wait for the next irrigation to try again. In heavy clay soil, the main problem can occur that the porous ceramics tips can be sealed avoiding the suction of the soil solution. In this case of very heavy soils, we recommend opening a hole in the soil and fill the bottom space of the largest hole with coarse sand only in depth that will have contact with the ceramic tip to avoid ceramic 71 sealing by thin clay while the sand is inert material that will not influence on the readings of the tests. Then fill the rest of the hole with the normal soil. 22. How to handle via Fertigation the BRIX or formation of sugars in fruits, or sugar cane, or sugar beet or industrial tomatoes or cherry tomatoes, based on the EC manipulation level and the nutrients that participate in the metabolism of sugars? In the biochemistry of the formation of sugars it is very clear that plants have a phosphate absorption peak some few weeks before begin maturing stage, because plants need accumulate ATP molecules as power reserve so that during the maturation that energy can break the long-chain polysaccharides to form mostly sucrose, glucose and fructose that will give the sweet taste. The other key element is potassium which is a mobile element in plants without being part of the cellular structures, but rather as osmotic regulator and mainly on activation of more than 60 enzymes in the metabolism of plants, with 72 about 40 of these enzymes are activated during ripening with direct influence in the formation of sugars into end of cycle. To a lesser extent the micros Fe, Zn and Mn are also enzyme activators in the maturation of few but important enzymes. Magnesium along with nitrogen on a small scale has great significance in the maintenance of chlorophyll before senescence to ensure metabolites of photosynthesis in formation of sugars and reserves of carbohydrates. Application of nutrient formulas rich in P, K, Mn, Fe, Zn and Mg via fertigation as well as foliar sprays will help to before start maturation is useful for increase BRIX for every plant with potential to accumulate sugars. Let's see now how to influence the Brix by controlling the EC via fertigation. It's almost a paradox when increasing the salinity in the soil would increase the sweetness in fruit or crops that accumulate sugars! Yes that's right. We know that after the development of plant and fruits have reached the desired level and we are waiting the ripening to harvest. From this phase we want to reduce water uptake by the roots and increase the solutes in soil solution mainly with potassium as dominant ion but other salts can contribute to increase the EC. Each EC unit causes tension (negative pressure) against the roots capacity of solution uptake of the order of -0.3 ATM and it is proportional, so EC = 2 mS/cm creates a tension of -0.6 ATM. EC levels below 3 mS/cm is relative easy for solution absorption by roots and with more water into the plant from a diluted solution the fruit or plant product will also get dilution due more water and little solute and the Brix falls. We should keep growing the soil salinity for the last period before harvest, suggested 4 – 6 weeks with EC always above 3 mS/cm and may overcome 4 mS/cm for intention to get higher salinity of the soil solution during the maturation period to force some difficult for the roots to absorb water and thus the Brix gets louder. In previous phases of crop cycle when the plant and the fruits are still in development, the EC should stay smoother between 1.5 to 2.5 mS/cm for most crops to 75 24. Subsurface irrigation. How to make fertigation management? The soil texture is critical to the depth and spacing of the drip lines which can be between 15 - 30 cm deeps. In clay soils the solution spreads and disperses in all directions by gravity and capillarity. In sandy soils the gravity is dominant and we have to choose low flow of discharge volumes by drippers and increase the frequency of watering to avoid leaching and put the drip lines only few cm deep into the soil between 10 - 15 cm deeps. From there with few adjusts to calibrated and uniform irrigation, fertigation management is very similar to that of the surface. The efficiency of urea via fertigation is high because there are no practically losses by volatilization. The water economy can be between 20% - 30% compared against surface drip irrigation and this mean also energy save. Also the subsurface protect the drip lines from sun radiation and other injuries as well as regional animals. 76 25. Why urea does not have electrical conductivity? Observe the chemical composition of the Urea CO(NH2)2 containing 1 carbon and so it is an organic molecule and not a salt. Salt while on the solid phase is neutral and after dissolves in water form ions that are cations and anions. These ions lead electricity measured in the ECmeter. Urea not being salt, not form ions in solution and does not conduct electricity. The vast majority of fertilizers are inorganic salts (no Carbon) and that's the difference. Urea granules and formula containing Carbon and 2 Amines. It is not a salt. 77 26. Must we consider the contribution of no nutrients ions in the EC, such as Bicarbonates, Aluminum, Sodium, etc.? Yes. The EC does not identify the origin of salts. The EC measured by the ECmeter identifies only the total salinity without knowing if came from natural fertilizers or soil or water. Just read the sum of total salts dissolved. 27. Are the relations between the 3 main cations K, Ca and Mg in soil solution depend on the phenology phase of crop development? The phenology stages are fundamental for better distribution of 3 main cations in soil solution. Vegetative phase must have about 50% Ca, 25% K and 25% Mg; Bloom stage must have around 40% Ca, 40% K and 20% Mg; Fill fruits or grains must have around 25% Ca, 60% K and 15% Mg; Maturation must have about 10% Ca, 85% K and 5% Mg. 80 29. Fertigation when the irrigation volume is low. What happens when the water deficit practice of irrigation supply less than would be ideal? Many irrigation projects are projected intentionally at low volume only to minimize the dry season effect, but this irrigation just to serve as palliative and minimize the hydric stress and not to give to plants the optimum watering for growth. In this case, this irrigation would not have the ambition to provide the full irrigation. The fertigations may however be the great advantage to provide even in irrigation of smaller volumes the necessary nutrients to the crop demands and at least ensure adequate nutrition during the months in which the irrigation are used. The cost of irrigation equipment to supply low volumes per day is cheap as well as the use of energy is less, but the ideal for maximum productivity and get the best benefit/cost would be full irrigation. 30. The so-called new theory of "Double-Relativity" for fertigation. What would be this theory? 81 First a very special thanks to Einstein for his first original relativity approach, that served as the inspiration for this new theory of double- relativity for fertigation, that start as one exercise or joke, but at the end of the way, it is very logic for people that wants challenges for interpretation. For explain this new theory, we will also use the format of a sequence of premises. Premises for interpretations of nutrients in soil solution with the “Double-Relativity” comparison between the same nutrient after at least 2 samples collections and its contribution to the EC: Premise 1. There is no absolute value in plant nutrition. Premise 2. Identify the total salinity in soil solution measured by the EC - electrical conductivity mS/cm, which is similar to unit of the international system dS/m; Premise 3. Consider the relationship for each measurement of EC = 1 mS/cm, represent 10 equivalents of cations and others 10 equivalents of anions, keeping this proportionality... EC = 2 mS/cm represents 20 equivalents of cations and other 20 equivalents of anions, and so on, till EC ~7.0 mS/cm. Premise 4. The main cations that form the ionic cocktail in soil solution are K+, Ca++, Mg++, NH4+, H+3O (hydronium), and the micros Fe++, Mn++, Zn++, Cu++. 82 Premise 5. The main anions that form the ionic cocktail in soil solution are Cl-, NO3-, SO4--, SO3-, PO4---, HPO4--, OH-, HCO3-, and the micros B4O7-- e MoO4--. Premise 6. Exemplifying with Potassium which has molecular weight 39 as a monovalent cation, its equivalent is equal to its own molecular weight, and each equivalent contributes in solution to the total EC with 0.1 mS/cm, so if the soil solution EC is of 2.5 mS/cm and K+ contributes with 10 equivalents, this mean that the other 15 equivalents in the soil solution cocktail must be composed by other cations. The concentration of K+ in ppm in the nutritive soil solution in this example that contain 10 equivalent will be 10 x 39 = 390 ppm (parts per million) of K+ and its contribution in the total salinity would be of 1 mS/cm within the 2.5 mS/cm the whole cocktail of cations. In parallel, this same nutritive soil solution with EC = 2.5 mS/cm must contain also other 25 equivalents of anions. The sum of all equivalents of cations + anions in this example is 50 equivalents. Premise 7. The concentration of K+ in soil solution is presented in ppm or mg/L or mg/Kg and all these units are similar. Let's consider that 1 Equivalent of K+ = 39 ppm K+ and contributes in the total salinity of the soil solution with EC = 0.1 mS/cm. Being proportional, 2 equivalents of K+ will be 2 x 39 ppm = 78 ppm of K+ and the salinity caused by K+ contributes on EC with 0.2 mS/cm. Premise 8. Example with one bi-valent cation like Calcium Ca++ which has molecular weight 40, but being bi-valent charged, its equivalent is 40/2 = 20. Therefore each 20 ppm Ca++ in the soil solution contributes with 0.1 mS/cm on the EC. If we identify for example in a soil solution 85 for the level of farmer; and up to +/-0.5 equivalent of tolerance for the level of researcher. Premise 15. The practical variations ranges for the nutrient levels in soil solution in the fields are much greater than 1 equivalent of the suggested tolerance the degree of accuracy of colorimetric kits with rapid tests for various nutrients such as K+, Ca++, Mg++, NH4+ for the main cations and Cl-, NO3-, SO4--, HPO4-- among the anions. This variation would be sufficient for this purpose and enough to identify the trends of the DELTA (∆) in two or more successive collections and use to support decisions of nutritional management of doses to be applied in the fields. Therefore, rapid or colorimetric digital portable kits serve that purpose within a reasonable tolerance. More accurate tests are much more expensive and time consuming, but without any practical advantage for use by farmers. Premise 16. Use of soil solution extractors in irrigated crops x dryland crops. Use in irrigated crops it is routine for many farmers, who can make the corrections via fertigation dosages; However, dryland crops have some tricks for using this method. The soil solution extractors tubes need to suck the soil solution under vacuum and put those vacuum tubes with the aid of a syringe 60 ml normally, only when the soil is wet and it occurs after a rain or we have to simulate watering manually with a bucket of water around the extractor tubes and so proceed with the vacuum in the tubes. No vacuum is possible in dry soil or with low humidity. Premise 17. Example for potato crop. The collecting of soil solution at the week before would identify the EC = 2.0 mS/cm indicating the total 86 salinity level in the solution. Considering the concentration of Calcium in the EC identified as 100 ppm. We know that 1 equivalent of Ca++ is 20 ppm, calcium in the EC's contribution would be of 0.5 mS/cm of total 2.0 mS/cm which is an excellent concentration during the filling phase of the tubers within the total salinity, and Calcium participates with 25% of the cations. However, the following week, after a possible rain, which caused a dilution and partial leaching of the soil solution, the total CE reduced to 1.0 mS/cm and calcium concentration within that EC identified as only 60 ppm, and then it lost 40 ppm of Calcium, and certainly other nutrients that make up the total EC. In percentage, the calcium got 3 equivalents (3 x 20 = 60 ppm) in a total of 10 equivalents of cations with the EC = 1 mS/cm, which implies a ratio of 30% of the EC would be the contribution of Calcium between the cations. The interpretation is that in general the soil solution lost part of all nutrients and in absolute numbers also of Calcium, however the concentration in the soil solution Calcium became more concentrated. If we wish to make a complement via fertigation with various nutrients to replenish the EC lost and get again EC = 2.0 mS/cm, we have to apply the "Golden Rule of Fertigation" which is: 100 g/m3 = formula guarantee changes from % to ppm Premise 18. If we wish to restore the Calcium concentration of 60 ppm to 100 ppm using the Golden Rule of Fertigation, and choose the source of Calcium as Calcium Nitrate that has the guarantees percentage of 15-00-00 + 19Ca, and to facilitate the round count of 19Ca content, let's consider only for this accounts of Calcium as 20 instead 19 in this example. We know that 100 g of this fertilizer in each 87 m3 of irrigation will contribute with 20 ppm of Calcium and if we wish to provide via 40 ppm of Calcium fertigation, by proportionality we should apply 200 g of Calcium Nitrate per m3 of irrigation. If the volume of water to be applied is of (example) 300 m3 of irrigation and each m3 receive 200g of fertilizer will be applied 60 kg of this fertilizer and the Calcium complement will increase the concentration within the soil solution. In this case, the same fertilizer would supply also 30 ppm of N, since we have 15 N in the formula guarantee. Then for every 100g / m3 represents 15 ppm, and for the 200 g / m3 will be 15 x 2 = 30 ppm N. If we would like to complement with more Nitrogen, together with other fertilizer like urea 45% N and apply 100 g/m3 of this fertilizer for the same volume of 300 m3 would be 30 kg of Urea to that Fertigation the sum of N would be the previous 30 ppm originated from Calcium Nitrate + 45 ppm from Urea and totaling 75 ppm of N. Premise 19. The EC of the soil solution is considered within the physiological range for the main cultivated plants between 1.5 to 4.0 mS/cm. When the EC < 1.5 mS/cm is a strong indicator that the soil solution is too much diluted and plants will be starving. When the EC = 4.0 mS/cm is borderline and is a clear indicative of excessive fertilizer (salts) applied. We know that for every unit of EC in the soil solution tension increases negatively in ATM -0.3 hindering the absorption by the roots. EC between 5 and 7 mS/cm inhibits the solution absorption by the roots and will force the closing of stomata for much of the daylight by decreasing the capacity of photosynthesis. When the EC > 7 mS/cm the reverse phenomenon can occur forcing the water loses by the plant to the soil and the plant gets dehydrated entering wilt and collapse. 90 several attempts to give explanations to justify the action mechanism against nematodes suggest disoriented them in soil, while it helps the antagonistic microbial flora, etc. It is not clear how it works, but it is a fact that the nematodes decreased dramatically in these irrigated areas after receive irrigation with this electromagnetic mechanism. The roots efficiency to uptake soil solution at more density water is also a fact compared against normal water not treated by this electromagnetism tool. 32. Fertilizer injection in the system must be made before or after the filter. The normal place for fertigation injection would be after the filters considering the use of fertilizers 100% soluble in good purity quality. We know that in the market for fertilizers, however, there are also some fertilizers not so pure with some dirty impurities. It would be prudent to filter the solution before inject them to the irrigation pipes. In addition there is the misuse of some soil fertilizers that should not be used via fertigation, but some farmers insist on trying to dissolve them even partially to inject them and these are of low efficiency and risk of clogging of emitters of drippers and sprinklers. 33. Any news in the market of soluble fertilizers? PeKacid 00-60-20 is a 2.2 pH buffer based on purified Phosphoric Acid (food grade) that is dried to be the unique powder phosphoric acid and fully soluble and stabilized by mix with MKP (00-52-34) which provides 91 the pH buffering and keeps the product in dry powder while stored. Its solubility is 680 g/L. Its salinity at 1 g/L gives the EC = 1.4 mS/cm which is well below the liquid phosphoric acid that has the EC = 2.2 mS/cm. The process of drying out the phosphoric acid and the end product is patented. PeKacid is also widely used as a raw material in NPK formulations to acidify and serves to maintain the irrigation system cleaned in regular applications. It is suggested at least 5 kg per week per hectare. PeKacid due to acidic pH and your composition be of PK that have high mobility in the phloem, has been also used as a foliar fertilizer tolerated by plants that enjoy it as nutrients in addition to the effect of pH against a wide range of pests and diseases that are sensitive to very acidic pH sprayed. PeKacid presented as a fully soluble and clean powder very acid PK fertilizer with 00-60-20 and buffer pH 2.2 as the unique and most effective acid PK in the market. Developed a new family of 100% acid soluble fertilizer called NovAcid with PeKacid providing the total or part the Phosphates of these formulas, with pH between 3 - 3.5 for use in fertigation with hard and alkaline water. It is also the ideal pH with buffer for use together with herbicides. 92 Examples of some NovAcid formulas: Magnific (11-00-00+9,3Mg) is the traditional Magnesium Nitrate from the reaction of Nitric Acid with Magnesium Carbonate eliminating Carbonic Acid as byproduct. However before crystallize the Mg(NO3)2 it was added a strong Micros cocktail with 6 elements (Mn, Zn, Cu and Fe as chelates of EDTA, and anions B and Mo as salts) to form about 4% of these Micros inside the Magnific grains forming the MagnificPlus(10-00-00+9Mg+Micros in ppm Mn2000, Zn1000, Cu1000, Fe1000, B 1000, Mo 200). Other highly soluble 4 formulas will be obtained from the mixture of Calcium Nitrate + MagnificPlus forming the family CalMagPlus: Magnific traditional white beside the new MagnificPlus green color grains that contain a strong Micronutrient cocktail into the grains 95 with little variation. The best management would always we irrigate, it is also a fertigation together. However, it is common, due to lack of automation or by lack of planning, growers usually irrigate for example daily and fertigate once a week, or use other intervals. The drip irrigation gives water savings and also fertilizers savings by use the application only for get fraction of reduced wet volume of soil rather than total area. It is without doubt the most efficiency irrigation method compared to every other irrigation system. Fertigation can supply the nutrients demand for any crops according to the dose to handle and choose the source to get the pH range to optimize the availability of nutrients. Drip allows in some subsurface irrigation crops, i.e. drip buried about 20 – 30 cm deep, more common for perennial crops, although it can also be used in annually. Buried hoses have longer life for being protected from solar radiation at the surface and are mild temperatures. There are considerable water saving an estimated of up to 30%. Surface or subsurface drip avoids wetting the air part is welcome to reduce the attacks mainly of some fungi and bacteria that like wet leaves. Dripping can be activating at any climate situation, winds, temperatures, and at any time of the day. For non-flat topographies, there is the drip technology self- compensating and anti-drainage, which keeps the flow indicated by the manufacturer from the first to the last dripper along the lateral line of drip, independent of it is moving up or down the slope, and after shut down the runtime and the system stop pumping pressurized water hoses stop dripping, usually when the pressure is <0.4 ATM and stands within the water hoses without draining waiting the next watering turn. 96 This technology is desirable in long sidelines when the flow is uniform along the whole line. Summary of curriculum of author: Luiz Dimenstein -M. SC. Agr.- Master Science of Agriculture - Fertigation and plant nutrition specialist. Current consultant for intensive agriculture tools. • Graduated in Agronomy by the Universidade Federal Rural de Pernambuco in 1985. • Master of science in Agriculture, the Faculty of Agriculture of Rehovot, the Hebrew University of Jerusalem, Israel, in 1990 and the Department of horticulture at Vulcani Center, between 1988-1990. • Seed companies agronomist Zeraim Gedera and Hazera between 1991-1995. • Agronomist invited by Ministry of Agriculture and Ministry of Foreign Affairs of Israel for technical support and courses abroad on agriculture, irrigation and fertigation, in 1995. • Consultant in Brazil by the company Dimenstein Consultoria Eireli for Fertigation management and intensive plant nutrition to about 60 companies of irrigated crops diverse as tomato, melon, watermelon, asparagus, grapes, mango, potato, coconut, cotton, sugar cane, vegetables, coffee, citrus, etc., from 1996 and currently. • Technical and manager and R&D of the Haifa chemical Brazil Ltda. between 1999-2004. 97 • International experience as a speaker in conferences and seminars about Fertigation in Mexico (Mexico City and Puerto Vallarta 2000 2002), USA (2001) and Orlando (2005), Israel (Tel Aviv 2000, 2008, 2009, 2011 and 2014, 2015 Haifa, 2003), Spain (Barcelona 2003), Venezuela (Caracas 2004), Argentina (Mendoza 2011), Peru (Lima 2011, 2014, 2016), Holland (Amsterdam 2015). And in Brazil about of 50 lectures at regional and national events. • Author of the patent of spray extreme pH solution based on PK fertilizers or very acid or very alkaline via foliar to reduce attacks of pests and diseases inhibited by contact action due the effect of pH against the pests and pathogens. (Submitted on 2009 and approved in 2013). • Business and Development Manager for special fertilizers of ICL Brazil ltda., ICL Group - Israel Chemicals Ltd., between 2007 – 2017.