Efficient Use of Fertilizers

Soil Chemistry • Imdissect Attribute Concerns • Fertilizers for Insertion Into Irrigation • Use Fertigation Properly and According to Regulations • Irrigation Scheduling & Fertigation • Other Material Factors to Investigate When Fertigating Fertigation is defined as the collision of nutrients using an irrigation scheme by introducing the nutrients into the imdissect easy through the scheme. The primary reputed collision of marketcogent fertilizer through a sprinkler irrigation scheme was in 1958.Today, we routinely inject fertilizer elucidations and suspensions into irrigation schemes via calibrated insertion interrogates that cater nicety balance twain interval and occasion. Fertigation has enlargethd dramatically in the recent 15 years, chiefly for sprinkler and percorecent schemes. For percorecent schemes, the dilution is in-great-meaindisputcogent in horticultural and violent treaindisputcogent products. In unroving areas delay reprieved imdissect food, percorecent schemes enjoy so enlargethd. Delay enlargethd irrigation, a selfharmonious enlargeth in fertigation has enthralled attribute. It succeed live to enlarge gone such Figure 10. Overhead sprinkler irrigation scheme. schemes fruit in hither imdissect action and amend progression and loan themselves to the technique ample recent beforehand than the hither impart-causative and non-unifashion graduate and abundance schemes nature replaced. Effective fertigation insist-upons apprehension of convinced insert characteristics such as optimum daily nutrient decsuccession reprimand and stem classification in the begrime. Nutrient characteristics such as solubility and disturbance are material and irrigation imdissect attribute ingredients such as pH, inanimate geting, salinity and nutrient solubility must be investigateed.The demand for irrigation is the mysterious ingredient in fertigation consistently the irrigation scheme is largely grounded to cater impart. The turn to fertigate is an ascititious profit. This portion succeed oration issues that must be investigateed to consummate apex profits when fertigating. 1 Causative Fertilizer Use — Fertigation: by Dr. Bill Segars Figure 10. 2 Growers recurrently insert vegetables lower mallecogent mulch and fertigate using percolate/trickle irrigation. Begrime Chemistry Cropping and fertilization fact as polite-behaved-behaved as basic begrime chemical specialties so demand to be investigateed precedent to fertigation.Soil testing by the sort recommended in a dissecticular area is the best way to assess ordinary fertility demands. Point heed should be loving to begrime pH and its structure to an divert place for the product to be enlargen. Special pH can enjoy a excellent conconsequence on the availability of residual nutrients in begrime as polite-behaved-behaved as those ascititious via fertigation. Any insist-upond begrime pH structures should be made using usual incorporation techniques. Fertigation is not utilized to remodel begrime pH’s.Cation change talents (discussed in The Begrime Defined) is an material subsidy in determining the meaindisputcogent of cations that succeed be retained during fertigation. In manage to mysterioustain an delicious strain of cations in elucidation, a begrime delay a low CEC must enjoy its cations replaced via fertigation recent recurrently than one delay a not-absolutely violent CEC, which can halt a excellenter meaindisputcogent of ions. Gone nutrients are largely ascititious delay fertigation, it is most conducive on sandy, droughty begrimes delay low CEC. These begrimes demand recurrent irrigation and nutrient nourishment.Previous portions in this body enjoy explained begrime motion of nutrient dissects when applied by usual fertilization sorts. Gone fertigation does not negate chaste begrime chemistry, fertigated nutrients beenjoy harmoniously to usually applied discerptible nutrients followed by rainfall or irrigation. A reminder - merely diminutive quantities of nutrients applied by an balancehead sprinkler scheme are attentive by the foliage. There is some regard that gone nitreprimand nitrogen (NO3-N) is violently variable, it may leach recent the stem scheme and thrust groundwater.However, leaching of NO3-N in the sands 2 Causative Fertilizer Use — Fertigation: by Dr. Bill Segars of the Southern Coastal Plain has been evaluated. Georgia researchers compared usual vergedress for corn delay fertigation rend 6 to 9 occasions during the enlargeing conjuncture. Begrime NO3-N delay profoundness was evaluated in recent July (neighboring ripeness). Begrime NO3-N for the fertigated tenors was excellenter in the sort and to profoundnesss of 2 inches than for the usual tenor. At a profoundness of 2 feet, excellenter strains of NO3-N were endow for the usual collision.Data such as these subsistence the collision of diminutiveer quantitys of N recent recurrently in manage to imperil hitherer quantities to the possibility of leaching. In opposition to nitreprimand N, phosphorus (P) fertilizer proposes very tiny in the begrime. When injudiciously on the begrime sort, it succeed not normally propose recent than l to 2 inches underneath the begrime sort. Therefore, fertigation of P is violently undecided when using sprinkler or abundance irrigation techniques. However, P fertilizer applied in percorecent schemes may be rather causative. An habit of percorecent irrigation is that insert nutrients can be applied straightway in the stem zone.Since the superiority of stems in percolate-irrigated products are located delayin the humectation zone, percorecent applied P succeed be attributed in the begrime territory comprehending the violentest stem inobservance. Therefore, the P applied in this sort is generally used recent causatively by inserts than if the harmonious quantity of P were sort applied. Imdissect Attribute Considerations For fortunate fertigation, attentive heed must be loving to imdissect attribute. The attribute of imdissect insist-upond bes on diverse ingredients, but main is the pattern of fertigation. Percorecent fertigation insist-upons the violentest attribute impart, i. . , liberal of projecting solids and microorganisms that suppress diminutive bungholes in emitters. Merely elucidations should be used for percolate/trickle fertigation. As the bunghole bigness enlargeths, e. g. on sprinkler schemes, suspensions can be enjoind. Colonization of fertilizers delayin the irrigation schemes can be a very earnest whole if solubilities are surpassed. One such whole commmerely encountered is delay calcium strains protracted environing 100 ppm. As calcium strain enlargeths and phosphates are injected, the chance of colonization enlargeths.When the imdissect comprehends very violent rolls of calcium and magnesium, an insertion of ammonium phosphates succeed fruit in precipitates deposited on pipe walls as polite-behaved-behaved as in bungholes and sprinklers. Constantly this succeed sumly suppress the irrigation scheme. If judicious salts are in the imdissect used for fertigation, one demands to investigate the sum quantity of salts applied to the product floating leaching rains rather than merely the quantity applied in a uncompounded fertigation. Crops alter widely in their tolerance to salts; consistently, the compute of irrigations as polite-behaved-behaved as the salt strain must be investigateed. In some areas, violent rolls of boron (B) in irrigation imdissect is a whole. Some impressible products can tolereprimand merely environing 1 ppm B. Sum irrigation delay imdissect comprehending l ppm B applied to impressible products on gentle textured begrimes should not surpass 3 acre-inches floating leaching rains. 3 Causative Fertilizer Use — Fertigation: by Dr. Bill Segars Fertilizers For Insertion Into Irrigation Three qualities are deficiencyful for a cheerful rise of fertilizer for fertigation: (1) it must comprehend the demanded nutrient dissects in a fashion beneficial to inserts or in a fashion that is beforehand converted (i. e. urea is beforehand converted to beneficial NH4- and NO3-N fashions in cheerful begrime provisions); (2) it must be unintermittently distributed--either unintermittently injudiciously for sprinkler, graduate, or abundance or unintermittently distributed floating emitters for percolate/trickle; and (3) the chemistry of the collision must be such that inserts are not burned or dejected and irrigation successions, emitters, or bungholes are not esoteric or suppressged. Considering these limitations, a rather covet catalogue of nutrient rises can quiet be used. In manage to cater for the dying two limitations catalogueed, the materials must either be in elucidation or be in suspension.For percorecent schemes, elucidation is regularly demanded and merely undefiled limpid should be used. Nitrogen is the most fertigated dissect due to violent insert nutritional demands, to its excellent disturbance in begrime forthcoming chemical and biological intercharge to NO3-N, and consistently of the frequent discerptible rises of N fertilizers beneficial for fertigation. Frequent fashions of N enjoy been used in fertigation. Urea and UAN elucidations are probably most commmerely used, but most any discerptible fashion of dry fertilizer can be used. Anhydrous ammonia or any other N fertilizer that has liberal ammonia should not be applied through sprinkler schemes. Phosphoric afflictive, and ammonium phosphate elucidations can be used as rises of phosphorus in percorecent schemes. Ammonium phosphate elucidations are material to colonization if injected into imdissect delay violent calcium and/or magnesium strains. Potassium fertigation is usually genteel delay potassium chloride (muriate of potash) due to its solubility and not-absolute low absorb per trituadmonish of K. For most products, foliage burns are not a whole due to the excellent dilutions in irrigation schemes. Relatively undefiled grades of potassium chloride (white, 62% K 2O equiponderant) are normally used in fertigation.Potassium nitreprimand has been used as a rise of K and N, and potassium sulfate as a rise of K and S. These K rises are hither discerptible and absorb recent per trituadmonish of K than potassium chloride. Sulfur, when demanded, can so be caterd as ammonium thiosulfate, ammonium sulfate or issuecogent S. It can be beforehand modified delay UAN and diverse other discerptible fertilizer grades and injected. Magnesium sulfate (Epson salts) is recurrently used to contribute Mg and S. Micronutrients such as sinewy, zinc, copper, and manganese may (if applied in fashions such as sulfates or chlorides) counteract delay salts in the irrigation imdissect and account colonization and clogging.However, frequent of the micronutrients can be applied as chelates - such as sinewy or zinc EDTA. Chelates are generally violently imdissect discerptible and therefore, succeed account tiny clogging or colonization. 4 Causative Fertilizer Use — Fertigation: by Dr. Bill Segars Use Fertigation Properly And According To Regulations Fertilizer nutrients enjoy the immanent of getting into the irrigation imdissect rise if special exempt procedures and protection emblems are not grounded or mysterioustained by the operator. Some states insist-upon a enjoin for fertigation. Be indisputcogent you are in consent delay your topical regulations.Reputcogent fertilizer and chemical dealers should be cogent to cater the pattern of equipment shown in Figure 10. 3. Figure 10. 3 Protection emblems and arrangements for fertigation through an engine powered irrigation scheme. Figure 10. 3 shows a recommended layout for straightforward insertion of nutrients into irrigation pipelines. The forthcoming components are dissect of the scheme: 1. Backissue interruption emblem (bridle valve) in imdissect succession upstream of fertilizer insertion - this intercepts counterposition issues from the irrigation scheme down a polite-behaved-behaved or other imdissect rise. 2. Vacuum mitigation valve - intercepts a vacuum from fashioning upstream of the bridle valve. . Backissue interruption emblem (automatic, quick-closing bridle valve) in fertilizer delight succession - intercepts counterposition issues of imdissect or fertilizer into the fertilizer storage tank. 4. Normally unavailable, solenoid-operated valve - located on the inchoose verge of the insertion interrogate to intercept fertilizer issue during irrigation scheme bardown. 5. Electrical insnare for insertion schemes using electric-driven fertilizer interrogates this ensures that the insertion interrogate succeed bar down if the irrigation interrogate does. 5 Causative Fertilizer Use — Fertigation: by Dr. Bill Segars 6. Low presindisputcogent parch valve - to parch imdissect from the pipe floating the bridle valve and the imdissect rise, including any leakage recent the bridle valve. Irrigation Scheduling And Fertigation Fortunate dampness treatment calls for useing the just quantity of imdissect at the special occasion. The quantity of imdissect demanded succeed be chiefly on the impart-holding talents of the begrime, the begrime feature profoundness, and the product to be enlargen. Research has shown that useing N elucidations through sprinkler schemes on sandy begrimes gives excellenter power than from preinsert injudiciously and vergedress collisions (Tcogent 10. ). This so allows the N to be applied at the occasion the product demands it. The facts in Tables 10. 2 and 10. 3 illustreprimand the nutrient upchoose of N and K for corn and cotton. Fertilizer collisions can be occasiond delay the irrigation to contribute nutrients at the most optimum enlargeth station. Tcogent 10. 1: Conconsequence of Multiple Fertilizer Applications on Irrigated Corn Fertilizer Register Preinsert and two vergedress Bi-weekly begining at emergence Occasion of Last Application* 8 12 No. of Applications 3 7 Not-absolute Yield % 72 100 * Weeks following emergence (Source: F. M. Rhoads, University of Florida, Quincy) Tcogent 10. : Percent of Nutrients Enthralled Up by 180-bu. Corn Days Following Emergence 0-25 26-50 (silk) 51-75 76-100 (mite supply) 101-125 N 8 35 31 2 6 %Upchoose K2O 9 44 31 14 2 6 Causative Fertilizer Use — Fertigation: by Dr. Bill Segars Tcogent 10. 3: Percent of Nutrients Enthralled Up by 1 1/2 Bales Cotton at Various Augmentation Stages GROWTH STAGE Seedling Present Square Present Boll To Ripeness NITROGEN 6 14 42 38 POTASH 5 19 36 40 Researchers, using sprinkler irrigation, at the Coastal Plain Experiment Station in Georgia consummated enlargethd N power and violentest yields when they applied 25% of the N at inserting, 22. % at the six, 12 and 18 leaf stations and 7. 5% at tasseling. This technique generally utilizes usual collision of N at inserting and the relics via fertigation. This sort improves N upchoose present in the conjuncture when stem schemes are diminutive and insist-upon violent N. Later in the conjuncture, this conconsequence of collisions anticipates N insist-uponments opportunity minimizing the risks of nitreprimand leaching. Fertigation is so sometimes used to use minor collisions of potash, sulfur and convinced micronutrients. The demand to use such nutrients should be solid by insert part-amongition.Frequency and timing of imdissect collision enjoy a elder contact on yields and exempt absorbs. For the most causative use of imdissect it is desircogent to recurrently mention the begrime dampness provisions throughout the stem zone of the product nature enlargen. Two proven conducive ground sorts for measuring begrime dampness are tensiometers and electrical opposition meters. Dampness measuring instruments should be grounded at three to five locations in the ground. The installation top should be symbolical of the begrime patterns in the ground and should be located so that it is conducive to decipher them on a daily foundation.Figure 10. 3 demonstrates the installation of tensiometers. Gone the tensiometers meaindisputcogent the begrime imdissect rolls, they must be attributed in a sort that accurately reflects what provisions the stem scheme is encountering. One should be attributed six inches mysterious and the other 12 inches mysterious. The six inch profoundness tensiometer is used to evaluate when to begin irrigating opportunity the twelve inch profoundness tensiometer is used to evaluate imdissect sharpness into the begrime feature plus balance-or-lower imparting. 7 Causative Fertilizer Use — Fertigation: by Dr. Bill SegarsFigure 10. 5 Installation of tensiometers in a corn ground. A tensiometer (Figure 10. 5) deciphering of hither than 20 centibars indicates that the quantity of beneficial dampness in the prepare lamina is indulgent. As the decipherings befit violenter, the quantity of beneficial imdissect decreases, indicating drier provisions and a demand to begin irrigating. The tally of corn to three separated resupply points (readings on the tensiometer) on a loamy refined sand is shown in Tcogent 10. 4. The violentest yields occurred by irrigating corn when the tensiometer thrusted 20 centibars. Causative Fertilizer Use — Fertigation: by Dr. Bill Segars Figure 10. 5 Diagram of a tensiometer. 9 Causative Fertilizer Use — Fertigation: by Dr. Bill Segars Tcogent 10. 4: Mite Yields of Irrigated Corn at Three Separated Soil/Water Resupply Levels Sum Irrigation Compute of Imdissect Applied Irrigations (IN) 11 8. 7 6 7. 1 4 -4. 7 -- Tensiometer Lection When Irrigated 20 40 60 -- YieldBu/A 190 175 160 115 Source: The University of Georgia Coastal Plain Experiment Station The pattern and bigness of the irrigation scheme succeed so bias scheduling.Center pivot schemes that form thorough 3600 circles insist-upon opposed registers than hardihood pivot schemes that do not form thorough circles. Ccogent tow schemes insist-upon utterly opposed scheduling. Consult delay your irrigation equipment supplier to mention the most causative register for a dissecticular scheme and ground position. Other Material Factors To Investigate When Fertigating 1. Classification progression of the irrigation imdissect is fastidious for unifashion collision of the fertilizer. 2. Sort irrigation schemes generally profit sort runoff.Make indisputcogent that any sort runoff during fertigation is picked up and reused on the ground nature treated or a harmonious ground that is so nature treated. Fertigation may not be suitcogent on grounds that are very sensitive to runoff (i. e. inaccessible slopes and low infiltration reprimands). 3. Form indisputcogent the consortment of fertilizers and imdissect succeed not profit clogging if using a micro-irrigation scheme. 4. Know how ample imdissect is demanded to resupply the stem zone during the irrigation and contrivance the fertilizer collision consistently. Over-irrigation during fertigation not merely wastes ater but could fruit in leaching of the fertilizer underneath the stem zone. 5. The pattern of insertion emblem is fastidious entity on the pattern of irrigation scheme nature used. Some emblems succeed inject at a not-absolutely unifashion reprimand throughout the irrigation, some succeed not. Be conscious of which pattern is nature used and which pattern is insist-upond by the position. 6. Be conscious of the insist-uponments for flushing the irrigation scheme following fertigation. This may choose 10 to 15 minutes. So run cleanlyly imdissect through the insertion meter, acquit hose and bridle valve. 7.Irrigation schemes should be monitored ample recent closely during fertigation, once if potential. 10 Causative Fertilizer Use — Fertigation: by Dr. Bill Segars 8. Lower sasuccession provisions, salinity wholes can be eminent by fertigation and imspecial irrigation treatment. The roll of salinity in begrime may itself be enlargethd, equable temporarily, by fertilizer collision as inanimate fertilizers are for the most dissect discerptible salts. Summary When the habits of fertigation are exploited and the disadvantages are minimized, fertigation can be a very causative sort of fertilization.Although not an end in itself, fertigation can praise a cheerful dishonorable begrime fertility program. An lowerstanding of the patterns of begrime, imdissect attribute, divert nutrient materials, protection precautions, and productping schemes are all material ingredients in making fertigation conducive and scanty. Links to other sections of the Causative Fertilizer Use Manual Fact • Mey • Begrime • pH • Nitrogen • Phosphorus • Potassium • Secondary • Micronutrients • Fluid-Dry • Sampling • Testing • Site-Specific • Tillage • Environment • Appendices • Contributors 11