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Fluid Journal : Spring 2016
19 The Fluid Journal Spring 2016 achieve a target pH are bicarbonate (HCO3-) and carbonate (CO3-). Since all waters vary in the amount and identity of dissolved ions they contain, including bicarbonate and carbonate, there is no one single recommended rate needed to achieve a desired pH range that will be correct for all water sources. Several methods are available to make this determination: • pH titration or “buffer” curve performed by a commercial laboratory • Installation of an injection controller that monitors irrigation water pH and adjusts USA injection rates to achieve the programmed target pH reached. • Use of pH paper or portable pH meter in the field is a crude but acceptable method as well. The user checks water pH at the end of the run and adjusts injection rate either up or down until the desired final pH is reached. Injecting USA Procedure for injecting USA into irrigation systems includes: 1. Turn on irrigation system and wait until system is fully charged before injecting USA. 2. Inject USA to achieve desired pH. Periodic use of pH paper or portable pH meter to verify that target pH is being achieved is a good practice. Take samples from emitters farthest away from the injector. 3. For shock treatments, inject for a period of 2 to 3 hours, turn off and completely flush system of clean water. Open ends of 8 to 10 drip lines at a time and flush until clear water flows. 4. For continuous injection at maintenance rate, follow steps 1 and 2 above. Inject for entirety of irrigation set, but allow the last hour to flush the system of remaining acid. Iron Chlorosis Because iron solubility and subsequent plant availability are so profoundly influenced by soil pH, most all iron deficiencies in alkaline soils are a factor of pH and not actual iron levels in the soil. A 1.0 unit change in soil pH can alter iron availability by 100 to 1,000 fold. USA products can be a very effective tool in combating this malady. Banding is the most effective and practical means of addressing lime induced iron chlorosis as broadcast applications would require astronomically high rates in many situations to achieve the desired results. So to correct: 1. Apply 15 to 20 gallons as a surface spray band, dribble or subsurface injection on alkaline, calcareous soils. Dilution with water may be required to reduce viscosity. Do not exceed 1:1 dilution with water. 2. Repeat treatments may be needed, based on limestone content of the soil and degree of iron deficiency. Sodic Soils USA products are very effective at providing near immediate remediation of sodic (high sodium) soils but require the presence of free limestone (calcium carbonate) to achieve the desired results. Presence of free time can be readily determined in the field by simply pouring USA or any other acid, such as vinegar, on moist soil and observing bubbling off of carbon dioxide gas. If any bubbling is observed, then there is an abundance of free lime contained in the soil. The reactions that take place are: • Acid digestion of limestone to release calcium ions. Sulfuric acid-- --gypsum + carbon dioxide + water. • Displacement of sodium from the soil exchange complex by calcium, which has a higher affinity for exchange sites than sodium. Sodium sulfate is then leached from the root zone, providing there are no hardpans or other restrictions to leaching. Gypsum + sodic soil------Calcium soil + sodium sulfate. Due to economic considerations, USA should only be used for immediate response as a band application and only comprise a small portion of the total amendment needed. More economical sources, such as elemental sulfur and/or gypsum, should be selected for broadcast applications to provide the majority of sodium remediation activity. True fluids calcium and acid- containing fertilizers offer use flexibility, convenience, and near immediate results when used properly. Contact a local Certified Crop Adviser (CCA) or product manufacturer for more information on the products discussed in this article and their value in solving your soil or water issue. Carl Bruice is National Nutrition Technical Manager for Wilbur-Ellis Co. Write, call or e-mail the Fluid Fertilizer Foundation Phone: 785-776-0273 •E-mail: email@example.com Research and education for efficient use of fluids. The Fluid Fertilizer Foundation We need you to join hundreds of other growers, dealers, fertilizer manufacturers and other supporting industries ACT NOW! JOIN IN THE SUPPORT OF THIS ORGANIZATION THAT DIRECTLY BENEFITS YOUR BUSINESS!