SOLUBILITY PROPERTIES OF COMMON NUTRIENTS
As referenced earlier in this feature, solubility of nutrients can vary significantly by nutrient source, as well as temperature. Take a look at the chart below which reports the solubility of some of the more common nutrient sources in the industry. Note that in every case, as temperature increases, so does solubility.
Some fertilizer labels contain a section called: “WIN” or “Water Insoluble Nitrogen.” This refers to any nitrogen in a compound that is not readily dissolvable in water and immediately available to a plant. Over time, this nitrogen slowly becomes available raw ingredient the compound breaks down.
SOLUBILITY OF HUMIC SUBSTANCES
Humic Substances
are highly valuable soil amendments because they chelate micronutrients, retain soil moisture, and create an ideal living environment for beneficial soil microbes. It is important to note that not all humic substances are alike. Humic substances range from highly soluble fulvic acids and moderately soluble humic acids, all the way down to completely insoluble humin substances. Humins are dark and tar-like in appearance and have no beneficial properties in plant-soil systems. Make sure that if you add humic substances to your soil, you are adding mostly fulvic and humic acids. For those applying liquid products through traditional spraying and fertigation, make sure your humic substances consist of mostly fulvics and lower molecular weight humic acids. Other humic substances may not dissolve in water, which could clog spray systems.
SOLUBILITY OF IRON SUBSTANCES
Iron
is an important micronutrient commonly used to give turf a dark, lush green appearance. Iron typically comes in two forms in the earth’s crust: Fe+2 (ferrous iron) and Fe+3(ferric iron). Plants prefer the ferrous form for uptake, however the ferric form is more abundant in the soil. Have you ever tried to dissolve iron oxide (rust) in water? Nothing happens- that’s because iron oxide is completely insoluble in water. Ferrous iron is quite soluble in water (hence its ability to be transported in xylem tissue), however ferrous iron is easily oxidized into the ferric form. For these reasons, iron sulfate and iron sucrate are popular forms of iron in granular fertilizer mixes. When iron is bound to a sulfate or sucrate, it becomes harder for the environment to convert it into an oxide. In order to maximize the solubility of iron in liquid fertilizers, iron-chelates are used. Chelates are extremely soluble in water; they surround the metal ion and protect it from the oxidative environment of pure water. The most common forms of chelated iron are Fe-EDTA, Fe-EDDHA, and Fe-DTPA. If you’ve ever used a liquid iron nutrient product, it more than likely contained one of the three aforementioned chelated iron complexes.
SOLUBILITY OF LIME
Lime
is primarily used to balance the pH of acidic soils. Compared to the solubility of most nutrients, lime’s solubility is relatively low. Interestingly, as opposed to most nutrients, the solubility of lime decreases as temperature increases. Solubility is also affected by particle size; the finer the particle, the more soluble lime becomes. Lime typically comes in two forms: CaC03 (calcium hydroxide lime) and Ca(OH)2·Mg(OH)2 (dolomitic lime). It is important to note that in the fertilizer industry, when we say “lime,” we are actually referring to ground-up “limestone.” Pure “lime” has the chemical formulas CaO or Ca(OH)2; both of which are purified in thermolytic reactions. Pure lime is extremely soluble, hence it forms the basis of concrete products. Before applying lime to your soil, perform a
soil pH test
first. When applying lime, make sure to water it thoroughly into the soil, as again, limestone is not very soluble.
TANK MIXING, BROADCAST SPRAYING, & FERTIGATION: WHAT YOU SHOULD KNOW ABOUT NUTRIENT CROSS-REACTIONSFor those who prefer
liquid fertilizers
and
soil amendments, it is important to note that regardless of the relative solubility of the ingredients you use, some ingredients simply don’t mix well with others (this is chemistry 101). When ionic compounds dissolve in water, the ions disassociate. For example, when table salt (NaCl) dissolves in water, the Na+ and Cl- ions split apart from each other. In nature, pure sodium is highly reactive, and pure chlorine gas is deadly, however when dissolved in water, they are quite safe. When two different kinds of salts are dissolved in water, it is possible for the ions to perform a double replacement reaction, meaning two entirely new compounds are created. Sometimes these new compounds are insoluble, and they immediately precipitate in solution.
Many liquid products will instruct the user to perform a small scale “jar test” when mixing with other liquid products. This is to ensure that precipitates do not form, but also to ensure there are no dangerous cross-reactions. The chart below compares the compatibility of different combinations of chemistries in solution. While most chemistries are compatible, there are three distinct patterns become apparent:
- Most nitrates are not compatible with elemental sulfur
- Calcium nitrate is only moderately soluble with most compounds
- Straight urea doesn’t mix well with some nitrates
Whether mixing nutrients, soil amendments, or pesticides, ALWAYS read and understand the label AND perform a small-scale jar test with new combinations of ingredients before large scale tank mixing. If you have any questions or concerns, contact the product’s manufacturer before proceeding.
Solubility & Compatibility
– master these two concepts and your fertilizer programs is sure to give you fantastic results whether your growing turf, ornamentals, trees, or vegetables!
For professional fertilizers, humic and AMP-XC™ enriched products available, please visit TurfCare’s online Product Catalog.
For green industry professionals or others interested in ordering Turfcare products, please contact our Customer Service
to find a distributor near you. References:
http://ipm.ucanr.edu/TOOLS/TURF/MAINTAIN/winamt.html
https://link.springer.com/article/10.1007%2FBF00011851
https://www.smart-fertilizer.com/articles/iron
https://www.lime.org/documents/lime_basics/lime-physcial-chemcial.pdf
https://www.growcom.com.au/_uploads/LWR/Fertigatoin Compatability and Solubility.pdf
Ecofarmingdaily.com/fertilizer-solubility
http://www2.ca.uky.edu/agcomm/pubs/agr/agr5/agr5.pdf
http://www.grounds-mag.com/mag/grounds_maintenance_dos_donts_tankmixing/
Pictures:
Solubility 01 (solution in beakers) - http://www.chemistryland.com/CHM130FieldLab/Lab5/PourWaterIntoFlask.jpg
Solubility 02 (salt ions in water) - http://www.discoveryexpresskids.com/uploads/2/5/6/9/25695369/3159547_orig.jpg
Solubility 03 (evaoptranspiration) - https://classconnection.s3.amazonaws.com/283/flashcards/723283/jpg/transpiration-21323269065290.jpg
Solubility 04 (xylem & phloem travel) - https://image.slidesharecdn.com/planttransport-120920020944-phpapp01/95/plant-transport-6-728.jpg?cb=1348107136
Solubility 05 (granular fertilizer) - http://okfert.com/wp-content/uploads/granular-fertilizer.jpg
Solubility 06 (liquid fertilizer) - http://www.spraytech.uk.com/ekmps/shops/spraytechuk/images/team-scout-60l-296-p.jpg
Solubility 07 (urea prills) - http://www.etherenterprise.com/wp-content/uploads/2015/03/canstockphoto6814252.jpg
Solubility 08 (humic substances chart) - http://home.fulvicforce.co.za/wp-content/uploads/2016/10/Humic-substances-classification-1024x770.png
Solubility 09 (EDTA iron) - http://en3img.allhaving.comhttps://www.turfcaresupply.com/upload/3755/o/2a-ferric-sodium_01.jpg
Solubility 010 (liming application) - http://www.dragtimes.com/img-videos/Liquid-Lime-Application-Terra-Gator-8103-Gromes-Plender-drone-only--v-SGzTSBeUMWs.jpg
Solubility 011 (tank mixing) - https://stowacres.files.wordpress.com/2011/05/img_0525.jpg
Solubility 012 (compatibility chart) - http://www.bing.com/images/search?view=detailV2&ccid=uMGE5AUC&id=0DBABA8CEB6E9169FFD194B7450AA92F455A231B&thid=OIP.uMGE5AUCVHH4xVrltZ6vAQHaEl&mediaurl=http%3a%2f%2fgrowmo.com%2fwp-content%2fuploads%2f2017%2f03%2fYara-fertilizer-compatibility-chart.png&exph=498&expw=803&q=fertilizer+compatability&simid=608013294072172315&selectedIndex=1&ajaxhist=0