Solublity of a Fertilizer & Jar Test

When applying fertilizers through the irrigation water, it is essential that you know

some important facts about the fertilizers solubility.


What Does Solubility of a Fertilizer Mean?

Solubility of a fertilizer is the maximal amount of the fertilizer, that can be completely dissolved in a given amount of distilled water at a given temperature.

Manufacturers may provide you with solubility data of their fertilizers upon request. Here is an example of solubility data for Potassium Nitrate (expressed as g/liter):

Temperature (C˚) 5 10 20 25 30 40
Solubility 133 170 209 316 370 458

Different manufacturers may provide slightly different solubility data for the same

fertilizer. This is because they use different additives in their products. There are also some fertilizers that may contain insoluble residues.


Dissolving a Fertilizer

When you dissolve a fertilizer, you should not exceed its solubility. Otherwise, a

precipitate may form and might clog the irrigation system. Moreover, the nutrients you intend to provide through the solution may not be fully available.

For example, according to the data in the table above, the solubility of Potassium Nitrate in 20oC is 209 g/l and the fertilizer contains 38% Potassium. If you attempt to dissolve 300 g/l in the fertilizer stock tank, you will not get 114 g/l of Potassium (38% of 300g), but only 80g. The remaining 34g will precipitate and will not be available.

Mixing Fertilizers Might Decrease Their Solubility

When dissolving together two or more fertilizers that contain a common element (for example Potassium Nitrate together with Potassium Sulphate) the solubility of the fertilizers is decreased. In such case, we cannot refer to the fertilizer solubility data alone. The same happens when the water used for dissolution is highly rich with minerals, e.g. calcium, magnesium or sulphate.

In such cases, additional chemical reactions come into play, and calculations become more complex. Usually, these are not calculated in the field and instead, trial-and-error practices are common.


Fertilizers Compatibility

Some fertilizers should not be mixed together in one stock tank because an insoluble salt may form very quickly. An example for such incompatibility is mixing fertilizers that contain calcium with those that contain phosphate or sulphate.

The Jar Test

We've established that when mixing fertilizers, we should be familiar with the solubility data of the fertilizers we use as well as with chemical reactions that may take place. In order to avoid unwanted precipitates, a common recommendation is to perform a "jar test". In this test, the fertilizers are initially mixed in a jar containing the same water used for irrigation.

Prueba de Jarro

Complete dissolution Precipitate formation

The fertilizers should be added exactly in the same concentration as intended to be used in the stock tanks. If a precipitate forms or if the solution has a "milky" appearance, the test should be repeated with lower concentrations of the fertilizers.

Fertigation fertilizers compatibility


All of these calculation and information are automatically incorporated into the simple fertilizer recipes produced by Smart!

Popular posts from this blog

Organic Fertilizers, Fungicides & Nutrients

Image
Organic fertiliser is obtained from various chemicals. It contains range of nutrients at different ratio, making it effective for plants. These are easily absorbed in plant systems. Organic Fertiliser are available as solid spray dried powder or liquid solution. This powder if fully soluble in water and can be dissolved in water to prepare formulation of required concentration HUMIC ACID: Application of humic acids has several benefits and agriculturists all over the world are accepting humic acids as an integral part of their fertilizer program. Biochemical active and plant responsive humic substance are naturally occurring humic acids. They can be applied directly to the plant foliage in liquid form or to the soil in the form of granules alone or as fertilizer mix. Benefits of Proper Application of Humic Acid increase soil fertility, Increase humus contents, Effectively chelates meta...
Read more

CarBon Di-Oxide

Carbon dioxide gas is colourless and odourless gas or extremely cold liquid under pressure or refrigeration. It will not burn. Carbon dioxide is a COMPRESSED GAS. It Can displace oxygen in air, it may accumulate in low areas and is a confined space hazard. Carbon dioxide is a very mild central nervous system depressant. Very high concentrations may cause headache, nausea, dizziness, sweating, restlessness and disorientation. Liquefied gas may cause frostbite. Where do you find carbon dioxide gas? CO 2 gas is used for the carbonation of beverages; for pH control; as a chemical intermediate; in chemical processing; as a food preservative; as an inert "blanket"; and in enhanced oil and gas recovery. Liquid CO 2 is used as a refrigerant; for low temperature testing of aviation, missile and electronic components; as a fire-extinguishing agent; for stimulation of oil and gas wells and for controlling temperature in chemical reactions. CO 2 gas is a by-product of carbonaceous ...
Read more

Complete defination of Fertilizers

FERTILIZERS : Growing plants are nourished by certain constituents which they absorb from the soil and air. The chief elements drawn from tho soil are potassium, calcium, sulphur, phosphorus, and nitrogen; other elements such as silicon, iron, sodium, magnesium, and chlorine are taken up to a less degree. The natural weathering of the minerals in the ground usually provide the elements necessary to plant life; but the supply of potassium, phosphorus, and nitrogen may be insufficient and become exhausted by frequent repetitions of the same crops on the same land. The soil becomes less productive, and finally the crops are failures. To supply this continued drain on the soil, fertilizers are employed. The natural fertilizers, barn-yard manure, urine, and decomposing vegetable mould or muck, will not be considered here, as they need little or no treatment before use. By artificial fertilizers we understand those manurial substances, prepared from materials which need some special treatmen...
Read more