Sodium (Na) is an alkali metal that is silvery-white and comprises about 2.6% of the earth’s crust. Sodium was named after the English word soda and from the Medieval Latin word sodanum, meaning “headache remedy” (Thomas Jefferson National Accelerator Facility – Office of Science Education, 2021). Interestingly, sodium is never found in its isolated or “free” state in nature due to it being an extremely reactive element. When sodium is mixed with water it will explode (therefore it needs to be stored in a moisture free environment) and when it’s combined with chlorine it can be eaten as common table salt.
Sodium-containing compounds have been used by humans since ancient times and according to Pappas (2021) the Ancient Egyptians used a substance called Natron (a mixture of sodium-containing soda ash and baking soda that occurs naturally) to pack mummies and their organs in their preservation process. Sir Humphry Davy is the person credited for first isolating pure sodium through the electrolysis of caustic soda (NaOH) in 1807.
Sodium is used in the production of titanium, liquid sodium is used as a coolant for nuclear reactors, and sodium vapour produces a brilliant yellow light which is used in streetlights. However, the most common use of sodium is in compounds such as table salt, borax, caustic soda, baking soda, and soda ash.
Sodium is Essential for Animals
The animal body is comprised of around 0.16% sodium, with 30-50% being found in an insoluble form in the bone, and the largest portion is found in soft tissues and body fluids. According to McDonald (2011) sodium is an essential macro mineral and has numerous important functions such as:
- Being the main cation of blood plasma and other extracellular fluids
- Being a major electrolyte concerned with the acid-base balance and osmotic regulation for body fluids along with potassium and chloride
- Playing a role in the transmission of nerve impulses and in the absorption of sugars plus amino acids from the digestive tract
Ewing (2007) lists other important functions of sodium as:
- Being essential for nutrient transfer to cells and removal of waste
- Being involved in body water regulation
- Assisting in pH control in the stomach
- Being necessary for muscle and heart contraction,
- Being important for appetite (palatability)
- Being a constituent of saliva salts to buffer acid from ruminal fermentation
Most of the ingested sodium by animals is in the form of sodium chloride (salt). Likewise, sodium chloride is also the form that sodium is excreted from the body via urine, sweat and milk and McDonald (2011) suggests that there is evidence that sodium, rather than chlorine, is the chief limiting factor in salt-deficient diets of livestock.
What Does Sodium Deficiency Look Like in Animals?
Sodium deficiency is quite common, especially in the subtropical and arid inland areas of Australia where pastures contain very low concentrations of the mineral.
According to McDonald (2011) and Ewing (2005) a deficiency of dietary sodium can lead to the following symptoms:
- Dehydration of the body due to lowering of osmotic pressure,
- Reduced water intake,
- Poor feed conversion (reduced utilisation of digested proteins and energy) resulting in poor growth,
- Lower fertility in males resulting in reduced reproduction efficiency,
- Loss of appetite and weight loss,
- Rough coat and lack-lustre eyes,
- Pica (depraved appetite – licking fences, dirt etc.),
- Reduced milk production in extreme deficiency,
- Shivering,
- Arrhythmia of the heart,
- Severe fatigue from sweating and exhaustion is commonly observed in horses.
Sodium in Relation to Soil and Plants
When it comes to sodium and plants it can be considered a ‘non-essential’ or ‘functional’ nutrient but can be beneficial to plants in many conditions, especially when potassium is deficient (Maathuis, 2014). Sodium has been shown to be essential for a small subgroup of C4 plants and grasses as it is required at trace levels to drive the uptake of pyruvate into chloroplasts via a particular transport process (Furumoto, 2011).
In many conditions low levels of sodium can be beneficial to plants. However, at moderate to high levels, salt (sodium chloride) is unfavorable to many plants that are classified as glycophytic (i.e., their growth is inhibited by saline soil). Therefore, the chief interest in sodium when it comes to plant and soil nutrition is through the negative consequences that it can cause.
Saline soils contain soluble salts, most frequently sodium chloride, at sufficient levels to negatively affect the development of most plants. Salinity impacts on a plant’s ability to remove water from the soil and can result in toxicities from specific ions. Soils develop salinity from the accumulation of salts and other substances via interactions with groundwater, irrigation, and fertilisers (Doula, 2016). The management of saline soils as described by (Silvertooth, 2021) involves “leaching” the soluble salts from the soil profile and this can be done by the application of “clean” irrigation water above the basic water requirements of the crop. Leaching takes place from the percolation (movement of water through the soil itself) of soluble salts under saturated conditions.
Soil that contain excessive levels of sodium can cause sodic soil conditions which are known to have poor physical properties caused by low microporosity and macropore instability due to the presence of sodium on the clay surfaces (Jayawardane, 1994), and are usually accompanied by nutritional issues with characteristics that may include reduced water penetration due to poor structure, unsatisfactory root growth and the potential for large amounts of sodium absorption by plants. Sodic soil properties include dispersive clay particles, soil aggregate instability in water, soil crusting and sealing, and increased chance of erosion.
To allow for successful crop growth in sodic soils, Glendinning (1990) recommends that excess sodium needs to be leached by other bases or cations, such as calcium, to remove the free sodium. To achieve long-term improvements in sodic soils Jayawardane (1994) reports that tillage techniques to increase microporosity need to be combined with chemical (soil ameliorants) and biological (organic matter) techniques to improve macropore stability.
How AgSolutions Can Help
Sodium is an important mineral to consider for both plants and animals, whether it is regarding meeting their daily dietary requirements for essential life functions in animals, or whether sodium is present in excessive amounts in soil that could have negative consequences for plant growth.
A good place to start to determine the sodium status of your land is by getting a soil test done. AgSolutions can assist your operation by taking a soil test and working with you to develop a soil management program. The NatraMin range is formulated to restore bio-activated broad spectrum minerals to your soil and is designed to help improve the three aspects of soil fertility – nutritional, biological and structural.
NatraMin Cal-S has been used successfully in many operations as an important soil ameliorant to help improve structure, friability and water holding capacity of soils. The excess calcium entering the soil from the applied NatraMin exchanges with the sodium and magnesium on the clay exchange sites. Both sodium and magnesium may be leached during subsequent irrigation or rainfall events. As a result, they are removed with the calcium left behind to initiate the process of aggregation, thus improving soil structure.
MegaMin Equine Supplements and MegaMin Livestock Supplements have several blends suitable to assist in providing stock with extra dietary sodium along with other essential macro and trace minerals, which in turn can help promote production and assist with getting a return on investment.
For livestock, including horses, it is recommended to have additional free choice plain salt available to help meet changing sodium requirements in the animal caused by environmental, production and seasonal conditions.
For further information on AgSolutions’ products contact Head Office on 1800 81 57 57.