Plant

Sodium is not considered an essential plant nutrient, however certain crops benefit from applications of sodium - predominantly high sugar crops including sugar beet and fodder beet,  grassland and other root crops.

Animal

Sodium is essential for all animals. It is required for maintaining osmotic pressure, water regulation and helps transport nutrients to where they are needed. It is also involved in nerve impulse transmission and muscle function.

For ruminant animals, sodium has an added importance in saliva, which is produced in vast amounts to help buffer the acid produced from fermentation in the rumen.

If there is a lack of sodium, animals substitute sodium for potassium which leads to resorption of magnesium in the blood, leaving animals vulnerable to hypomagnesemia (grassland staggers). To help prevent this, the potassium:sodium ratio of the forage should be kept at 20:1 or below.

Soil

Sodium exists in the soil as a positively charged nutrient (Na²⁺) and so, in theory, is able to bind to negatively charged clay particles within the soil.

However, of all the positively charged nutrients sodium is the smallest and regularly has to compete with other much larger nutrients (E.g. Ammonium, calcium and potassium) for space on the exchange sites on the clay particles.

Because of this, it is difficult to build soil sodium reserves easily.

Since sodium is not plant essential, plants are unlikely to show visual signs of sodium deficiency. In grassland, deficient plants are likely to have a lower sugar content, be less digestible and less palatable. 

Where is the risk of deficiency highest?

• Sandy soils with a low clay content 
• Low organic matter soils
• Soils with a high potassium  index

Testing

A Broad Spectrum (BS) soil analysis can help determine the quantity of sodium which is likely to be available for crop uptake and can be used to tailor fertiliser plans and to help prevent deficiencies within the season. 

Tissue testing is also useful to determine the sodium concentration of the plant mid-season in order to compare against optimum levels. Although laboratory results may be available too late to correct the deficiency in the current crop, they can be useful for decisions on sodium use for future crops.

Blood tests on livestock can help indicate whether there is a sodium deficiency within the animals diet. 

Because sodium is much smaller than other positively charged nutrients, such as calcium, potassium and ammonium, it is less likely to bind to clay particles and so is vulnerable to being leached, particularly in sandy soils with a low clay content. 

Right Product

Refined sources of sodium with low hygroscopicity are more suitable for storing than standard agricultural salt.  

Right Time

There are benefits to applying sodium to grass throughout the growing season. Potassium uptake is highest during rapid spring growth and applications of sodium can help maintain optimum potassium:sodium ratios for animal health. During the summer, as grass becomes more fibrous and less digestible, sodium can increase forage palatability, digestibility and intake.

Right Place

Avoid applying large rates of sodium to light, sandy soils or in areas of high rainfall to avoid potential nutrient loss. 

Right Rate

Best applied little and often to minimise losses. To improve grassland palatability, we suggest regular dressings of 7 kg/ha of sodium throughout the season.

Fertiliser	Analysis	Features
Sweetgrass	23-0-0 + 2%S + 1.2%Mg + 5%Na	Improves grassland palatability and subsequent forage intake, leading to higher milk or meat production where no P or K applications are required
Sweet 18s	18-6-10 + 3%S + 4%Na	Improves grassland palatability and subsequent forage intake, leading to higher milk or meat production. For use where soil P and K levels are low
Sweet Sustain	35-0-0 + 5%S + 5%Na	Improves grassland palatability and subsequent forage intake, leading to higher milk or meat production. Nitrogen source is protected Urea