Sodium Management

Often toxic, sometimes beneficial.

Sodium in the Soil

Sodium (Na) is one of the most common elements on Earth, but the levels of it vary greatly geographically. Areas that receive lots of rain may have soils depleted of Na, whereas some arid areas have such high concentrations of Na and other salts that the soils are more saline than seawater.

Sodium is typically viewed as a toxic salt in agricultural systems, and with good reason: in arid soils, sodium toxicity can pose a real issue to farmers and their crops. But like almost all elements in the soil, sodium is not toxic in its own right, but becomes toxic when it accumulates to an unhealthy level, or when other critical nutrients are out of balance. In fact, some plants use Na as an enzyme cofactor, and low concentrations of Na have been shown to improve flavor in many plants.

Sodium in the Plant

Sodium isn’t an essential nutrient for most plants. The plants that do use Na only require it in small amounts to act as an enzyme cofactor. However, low concentrations of Na do improve flavor in many crops, and thus it is beneficial to have some sodium in the soil. Additionally, Na+ ions are able to fill some of the metabolic roles of K+ in plants. Therefore, K-deficient plants can benefit from access to low concentrations of Na. This can lower the use of expensive K fertilizers.

A photo of a salt-stressed wheat field. Image from Flickr.

Sodium Toxicity

High concentrations of salts like sodium (Na) and chloride (Cl) cause salt stress. Salt stress is the term for the osmotic stress or pressure created by an accumulation of these ions in the soil. Salt stress makes it difficult for plants to take up water from the soil. The high concentration of salts in the soil has a strong affinity for water, and the negative pressure generated from evapotranspiration is not enough for roots to pull water from the saline soil. To counteract this, plants absorb the salt ions and concentrate them in their cells to draw in water. This can lead to toxic levels of salts accumulating in cells, disrupting macromolecules and overall biochemistry.

For more information on managing sodium toxicity, please read our post on Salt Stress.

Further Reading

Acosta-Motos, J. R., Penella, C., Hernandez, J. A., Diaz-Vivancos, P., Sanchez-Blanco, M. J., Navarro, J. M., Gomez-Bellot, M. J., and Barba-Espin, G. (2020). Towards a sustainable agriculture: strategies involving phytoprotectants against salt stress. Agronomy.

Ahmad, P., Ahanger, M. A., Alyemeni, M. N., Wijaya, L., Alam, P., and Ashraf, M. (2018). Mitigation of sodium chloride toxicity in Solanum lycopersicum L. by supplementation of jasmonic acid and nitric oxide. Journal of Plants Interactions.

Keisham, M., Mukherjee, S., and Bhatla, S. C. (2018). Mechanisms of sodium transport in plants: progress and challenges. International Journal of Molecular Sciences.

Maathuis, F. J. M. (2014). Sodium in plants: perception, signalling, and regulation of sodium fluxes. Journal of Experimental Botany.

Qin, Y., Druzhinina, I. S., Pan, X., and Yuan, Z. (2016). Microbially mediated plant salt tolerance and microbiome-based solutions for saline agriculture. Biotechnology Advances.

Wang, X., Geng, S., Ma, Y., Shi, D., Yang, C., and Wang, H. (2015). Growth, photosynthesis, solute accumulation, and ion balance of tomato plant under sodium- or potassium-salt stress and alkali stress. Crop Ecology & Physiology.

Yamaguchi, T., Hamamoto, S., and Uozumi, N. (2013). Sodium transport in plant cells. Frontiers in Plant Science.

Zhang, H., Xu, N., Wu, X., Wang, J., Ma, S., Li, X., and Sun, G. (2018). Effects of four types of sodium salt stress on plant growth and photosynthetic apparatus in sorghum leaves. Journal of Plant Interactions.