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Feature Article July GT Newslink |
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Sodium (Na+) can make up about 1% of dry matter in plants and is the 7th most abundant element.
However unlike other elements (N,P,K etc) not much is known about the role of Na.
It is not considered an essential element for plant growth.
It is important in animal metabolism and is given as a supplement for stock who struggle to get sufficient Na from grass.
The most common association with Sodium and negative effects on plants is with seawater. It's the salt, 'sodium chloride' that causes the problem. The negative attributes of chlorides are well documented so it may well be the chloride that makes sea water the 'baddy' for plants. However we do know some plants are sodium loving such as sugar beet and barley. It is thought that the sodium affects water relations and helps sugar beet withstand drought. Some plants may be sodium sensitive, in that it somehow affects the workings of the plant in some unknown or yet to be documented way. Certainly some plants are considered more sodium tolerant than others just by observation of growth in high sodium (sodic) soils. One thing that is well known with high levels of Na+ in a soil or substrate is that it displaces other cations that are well documented as being important in plant nutrition, and causes deficiencies and imbalances. The most common solution to a substrate with high levels of Na+ is to add other cations to displace the Na+ which is then leached away. Gypsum is commonly used with the much need Ca+ to displace the Na+. This is the principal of flushing that Grower Technology use when treating Coir when making up batches for growers. Additives of Ca+, Fe+ and Mg+ are especially used to bring the mix back into a healthy cation balance. The implications for you as a grower is to facilitate some flushing, ideally early in your growing cycle without exposing your plants to a substrate that's too wet over an extended period of time. |
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