Beneficial Elements

Beneficial Elements are elements that help optimize the growth and development of plants but they are not essential for growth.  When they are absent in the soil, plants can still live a normal life.  Here are some criteria that separate beneficial element from the essential ones:

1. It can compensate for the toxic effects of other elements.

2.  May replace mineral nutrient in some other less specific function such as the maintenance of osmotic pressure.

3.  May be essential to some but not to all plants.

Examples of beneficial elements are:

Silicon (Si)

Silicon increases the resistance of plants to pathogen and pests.  It also increases drought and heavy metal tolerance of plants.  Overall it improves the quality and yield of agricultural plants. 

Cobalt (Co)
Cobalt is essential for the growth of Rhizobium bacteria for N fixation and thus beneficial for the plant.  Nitrogen fixation is the process by which the atmospheric molecular nitrogen (N2) is reduced to form ammonia (NH3).  This process is carried out by nitrogen-fixing bacteria which are found in the roots of most leguminous plants.  Ammonia is the form of nitrogen that is used by plants and other living systems in the synthesis of organic compounds. 

Lithium (Li)
Affects transport of sugars from leaves to roots.  Production of food (carbohydrates and sugars) happens in the leaves during photosynthesis.  This food will be transported to the different parts of the plant such as the roots, fruits, new shoots, and stems.  Lithium enhances the transport of such food to the roots.  

For the backyard gardener, there is no need to worry about artificially applying them to the soil or any growing media that you might use.  Your plants will still survive.  In case you want to insist, then the best thing for you to do is apply compost around your plants. 

Beneficial elements are not essential for plant growth.  Lithium for example, is indirectly beneficial to the plant by its benefits to the bacteria rhizobium.  Plants don't need the bacteria for growth.  They need nitrogen.