Kelp (or seaweed) is probably the most popular form of organic fertiliser for lawns, and usually comes in a blend with additional nutrients like Iron and wetting agents included as well for use on lawns. Traditionally kelp was collected off beaches, composted and applied as a fertiliser or top dressing.
Kelp is one of the most universally recognized natural biostimulants and is the most widely used biostimulant in both agriculture and turfgrass management. It contains many important plant growth regulators, such as auxins, cytokinins and gibberellins. It also contains micronutrients to enhance a plant’s ability to resist pest and disease attack.
There has been a lot of recorded data over the years, that has documented the effect kelp has on plant growth. The key component that aids in the development of healthy plant roots is phosphorus.
Kelp concentrates contain plant nutrients, carbohydrates, trace elements, alginic acid and other bioactive compounds. Alginic acid is a soil conditioner, the other components are considered plant conditioners. Alginic acid combines within the soil to form a polymer which swells when wet, which helps with water retention.
These components make kelp ideal for promoting healthy roots and encouraging beneficial micro-organisms within the soil. As a result of this, organic matter will be broken down more efficiently, helping to prevent thatch build up.
By promoting healthy roots, you are also helping your lawn to become more drought, frost and heat tolerant.
Kelp has also been found to increase stress tolerance in turf. One study found significantly lower proline levels (Proline is a measure of stress levels within a plant and proline concentration increases as stress levels increase), on turf that had been treated with kelp compared to turf that had not.
Another important mineral found in kelp is Iodine, which aids in the defence against turf disease. It has been shown that plants treated with kelp products develop a resistance to pests and diseases. It is important to state clearly that this resistance is often quite limited and the use of chemical control is still required. However, kelp extracts may be useful as a supplementary biological control factor in the race against pest and disease problems.
Using kelp concentrates on your lawn before summer and winter is a great way to keep your roots and lawns healthy, and mitigate any stress that your lawn may encounter due to extreme temperatures and lack of water.