Benefits of Seaweed and Fish Fertiliser

Soil conditioner
Foliar feeding
Combining seaweed extracts with fish emulsion

The use of seaweed in farming and agriculture has a long history. Seaweed has always been harvested in coastal areas to be used as mulch in vegetable gardens and to supplement feed for animals.

It was not until after WWII that systematic research into the benefits of seaweed took place. Even though seaweed has been researched for over 50 years now, the exact mechanism through which seaweed exerts its positive influence is still not fully known.

Initially the thought was that the benefits derived from seaweed use were mainly caused by the trace elements.

Seaweed contains all elements. Some in substantial amounts like potassium, but most only in trace amounts. Minerals leach out through the effect of weathering from all landmasses. In the long term these elements invariably find their way into the sea, where they are used by the plants growing there. In seawater you find a natural blend of all the minerals available on earth. Unfortunately seawater contains levels of Sodium Chloride that are too high for land-based plants to tolerate in any substantial amount, otherwise seawater would be an ideal fertiliser.

Australia is an old continent and is probably the poorest in its trace element content. The soils are leached of most of their trace elements and therefore farmers in this ancient continent can have the most potential benefit of using sea minerals in the form of seaweeds and fish. These nutrients are high in the same elements that have been steadily leached and eroded from the soil.

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Seaweeds, unlike plants growing in soil, take up the majority of their nutrients from the medium they live in: the seawater. They absorb nutrients directly into their tissues. The 'roots' on seaweed have the main function of anchoring the plant. Seaweed takes up all the trace elements, and stores them in a bio-available, or chelated form. This means that when the breakdown products of seaweed are presented to a plant it will be able to utilise these nutrients. Chelation is a process of incorporating a mineral element in a protein molecule to stop it from reacting with its environment. This means it is in a stable form, and won't react with other elements in the soil, which could make it unavailable to plants

For most of the trace elements scientists have not worked out exactly what role they play in human, animal or plant nutrition. Until fairly recently only the trace elements Zinc, Iron, Manganese, Molybdenum and Copper were considered to be relevant for human and plant health. Now this list has been expanded to around 20 elements, but the majority of trace elements are still 'irrelevant' according to major nutritionists.

It is not inconceivable that in future the role of more elements might be discovered. The same goes for plant nutrition. The role of most elements is unknown, but supplementation of even the most obscure elements in trace amounts give substantial boosts in yields and in plant health. It is therefore a good idea to provide the widest range of elements to plants that you can think of. Even elements that are considered to be toxic might play an important role if they are provided in trace amounts. In this way seaweed fertilisers act as a 'nutrition insurance', you know that all the trace elements, even the ones you don't know exactly the function of, are provided.Liquid concentrates are usually applied in such limited amounts that there is no fear for toxicity.

Liquid seaweed concentrate is used either as a soil conditioner or as a foliar fertiliser. It can be applied in concentrated form or much diluted and can be easily mixed with other sprays. Use of liquid concentrate for soil conditioning gives quick results, but not necessarily long lasting. For problem soils a seaweed meal might be more beneficial in the longer term. The cost of seaweed meal applications are considerably higher than for concentrate applications, which is a point that has to be taken into consideration for larger acreage.

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Liquid extract is used for almost immediate effects. When applied as a foliar spray the nutrients are directly available to the plant, but as a foliar application also causes the plants to increase its uptake of soil nutrients through the roots there is a longer term effect as well.

The importance of trace elements lies mainly in their role in the formation of enzymes. Enzymes play an important role in all living organisms because they act as catalysts, without which many important functions such as the sugar production in plants would not take place. Most enzymes contain an inorganic compound. Often there is just one atom of a metal in the complex molecules with dozens and sometimes hundreds of atoms of Carbon and Hydrogen. Without this one metal atom in each of these enzymes it would not be able to function at all. Without these atoms of metals the enzymes could not function, the organism would not function properly either and start to show signs of disease. Sometimes these elements are only needed in concentrations of 1 in one-million or one in ten-million or even less. They are still needed and if not provided the whole system could be harmed.

Another major component in liquid seaweed extracts are the hormones. The main hormones in seaweed are auxins, gibbelerins, cytokinins and betaines. The roles of these hormones are also essential to plant health. Most of them are required in only very small proportions. They occur naturally. Plants are sometimes able to produce these hormones themselves. There are many different auxins and they all have their specific roles. Their main functions are the balanced control of speed of growth. They have both growth stimulating as well as delaying functions. They stimulate root-growth, prevent bud-forming or opening at the wrong times. In the past they were even used in synthetic form as weedkillers.

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Seaweeds can even play an important role in the production of the plant's own auxins, because the enzymes formed with the help of

trace elements from the seaweed often play an important role in the formation of these auxins.

Cytokinins are another powerful group of plant hormones. They initiate and activate basic growth processes. The cytokinins available in seaweed stimulate growth with greater vigour, because they mobilise nutrients in the leaves. They also provide protection from marginal frost (to -3 C). Cytokinins also retard the senescence (aging processes) in the plant.

Betaines play an important role in the osmotic processes in plants. They help to increase the water uptake in plants and are extremely helpful in dry or saline conditions. Betaines are particularly helpful to plants in stress.

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Soil conditioner

Seaweed and especially the alginates in the seaweed act as soil-conditioners. The alginates react with metals in the soil and form long and cross-linked polymers in the soil. These polymers improve the crumbing in the soil, and swell up when they get wet, and retain moisture for a long period.

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Foliar feeding

Nutrients are absorbed through leaves more speedily than through its roots. A foliar spray can also work as a stimulant for the plant to take the nutrients up through its root system.

Seaweed and /or fish emulsion sprayed on a crop can have an almost instant effect on the health of the plants. A dramatic increase can be achieved overnight.

Many farmers use the fish and/or seaweed as soon as they find the start of a pest infestation. The day after the foliar application the pest have usually disappeared or are not feeding.

Caution

Seaweed should not be seen as a panacea for every ill. I have found over the years that farmers and growers who have worked toward establishing a balanced soil find they have the most benefit from these applications. On some farms, especially the ones with low pH or extremely low Calcium levels, there has been hardly any benefit in applying seaweed and fish. I would recommend users of fish and seaweed to keep checking the pH of their soils after using fish and seaweed, but especially fish. There seems to be a tendency to a lower pH. This may be due to increased biological activity, and may be self limiting, but I recommend regular users to keep an eye on the development of the pH.

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Benefits from use of seaweed:

• " - stronger plants with greater vigour
• " - protection from marginal frosts
• " - plants stay longer in production
• " - Produce travels better and has longer shelf life
• " - Improved root formation
• " - Improved survival of seedlings
• " - Resistance to mildew and other diseases
• " - General increase in health, so less insect damage

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Combining seaweed extracts with fish emulsion

Fish emulsion, with its high Nitrogen content complements seaweed extracts well. Fish emulsion also supplies bulk organic matter, which helps to buffer the nutrients available in seaweed. In combination they provide both the trace elements, main nutrients and essential hormones.

In recent research fish emulsion by itself has been shown to increase the growth of plants through the stimulation of some bacteria strains. The bacterial and actinomycete isolates were capable of producing auxins, gibberellins and cytokinins and appeared to use fish emulsion as a source of nutrients and precursors for these Plant Growth Regulators( PGR). PGR levels in planta following combined treatments of the bacterial and actinomycete isolates and fish emulsion were found to be significantly enhanced over other treatments. The effect of fish emulsion appeared to be more related to its role as a nutrient base for the bacterial and actinomycete isolates rather than to the increased activity of the general microflora of treated soil. According to the research report this was the first report of fish emulsion as a nutrient base for plant growth promoting rhizobacteria. These results also indicate that the successful treatment can be effective and economical for horticultural production, especially in sandy soils (Khaled A. El-Tarabily: Fish emulsion as a food base for rhizobacteria promoting growth of radish (Raphanus sativus L. var. sativus) in a sandy soil).

At Sea Magic Organics we use mainly shark as input for our liquid fish fertiliser, and use a natural, enzymatic digestive process to hydrolyse the fish. Because we use mainly shark, we have to avoid using the fatty tissues and the livers, as sharks are at the top of the food chain and tend to accumulate the toxins in their livers and in fatty tissue. Our product therefore does not have the thick consistency of other fish emulsions, but as the meat is completely digested the final product is completely liquid and still contains a considerable amount of oil.

The enzymatic digestive process is anaerobic. Because of this the final product has a distinctive anaerobic smell. We are currently working on different microbial cultures that are still anaerobic, but produce a less offensive smell. The process needs to be anaerobic, because in an aerobic process too many nutrients would become volatile, and in an anaerobic environment a substantial content of auxins is preserved/created.

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PO Box 251,Coffs Harbour. 2450, Ph 02 6655 4332 • Fax 02 6652 3132, enquiries@seamagic.com.au