Technical - Soil Biology
survive to make these elements available to enhance the growth of the plant.
There are two main reasons for using biostimulants to improve the growth and health in amenity turf.
Firstly to feed the soil microbiology because the organic substrate needed by soil microbes has been designed out of the rootzone specification. The power of the microbes to retain nutrient, convert exudates to plant food, degrade thatch, prevent disease and maintain soil friability is far greater than the action of the biostimulant on the plant itself. Most biostimulants do not differentiate between beneficial and pathogenic microbes, so care is needed in application not to apply them directly to active pathogens.
Secondly, many biostimulants have a direct effect on the health of the plant. In perfect growing conditions, biostimulants will do little for plant health, but sports turf, especially golf greens and stadium pitches, are some of the most artificial environments created for plant growth and the grass plant benefits from the addition of the stimulants that it cannot produce in sufficient quantities itself.
Humus, Humic and Fulvic Acid Soil Enhancers the Building Blocks of Soil
Sports turf rootzones are designed with minimal organic matter and, what there is, is often peat which supports very low levels of microbial life. Because sports turf rootzones are continually topdressed, they seldom have the chance to mature and become rich in humus and humic compounds so they are added in the form of humates, humic and fulvic acid
Humus is generated by degrading thatch. It contains humic substances, the biostimulants fulvic acid, humic acid and humin, which are complex structures with high molecular weight.
Humus, humic acid and fulvic acid act in many ways. Physically, humic compounds improve soil structure, creating space to retain oxygen, store water and improve drainage; they promote soil agglomeration which is important if invasive hollow coring is to be reduced.
Chemically, humic compounds are negatively charged and increase cation exchange capacity, i.e. the soil’s ability to chemically retain nutrients and reduce leaching and coat soil particles in positively charged nutrients, such as calcium, potassium, magnesium, iron and micro nutrients.
Humic acids reduce soil pH by reacting with the calcium carbonate in the soil to produce carbon dioxide and, when excessive amounts of inorganic fertilisers have been applied, humic compounds can reduce sodium and other mineral salts in the soil by exchanging them for other cations, e.g. calcium.
Humates, humic and fulvic acids also have many beneficial effects on the grass plant, improving cell division and elongation and also chlorophyll content.
Fulvic acid, when extracted by itself, has a smaller molecular weight, so it can penetrate leaves, roots and stems, which makes it an excellent chelating agent when mixed with other biostimulants, liquid fertilisers or pesticides, helping them to enter the plant when applied as a foliar spray. This makes fulvic acid an excellent low light, cool season biostimulant by helping get nutrient, carbohydrate and protein into the plant.
In temperate climates, if applying the individual
Comparison of Biostimulants on beneficial bacterial and fungal populations in compost tea
Chitin Trial - Frost Tolerance and Winter Growth December to March 2013 Source G. Giardina, University of Surrey
products, humates and humic acids usually give the best results when applied during the warmer months, whilst fulvic acid is best applied to encourage growth in the cooler, low light seasons. It can be used as a chelating agent year round
Chitin - the missing link
Chitin is a polymer containing nitrogen and is very common in nature as part of animals and insects physical structures. Only cellulose is more abundant than chitin. It is found in arthropods, insects, fungi and algae and returned to the soil when they die. However, in sports turf rootzones, these sources of chitin are low or non existent, so chitin is always in short supply.
Effect of Chitin on grass seed germination trial showing increase in germination of Festuca Rubra Lolium Perenne compared to control Source G. Giardina, University of Surrey
Seaweeds
Applying chitin has many beneficial effects, improving fungal growth for the degradation of thatch and disease resistance. It has a positive effect on seed germination, increasing grass seed germination rates by up to 20% (see photo 1). It also increases carbohydrate production in the plant and one benefit of this is an increase in frost tolerance (see photo 2).
Seaweed production and use is a complex subject, with many different types of source material with four common extraction processes generating products that have different properties and uses, but in many respects all seaweed products have similar responses
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