The USGA greens specification, sandsports pitches and the use of puresand topdressing, coupled with acontinually stressed plant, means thatthe microbiology found in most

healthy perennial grass systems does not havethe food or substrate needed to survive.Microbial food has to be added in the form ofbiostimulants.

What do biostimulants do?

- Biostimulants applied in small quantities,enhance plant and microbial growth anddevelopment

- They improve the efficiency of plantnutrients, by improving uptake or reducingleaching or both

- Some biostimulants are soil amendments,

improving soil structure and its ability toenhance plant and microbial growth

- Some improve the plants ability to resistdisease

- Many assist all of the above functions

The turf manager is confronted with a mass ofbiostimulants, all claiming to promote healthygrass and solve a myriad of problems. Manyproducts contain mixes of different rawmaterials but, in the following paragraphs, wewill take a look at the main biostimulantsavailable to turf managers.

In simple terms, plants and microbes both needcarbon, nitrate, phosphate, carbohydrate andsugars; some biostimulants provide all or someof these elements, whilst others provide asubstrate on which plant and soil microbes

What are theyand what dothey do?

Biostimulants

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In his previous article, Symbio’s Managing Director MartinWard looked at how important it is to have a diverse range ofbeneficial microbes, including bacteria, fungi protozoa andnematodes, in the rhizosphere if you want to grow healthy,disease resistant grass

Unfortunately, he says, the development of sports turf rootzoneshas concentrated on physical and chemical management of thegrass

survive to make these elements available toenhance the growth of the plant.

There are two main reasons for usingbiostimulants to improve the growth andhealth in amenity turf.

Firstly to feed the soil microbiology becausethe organic substrate needed by soil microbeshas been designed out of the rootzonespecification. The power of the microbes toretain nutrient, convert exudates to plant food,degrade thatch, prevent disease and maintainsoil friability is far greater than the action ofthe biostimulant on the plant itself. Mostbiostimulants do not differentiate betweenbeneficial and pathogenic microbes, so care isneeded in application not to apply themdirectly to active pathogens.

Secondly, many biostimulants have a directeffect on the health of the plant. In perfectgrowing conditions, biostimulants will do littlefor plant health, but sports turf, especially golfgreens and stadium pitches, are some of themost artificial environments created for plantgrowth and the grass plant benefits from theaddition of the stimulants that it cannotproduce in sufficient quantities itself.

Humus, Humic and Fulvic Acid Soil Enhancersthe Building Blocks of Soil

Sports turf rootzones are designed withminimal organic matter and, what there is, isoften peat which supports very low levels ofmicrobial life. Because sports turf rootzones arecontinually topdressed, they seldom have thechance to mature and become rich in humusand humic compounds so they are added in theform of humates, humic and fulvic acid

Humus is generated by degrading thatch. Itcontains humic substances, the biostimulantsfulvic acid, humic acid and humin, which arecomplex structures with high molecular weight.

Humus, humic acid and fulvic acid act in manyways. Physically, humic compounds improvesoil structure, creating space to retain oxygen,store water and improve drainage; theypromote soil agglomeration which is importantif invasive hollow coring is to be reduced.

Chemically, humic compounds are negativelycharged and increase cation exchange capacity,i.e. the soil’s ability to chemically retainnutrients and reduce leaching and coat soilparticles in positively charged nutrients, such ascalcium, potassium, magnesium, iron and micronutrients.

Humic acids reduce soil pH by reacting with thecalcium carbonate in the soil to produce carbondioxide and, when excessive amounts ofinorganic fertilisers have been applied, humiccompounds can reduce sodium and othermineral salts in the soil by exchanging them forother cations, e.g. calcium.

Humates, humic and fulvic acids also havemany beneficial effects on the grass plant,improving cell division and elongation and alsochlorophyll content.

Fulvic acid, when extracted by itself, has asmaller molecular weight, so it can penetrateleaves, roots and stems, which makes it anexcellent chelating agent when mixed withother biostimulants, liquid fertilisers orpesticides, helping them to enter the plantwhen applied as a foliar spray. This makes fulvicacid an excellent low light, cool seasonbiostimulant by helping get nutrient,carbohydrate and protein into the plant.

In temperate climates, if applying the individual

products, humates and humicacids usually give the best resultswhen applied during the warmermonths, whilst fulvic acid is bestapplied to encourage growth inthe cooler, low light seasons. Itcan be used as a chelating agentyear round

Chitin - the missing link

Chitin is a polymer containingnitrogen and is very common innature as part of animals andinsects physical structures. Onlycellulose is more abundant thanchitin. It is found in arthropods,insects, fungi and algae andreturned to the soil when theydie. However, in sports turfrootzones, these sources ofchitin are low or non existent, sochitin is always in short supply.

Applying chitin has many beneficial effects,improving fungal growth for the degradation ofthatch and disease resistance. It has a positiveeffect on seed germination, increasing grassseed germination rates by up to 20% (seephoto 1). It also increases carbohydrateproduction in the plant and one benefit of thisis an increase in frost tolerance (see photo 2).

Seaweeds

Seaweed production and use is a complexsubject, with many different types of sourcematerial with four common extractionprocesses generating products that havedifferent properties and uses, but in manyrespects all seaweed products have similarresponses

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Comparison of Biostimulants on beneficial bacterial and fungal populations in compost tea

Effect of Chitin on grass seed germination trial showing increase ingermination of Festuca Rubra Lolium Perenne compared to control

Source G. Giardina, University of Surrey

Chitin Trial - Frost Tolerance and Winter Growth December to March 2013Source G. Giardina, University of Surrey

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Seaweed extracts act as biostimulants onthe microbes in the soil because of thecarbon and carbohydrate content anddiversity of nutrients that act as amicrobial food source. Generally,potassium hydroxide extracted seaweed,which has a higher organic content thancold pressed solutions, is best for soilmicrobe growth and was shown to be abetter biostimulant for bacterial andfungal growth than fish hydrolysate orcomplex sugars see photo 3. So, whileseaweed itself does not make all theimprovements attributed to it, theincrease in beneficial soil biology does.

Cold pressed seaweeds with a smallermolecular structure are more readilyabsorbed by the plant and work well onthe plant, mainly due to the presence ofplant hormones: auxins, cytokinins,gibberellins. Auxins are responsible forelongational growth of plant tissues, celldivision, plant movements and plantaging; cytokinins help transportnutrients, regulate cell division andinhibit ageing of plant tissues, whilstgibberellins regulate growth and stemelongation, germination, dormancy andseed production and germination.

Amino Acids

There are twenty amino acids that formthe building blocks of protein. In goodconditions, plants can usually produce allthe amino acids required but, whenunder stress due low cutting height,poor light and drought, photosynthesis isinhibited and amino acid productionreduced at a time when more is needed.Amino acids tend to give the best resultsfor turfgrass, applied during the earlyspring when the plant finds it hard toproduce the proteins needed to startgrowth after the winter, and duringtimes of heat and drought stress insummer. Amino acids are also a sourceof nitrogen.

Molasses

Molasses is an extract of sugar cane andis available in many forms, but whenused on turf grass it is usually best touse the complex carbohydratesproduced after the simple sugars andsalts have been extracted in theproduction process.

Its primary function as a biostimulant isa food source providing carbon, sugarsand carbohydrates for soil microbes,particularly bacteria. Most molassesbased products also contain a quantityof trace elements which are also used bysoil microbes that require trace mineralsto act as catalysts to produce enzymesthat make nutrient available to plants.

Molasses also works as a chelating agentto convert the soil’s tied-up nutrientsinto a form that is easily available toplants. Chelated minerals can beabsorbed directly into the plant, so it is agood idea to add a complexcarbohydrate and fulvic acid to liquidinorganic fertilisers to improve fertiliseruptake and efficiency and help thenutrient remain available and stable inthe soil.

Molasses and concentrated molassessolubles give best results when appliedin spring to get needed carbohydrate

into the plant and as a plant nutrientand soil microbe biostimulant insummer.

Care should be taken when applying it inautumn, or at times of high diseasepressure because, if applied onto newlyactive fusarium or other diseases, it maybe used as a food source by thefusarium before the beneficial microbescan use it for their own growth.

Fish Hydrolysate

Fish hydrolysate is basically the parts ofthe fish not used for humanconsumption, with the bones degradedby enzymes, though for turf useproducts that do not smell of fish shouldbe used. Whilst fish hydrolysate containsNPK when used in small quantities as abiostimulant, the nutrient content isnegligible. It is as a microbial feed that itcomes into its own and, when brokendown, its high protein content is goodfor increasing protein in the plant intimes of stress.

Fish Hydrolysate is another good coolseason growth promoter that can beused through out the growing season.

Oxygen

The above compounds are the base rawmaterials for most biostimulants, andmost of the products available to turfmanagers contain one or more of theseproducts. But it is important toremember that all beneficial soilmicrobe and rootzone plant growthpromotion takes place in aerobicconditions, which means that oxygen isthe best biostimulant. Frequent aerationwith microtines or sarrell rollers isessential for any biostimulant to work ona frequently compacted rootzone.However, there are now liquid productsavailable that can be sprayed over thesurface to release oxygen atoms tosupport even microbial metabolism and,in my next article, I will look at how soilmicrobes, biostimulants and frequentsolid tine aeration may end the need foraggressive hollow coring and thatchremoval.

Hopefully, this article will help managersto use the correct biostimulant toachieve the desired results. Biostimulantuse is a very well researched topic andthere is a wealth of information availablefor further study. Knowing whichbiostimulant to use, and when to applyit, can really improve conditions andreduce costs by improving nutrient andoxygen availability and uptake, diseaseresistance, soil friability and waterretention.“Fish hydrolysate is basically

the parts of the fish notused for humanconsumption, with the bonesdegraded by enzymes,though for turf use productsthat do not smell of fishshould be used

Symbio is dedicated toresearching solutions torestoring the naturalbiological activity insoils and growing mediaessential to ensure thelong term sustainability offood production and amenity plantresources for the world’s increasingpopulation.

www.symbio.co.uk

Seaweed extracts act as a biostimulant

Fish hydrolysate comes into its own when broken down