Simon NeufeldChief Agronomist, Earth Alive Clean Technologieswww.earthalivect.com

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There is a common misconception about organic farming – that it is farming without any inputs.On top of this, many organic farmers feel nervous about using a sprayer on their farms for fear that neighbours will think they are cheating.

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In fact, there are many reasons for an organic farmer to use a sprayer, from plant fertility, pest control, soil building, and more.This session will survey several of the most common uses of sprayers on organic farms of all scales, and my hope is that I will convince you guys to hang onto your sprayer equipment when you transition, or look for some good sprayer equipment if you don’t have any.I will also provide a brief crash-course/refresher on how to calibrate a sprayer and calculate how much product you’ll need for a particular application.

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There is no magic bullet when it comes to well-managed plant nutrition. The basic principle is:

Feed the soil to feed the plantThe most common ways to do this are

Compost and manureGreen manuresMineral fertilizers (Calphos, Sulphate of Potash, Greensand, etc.)

In the long-run, these are methods for building the soil to meet the general crop needs. There are times, however, when environmental stresses like cold soils, flooding, drought, or disease pressure can impede a plant’s ability to access nutrients in the soil.At these times, feeding the plant through foliar sprays is an important technique.

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One example of this is liquid fish.Liquid fish is a source of basic nutrients like nitrogen and phosphorous, as well as a wide range of trace elements.The nutrients are present in proteins, fats, and other complex forms

These make good food for the microorganisms that cycle nutrients in the soilThey also feed the microbes living on the leaf surface, where they are converted to absorbable forms.

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Liquid fish is available as an emulsion or a hydrolysate. Emulsions are a by-product of fish processing, and are produced by cooking the fish components left after oils have been removed for use in cosmetics, pharmaceuticals, and supplements.Hydrolysates are produced by cold-processing the complete fish, which avoids denaturing the fats and proteins.

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At other times, the soil is unable to provide trace minerals to the plant because they are deficient or soil pH makes them unavailable.

Boron is a good example of a nutrient that should be applied in water solution, either directly to the soil or as a foliar spray.

Boron is easily deficient, but just as easily toxic. Applying as a spray diluted in water allows for much greater control over the rate, avoiding hot spots in the field.

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There are also “generalist” trace mineral sprays that can provide a wide range of trace elements to plants through a foliar route.

Leibig’s law of the minimumFoliar application of trace minerals can help plants achieve their maximum potential, event when the macro nutrients are available in sufficient quantities.

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Compost tea has plant nutrition functions, but it is such a multi-faceted subject it will get its own section later on.

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Plants are living things…They produce enzymes and other molecules that are used to signal different actions in the plant.For example,

auxins are released in the terminal buds to promote shoot growth, suppress side buds, and also promote root growth.Others control stem elongation, disease response, water management, chlorophyll production, etc.

The production of these molecules is governed by genes in the DNA of the plant, and the genes are turned off and on (or down/up-regulated) based on environmental conditions or exposure to external stimuli.

We can expose plants to external stimuli of our own in order to inspire a positive response in the growing crop. This is known as bio-stimulation.There are synthetic growth promotors available on the market. You can buy gibberellic acid for use in certain conventional crops. For organic farmers, there are also options: for example, seaweed extract.

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Seaweed is an amazing plant:In summer, it goes through a 12-hour cycle from sitting on a dry rock in the blazing sun to full submersion in salt water.In winter, the dry rock is encased in ice.Somehow the kelp has developed internal systems for regulating water in saline conditions, while at the same time tolerating drought, heat and freezing temperatures.When kelp is liquefied and sprayed onto terrestrial plants (your crops), those internal chemical systems become external stimuli that trigger beneficial plant responses.

Root developmentDrought toleranceFrost toleranceSystemic Acquired Resistance

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Pest ControlI don’t want to spend too much time discussing the methods of using pest control sprays, because it is very important to always apply pesticides following the pesticide label.Suffice it to say there are many registered pesticides available in Canada that are also permitted under the Canadian Organic Standard.

A few examples include: Serenade (Bacillus subtilis), Bioprotec (Bacillus thuringensis), Kocide (copper), Entrust (Spinosad), Insecticidal Soap, Hort. Vinegar, etc.READ THE LABEL, and FOLLOW THE INSTRUCTIONS, and DO THE MATH, and MEASURE CAREFULLY.

There are also home-made options that you will hear discussed by folks like Ed Lawrence like

Insecticidal soap (40:1 water to soap, sometimes with other stuff added for specific issues)Compost tea

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Compost TeaCompost tea gets its own section because it can serve so many functions on an organic farm.

Speeding up the breakdown of crop residuesFeeding the soil to boost nutrient availabilityFeeding the plant some nutrients directlyStimulating disease resistance in some crops/situationsPreventing disease by ecological exclusion

The primary objective of brewing compost tea is to extract the living microbes from the compost, and then multiply them as much as possible while maintaining the diversity.The method and recipe of a compost tea brew depends on the purpose of the spray

Certain recipes will favour certain types of microbes in the final spray.Some applications might require a more bacterial tea (foliar pathogen exclusion), while others require a more fungal tea (residue breakdown)

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There are some common ingredients for a general-purpose compost tea:Compost: well cured, certified organic, often vermicompostWater: clean and free of chlorine or other anti-micobialsOxygen: It is important to keep the brew well oxygenated to produce a thriving aerobic tea

Microbe food: can be liquid fish, molasses, seaweed, straw, humates, or a combination of all of these depending on the goal of the tea

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Equipment for brewing tea can range from the home gardener’s 5-gallon bucket DIY model to the ready-to-use machines that can be added to an existing 1000-L liquid tote.Here’s a 3000-gallon compost tea factory used by Kroeker Farms in Manitoba.

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There is a lot of information available about different recipes for brewing teas for specific applications.

Soil Food Web – www.soilfoodweb.comBasic recipe:

100 L of waterAerate this in advance to remove chlorine

30 mL humic acid or liquid fishPre-dilute this in water before adding to tea

125 mL liquid seaweed2.5 kg aerobic compost

Other ingredients can be added to promote fungal growth in the tea:Steel-cut oats, bran flour, shrimp shells, bark, etc.

Combine all the “dry” ingredients in a contained compost bag/sock.Paint strainer bag can work just fine.

Let the compost steep for up to 24 hours, as long as the dissolved oxygen levels in the water can be maintained at 8 ppm.

Use an aerator that is able to pump enough air through the brew to maintain this level of oxygen.

This can be scaled up to meet any scale of farming

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Apply diluted with water. Good compost tea will have enough microbes in it that you can apply as little as 20 L/acre – which can be diluted with water to give good coverage with your spray equipment.If you aren’t sure of the quality of the tea, dilute it less and apply more tea per acre.

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How much do you need?First question: how much active ingredient do you want applied per acre?

Usually this is either specified by the label, or is part of the recipe.For example, compost tea is applied at 20 L/acre

Second question: how much total solution will be applied?Figure this out based on the type of equipment you are using.E.g., a large sprayer might be set up to apply 20 gallons/acre

So you now know that for every 20 gallons of total solution, you will need 20 L of compost teaThird question: how much total solution will be required?

How much area is going to be sprayed – let’s assume a 40 acre field.This will require 800 gallons of total solution, and 800 L of compost tea.

Last question: how much spray solution fits in your sprayer?If it’s less than your total needs, you’ll need to do the calculations for each batch.

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Go to the OMAFRA site for details about calibrating sprayers and an online calculator.http://www.omafra.gov.on.ca/english/crops/sprayer/ep75.htm

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Miscellaneous thoughts on sprayingSprayer inspections

To ensure that the sprayer is in good working order.No leaks, all the nozzles working, etc.

Droplet sizeAffected by nozzle, pressureSmall droplets give better coverage but are more prone to drift

PluggingChoose appropriate nozzles, screen size, remove screens altogether.

LabelsRead them. Always.

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A few important elements of a pesticide label:Front page - active ingredient and PCPA numberInside – safety info, general use info, mixing instructions

Appropriate rate and instructions for specific crops

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