Looking at Leachate - what are my EC, pH and volume telling me?

Wednesday, May 11, 2022

 Production systems based in soilless substrate require close attention to the fertigation solution going in, as well as what is coming out. Daily monitoring of EC, pH and % volume allow for corrections that will solve a whole slew of problems before they happen (nutrient deficiencies, salt buildup, root rots, low yield etc), saving the producer a lot of time, money and remediation efforts. 

pH

It is important to observe the pH of your leachate, that is the solution that is draining out of your pot after an irrigation event. pH is largely tied to nutrient availability. While we might be feeding the crop with a solution that is on target, the substrate can be a bit of a confounding factor. Looking at the drain that comes out of the pot is a good way to get an idea of what is happening in your growing matrix. A pH that is significantly higher or lower than what you are feeding the plants is an indication that there is something happening to your nutrient availability in the substrate, and that you may be at risk of nutrient deficiency in the crop. Different substrates (pine bark vs coir vs peat) are going to have different baseline levels of acidity, which will impact the interactions between the plant and the irrigation feed. 

Target value should be between 5.0-5.8, depending on your substrate and the crop you are looking to grow.

EC

The EC of your leachate solution will give you an indication of the salt level in the substrate. While we know the EC of our feed solution, it is important to directly compare with what we are getting after the plant has been fed. An extremely low EC value in the drain sample indicates that there is very low salt in the substrate, and that the plants likely require a higher EC in the feed solution to make sure that the plants are getting all of the nutrients that they need. A high EC value indicates a high concentration of salts in the substrate, and action should be taken to either flush the pots with straight water (depending on how high this value is) or reduce the EC of the feed solution to bring the growing media back to a more balanced nutrient content. 

Target values should be 10-25% higher than your feed solution. A feed EC of 1.5, and a drain EC of 4 indicates there is a problem with salt accumulation in the pot. 

Volume


The volume of liquid that drains out of your growing container/bag is a good way to monitor if your plants are getting sufficient water throughout the day. Leachate is a necessary evil for substrate production. Ideally the leachate sits between 10-20% of the total volume that was fed to the crop. If you find that your drain is lower than this percentage, it is recommended to increase the amount of water fed to the crop. Not only is water required for the plant to grow, but it also acts as a cooling mechanism through the heat of day. Plants that are actively transpiring water are much happier than ones that are experiencing a shortage of water, while still keeping up with the demands of fruit production and vegetative growth. When considering higher % drainage values, it is important to consider the time of year. 30% leachate in the spring or in the fall is not necessary. There is a significant amount of water and fertilizer that is being wasted at this point, not to mention the spike in humidity associated with the excess water which could lead to other problems in the crop. 30% leachate during the peak of the summer, with high temperature and radiation levels is a different story. The plant is very actively transpiring at this point, and you don't want to run the risk of under-watering your crop. Providing excess water at this stage in production is a good strategy to reduce the temperature of the plant and allow it to maintain peak productivity. 

                                            

Photo 1. Here is an example of a very basic leachate collection container. It is important to collect the drainage from a series of pots that are representative of the crop. That means that your monitoring station should not be raised up above the rest of the pots, as your sample is now going to dry out faster than the rest of the plants, and lead to overwatering due to a response to the measured values.

How can I monitor this?

Keeping an eye on your irrigation solution is easy to incorporate into the daily routine. Ideally you are monitoring the volume of water coming out of your emitters every day, in addition to the amount of water draining out of the pot. It is best to set out your collection bins before the first irrigation event of the day, and collect/assess that solution 24 hours later, before the first irrigation event of the following day. This 24 hour period will take fluctuations in your irrigation volume into account - the amount of water draining from your pot after the first irrigation event of the day should be little to none. The amount draining from the pot at 2 pm on a hot sunny day is going to be quite a lot. 

                                Photo 2. A basic example of a drip irrigation monitoring setup. Photo credit: Talia Plaskett

In terms of equipment, basic plastic containers are all you need to collect the drain solution. To set up a drip monitoring station, be sure to install an extra dripper along your irrigation line that can feed directly into your monitoring station. After that, you will need an EC/pH meter, as well as something to measure the volume of liquid. And last but not least, a notebook or form of electronic record database, to record the values you observed. 

For more information on irrigation management:



Webinar Alert - Energy Alternatives in Protected Production

Wednesday, May 4, 2022

 Greenhouse Canada is hosting two free webinars on energy that are coming up soon!

Thurs May 5 at 3pm (Atlantic):  Biomass – Fire up the greenhouse

Biomass may be considered a renewable energy source, but where does it fit into Canada’s clean energy future for greenhouse agriculture? Learn about its use, the importance of fuel sources, as well as new developments that could give it a place on the journey towards net-zero emissions. Register here: https://us02web.zoom.us/webinar/register/WN_s8xsNXl7Rd-jNwiaB_tG0A


Wed. May 11 at 3pm (Atlantic): Reducing Carbon Emissions – Now and in the Future

What can greenhouse growers and vertical farming operations do to reduce their carbon emissions both now and over the next decade? This webinar will be centred around three main pillars: natural gas, demand-side management and low carbon solutions. Register here: https://us02web.zoom.us/webinar/register/WN_fVz9J78TS-WX5SlGY1E_aw


Each session will have a live Q&A, where you will have an opportunity to chat to the experts directly! Can't attend the event? Registering for the webinar will give you direct access to the recording afterwards, so it is worth putting your name in!

More info and registration can be found in the links above! See you there

Posted by: Talia Plaskett



Managing a Substrate-Based Production System

Monday, April 25, 2022

The shift from soil to substrate is more involved than simply switching the grow medium and hoping for the best. Every base growing material is going to have different physical and chemical properties that impact the way it behaves in production. As a result, management is going to vary across soilless substrates. Despite the differences across alternative grow media, there are a handful of things, however, which do hold true when switching out of soil-based crop production

Irrigation Management is Crucial. 

Managing the water demands of a crop that is restricted to its container is very different than that same crop being grown in 'infinite' soil. The biggest differences you will see is the rate at which it dries out - a 4L pot has a significantly decreased ability to hold moisture compared to a soil-based farm. On that same note, the ability to drain water is also different when producing in a restricted volume of growing media. The potential for over-saturation of the growing media, as well as the heightened risk of salt accumulation, are also important characteristics to be aware of. 

Growing in a container is going to result in a smaller root volume on a plant, which is going to impact the ability to uptake water. For containerized crops we see that water needs to be more readily available for uptake compared to a soil based system. This metric is referred to as 'moisture tension'. Moisture tension can be measured a handful of ways (tensiometers, squeeze tests, capacitance probes), and it is important to recognize that the target moisture tension values are going to be different than a soil-based system. The ideal moisture tension for peat-based tomatoes runs from 1 to -5kPa, which is higher than what a field producer would aim for. By maintaining the moisture tension in this range, the plant roots have consistent access to water that is readily available for uptake. Values higher than this indicate a substrate that is too wet, which will limit air pockets in the media and increase the risk of disease in the roots. Values lower than this mean that your substrate is running too dry for your crop. The miniaturized root system is unable to extract water from the pore spaces in the media, and plant growth will be immediately impacted. 

Fertilizer Management Regime

Soilless substrate inherently contains very little, if not zero, baseline nutrition for your crop. While soil systems rely on pre-treatment of the soil and scattered nutrient applications through the season, a substrate-grown crop should be fertigated multiple times per day. By combining your irrigation and soluble fertilizer applications, you can be sure that the crop is getting the right amount of nutrients to sustain healthy and productive plant growth. 

What happens if I only fertigate once a day, and the remainder of the crop receives straight water? Any fertilizer that has been applied will be significantly diluted, if not completely run out of your substrate by selectively applying fertilizer through the day. Consistency bodes well for containerized crops in producing a healthy and productive root system, so save yourselves the trouble and plan accordingly for your daily watering regime. 

The soluble fertilizers that are being introduced into your system should be monitored on a regular basis. Daily checks of the EC and pH of the water that is being fed to your crop will ensure that your dosing system is working properly and that your fertilizer mix was diluted accordingly. These systems can see change on a daily basis, so it is important to stay on top of it to maintain healthy plant growth.
Speaking of pH....the target values for a soilless substrate are going to be lower than what you are aiming for in a soil-based system. While this depends on what the base material of your growing media is, you can anticipate that the pH of the fertigation solution should be somewhere in the 5.4-5.8 range.

If you are interested in learning more about managing a substrate-based production system, click here to check out our new factsheet. If you have any questions that were not addressed here, don't hesitate to reach out and we will be happy to talk to you about your production setup.

Posted by: Talia Plaskett


Thursday, April 21, 2022

On May 11th, we will be hosting a webinar with Neil Stephen on how social media can help your business. 

Tuesday, April 19, 2022

 

Accessing Perennia Pest Management Guides 


Perennia specialists create pest management guides for industry every year. We are in the final stages of preparing them this season and will be releasing them by the end of April. 

 

As we look to the future, we really want your feedback on how you access the guides, as well as some things we are considering when sharing the information to make it easier for you to use. 

 

If you can please take 2 minutes to complete this short survey for us that would be very helpful and much appreciated. 

Weather Station Assistance Program

Wednesday, April 6, 2022

 

To understand the agricultural benefits of weather stations, you need to understand the importance of weather forecasting to growers. Weather plays a crucial role in commercial and domestic agriculture, and one miscalculation can result in a poor harvest. With labour and material costs increasing, there is very little room for error. Weather stations will not stop a hurricane or a heat wave, but they will provide you with hyperlocal weather data that can be used to make proactive planting and harvesting decisions. Climatic variations across Nova Scotia, particularly the Annapolis Valley, can be extreme. Due to the unique topography and proximity to the Bay of Fundy, weather conditions may vary greatly between two farms separated by less than 25 km.

Agricultural weather stations are specifically designed to deliver more valuable information to growers through real-time data monitoring. For example, weather conditions have a huge impact on crop growth. Many crops require high temperatures and humidity, while others thrive in colder, dry environments. Many growers also use temperature, humidity, and other factors to predict pest infestations and disease outbreaks, so that they can proactively plan planting, harvesting, and protection accordingly. You can accurately track climatic changes over the course of a day, week, season, or year with a weather station depending on your location, allowing you to make informed decisions in subsequent years.

 

Weather Station Assistance Program

The Weather Station Assistance Program encourages producers to embrace on-farm weather station technology and adopt tools that allow them to fully utilize the data gathered. This will strengthen the industry and empower producers to make necessary proactive management decisions to mitigate the impacts of climate change and adverse weather conditions.

Eligibility

A farm that:

  • is currently and properly registered in the correct income category under the Farm Registration Act
  • applicant is at least 19 years of age and actively farming in the program year

Agricultural Industry Association:

  • represents identifiable Nova Scotia agriculture and agri-food products; and
  • demonstrates not-for-profit status by providing documentation

Read the Program Guidelines for detailed eligibility criteria.

Deadline or important dates

Program Opening: 15 March, 2022
Application Deadline: 30 April, 2022

How to Apply

Complete and submit the Weather Station Assistance Application to the Programs office.

Clients new to programs since 2018 must complete the Program Funding Registration (PFR) Form. Returning clients to update PFR form as necessary.

Supporting Documents

Program Guidelines, Application Form and Program Funding Registration Forms are available in the “Downloads” section.

By: Dustin MacLean, Horticulturalist/Field Plant Pathologist 

Chlorothalonil De-registration Information

Tuesday, April 5, 2022

 

Health Canada’s Pest Management Regulatory Agency (PMRA) initiated a special review of chlorothalonil (i.e. Bravo, Echo, etc.) in 2018. The entire consultation document can be found here [Proposed Special Review Decision PSRD2022-01 Special review of chlorothalonil and its associated end-use products - Canada.ca]. PMRA has come to the conclusion that chlorothalonil use poses a concern for human health and the environment. Health Canada is proposing continued registration of greenhouse ornamentals but all other uses of chlorothalonil are proposed for cancellation. If you wish to read the consultation documents and raise any concerns, you can do so at the PMRA publication section [https://www.canada.ca/en/health-canada/corporate/contact-us/pest-management-regulatory-agency-publications.html] by May 11th, 2022. Please consider making your voice heard. The Fruit and Vegetable Growers of Canada (formerly Canadian Horticulture Council) is also conducting a survey so that they can respond to PMRA’s proposed cancellation. You can find the surveys here:

·       Fruit and Vegetable Survey: https://www.surveymonkey.com/r/NJ3WJHF

·       Potato Survey: https://www.surveymonkey.com/r/P98D3Q7

Responses will be accepted until April 15, 2022.

Chlorothalonil is one of the few Class M (multisite) fungicides available in a number of crops.  Without it in a rotation, growers will be forced to rely on single site fungicides that all pose a greater risk of pathogens developing resistance. For many diseases, growers have other control options available to them, but with the loss of a multisite fungicide, great attention needs to be paid to rotating FRAC Groups. As always, you can find further information on control options on Perennia’s commodity specific pages. Pest Management Guides are in the process of being updated for the 2022 growing season and should be available in the coming weeks.  In the meantime, Management Guides from 2021 are still available.

Brassicas:

In Brassicas, chlorothalonil has been used to control Alternaria leaf spot and downy mildew in broccoli, brussels sprouts, cabbage, and cauliflower. Other products are available to use to control Alternaria such as Fontelis (7), Luna Privilege (7), Inspire (3) and Quadris Top (11, 3).  For downy mildew in Brassicas, available products include Pristine WG (7, 11), Zampro (40, 45), Quadris Top (11, 3) and Captan 50-WP (M4). Please check out Perennia’s Broccoli, Brussel Sprout, Cabbage and Cauliflower page: https://www.perennia.ca/portfolio-items/brassica/?portfolioCats=122  for PHI and REI details.

Carrots:

In carrots, Bravo has been historically used to manage leaf blights (Cercospora and Alternaria). Other control options include Quadris Top (11, 3), Cabrio EG (11), Fontelis (7), Luna Privilege (7) and Miravis Duo (7, 3) for Cercospora and Quadris Top (11, 3), Cabrio EG (11), Pristine EG (7, 11), and Fontelis (7) for Alternaria. Please check out Perennia’s Carrot page: https://www.perennia.ca/wp-content/uploads/2018/03/Guide-to-Pest-Management-in-Carrots-2021.pdf for PHI and REI details. 

Celery:

In celery, Bravo has been historically used to manage leaf blights (Cercospora and Alternaria). Other control options include Quadris Top (11, 3), Cabrio EG (11), Fontelis (7), Luna Privilege (7) and Miravis Duo (7, 3) for Cercospora and Quadris Top (11, 3), Cabrio EG (11), Pristine EG (7, 11), and Fontelis (7) for Alternaria. Please check out Perennia’s Celery page: https://www.perennia.ca/wp-content/uploads/2018/03/Guide-to-Pest-Management-in-Celery-2021.pdf   for PHI and REI details.

Cucumbers:

Anthracnose, powdery mildew and scab in cucumber, controlled by Cabrio EG (11), Pristine WG (7, 11), Proline 480SC (3), Inspire (3), Fontelis (7), Vertisan (7), and Miravis Duo (7, 3) for Anthracnose, Cabrio EG (11), Pristine WG (7, 11), Proline 480SC (3), Inspire (3), Fontelis (7), Vertisan (7), Luna Privilege (7), and Quadris Top (11, 3) for powdery mildew, and Pristine WG (7, 11), Inspire (3), Fontelis (7), Luna Privilege (7), and Miravis Duo (7, 3), for scab. Please check out Perennia’s Cucumber page: https://www.perennia.ca/wp-content/uploads/2018/03/Guide-to-Pest-Management-in-Carrots-2021.pdf for PHI and REI details.

Onions:

With the loss of Bravo, botrytis leaf blight in onion has other control options such as Scala SC (9), Fontelis (7), Luna Tranquility (7, 9), Quadris Top (11, 3), Sercadis (7), and Miravis Duo (7, 3). Please check out Perennia’s Onion page: https://www.perennia.ca/wp-content/uploads/2018/03/Guide-to-Pest-Management-in-Onion-2021.pdf for PHI and REI details.

Parsnip:

Root canker in parsnip, unfortunately has no registered fungicides that do not contain chlorothalonil. If you are struggling with this disease, please reach out to myself, Dustin MacLean at (dustinmaclean@perennia.ca or 902 324-9623.)

Potato:

Late blight, early blight, and botrytis vine rot in potato, controlled by Dithane F-45 (M), Ridomil Gold MZ 68 WP (4, M), Quadris (11), Headline EC (11) for late blight, Fontelis (7) and Ridomil Gold MZ 68 WP (4, M), Quadris (11), Scala SC (9), Inspire (3), Luna Tranquility (7, 9) and Miravis Duo (7, 3) for early blight, and Ridomil Gold 480SL (4) being the only registered fungicide that does not contain chlorothalonil for control of botrytis vine rot in potato. Please check out Perennia’s Potato page: https://www.princeedwardisland.ca/sites/default/files/publications/potato_guide_2016.pdf for PHI and REI details.

Tomato:

Early blight, late blight, Septoria leaf spot, anthracnose, and botrytis gray mold in tomato, controlled by Cabrio EG (11), Inspire (3), Fontelis (7), Vertisan (7), Luna Privilege (7), Luna Tranquility (7, 9), and Miravis Duo (7, 3) for early blight, Acrobat 50WP (40) for late blight, Cabrio EG (11) and Fontelis (7), and Cabrio EG (11) for Septoria leaf spot, Dynasty 100FS (11), Inspire (3), Quadris Top (11, 3), Aprovia Top (3, 7) and Miravis Duo (7, 3) for anthracnose, and Cyproflu (9, 12), Fontelis (7), and Luna Tranquility (7, 9) for botrytis gray mold. Please check out Perennia’s Tomato page: https://www.perennia.ca/wp-content/uploads/2018/03/Tomato_2018.pdf for PHI and REI details.

Perennia spray guides are updated annually and will be posted on the Perennia commodity pages in the coming weeks. As always, this information is continuously changing and therefore it can cease to be current and accurate. Pesticide labels are the best source of information and should always be consulted prior to using a product. The best source for the most up to date labels is the Health Canada website: https://pr-rp.hc-sc.gc.ca/ls-re/index-eng.php

By: Dustin MacLean, Horticulturalist/Field Plant Pathologist