Measuring the Benefits of Castings & Leachate on Plant Growth

** Guest Post Alert ** – Hi everyone, Bentley here. I just wanted to let you know about a new experiment and blog series being put together by Myckel (from the Netherlands)! This is a topic a lot of people are interested in, and Myckel (as a plant biologist) is just the man for the job. I’m very excited, and appreciative of the time and effort he will be putting into this. Just so you know, Myckel will be added as an RWC author, and all future posts will only have his commentary (if I have comments I will leave them at the bottom like everyone else).

Take it away, Myckel…😉

Last week there was a question here on Red Worm Composting regarding the usefulness of leachate and worm castings for plants. Bentley gave an insightful answer to the question, but the bottom-line is I felt that this actually needs to be tested. As a plant biologist I felt the need to share my view on the topic as well (in the comments section of the post linked above), but it kept me thinking that there is much “copied from others” information and it would be worthwhile to set up an experiment to see and measure how big the advantage (or not) worm castings and leachate have for plant growth.

With spring just started I will be running an experiment to test this and if you would like to join me, feel free to do so, because it would be interesting to see if others can replicate the experiment. I will be giving a description of when I will be doing what and some background information regarding why I do some things the way I do them. If you will replicate the experiment, but change things along the way write them down. You’ll never know if those changes will be important later on.

What are we going to do?

Over the next few months we will sow some seeds in various soils, observe how they germinate and grow into adult plants. Depending on the growth we will stop the experiment and harvest the plants, do some measurements on the plants and analyse that raw data. With this we hope to get an answer to our question. During the experiment I will post updates and information regarding the next steps.

Let’s get started!

I’ve already made an experimental outline. The first part is the “preparation phase”, this takes about two weeks and give the time for everyone who wants to join to prepare all the things needed. It is also a way to prepare the soils we will be using. Preparing the soils is not really needed, but could prevent some interfering factors. When doing an experiment you want to control as best as possible all the factors involved (well, at least the ones that are known).

I’ve already prepared my soils: a “basic” soil and a batch of potting soil. The “basic” soil I’m using is soil from my own garden. It’s a sand soil, plants can be grown in it, but should be far from optimal. The potting soil is a commercial soil, that I will be using to mix it in similar quantities as the worm castings with the “basic” soil. The pure potting soil, mixed potting soil and the pure “basic” soil will be the controls used in this experiment. It will be used to compare the results from the experiments with these soils.

To start the preparation of the soils I took two buckets (ca. 12L) and filled them both with about same volumes of each soil. I added 500 ml of rain water to both buckets and covered them with some plastic bags.

Below you’ll see pictures of the two buckets.

Figure 1: Overview of the preparation phase results. (A) “basic” soil with added water. (B) Commercial potting soil with added water. (C) Both soils are covered by a piece of plastic.

These two buckets will be like this for about two weeks, feel free to mix them from time to time, but watch out for carrying over too much soil between the buckets. During this time you can see if you can get the following things ready:

• Seeds, sufficient for 5 different groups.
• Pots or similar containers to grow the seeds in.
• Stable growth environment; somewhere the plants will grow without much problems.
• Drying containers; we will have to dry the plants at the end of the experiment.
• Balance; at the end of the experiment the plants will be weighed.
• Source for worm castings and leachate.
• (Rain) water

In my next post we will preparing the seeds, to obtain better and more equal germination. I will also disclose which seeds I will be using (not doing that now, because you should pick what you like best to grow) and which problems I might expect with them and how I should deal with that when the problem surfaces.

Until next time,

Myckel, from The Netherlands

About the Author
My name is Myckel Habets from the Netherlands and for the past decade I’ve worked as a plant biologist at Leiden University. There I investigate developmental-related aspects of plant growth, on a molecular and cellular level. Last year I moved to a new house, with a large garden and obtained my first wormery. During the time since starting this system I’ve learned a lot about how to handle my worms properly, mostly due to the hot summer of 2018. My interests are plants and things related to them in a broad sense, computers and software development, small scale experiments and crowdfunding local entrepreneurs.

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    • Sam
    • April 10, 2019

    I’m very excited to follow this and see how your experiment goes Myckel! Thank you.

    • Barb
    • April 23, 2019

    What is the purpose of letting the soil sit for two weeks? Also, what is the purpose of covering the soil with plastic? Thanks in advance.

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