I thought it might be interesting to share this question about crop rotation. The question raises a number of points, not all about gardening. Although I have covered this in my eBook on crop rotation, hopefully this clarifies the basis for this 4 course rotation.
I’ve been reading your book and e-guide and have noticed that your 4-year crop rotation seems to differ to others I’ve seen online in that you recommend:
Potatoes, followed by Legumes, Brassicas and Onions/Roots
Please can you help me understand which is the best method and why, is it because Onions don’t like acidic soil?
If I follow your method and do first early potatoes after my overwintering leeks then is it OK to add manure at say the end of January on the top of the soil or would there not be enough time for the worms to carry it down before planting the spuds in mid March, in which case is it better to dig it in?
Online Misinformation
First of all, online information. So much of the information online now is merely scraped from other sites with no checks or controls by knowledgeable humans. The growth of AI systems that can write very readable text, perfectly optimised for Google to search and present, is already a problem. The AI systems just soak up information online without critical consideration, stir it around and spew it out.
Because the AI written information is received so well by search engines, other AI systems take that as being factual information – They consider it correct as it is ranked highly. I fear the internet will become a sea of misinformation swamping reasoned and factual in nearly every area. In other words, rubbish and nonsense based on rubbish and nonsense.
Regardless, opinions do differ, and it’s possible to have differing opinions that are both essentially correct. There’s not ‘one true path’ in gardening.
4 Course Crop Rotation
The logic on rotation is this.
Potatoes are a hungry crop and ideally will be heavily manured prior to planting. Adding manure will acidify the soil and pH does tend to decrease with time unless growing on calciferous (chalk) soils. Potatoes, unusually for a vegetable, are arguably better at a low pH of 5.5 or 6.0 than higher. Following the potatoes, an acid soil should be limed, increasing the pH to 6.5–7.0
Legumes are not very greedy crops, so they won’t greatly deplete the nutrients from the manure and may even add nitrogen due to their symbiosis with nitrogen fixing bacteria in root nodules. That is very variable though, it depends on the available bacteria. I believe some commercial growers actually provide inoculants to kick-start the process, like mycorrhizal inoculants for trees and bushes.
Legumes really like a high pH, so they benefit from the lime. Whilst the legumes are in, the soil microorganisms are working on further breaking down the manure and helping the nutrients to become bio-available.
Brassicas are a greedy lot and they also like a high pH. So they utilise much of the nutrients and benefit from the high pH.
Onions / roots generally are OK with slightly lower pH (say 6.0 to 6.5) and neither need nor want fresh manure.
Which takes us back to manuring the spuds. The great wheel turns another circle.
Manuring in January
Yes, it’s fine to add manure at the end of January, but I’d always fork it in to the soil rather than just leave it on top. Ideally, manure should be added during the autumn and early winter digging. When planting potatoes, provide a layer of manure at the bottom of the trench. This will feed the potatoes along with subsequent crops and the soil.
The thing is, there is not one system that suits all. You have to adapt according to your soil, microclimate and what you are growing.
Crop Rotation – Three, Four, and Five Year Planning eBook
This guide is aimed to help you create your own crop rotation based on what you want to grow. It includes three, four, and five year plans; plus detailed plant family and group lists to aid you in your planning.
Full information, chapter list and special offer details here
Thank you for your article on crop rotation, I have inherited a book :- VEGETABLE GROWING FOR AMATEURS By H,H,THOMAS First published in February 1916, Revised Edition 1924 – reprinted March 1927. It gives details of 4 year crop rotation and divides the plot into four sections.
This book has been in my family I believe, since my father was old enough to be able to work a garden, he was born in 1902 and I am now running a 5 rod plot allotment with raised beds, as it is designated a ‘disabled person’s plot’ am now in my 86th year; and find the book invaluable! plus your detail on certified potatoes, for which I thank you. Yes, be wary of the internet, especially when buying from non registered sources, unfortunately the world is not HONEST in some cases. Keep up the good work John!
Amazingly, you can still buy this book new, in the 1917 edition at least. It’s available from India in a leather-bound edition. The 1924 edition is available second hand. Tempting!
This is the rotation I use and is accepted as the most efficient. Manure and lime on rotation assures your plot gets the proper attention. Always test the pH before liming.
I agree with misinformation online. As a horticulturist I will advise where needed and sometimes I get a comment about contrary info found online. Too often that is not founded on solid evidence but supposition. If you want to ignore good advice and trash your plot, on your head be it.
Listened to GQT years ago and have followed 5 year crop rotation ever since.
My aide-memoire is
Boys Only Ride Posh Pedals (bikes!)
Brassicas followed by Onions followed by
Roots followed by Potatoes followed by
Peas/beans (legumes).
It works for me. Aged 83 and was given a little plot in back garden age 5 in 1946
Am I grateful I was encouraged!
So sweet that you had a plot at 5 years old!