24/1/26 - Broad Bean Experiment: The Beginning
Good day to you, and welcome to the first of a double post for this weekend's allotment diary. To stop things getting mixed up with other diary activities, I'll be keeping posts on the Great Broad Bean Experiment separate to my other normal diary ramblings. So, let's get stuck in.
Last week, I mentioned the idea of setting up a test using the new mulch/manure medium that has been provided to us on the allotment. As a reminder, the new medium is a mixed blend of chicken manure, cow manure, gypsum and straw which I assume was used as bedding used in cattle sheds. It's generally well mixed, fine and broken down apart from the occasional large lump of gypsum or compacted clumps of straw. It doesn't smell particularly strong at all suggesting it's relatively well rotted or dry. When you dig into the heap, there is still a residual bit of heat still in the pile which I think shows it's still not completely rotted down yet though.
The Experiment
This experiment is nothing more that a bit of fun just to appease my curiosity. I want to find out if it makes any sort of different when it comes to germination and early stages of growth to plants which may give an indication on how well it will perform when added into main growing beds.
The seed of choice for this experiment is the Aquadulce broad bean. There are two reasons I have chosen this seed. Firstly, I sowed my broad beans at the end of last season, and while germination has generally been really good, a handful of plants have been a bit battered by winds, and so I will replace them with plants started now in pots and undercover. The second reason is that a broad bean test is often used as a good indicator of residual weed killers of the aminopyralid type, which are known to persist for several years in soil and commonly affect broad leaved plants by either stunting their growth or killing them off soon after germination. This type of weed killer is sometimes used on farmland where weeds need to be killed off in pasture. However, when cattle then feed on that pasture, or silage made from the grass, the active weed killer residue passed through the digestive system of the animal (without harming the animal) and comes out the other side. As mentioned, it can take multiple years for that to break down.
In order to test the effect of the new medium, I'll be using ordinary shop bought compost which contains some peat (I know, I don't need the lecture 😉) as a comparison. Also, this experiment isn't going to performed at any sort of scale. The last thing I need is a polytunnel full of broad bean plants I don't need. Finally, I intend the experiment to end when either the plants are ready to be transplanted out, or don't make the grade. They will all be kept in the same conditions in the polytunnel, so receive the same light, temperature and amount of rainwater collected in my water tank.
Method
Time to stop waffling and get the hands dirty! First thing, I ran a few scoops of the shop compost through the sieve into one tray, and a few scoops of the new manure based medium into another tray. The first observation at this stage was aside from the larger lumps in the new medium, once it had gone through the sieve, it actually felt finer and lighter compared to the bagged compost.
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| Shop bought compost on the left with the manure based medium on the right. Notice how finer the medium on the right is compared to the tray on the left. |
Next, I chose 6 bean seeds from the pot, making sure that they were all roughly the same size. Though I have some seeds still left from last year, I made sure I used seeds bought for specifically for this season.
The first planting was going to be 2 pots using shop bought compost. This is our control and will show beans germinating and growing under 'normal' conditions.
Next, two pots were planted using the manure based medium only. This will show if it is possible to grow a bean crop purely in this type of medium and will also potentially indicate the presence of any sort of contamination.
The final two pots were planted using a 50/50 mix by volume of the two materials. In a 3rd tray, I added 2 scoops of each and mixed it through by hand.
With all 6 pots planted and labelled, all had a light watering and have been placed in a tray and left on staging in the polytunnel.
Possible Outcomes
With the planting all done, you could ask what I'm expecting to happen. The initial answer to that question is, I don't have the foggiest. But, we could also say that there are several possible outcomes. The way I see it, those outcomes could be any of the following:
- They all fail. Everything fails germination and we learn nothing. Plus I end up with some bare patches in my bean bed.
- They all germinate but we see 3 different rates or quality of growth ranging from relatively poor, to OK to really good and beating everything else hands down.
- They all germinate and all grow to the same size and quality. Again, we learn nothing other than saying it doesn't matter if you use normal compost or a manure blend to start growing your beans in.
- We end up with 6 different sized plants with no evident reason why any of them are doing better or worse than the others.
