A Christmas puzzle

What might a microscope tell us?

Last month a marvellous opportunity presented itself. I spoke with a UK grower, who had just completed a trial. They were interested in how different soil treatments might impact growth of annual flowers. These might possibly be perennial, if it was a mild winter (though effectively they are treated as annuals).

The grower had taken 6 planting containers, grew the same plants in each, “just” treated the soil differently.

They gave me 6 soil samples to have a look at under the microscope, but haven’t yet told me how well things grew in which pot, only how each sample was treated.
My challenge was to guess which soil sample came from which pot, purely based on a soil microbiological assessment.

Now, this had some flaws:

• They had only one pot of each, so any finding could be a chance finding, as soil is highly variable. Having had at least x3 pots each treated the same way would have been preferable.
• I wasn’t able to assess them all at the same time. This is likely to have impacted soil biology. I kept them all in open bags, so oxygen was available to the soil organisms.
• I am not yet a qualified soil food lab technician. I am learning, and mistakes are likely.
• I haven’t seen enough soil diversity yet. One reason why I jumped at this opportunity was to expose myself to soils I had no personal relationship with.

But what fun! It was intriguing to see how the soil was so significantly different in the 6 pots, given they grew the same plants, and were, apart from the amendments or growing containers, treated the same. Even the seedlings planted in the pots were graded so that each pot to start with was as similar as possible.
I met some soil critters that I had never encountered before. Wish I had my camera sorted to share some good images here (Camera not connecting to software, and thus my white balance is off – any help welcome!).

Here are the growing conditions:

All pots were planted up with shop-bought soil (think John Innes type, felt a little sandy), to which some composted manure was added. Then they were treated as follows:

1. Control – just watered
2. One plant pot received composted pumpkin
3. One plant pot received composted pumpkin plus urine
4. One received more composted manure
5. Instead of a plastic pot, the plants grew in a wooden box (made from a local tree). No additional amendments.
6. Instead of a plastic pot, the plants grew in a cone-shaped clay pot. No additional amendments.
   
   

I don’t know yet which plants grew strongest, had the most flowers, most pollinators and fewest pest problems. Was there any difference at all?
I am in suspense to finding out the answers, but don’t think I will know until next year.
So, to share the cliff-hanger, here are the soil biology assessments. Have a go – which sample (T-Y) was treated with which soil amendment (1-6)?

Let me know your thoughts in the comments!
Resolution to follow (drop me a line through the contact section if you want to know the answer).

Sample Evaluation date	T 16/12/20	U 15/12/20	V 07/12/20	W 10/12/20	X 10/12/20	Y 30/11/20
Biomass
Bacteria microgram/gram	144	123	164	103	164	191
Fungi microgram/gram	503	544	971	444.9	91.8	56
Fungi:Bacterial ratio	3.4:1	4.2:1	5.7:1	4.2:1	0.6:1	0.3:1
“Oomycetes”/possible pathogenic fungi	0	29.2	0	19.4	3.9	0
Actinobacteria Microgram/gram	4.1	6.1	4.8	2.6	2.2	8.2
Protozoa in numbers/gram	32608	24456	40760 + 8152 ciliate	57064	40760	17119
Nematodes in numbers/gram	0	0	0	0	0	210
Biodiversity
Types of bacteria present	cocci, coccobacilli, bacilli, actinobacter	cocci, coccobacilli, bacilli, actinobacter	cocci, coccobacilli, bacilli	cocci, coccobacilli, bacilli, actinobacter	cocci, coccobacilli, bacilli, actinobacter	cocci, coccobacilli, bacilli
Types of protozoa present	Testate amoeba	Amoeba	Amoeba (arcella) Flagella Ciliate (single ciliate in one drop)	Amoeba (arcella, testate amoeba)	Amoeba (testate, arcella)	Testate amoeba
Types of nematodes present	N/A	N/A	N/A	N/A	N/A	Bacterial feeder
Microarthropods in numbers/drop (1 drop = 0.05ml)   Group	0	0	0	0	0	1       Crustacean
Types of beneficial fungi	Present in 6/50 FOV. Diameters 3, 3, 4 and 6 micrometer, septate, clear (5/6) and dark brown (1/6)	Present in 5/50 FOV. Diameters 2, 2.5 and 5 micrometers, clear, septate	Present in many frames.	Single strand in 1/50 FOV	Small strands in 3/50 FOV (tan/clear)	Few strands in 4/50 FOV, ? 3 species (clear/brown/tan)
Possible pathogenic fungi: (classified as oomycetes according to Dr Elaine Ingham, though there is some discussion around the accuracy of this classification)			Single strand in 1/50 FOV	Single strand in 1/50 FOV	Single strand (very small) in 1/50 FOV
Other			Unidentified multi-cellular organisms, with rotavators. ? free swimming rotifer			Rotifer (extend/contract movement)

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