Peat-free trial – final results
The final results of the trial are given in the poster (see left); click on the link to download a copy. The Soil Association funded the production of the poster and paid for the growing media analyses.
second assessment 13 Aug 2013
John made the second assessment today: number of cells per tray with no germination or very small/abnormal seedlings.
The average number per tray varied with crop, but this may not be significant:
| Lettuce | 3.9 |
| Chinese cabbage | 8.9 |
| Cabbage | 9.2 |
The differences between the growing media were small, apart from No.3 which was much worse for lettuce and cabbage. No single medium is a clear winner over all three test crops, so far.
| best | worst | |
| Lettuce |
4 1,2,6 very close second
|
3 – |
| Chinese cabbage |
8 – |
1 3 very close second |
| Cabbage | 8 | 3 |
Click on the images of the trays to enlarge them and view as a slide show.
Samples taken for analyses
7 Aug 2013
I’ve taken samples of each growing medium to send off today. Each sample is about 2 litres, consisting of about 20 sub-samples.
The following tests will be carried out:
Extraction according to BSEN13040 2000 [1:5]
Includes Dry Matter, Bulk Density, Dry Density, pH, Conductivity, Nitrate-N and Ammonium-N with calculated soluble N, Chloride, Sulphate, Potassium, Phosphorus, Magnesium, Calcium, Sodium, Iron, Manganese, Zinc, Copper and Boron.
A low conductivity is desirable for good germination. A modest amount of water-soluble Nitrogen makes it easier to control the growth of brassica plants.
13 Aug 2013
The results came back today – there are large ranges for each nutrient e.g.
| pH | 6.4 – 8.0 |
| Conductivity μS/cm | 215 – 727 |
| Total soluble Nitrogen mg/l | 16 – 451 |
first germination assessment
John made the first germination assessment today. Seed showing any sign of germination was counted, though some may not make the grade at the next assessment.
The average number of seeds per tray not germinated varied with crop, but this may not be significant:
| Lettuce | 4.86 |
| Chinese cabbage | 5.92 |
| Cabbage | 7.72 |
The differences between the growing media were small, apart from No.3 where germination was much worse for lettuce and cabbage. No single medium is a clear winner over all three test crops, so far.
| best | worst | |
| Lettuce | 1,4,9 | 3 |
| Chinese cabbage | 8 | 1 |
| Cabbage | 2 | 3 |
Click on the images of the trays to enlarge them and view as a slide show.
trays laid out in greenhouse
trays laid out in greenhouse
Monday 5 August 2013
Today we laid out all the trays in the greenhouse. They are raised on plastic pots to ‘air-prune’ the roots and stop them from ramifying underneath the trays and tangling up; this would make it difficult to pull the plants from the modules at planting time.
The trial is divided into three main blocks according to plant type:
Lettuce
Chinese cabbage
Spring cabbage
Within each crop there are four rows each containing one tray of each growing medium.
After the trial was laid out, it was given its first watering with plain water. In 7-10 days we will assess the germination/emergence. Meanwhile we will send off samples of unused compost for nutrient analyses.
Peat-free trial
Today we began a trial of professional peat-free growing media. We have 9 different types, each sown with:
LETTUCE-Maureen (little gem type)
CHINESE CABBAGE-Kaboko
CABBAGE-Caraflex (pointed Spring cabbage)
We have 8 organic media and one conventional X 3 crops X 4 reps = 108 trays
The trays were filled by hand, then sown using our automatic Visser sowing line. The trays will remain in the germination room for 3 days. In hot weather, lettuce seed is prone to thermo-dormancy, so it’s better to germinate at a constant 16°C. It’s also difficult to manage the watering if the trays are laid out in the greenhouse, when temperatures can reach 43°C. We want to give optimum conditions for germination so that any differences we measure in germination and emergence will be due to the growing media.
Once the seed has chitted, we will lay the trays out in randomized blocks on a concrete floor. Watering will be via gantry, which is very uniform. We will water (and later feed, if required) according to the needs of each product.
I will post results and pictures on this blog, but the test media will be referred to by code number only until the end of the trial. Thanks are due to the growing media manufacturers who provided samples free of charge.
With the help of the Soil Association, we are planning to write a full report. It’s also possible to post trays of the plants at the end of the trial. If you are willing to test how well the plants pull from the trays and establish in organic fields, please contact me: jill@delfland.co.uk
Trays laid out in our germination room
