Event date: May 2015
Speaker: Mike Dale
Write-up by Sylvie Field
Mike looked at the impact of soil and soil management. Firstly we were talked through a series of experiments using French marigold seed and night scented stock using 5 different mediums from builders sand to a mixture of multi-purpose compost with coarse sand. We all watched in fascination as Mike explained the very thorough trials he had conducted as one by one these little seedlings revealed their progress.
After factors like branching (good root formation), transplanting (the seedlings need to break up easily) and damping off were taken into consideration, we learned that the mixture of multi purpose (peat based) with 20 per cent coarse sand was best.
We then looked at the importance of humus in the soil which helps to retain moisture. Leaf mould was the Holy Grail here with leaves and grass cuttings providing leaf mould in about a year. Too much grass makes it slimy so Mike reckoned a ratio of between 1:3 and 1:5 was best. You could also use pine needles, beech leaves and oak leaves, the latter being an acid growth promoter which breaks dormancy, but if too strong retards root growth.
Next we looked at the importance of lime in the soil. Important both for clay soils, where it improves friability and releases nutrients, and sandy soils where it releases nutrients from the silica in the sand. Liming for cabbages was recommended at a rate of 4 parts per millilitre. A balance of nutrients was required. Additionally, Mike recommended dolomite limestone as natural limestone in the soil may not break down enough. He pointed out the magic figure of 7 which was the neutral point between acid and alkali soils.
This was altogether a very informative and thorough presentation.