Page 38 - Simply Vegetables Spring 2022

50mm deep, but take care with cucumbers and melons to keep it away from the stems at is could easily lead to rots which they are prone to especially if wet.
Commercially there are a range of mulching materials used around the world, these include:
Straw – this has already been mentioned above and is used more in some countries than others, those with dryer less windy climates than the U.K. but if you have access to a cheap or free supply is
well worth considering. It can be used around widely spaced crops like the legumes above and when the crop has been harvested the straw can be dug in, composted or left in-situ if no-dig. Straw used to be fairly widely used but has now become expensive; it can also be a source of weed seed as well as using some of
the nitrogen from the soil to decompose. If using straw, a sprinkling of nitrogen fertiliser will overcome this problem. Straw is easy to spread, gives a good weed control and reduces moisture loss but can blow about if windy. If you have a source check it has not been sprayed with a clopyralid weedkiller (like aminopyralid) as this could affect your crops.
In the last few years there has been a bit of a renewal of interest in straw mulches by some of the organic growers as labour is getting expensive and harder to find. Straw is reasonable cheap and easy to apply
for many crops, so its use is increasing.
Research in the 1980’s showed that wheat and rye straw contains some natural phytotoxic chemicals that suppress some broad-leaved weeds.
Commercially the main growers have replaced straw with polythene mulches which can be quickly laid by machines and the plants planted straight through into the soil. After cropping
mulches as they last longer so are useful on fruit crops and other perennial crops. Most of the plastic mulches are black so absorb sunlight and warm the soil which can help give earlier crops especially tomatoes and pumpkins. Research has shown that the soil below black mulches can be up to 2˚C higher than un-mulched areas which can
the mulch can be removed by machine saving labour. Polythene mulches also keep crops like lettuce clean as they prevent rain splash.
Most of the plastic mulches are black so absorb sunlight and warm the soil which can help give earlier crops
result in crops being 7 to
21 days earlier depending on the crop. They also give higher yields owing to better water availability and less weed competition.
A newer advantage is that plastic mulches slow down the water percolation in heavy rains which helps to reduce leaching of nutrients and soil erosion. Although in heavy rains much of
the water can just run off! Plastic mulches help to keep the crops cleaner, and this
PLASTIC FILM
MULCHES
There are several plastic
type mulches available like
Mypex, Plantex, etc. and
are usually sold by the roll
or lengths cut off a roll and
come in widths of 1m, 2m
and 2.5m. The ground is
prepared for planting as
normal and then the mulch laid and pinned on the soil or the edges tucked into the soil with a spade. The manufactured mulches usually have minute holes in to allow water and air to pass through but not enough light for weeds to germinate and grow. Black polythene does not have holes so if using this punch some small holes in for water to enter the soil. The textile mulches have a few advantages over the organic
can reduce disease infection and therefore less waste and rotting.
If using plastic mulches, it can pay to install drip or similar irrigation under the mulch for watering. As mentioned above most of the plastic mulches are available
in black but commercially there are other colours available. The other common colour is white which reflects the light back up
to the plant which helps with growth and ripening. I have also seen green and blue
38 Simply Vegetables