Page 39 - Simply Vegetables Spring 2022

which seem to work O.K. if clear plastic is used the weeds can grow under mulch but it does help to warm the soil by up to 4.5
to 7˚C in the top 5cm of soil. There is also extruded polythene which is black on one side and white on the other, this is widely used in commercial tomato, cucumber, pepper and strawberry growing and is used white side up.
Plants can be planted through the paper / cardboard using a Stanley knife to cut an X for the plant.
There is a bio-degradable mulch made from corn starch and some bonding agents that help it to last a season and then biodegrade and is approved for use on organic farms so could be used by organic gardeners.
and what affect it has on the main crop. I think it could work with some of the wider spaced crops like sweet corn, brassica, French and runner beans etc. I tried it last year with my sweet corn, but it was too
dry for the green manure to germinate. It is important that the green manure does not compete with the main crop either in size or takin gup to much water or nutrients. For this reason, the green manure should be a low growing one such as one of the clovers. Sow or plant your main crop and allow it to establish then sown thinly with the clover, remove any weeds that grow by hand
to prevent them seeding. Once the main crop is harvested remove the remains and allow the green manure to keep growing.
It can be dug in during the winter / spring depending on your soil type or it can be cut and composted. No-diggers could cut and compost or strim / mow down and allow to compost on the surface.
The uses of mulches could save you a lot of time in weeding and watering and improve your crop yields, so they are worth a try especially if you have taken over a weedy allotment with a high weed seed level. If you have a clean mulch, you can walk down your garden in your slippers to harvest your crops and not get them dirty!
Some other colours that have been experimented with include silver which apparently repels aphids and has been used
If using plastic mulches, it can pay to install drip or similar irrigation under the mulch for watering
You may have other materials in your shed / garage that could be used, old carpets used to be popular but are frowned
on by some councils and allotment committees now. They work well especially for clearing overgrown allotments but may contain contaminants, although if you use Axminster or Wilton, these are biodegradable as made from wool!!
Recent developments in organic farming have seen the use of living mulches,
on squash to reduce
virus infection, a slight
disadvantage is that it
reflects light and the soil
is cooler by 3 to 4.5˚C
compared to black mulch.
Red plastic mulches have
been tried on various crops
with varied results, they
raise the soil temperature to
similar levels as black. There
is also a slight difference in
the light reflected as red and far-red light affects plant growth, but this does not appear to be significant. One side affect
of red mulches is that aphid populations increased! Other colours that seem to attract insect include yellow, which attracts beetles and work like the yellow sticky traps used in greenhouses. Other colours tried include grey, brown, blue and orange but these appear to be no better than black.
this is where the main crop in under sown with a second crop of green manure. The farmers are at present experimenting with the concept to see if and how well it works
The other factor to consider when choosing mulches is the thickness overall, the thicker the better as they will last longer. In perennial crops the mulch is left down until it disintegrates, or the crop is removed. In annual crops it is lifted after the crop is harvested and if careful it can be reused. It is difficult to recycle plastic mulches as they tend to be contaminated with soil and crop remains. It is now possible to recycle polytunnel covers so recycling mulches may not be too far in the future. Most mulches can be reused for 2 to 4 years if handled carefully, rolled up and stored under cover. They can also be used to cover bare of recently dug ground over winter to reduce nutrient loss and weed growth, but beware they provide a good home for slugs!
A more sustainable option is to use biodegradable mulches that can be
left down to decompose or lifted and composted. The most common material
is thick paper, one make is Hortopaper although this is fairly expensive and comes in rolls of 15 and 30metres. It is laid the same as plastic mulches and held in
place by pegs or the edges slotted into
the soil with a spade. An alternative is to use newspaper or cardboard (from boxes) these will usually last a season. Newspaper should be laid 8 to 10 sheets thick and held down with stones, piles of soil or wire pins.
Simply Vegetables 39