MULCH FOR 'GRANDE' YIELDS
Gardeners enjoy rushing the natural occurrences of soil warming and frost-free
dates. This can be safely done if you are willing to make the necessary
efforts. The reward for such an effort is an earlier and prolonged production
One item which can be used to stimulate earlier, prolonged production is
plastic mulch. Most gardeners are familiar with organic mulches such as
leaves, compost and grass clippings but overlook the many benefits of plastic
mulches which do the following things:
- Reduce evaporation of soil moisture
- Reduce fluctuations in soil moisture
- Retain soil moisture
- Reduce fluctuations in soil temperature
- Provide warmer daytime surface temperature
- Reduce weed growth
- Reduce soil compaction
- Reduce leaching of fertilizer salts
- Prevent soil crusting
- Promote activity of micro-organisms
- Reduce soil rot of fruit
- Increase water use efficiency
- Increase fertilizer use efficiency
- Increase yield and improve quality
Black or very dark plastics, usually made of polyethylene, have proven effective
in hastening maturity as well as in controlling weeds. They frequently
increase the yield of the warm-season crops such as squash, peppers and
tomatoes and may increase the yield of all early planted crops. During
the day, the plastic absorbs more of the sun's heat than organic mulches
and radiates the heat back faster at night. Thus, plants mulched with plastics
are less susceptible to frost injury than those mulched with organic mulches
such as leaves and compost.
Make black plastic sections for mulching by splitting regular garbage bags
on the seams. Heavy duty bags last longer.
It is important that the soil is well supplied with water from rain or irrigation
a few days before the plastic is laid. It is difficult to lay plastic on
a windy day. Plastic mulch can be laid immediately after planting, but
for most transplanted crops, it is much easier to apply the plastic first
and plant through it. If drip irrigation is to be used, put drip hoses
in place on or in the planting bed before covering with plastic.
When applying a plastic mulch, make small furrows with a hoe or shovel about
3 to 4 inches deep on each side of the planting bed with the distance between
the furrows slightly less than the width of the plastic. Place the soil
from the furrows on the outer edge of the plastic. Do not over stretch
the plastic, especially in warm weather, since it shrinks when cooled.
The use of organic mulches is also very important. An organic mulch is
especially desirable on light, sandy soils and on cool-season crops. Organic
mulches keep the soil several degrees cooler than bare soil and soil covered
with black plastic mulch. Mulches reduce heat radiation from the soil,
increasing the chance of frost damage on a cool night. Organic mulches
are best when applied after the soil is warm.
Use organic mulches when vegetables are 2 to 3 inches high. Before applying,
remove weeds; any weeds remaining in the soil will grow through the organic
material, but they can be removed easily by hand.
Old straw or hay which is free of weed seed is ideal. A 3-to 6-inch layer
of straw or hay is required, whereas a 1- or 2-inch layer of peat moss,
grass clippings or composted leaves is sufficient.
If a large quantity of organic mulch is plowed under or worked into the
soil, it may cause a temporary shortage of nitrogen so that the crops become
yellow. To prevent this shortage add approximately 3/4 cup of ammonium
sulfate to each bushel of organic material.