Soil Management Handbook - Ministry of Agriculture and Lands

If cereal or grass crops are grown, there are three
groups that should be considered. Firstly, spring
cereals, particularly barley and oats, or annual or
Italian ryegrass, such as Westerwolds, grow well from
spring through the late summer. They will usually
winter kill if planted in late September, but can
provide rapid fall cover. Secondly, winter cereals,
such as winter wheat and fall rye, are better used for
late summer and fall growth or where an
overwintering cover or early spring forage is desired.
Winter cereals grow slowly in the fall, but will
continue to grow later than spring cereals. One
advantage of cereals is that they are large seeded so
they can be seeded by many methods including
broadcast-harrow. Thirdly, perennial cover crops,
mainly grass species such as fescues, ryegrasses and
wheatgrasses, should be utilized for perennial crops
such as grapes and tree fruits.
Before making the decision to plant cover crops,
some other factors must be considered. The method of
managing the cover crop residue prior to planting the
following crop is the most important. If the cover crop
survives the winter, it must either be controlled by
mechanical means (tillage or mowing) or sprayed out
with a herbicide. Cover crop species which winter kill
may be appropriate if early spring planting is desired.
Cover crops can become difficult to manage if they
are allowed to set seed, so planting date and control
methods are crucial for in-season or overwintering
cover crop species. Some cover crop species have
been reported to adversely affect following crops
either due to the amount of cover crop residue
remaining at the soil surface or due to chemicals
present in the residue. Other cautions for cover crop
use are that they may harbour diseases and insects and
may change microclimates in perennial crops. Their
management is important. Cover crops used for
winter erosion control must be well established by
late August to early September. After this date, cool
temperatures reduce growth. Surface protection of the
soil, to prevent structure degradation and soil loss,
will be provided by either a standing or matted down
cover, but volume of plant leaves or residue is
important.
Although the use of cover crops can pose
management challenges, their use for erosion control,
nutrient capture and soil structure improvement is
very beneficial for this region.
Where permanent cover is established in perennial
crops, these covers require some annual maintenance,
i.e., mowing over the summer especially near harvest.
Use of tillage or herbicide will be required to control
vegetation in the row and in the area adjacent to the
crop.
6.3 Mulching
A mulch is any material placed on the soil surface for
the purpose of reducing soil erosion, insulating the
soil surface, reducing evaporation of soil moisture or
weed control.
Crop residues left on the surface are a type of weed
free mulch. Other materials which may be used
include: straw, woodwaste, compost or plastic
materials. Use of woodwaste is generally only
recommended for blueberry production or in nursery
container operations.
When mulches are used over the winter, soils do not
warm us as quickly in the spring. This may be a
disadvantage for certain crops. Where hot, dry
summers lead to high soil temperatures and high rates
of evaporation, a mulch is effective in reducing soil
temperatures and evaporation. Organic materials used
as a mulch will be decomposed by soil organisms and
the mulch will eventually become part of the soil
humus. When woodwaste or straw are used, their
decomposition may result in some soil nitrogen
deficiency for the crop, and it is recommended that a
nitrogen fertilizer be added to the mulch to overcome
this situation. The suggested rate of application is 20
to 40 kg/ha actual nitrogen (equivalent to
approximately 1% N by weight of organic matter).
A mulch which becomes compact may reduce
aeration in the soil below the mulch. For most
situations, a mulch should not be greater than 10 cm
thick.
Various plastic or fabric mulches have also been used
successfully in field production of vegetables such as
peppers, tomatoes, cucumbers and strawberries. Some
use of plastic mulches is also recommended for tree
fruit production if rodents or weed control are
problems.
6.4 Conservation Farming
Conservation farming must address the issue of
maintaining environmental quality while maintaining
or improving production levels. All factors that affect
Soil Management Handbook – Okanagan-Similkameen Valleys 85