Ian Chivers, Native Seeds


In the two previous articles I have talked about the different characteristics of the
grasses and in particular the Australian native grasses and how they might be used
to prevent the encroachment of pastures by African Lovegrass. This article aims to
give people simple instructions about how to get the grasses established and how to
get the most out of every kilogram of seed.

Seedbed Preparation
It might seem obvious but I need to stress to everyone that just because the native
grasses are able to grow on compacted soils and with little rainfall, that is not the
way to sow them. They, like any grass, need to be sown into a condition in which
they can establish successfully and develop deep and fibrous roots. Broadcasting
the seed onto compacted soil and hoping for a result will not give you one but sadly
this has happened in the past. They need to be sown into soil that is free of weeds,
decompacted and with sufficient niches to allow for the seeds to be surrounded by a
mix of fine soil particles, moisture and air.

This may not mean a full seedbed such as would be prepared for a lucerne sowing,
although that would work well, but it involves as a minimum killing off weedy growth
on the surface, creation of grooves or niches in the soil and burial of sown seed.

Taking each one of those in turn, killing off the vegetation can be through chemical
means such as Glyphosate or through some organic chemicals such as Pine Oil or
other essential oil compounds. At the moment we are trialling a new organic
herbicide (not Pine Oil) that involves a range of different essential oils which operate
in a different manner to herbicides such as Glyphosate and which are seemingly
equally effective at killing off the foliage. This organic herbicide does not have the
problems of residual chemical and off-target effects that are being reported with
herbicides such as Glyphosate. Maybe I can talk about that more at some future time
when we have more experience with this product.

Creation of grooves in the soil surface can be through rudimentary means such as
dragging harrows or even a spiked roller over the surface. The grooves do not need
to be continuous or deep, as long as they are creating a niche where the seed can
fall. The niche need only be around 5 to 10 mm deep.

For some grasses the use of a deep litter layer can work very well to provide a
sowing medium and indeed this can be applied directly over compacted soil. We
have done this very successfully with grasses such as Weeping grass (Microlaena
stipoides) as it is very able to punch through deep litter layers, even as a seedling,
and emerge strongly. I did this once in an unplanned way where some seed was
sown and then a load of sheep droppings were placed over it. Even in those places
where 100 mm (4 inches) of droppings were dumped the weeping grass emerged!

This grass is well adapted to this circumstance. Maybe this method could be applied
on rocky areas where cultivation is impossible. I know that we sell a lot of seed for
sowing blended in with a fine compost onto bare areas such as roadsides and the
results are very good.

Seedling
establishment is
aided by simple
grooves or
cracks within the
soil (left) or
under mulch
(right).

Ignoring the step of seed sowing for the moment, let’s go to seed burial. Once the
seed is on the soil and has found its way into the niches, it needs to be covered by
soil. The germination rate of seed on the surface is less than half that of seed that is
slightly buried, so it is vitally important to cover the seed in some way. This allows the
seed to remain moist which is really the key to good germination success, especially
with the cool season grasses. To achieve this is less difficult than might be imagined.

Simply dragging a sheet of mesh or some old heavy cloth will shift soil that is loose
into the niches and cover a lot of seed. There is a less effective but cheaper option of
bringing in a large number of stock to shift the soil, a favourite tactic use in New
Zealand.

Seed Sowing
Many people get hung up on this and try to find elaborate precision methods of
getting seed into the soil. My advice here is not to let this step be the make or break.
With some of the native grasses the seed is very fluffy and chaffy. It will not sow
evenly in that form and you are better off buying seed that has been pelletised. While
you get fewer seeds per kilogram of seed and you are paying for the clay and
colouring, it does help get the seed onto the soil in the area where it is desired. It is
definitely worth the cost. I expect some of you will have tried some seed balls where
big balls of clay the size of marbles are impregnated with seed (usually trees) and
they can then be spun out or tossed out onto the soil. The concept is that with rainfall
the clay will melt away and in effect create an instant seedbed for the accompanying
seed. The same concept applies here for the grass seed, except the coated grass
seed is much smaller than marble size.

Chaffy wallaby
grass seed
(left) is difficult
to sow, but
pelletised
wallaby grass
seed (right) is
easy to sow.

For small areas sowing seed from a bucket, like feeding the chooks, is quite
legitimate and successful and it is surprising how much area can be covered in a
short time.

Seed treatments are now available for the native grasses that allow even those with
long awns to be sown through most spinner-type spreaders, so they are no longer
impossible to sow evenly.

One step that I always encourage people to do is to establish some monitoring
points. Usually putting two pegs in the ground about 1 metre apart and sowing
heavily into a well-prepared groove between those pegs will provide a reliable and
useful monitoring point. This helps both to show when the seedlings are emerging
and what they look like. This makes the evaluation of the success or failure of the
sowing to be more realistically undertaken.

Fertilizer for sowing
Applying fertilizer to a native grass sowing? I hear you ask. Yes I do recommend it
and this is probably the only time in the life of the grass that this is really important.

Usually the seedlings will go through a phase about 6 weeks after they emerge when
they will benefit from an application of a nitrogen fertilizer to help grow a strong root
system and more foliage. Applying moderate rates of N at 6 weeks of age will give
substantial benefits to your sown native grasses.

I do not recommend sowing and applying fertilizer at the same time as this will
usually benefit the weeds more than it will the native grasses.

What about Lime? No thankyou. These grasses are really well adapted to low pH
soils and applying lime will only benefit the weeds.

Or gypsum? I am not opposed to gypsum applications when they are warranted on
the basis of a reliable soil test. Just be wary of applying too much at any one time
and remember the effect of gypsum is slow and cumulative, and to get good results
you will need to apply it consistently.

What to watch out for
I have lost seedlings of native grasses to Red Legged Earthmites and Gnats so I am
quickly warning you of them. You should keep an eye open for these pests. Less
likely are problems such as Damping Off and Fusarium, but you might need to be
watching for them.

I know that severe and repeated frosts can kill off seedlings of many native grasses
in their early stages, so picking the time of year to sow is also important if you are
subject to those.

Things that are coming soon
Technology is emerging around seed treatments prior to sowing that increase the
stress tolerance of the seedlings and will help to prevent seedling deaths. This will
be amazingly helpful in achieving good sowing results.

New seed treatments are also emerging that are taking difficult-to-germinate seeds
and making them far simpler. A recent test of one of our weeping grass lines raised
the germination rate at 7 days from 23% to 75%, so this is looking very helpful.

When these technologies are verified and scaled up we will be trying to tell everyone so keep your eyes peeled, it might be only a year or so away.

All the best with your sowing of native grasses.

Dr. Ian Chivers