Peter,
Questions to answer:
Is soil moisture limiting?
Plant nutrient status?
Do you need the feed?
What is your irrigation set up (surface or spray)?
What other events will limit growth over this period and can they be
managed?
What will be cost of feed grown vs. bought in options?
What will be benefits in growth later in year?
We are in similar situation here in SE of South Australia. In fact have run
a number of pivots over the past week in response to moisture stress showing
up in plants (and initially picked up through soil moisture monitoring). Out
of interest rainfall in April was 120mm, May 60mm (early in the year), June
to date 16mm. Average evaporation rates have moved from 3mm / day in April
to currently 1 - 1.4 mm / day.
Even with current weather conditions we are still growing at 35 kg DM / Ha
/day average (where we are maintaining soil moisture and plant nutrient
levels).
Important point being that we aren't having the same number of frosts on the
properties closer to the coast. However still achieving good growth rates on
inland property currently working with that has had a number of "serious"
frost events (don't have temp data for this one, but have had 6 frosts in a
row a few weeks ago). Soil temps south of Mount Gambier 6 - 7.5 degrees at
present fluctuating between 4 - 10 degrees.
One thing that we definitely see is that plants that are under stress
(particularly N) or water stress are more severely affected by frost than
plants not under stress. Have a look at growth in urine patches or dung
areas. Overgrazing is also another good way to induce stress in plant.
If you wait until temps increase, you may miss a growth window, always try
to optimise the environment when & where you can to make the most of the
sunlight we are receiving during the day. At least try this on an area and
build some data for yourself for the future.
All of this of course depends on where you are (is snow a possibility?), and
can you put on a small application 8 - 11 mm or do you need to put on 25mm?
If your cows are out for 6 weeks potential pugging damage is not an issue
over next 6 weeks. So this presents an option to grow some feed now
(assuming soil moisture is the limitation). If your potential growth rates
are 20 - 30 kg DM / HA / day then in 6 weeks you can put on 1000 - 1200 kg
over this period (most likely more than this given increasing growth rates
into the spring).
For us, irrigating to avoid moisture stress now will make minimal difference
to when we get "waterlogged" if we get typical rainfall patterns. The extra
grass we have grown over last 6 weeks is actually more than we would
typically utilise during a normal July. We are already in front..... (not on
our dryland though!!)
Trust this helps
Regards,
Rick
Rick Jordan
General Manager
Horizon Farming Pty Ltd
Mount Gambier SA.
mob: 0427 447753
fax: 0887 247174
email rick@horizonfarming.com.au
----- Original Message -----
From: "Peter & Felicia Aldridge" <p.f.aldridge@bigpond.com>
To: <vicdairy-l@unimelb.edu.au>
Sent: Saturday, June 17, 2006 7:12 AM
Subject: Irrigation in winter
> Hi all,e 6C or less.
>
> The issue is - we have had frosts since April, and although we had good
> early rains, there has been little for May and June. We have plenty of
> irrigation water, but its temp is 4C or less. Cows are now out, and won't
> be back for 6 weeks. Soil T will be 6C or less. Soil moisture is now low,
> getting critical.
> Question - is it worth putting 25mm water over the pastures, or better to
> wait for higher temps or rain.
>
> Peter
>
> Peter & Felicia Aldridge
> 1542 Warrentinna Rd
> Branxholm Tas 7261
> ph 0363546102
> fax 0363546106
> 0419501990
>
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