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Soil Moisture and Weather Station paddock report - 30 October 2017

 

View the monthly report below (or download a printable version).

 

FLAXMAN VALLEY

 
Growing season rainfall (Apr-Oct):
361mm
Estimated available soil water capacity:
36%
Soil type: Sandy loam over clay
Pasture type: Phalaris/ryegrass/clover based pasture
Current pasture status
(see photos below)
Composition: Phalaris 40%, Ryegrass 50%, Clover 5%, Broadleaf weeds (dock) 5%
Estimated Feed on Offer (FOO): 3400 kg DM/ha
Paddock and grazing management During October 72 cow and calves grazed the paddock for three days (7-10/10/17) to a FOO of 1600 kg DM/ha. Since then production in the paddock has doubled.
Narrative For this report we have dropped the graph span back to 120 days, in the aim of focusing more on recent changes (if you check the graphs on the BIGG website, you will see the shorter time period on the Plant Available Water graph).

 

Water use increased from around 1mm per day in September to 2.8 mm per day over the last week. The high rates of water use match the observations on increased pasture production. Rates of water user are likely to increase further as temperatures increase in the coming weeks.

 

The rain events on the 13th (8mm) and 24th (5.6mm) are evidenced as a slow down in the rate of water use as the rain infiltrated into the soil and was used by the plants. A check of the separate level graph showed that this water did not make it past the top (15cm) sensor. At 3mm per day water use, the moisture in the profile will last 17 days; if this increases to 4mm, it will last only 12 days.

One month ago (29 September 2017)

Now (26 October 2017)

 

KEYNETON

 
Growing season rainfall (Apr-Oct):
309mm
Estimated available soil water capacity:
30%
Soil type: Red loam over clay
Pasture type: Annual grass and sub-clover based pasture, including some phalaris
Current pasture status
(see photos below)
Composition: Annual grasses 85% (predominately silver and barley grass), Broadleaf weeds (capeweed) 10%, Clover 5%
Estimated Feed on Offer (FOO): 3300 kg DM/ha
Paddock and grazing management The paddock has had no stock in for over two months until 1000 wether lambs (stocking rate of approximately 7 DSE/ha) went in on 24/10/17.
Narrative August rainfall at this site was 89mm whilst September dropped to 23mm. It received 5.6mm of rain on 11/10/17 and 6.4mm on the 24th.

 

Daily water use in September peaked at 1.3mm per day and has fallen back to below 1mm per day this month. This low water use is indicative of pasture that is ticking over with no grazing load.

 

It will be interested to watch the impact of the stock coming into the paddock on water use over the next fortnight. If for instance water use climbs to 3mm per day, the moisture reserves in the paddock will only last 6 days. Any rain in the period will certainly lengthen this. So maintaining a close watch on the PAW will help inform decisions on how long to keep the stock in the paddock.

One month ago (29 September 2017)

Now (26 October 2017)

 

KOONUNGA

 
Growing season rainfall (Apr-Oct):
275mm
Estimated available soil water capacity:
25%
Soil type: Red brown earth
Pasture type: Oats / vetch
Current pasture status
(see photos below)
Composition: Oats 80%, Vetch 15% (Trash 5%)
Estimated Feed on Offer (FOO):- (cut for hay)
Paddock and grazing management The paddock was cut to a height of 10cm on 16/10/17 and will soon be baled for hay (note line on above graph which shows water use decline being halted at this timing).
Narrative This site provides an interesting insight into water use by annual crops. In an ideal situation, rainfall meets all of the needs of the growing crop and as a result, the crop grows at its maximum potential. Through September and early October, water use was very consistent and high – up to 6mm per day. When moisture starts to run out, the rate of daily water use declines – signifying moisture stress. The only change in water use evidenced at this site was due to rainfall: the crop would have used the same amount of water, it is just that water coming in helps reduce the effect of water going out.

 

When the crop was cut on the 16th of October, water use came to an abrupt end: since the profile was still holding 25% of capacity, you can speculate as to whether there was the potential for even higher yield if it was left to run longer. However this must also be balanced with hay quality.

 

And what of the remaining moisture that can be considered as a reserve for the next season. In some areas this is exploited with a summer crop. Another way of looking at the residual water is to say that the paddock would have coped with a higher sowing rate this season. But that is just one of the many risk return trade-offs that growers must constantly make.

One month ago (29 September 2017)

Now (26 October 2017)

Thanks to Adelaide and Mount Lofty Ranges NRM Board and SA Murray Darling Basin NRM Board and TOIP Pty Ltd.

Disclaimer: this report has been prepared by BIGG and TOIP Pty Ltd. It is for information only and any actions or decisions made by readers from it are at their sole discretion.