Accelerating Change

Newsletter 3 - October 2015

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Springing into action

A lot has been happening in the Accelerating Change project and the broader industry over the last month. The hot dry start to spring meant irrigation was well under way when the Stewart Performance Innovation Team (PIT) met on 17 September. With the upturn in water prices, many farmers involved with Accelerating Change are reviewing their summer feeding strategies. Initial data collection will help assist with the calculations to weigh up whether certain pastures will be watered through or dried off. The Stewart PIT met in September to review farm performance, receive a technical presentation on moisture probes from Dale Boyd of DEDJTR and discuss and the monitoring and measurement strategy and pasture reading technology on the Stewart’s farm.


Accelerating Change is using the Automated Pasture Reader (APR) to collect data about the average pasture height, uniformity and estimated mass (kgDM/ha) across selected paddocks. In a number of these paddocks on both farms, we have taken sample cuttings on both the Stewart and Humphris Partner Farms to compare to the figures presented by the APR, which enables us to evaluate the accuracy of the device and better calibrate the input figures for the equation it uses to calculate mass. This will enable us to monitor growth rates and grazing consumption figures.


We have also made some visual assessments of the different paddocks and fodder types, and have taken fresh samples for nutritive analysis. With this information we will get a better idea of optimal grazing times and the best management strategies for different pasture types.

Monitoring and measuring update

The Stewart PIT spoke at length about the data that could be collected on the farm to inform some key management strategies for the group. In the first couple of meetings the watering strategy utilised on the farm, in particular the longer irrigation intervals that Kelvin and Don use, were of particular interest to the other farms in the group. Some felt that the longer intervals might be causing a yield penalty where others were keen to know if they could implement a longer irrigation interval to save on water use without compromising on pasture accumulation. The PIT team discussed the monitoring and measurement methodology and it was agreed that Accelerating Change would measure the impact of different watering strategies on the Stewart’s lucerne and perennial pastures.

The following methodology was agreed to. Each square represents a different irrigation bay.


On the Stewart farm, we are taking regular weekly readings to examine pasture growth at different irrigation intervals and on one dried off paddock (all these paddocks have moisture probes installed in them). This strategy will help the Matthews and the Stewarts work out whether it is feasible to push out the length between waterings and dry off perennial pastures without compromising plant growth or quality.

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In contrast, the Humphris PIT team are keen to understand the contribution each forage type is making to their overall system. On the Humphris farm we are taking pasture readings pre- and post-grazing to compare the growth rates of different paddocks and the relative value of each fodder type for the herd. With consideration of the price of water and the price of hay, this strategy will help Tim and Lyndal decide which paddocks, if any, to water through the dry season.

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Exact plans for the Humphris pasture management over the summer period are currently being discussed as they weigh up options for securing water and alternate feed sources. This will be discussed at the next Humphris PIT meeting scheduled for the second week of November. The monitoring strategy will be adjusted accordingly.

What is the go with moisture probes?

Recently both PITs have had technical sessions on the value of moisture probes. Rob O’Connor and Dale Board, both from DEDJTR, have been talking to PIT farmers about the benefits and challenges of using soil moisture monitoring tools. A summary of Dale’s previous research into these tools in the region can be found here: http://irec.org.au/farmer_f/pdf_186/Soil-moisture-monitoring.pdf


Soil moisture monitoring provides a tool that enables irrigators to make more informed decisions regarding water requirements of various crops, which can result in on-farm water efficiency gains and increased productivity.


Some key lessons discussed for moisture probe sessions:


  • Moisture probes allows you to refine your irrigation schedule to increase water efficiency and productivity
  • You get the best value from moisture probes when you aim maximise production rather than to minimise absolute water use
  • Moisture probes allow you to maximise return on investment in farm layout and delivery upgrades as you can improve the timing of irrigation. This compliments greater precision and flexibility offered with improved infrastructure to apply water.
  • There are a number of different types of soil moisture monitoring devices that can be installed in a range of price ranges. To assist you choose the right device DEDJTR have developed this note: http://agriculture.vic.gov.au/agriculture/farm-management/soil-and-water/soils/choosing-the-right-soil-moisture-monitoring-device
  • Probes with telemetry systems (wireless systems that use the phone network to remotely send data from the paddock back to your phone or computer) are rising in popularity and can be used in conjunction with automation to irrigate your farm remotely.

Benefits of moisture probes:

Number 1

You can clearly identify periods when your plant is not using moisture and therefore not growing at full potential. This could be from waterlogging or moisture stress.


Click on the graph to enlarge. The flat line period after this indicates some water-logging (blue oval). The dry autumn had the soil profile dry out from Lucerne growth to wilting point (red oval) and moisture stress occurring in mid-April. The coloured lines show the moisture level at different depths in the soil profile while the vertical bars show rainfall.

Number 2

You can see the impact of rainfall events. This will allow you to reschedule irrigation events to maximise the impact of rainfall and reduce water applied without the risk of loss of production. The target is to apply water to the root zone and not beyond.


Click on the graph to enlarge

Number 3

You can use moisture probes to assist plan the first irrigation for the season.


Click on the graph to enlarge. It shows the accumulation of soil moisture over winter and depletion in spring until the first irrigation was required in October.

Challenges:


  • A number of PIT farmers that use soil moisture probes have indicated that it can be difficult to work out the refill and saturation point for their pastures. Probe data is displayed with graphing software allowing the ability to apply indicative wilting and saturation point usually highlighted in background colours like red or blue on these graphs. It is important to ground truth what your particular points are specific to your farm by validating soil moisture conditions with a physical examination of the soil at the depths where the sensors are located in the soil profile. Further steps can be taken to dry these soil samples in ovens to determine the mm of water in the soil by using the wet weight and dry weights in a volumetric soil equation. Alternatively ground truthing can occur by using cumulative evapotranspiration data or other scheduling methods that have been established on the farm.


  • The graphs with one line show the summed value of soil water content over the total depth of the probe. This could be 80-120cm or more. It is also important to look at the individual stacked sensor graphs that show soil moisture change trend lines over different depths. This will show you where moisture reaches with irrigation events and the impact of rain. This graph will also display the rootzone of the plant and where the moisture consumption is occurring. This will , indicate if the plant is nearing moisture stress so irrigation scheduling can be planned in conjunction with forecast weather, plant growth and future management activities on the paddock.

Evapotranspiration and Rainfall-one way of validating soil moisture conditions

Cumulative evapotranspiration data can help you validate the soil moisture conditions you are viewing on your soil moisture probe. You can use this data to estimate how much and when you soil moisture content is likely to have decreased and the impact of rain on your soil moisture. For example if you require 40mm of readily available water in the root zone:

For the past week at Kyabram, Evapotranspiration –Rainfall=37mm. This equates to an average daily ETo of 5.3mm /day

To work out the irrigation interval, divide the desired mm of readily available water in the root zone by average daily ETo and add 2 days to allow for excess water to drain away, which is typical following a surface irrigation event:

40mm/5.3mm+2=rounded up to 10 days.

ETo for next week is forecast to be 36mm. The good news (unless you have hay down) is that 22 mm of rainfall is forecast, which will allow the irrigation interval to be extended.

Daily historical (eg. past week) ET figures for select locations are available on the BOM 'Water and the Land' site http://www.bom.gov.au/watl/eto/

The forecast ET figures provided are from a 'fee for service' web site.

Rob O’Connor from DEDJTR also provides a weekly ET email update "Irrigation Requirements Summary".


Contact Rob at robert.oconnor@ecodev.vic.gov.au to sign up.


Example Evapotranspiration and rainfal data at Kyabram:

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Coming up in Accelerating Change:


  1. Summer strategies from our leading farmers-what are they doing to optimise this season
  2. Insights into innovation and technology from the cotton industry-what lessons can be applied to the northern dairy industry
  3. Fescue-examples of how it is performing in the region. Is it matching it's potential?


Look out for our next newsletter!

Accelerating Change is a three-year project that aims to help farmers increase their home-grown pasture production, efficiency of pasture management and utilisation, and efficient use of irrigation water. This project is funded by the Department of Economic Development, Jobs, Transport & Resources and Dairy Australia.