Newsletter 5 - September 2016
Accelerating Change setting up for the new irrigation season
Accelerating Change has been busy over the winter months setting up technical extension activities and continuing measurement and monitoring activities on our Partner Farms where possible, incorporating winter feeds into the mix. Difficult wet conditions for our farmers have also limited how much pasture accumulation and nutritive data we could collect so, like everyone, we are looking forward to seeing some drier paddocks in spring.
Our monitoring and measurement strategy will soon kick off again as the irrigation season starts up. We will be continuing our look at the performance of perennial pasture and lucerne on farm, as well as alternative summer forage types such as sorghum, their contribution to the feed budget, and their respective costs and benefits. We will also look at the performance of different aged lucerne to assess its value over the long term and continue with our trial of different irrigation strategies.
Soil Constraints Roadtrip
Working with our farmers, we delivered a Soils Constraints Road Trip in July, taking participants to three different sites in the Tatura-Stanhope region to look at different structural soil issues and ways to address them on farm for improved productivity. The Road Trip was delivered by soil scientist, Christian Bannan, who took farmers through issue identification and possible practical remediation actions in an interactive format.
The feedback from the day indicated that the event was particularly relevant for farmers in our region, given the wet conditions of each site. We are developing up a full report and video of the day so watch this space for more information. Accelerating Change is making this workshop available for delivery upon request. If you and your neighbours, or Discussion Group is interested at having a closer look at your soils, please get in touch.
Successful Summer Cropping Workshop
Accelerating Change, in partnership with Tactics for Tight Times and The Gardiner Foundation, ran two Summer Cropping Workshops this month to get farmers thinking about how they could get the most value from maize or sorghum crops in their respective dairy farming operations.
Together, Matt Nihill, Cropping Agronomist from Landmark, and Lisa Birrell, Murray Dairy Extension Officer, discussed the agronomic, financial and nutritional considerations of growing a good crop and effectively utilising the feed. Service providers and dairy farmers in the room also shared their experiences of summer cropping.
Matt and Lisa spoke about the differences between maize and sorghum, their availability at different times and different nutrition characteristics they offer your cows. Sorghum can be a good option to fill a summer feed gap and, as it can be directly grazed, there is significantly less capital infrastructure required to trial it. On the other hand, farmers growing maize silage spoke about its value when stored and fed out to bulk out autumn pastures, and as a risk management strategy to have on hand for future feedgaps. Matt also spoke about the several varieties of maize and forage sorghum-sudan grass hybrids available, and how to select one for your system (considering use, environment and growing period, for example).
Matt stressed the importance of understanding the commitment and the outlay required to achieve the yields of maize or sorghum that participating farmers were looking for. He likened growing maize to baking a cake – he emphasised that you need to follow the recipe to the letter to achieve the best outcome. This includes preparation, site selection and sowing, in-crop management, harvest, storing and feed-out.
If you are thinking about growing maize or sorghum this year, it’s vital that you plan and prepare your full agronomy program before you start to ensure you get the best return for your investment. To assist you do to this, click here for a copy of the workshop presentation, which provides details of each step of the "recipe".
When asked what they had taken from the session, many participants indicated that they were going to pay more attention to planning, paddock selection and preparation, especially after the wet winter which has resulted in pugging and compaction in paddocks as well as an increase in weed activity. Other participants said that they were not going to skimp through the growing season after hearing just how critical nutrient, water and pest management is.
Accelerating Change is making the Successful Summer Cropping workshop available to groups upon request. If you and your neighbours or discussion group would like to host a workshop please contact us.
This workshop will be followed up by a practical crop tour of summer crops in the region to see how some of the agronomy considerations are playing out in the paddock this season. Watch our website or the eNews for upcoming details.
Check out Matt Nihill, Landmark Agronomist, sharing some key messages from the workshop
We are still working on our radio presenting skills but click the below link to hear some more in-depth messages about sorghum management through our podcast!
Rob O'Connor, an experienced Irrigation Officer with DEDJTR works with Accelerating Change on all things irrigation, including scheduling. Rob shares with us, below, lessons learnt from the project about soil moisture monitoring and the use of moisture probes, and the value of using ET data to schedule irrigations.
Lessons learnt about soil moisture monitoring
Soil moisture probes have been used on the partner farms under different forages in 2015-16 and through the recent winter-spring period. The probes have provided useful information largely for irrigation scheduling, particularly when the moisture probe information was regularly revised and used in conjunction with other scheduling methods already used on farm.
Getting the most out of probes
It was evident from probe data that a shallower depth of moisture extraction was occurring under pasture compared to lucerne. Moisture uptake was typically occurring to a depth of 50-70cm under pasture and 100-120cm for lucerne. (Refer to figures 1 and 2 below.) Usually when the soil probe software was configured to only collect moisture data from soil depths where plant roots were active (rather than leaving all the probe sensors switched on for the different depths), more representative soil moisture information was obtained.
A means of using probe data to determine when to irrigate is to observe when the rate of soil moisture extraction begins to slow down and plant available moisture becomes limiting. This point is identified on the moisture graph where the slope of the line starts to flatten out and takes on a curve-like shape. (Refer to figure 3 below – labelled “classic moisture stress curve.”) The point at which this change occurs was more obvious over-all for probes installed under lucerne than for pasture, making optimum irrigation timing more obvious for lucerne using this approach.
In a pasture situation, plant roots are likely to be most active in the top 10-20cm with activity progressively declining down the soil profile to a depth of approximately 60-70cm. With some software packages this variation in root activity can be accounted for by changing the relative weightings of moisture probe sensors at different depths. More accurate estimates of the relative moisture uptake occurring at each depth down the rooting profile results in a better representation of changes in plant water availability. This enables improved irrigation scheduling.
One tool in the toolkit
For Stewart-Matthew’s lucerne there was a reasonably good match of the indicators for optimum irrigation timing sourced from the probe data and from ‘evapotranspiration minus rainfall’ (ET-R) data. Typically, the soil moisture depletion between irrigations shown in the moisture graph (or the size of the “dip”) corresponded with the magnitude of cumulative ET-R. (Refer to figure 3 below.) This match provided increased confidence in the use of the moisture probe in this situation and demonstrates the value of using more than one tool for irrigation scheduling. Kelvin (partner farmer) relied heavily on probe data to determine when to irrigate his lucerne for a significant part of the season.
It should be noted the correlation between probe readings and ET-R data is never going to be perfect in this situation because of other factors influencing the water requirement of lucerne including variation in canopy height and grazing.
Figure 3. Average soil moisture content for Stewart-Matthew’s lucerne, combined with ETo-R between irrigations. There was a reasonably good correlation between recorded soil moisture depletion and ETo-R.
Advantages of moisture probes
An advantage of moisture probes is they can provide a permanent record of soil moisture levels. In the words of one Coleambally agronomist “probes gather information day in day out, without forgetting, changing their mind or only remembering the good bits.” This information can then be used to review irrigation management practices through the season and help with better irrigation decision making in the future. Using cumulative ET-R between irrigations in conjunction with probe data provides a comparative benchmark to review probe data and irrigation timing. In figure 3, it can be seen irrigations usually occurred at approximately ET-R=100mm, which is well in the recommended ballpark for lucerne. Where there were any significant variations from 100mm, questions can be asked about reasons for this variation. In this case, farm management practicalities such as grazing management and trafficability provide a reason for varying irrigation timing - particularly extending the interval for a drought hardy plant like lucerne.
Partner farmer feedback
The partner farmers (Kelvin and Tim) both mentioned another advantage of using probes is an ability to see the impact of rainfall events on soil moisture at different depths and how quickly it is used up by plants. “It’s easy to think you won’t have to irrigate (pasture) for another 9 days after an inch of rain, but you might realistically only get another 5 days when you look at it” explained Tim. Tim added “I’ll also be watching the probes when I think it’s time to start-up irrigation (for the season), which is beneficial.” Kelvin summed up. “I’m happy with the probes. There is definitely a place for them. They give you more confidence with your decisions.”
As part of the Accelerating Change project, capacitance probe data will continue to be monitored under perennial pasture (seasonal conditions permitting) and lucerne on the partner farms through the 2016-17 season. The suitability of gypsum blocks to gauge soil moisture conditions on dairy farms is also likely to be examined. Like capacitance probes, gypsum blocks can be connected up to telemetry systems for screen viewing. The value provided by soil moisture monitoring under sorghum, fescue and annual pasture is also up for investigation.
Cool tool back soon
The weekly evapotranspiration (ETo) email updates that were received by PIT members last irrigation season will start up again in the next couple of weeks (or when it stops raining,) for the 2016-17 irrigation season.
How irrigators have been using the ETo updates
It’s been great to receive feedback over the last 12 months about the ETo emails. Most of the feedback has been positive and there were also some questions about ETo and how it can be used to improve irrigation management.
Some PIT members have been getting good results from using the service as described in the following quotes, “With ETo, I’m improving efficiency heaps” and “I’m growing the best pastures on this place… (along with some other changes on farm) milk production is up…”
Irrigators have been using information in the ETo emails in different ways. Some say they simply use the recommended surface irrigation interval as a guide for irrigation timing in conjunction with other scheduling methods they already use on farm. “I use it (ETo) to see if I’m on the right track… now I check more often and do some ground-truthing (in the paddock).”
Other farmers said they used both the recommended irrigation interval and daily ETo figures shown in the email. “I look at the recommended irrigation interval first, then at the ETo figures.” Typically the ETo figures were used for checking other scheduling methods already being used by calculating cumulative ETo minus rainfall (ETo-R). For rye grass based pasture, irrigations are usually timed when ETo-R equals 40mm to 50mm, starting from when surface water has drained away following the last irrigation.
A number of irrigators commented they browse the forecast information to alert them of upcoming weather events so they can better plan for their next irrigation. “I look at what the ETo rates are and if there are any high days or low days, and I look at predicted rainfall.”
One farmer with pressurised irrigation was using the ETo data to plan irrigations to minimise pumping at the higher electricity tariff or the “day rate,” to reduce power costs.
Using ETo to schedule irrigation for crops other than pasture
“Irrigation boffins” regard good pasture as the “reference crop” and give it a ‘crop coefficient’ of 1. ET from a stand of good pasture is referred to as “reference ET” or “ETo.”
The theory is other crops that use more water than pasture such as a good mature stand of lucerne or a tall dense maize crop are given a crop coefficient closer to 1.2. Where-as recently grazed lucerne, which has a low canopy density will use less water and will typically have a crop coefficient of less than 1. The appropriate crop coefficient can be multiplied by cumulative ETo since the last irrigation (also taking rainfall in to account) to determine the irrigation requirement of the particular crop (“ETc”).
Deeper rooted crops will typically be able to access more available moisture in the soil profile. This explains why a crop with deep roots like lucerne is suited to a longer irrigation interval (than pasture) of ETo-R = 80mm to 100mm. Whist maize is usually suited to an irrigation interval of ETo-R = 60mm to 70mm.
That’s the theory, which can be very useful for irrigators to know. In practice on most farms, like with pasture, irrigation scheduling for crops is typically determined using a number of tools that have already been tried and proven. However, ETo can be an objective measure to add to the toolbox to help ‘keep on track’ and better plan irrigations for optimal production. As one learned cropping farmer explained, “I use the ETo figures in combination with my bike and shovel…. ETo is handy because sometimes you don’t realise how much the plants have used, 50mm can come up pretty quick.”
Other ETo Services
ETo is widely regarded by different agricultural industries as an objective and reliable tool for scheduling irrigations. As well as dairy farmers, irrigation croppers and horticulturalists in the region have subscribed and are using the (‘northern Victorian’) ETo email service. Currently there are approximately 300 irrigators and service providers on the email list. AgVic provides other ETo email services in North East Victoria, Macalister Irrigation District (East Gippsland) and in Sunraysia.
Keep your eyes out for a simplified weekly ETo feature in future editions of the Country News this irrigation season.
Of interest is that cumulative daily ETo (17mm) only just exceeded cumulative rainfall (15mm) over the last seven days at Kyabram indicating practically no irrigation was required. Next week cumulative rainfall (40mm) is forecast to exceed cumulative ETo (20mm).
If you would like to subscribe to the weekly ETo email update, or find out more on irrigation scheduling, please email firstname.lastname@example.org
Improving Feedbase Performance – listening to dairy farmers. We need you!
Gaining efficiencies in feedbase management is a key profit driver for dairy businesses now and into the future. In order to make sure industry is investing to support farmers to get the most out of their feedbase, we want to hear from you about what you need to better your business.
- What has been your involvement in feedbase programs in the past?
- Is available information relevant to your business and can it be integrated into your system?
- Where do you source your feedbase information from and how would you like to receive it?
- Do we have the right benchmarks for assessing progress and targets for feedbase performance?
Gardiner and Dairy Australia are initiating a new study that will talk directly with dairy farmers across Victoria to understand their motivations, goals, current practices, skills and information needs for feedbase management. This will aid in understanding the impediments holding back a sustained, improved performance in feedbase management. This is a great opportunity for dairy farmers to tell us what they want and need and also tell us what works and what doesn’t. If you can help us by participating in a one-on-one interview of approximately 1 hour, please contact Murray Dairy.
Coming up in Accelerating Change:
- Monitoring and Measurement for 2015-16
How does perennial pasture and lucerne perform after a wet winter?
What impact does stand age have on the performance of lucerne?
What is the relative cost-benefit of growing sorghum?
Do moisture probes work in pasture?
What tools are most useful for irrigation scheduling?
- Future Dairy Systems
Accelerating Change teams up with the Murray Dairy Business Forum to discuss what our future systems will look like and what needs to happen to get us there
- Successful Summer Cropping
We've had a look at the planning and preparation that must go into maize and sorghum, next we are going on a road trip to look at how that is actually playing out in the paddock
- Soils-we want to have a look at your farms!
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.