Newsletter 3 - November December 2015
The season so far
Accelerating Change Performance Innovation Teams met in November and December. A significant amount of the discussion focused on the group's summer feeding strategies, characterised by limited water availability and high prices.
Kelvin Matthews and Don Stewart are already seeing the results from improved data collection on farm. The nutritive sampling Accelerating Change has been conducting has revealed that their lucerne pasture was of excellent quality, much higher than the PIT group expected (ME 10.7, CP 29.4%, NDF 36.6% and ME 11.5, CP 33.2% & NDF 34.2%). Working with their nutritionist Andre Nel from Ridley's, they worked out their cows were receiving an extra 30 ME per day than required, and body condition score was increasing over time. Armed with this information they have reduced their grain intake by 1kg in the dairy, saving approximately 27c per cow per day. Over 500 cows this is a significant saving. Body condition is now being maintained. The herd will be monitored over time to ensure this continues, particularly over periods of extreme heat.
On the Humphris Partner Farm, they are moving to a temporary partial mixed ration and drying off a large portion of their pasture for the summer period. This involves feeding the cows on a standoff area during the day and grazing them on perennial pasture overnight. The feed ration consists of a mixture of barley grain, shaftal and maize silage.
The Humphris PIT had a lengthy discussion around balancing nutrition requirements, particularly as the Humphris' typically utilise a pasture based system. Tim has used the Rumen8 program in conjunction with the pasture and silage nutritive samples Accelerating Change has been collecting to do an analysis of his herd's diet and is confident in the mix. You can have a go at the Rumen8 program to check your own ration by following the below button.
How good is your eye?
At the Stewart PIT meeting in December, the group reviewed the pasture accumulation data and nutritive values for the season so far. The group was put to the test to see if they could judge by eye the pasture mass and quality characteristics Accelerating Change has been collecting. One of our twitter followers guessed in first go! What do you reckon?
Match the nutritive results with the pasture species on the left:
(answers at bottom of page)
Soil Moisture Monitoring
At their meeting the Stewart PIT also discussed initial data from the 5 Observant capacitance probes installed on the Stewart farm. Throughout the project the PIT farmers have had numerous discussions on the value of moisture probes and how to use them most effectively.
Moisture probe take home messages
- Look for the decline in daily water use and ground truth what the cause is. Is it moisture stress or another factor?
- Set your own refill and full point management lines. Probe software might give you indicative positions but you have to tailor it to your farm, your soil, your crop and your water infrastructure. If it takes a few days to order or apply water give yourself a bigger buffer between timing of irrigation and the point of water stress, in case things go wrong.
- Check it regularly! Read the soil moisture probe graph every couple of days and more frequently if you are nearing irrigation or there is a big change in weather-either rain or heat wave.
- Look at both your summed or average graph and your individual sensor data graph and understand how they fit together and at what depth water is being used from at different times.
- Make notes in your software if you can. This will help you improve your irrigation practice over time and identify how different factors e.g. rain and heat, have impact on soil moisture use.
How do you use your capacitance probes?
There are many different software options for different commercial moisture probe offerings. Understanding how the software is set up and what information or parameters are fed into the graphs you are looking at is critical to interpreting soil moisture conditions and actioning irrigation accordingly.
The most important question when considering information from soil moisture graphs and other sources is "when will the pasture or crop start to become too limited by soil moisture?" This is the refill point for your particular soil and pasture type. If irrigation is not applied prior or at this point then a yield reduction will occur, depending on the stage of crop development.
There are many ways to work out where your refill point is. One of the simplest ways is to look for a change in water use in your soil moisture graph. When a crop or pasture is becoming water stressed, water use will decline as it works harder to access moisture. The slowing of the rate of uptake of soil moisture will flatten off, showing a shallower slope, compared to peak uptake of soil moisture, or the "steeper" part of the graph.
Graph 1: change in water use over time
Note: other factors such as heat stress, water logging and soil compacting will also cause a decline in the daily water use of a crop that is not related to water stress, so it really important to ground truth your decision making with other methods. Refer to our last newsletter for more information on this.
Once you have monitored changing conditions on the soil moisture graph and ground truthed conditions physically in the field, you can adjust the refill and full point management lines on your software to help you plan future irrigations.
It is really important to revisit and revise your refill and full point management lines because they can change in different stages of crop or pasture development over the season.
Should I calibrate my probe?
You can use your moisture probe "uncalibrated". As mentioned above, look for the trends in change in water use and ground truth with your existing irrigation scheduling methods. Calibration becomes important when you are using the probe to understand the exact magnitude of plant water use or the soil moisture deficit. Calibration is not a straight forward process and is usually only done in research projects. In an uncalibrated probe, the absolute figures will not necessarily be an accurate representation of mm of soil water use, or % of soil moisture content. But the relative changes to soil water use will be. This is why it is easiest to use soil moisture use trends provided by soil moisture graphs rather than absolute numbers to schedule irrigation.
Summed graph versus individual sensor data graph
Most moisture probe software can provide you with a summed graph of soil moisture, which is either the average or the summed value of soil moisture at each sensor depth. On a 100cm probe there is typically 10 sensors, one at each 10cm interval. You should also be able to look at a graph that shows individual soil moisture data at each sensor. This graph shows how soil moisture is being used at different depths under a perennial pasture and lucerne.
As you can see from the below example from the Humphris farm, the majority of water use by pasture is from the top 50 cm. This is typical of where the majority of roots will be in a perennial pasture.
Know how your probe software operates. Some software will take an average of all the sensor depths and some will add them to form an average soil moisture graph or total soil water graph. Accordingly, some software gives you options to change the weightings of each sensor and/or turn them on and off. By understanding how this works for your gear, and looking at soil moisture use at each depth you will have a clearer picture of where soil moisture is being extracted. If you do turn off lower sensors or adjust them, it is important to regularly look at the lower depths so you can detect any water movement.
Graph 2: soil moisture use at each sensor depth. There is significant use at 10-30cm with gradual decreasing use with depth.
There has been significant excitement amongst farmers in the Accelerating Change project around the potential for fodder beets as a direct grazing option for the region. Fodder beet is high yielding annual crop which provides feed over late summer and autumn. It has large leafy top and large bulbs that sit high up out of the soil. This distinguishes it from sugar beet, where the majority of the bulb sits within the soil, and needs mechanical lifting in order to be grazed directly. Fodder beet also has a slightly softer bulb, and has been specifically bred for animal feed purposes, so has a lower nitrate content in the leaf than sugar beet.
Fodder beet is grown extensively in New Zealand and the UK, and has the potential for very high yields (30t/ha plus) under good management. Nutritive characteristics are around 12.5-13.5 ME and 6-8% protein. In Australia, fodder beet has been trialled in QLD, Tasmania and WA. There is an excellent video series developed by the C4 Milk project by University of Queensland and the Department of Agriculture and Fisheries. These cover establishment, crop and grazing management.
Recent yields on this site have measured 26t/ha and farmers viewed the results at a recent field day. Subtropical Dairy and the C4 Milk project has provided some very useful information on the trial and how to manage grazing of fodder beat to ensure cow health, including gradually introducing fodder beet into the diet and restricting volume. This is critical to avoid acidosis.
Locally, service providers Kober are managing two trial plots across 55 ha in the Goulburn Valley, under both flood and pivot irrigation. Both plots are establishing well and will be ready for grazing in late January or early February. An open day will be conducted on 3 February 2016 in Girgarre. For more information contact Kober.
Accelerating Change will be watching this closely to see how lessons may be applied onto our Partner and PIT farms.
Coming up in Accelerating Change:
- Review of the summer irrigation period pasture accumulation and nutritive value data
- Insights into innovation and technology from the cotton industry-what lessons can be applied to the northern dairy industry
- Alternative forage options. How is sorghum working in our region?
Look out for our next newsletter!
From the Accelerating Change project Merry Christmas and a Happy New Year!
Answers to pasture guess game: A1 B4 C2 D3
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.