Variable Rate Irrigation and Soil Moisture Management - Introducing The Kowhais

Name: Tom Macfarlane

Farm: The Kowhais

Type: Intensive grazing

Location: Raincliff

Total Area: 800Ha

Total Effective Area: 655Ha

Area under VRI: 86Ha

AquaCheck soil moisture probes: 6

Annual Production: 1000 Lambs, 1500 deer and 1000 bulls

Average Pasture Production: 9500kgDM/Ha

Efficient meat production is the goal for Raincliff farmer Tom Macfarlane. After taking over the property 3 years ago Tom is striving to lift production whilst doing so in a sustainable manner. The Opuha River runs along the boundary of the property and this means that Tom is wary of the impact that his intensive farming operations may have on the environment.

Finishing 700-800 bulls before their 2^nd winter on farm requires a high level of feed intake and the bulls need to be growing every day. The techno system is intensive and requires daily management of multiple small mobs of animals. Juggling the stocking rate according to the feed supply and demand requires effective pasture management strategies to maintain quality throughout the spring and summer.

Water use efficiency is also high on the agenda at Macfarlane’s as water for the properties irrigation system is supplied from the often restricted Opuha Water scheme. Roughly 180 Ha is under irrigation on the property and his pivot and lateral, both with Growsmart Precision VRI, water an area of 86 Ha. Irrigation is also applied through K-Line, hard hose gun and Roto-Rainer systems which cover 31.8, 32.5 and 56 Ha respectively.

The Kowhais EM Zone Map to be used with VRI

The Growsmart Precision VRI really proves its worth when water restrictions kick in as Macfarlane is able to use planned moisture deficit management to water different areas of ground cover at reduced rates. When water is short the fodder beet is watered less frequently to free up more water for the higher quality pastures. Macfarlane also is able to reduce applications on heavier soils to spread his water further. All of this is enabled by the combination of EM Soil Surveys, AquaCheck soil moisture sensors and Growsmart Precision VRI.

The installation of AquaCheck soil moisture sensors has added to Tom’s suite of decision support tools. Tom is now aiming to forecast potential pasture production from soil temperature and moisture data received from the AquaCheck probes. This will enable him to better decide how many head of stock he will be able to carry and will aid in planning for the upcoming season.

The combination of AquaCheck moisture probes and a Growsmart Precision VRI system enables Tom to better manage his irrigation scheduling. The ability to see what is happening to soil moisture and applying the correct amount of water at the correct time has benefits in terms of sustainability and pasture growth. Pasture growth is critical in Macfarlane’s techno beef system where pasture utilisation needs to be kept as high as possible. With potential harvest efficiencies of up to 85 to 90% the cost of overwatering is not just limited to run off and nutrient loss. Pasture damage caused by heavy 18 month old bulls has a significant impact on the level of wastage and future pasture production. The AquaCheck probes will allow Tom to see how soil moisture is tracking and can alert him to when soil moisture rises above the pasture damage threshold. 

With one eye always on efficiency at The Kowhais the use of variable rate irrigation, EM soil surveying and AquaCheck soil moisture probes has given Tom Macfarlane the tools to help improve efficiency and productivity. Watch this space to see how things evolve at The Kowhais.

Managing Pivot Wheel Track Problems

While centre pivot track management is fairly routine for most growers, those working in more challenging paddocks often need to take extra measures to avoid creating deep tracks or getting stuck.

“During the design phase of a centre pivot is the most cost-effective time to manage tracking issues,” said Steve Melvin, Irrigation Applications Specialist with Lindsay Corporation. “However, there are steps growers can take at any time to help reduce tracking problems.”

Following good maintenance practices is the first and most cost-effective step in reducing tracking problems. Melvin suggests:

• Check the owner’s manual and adjust the tyre pressure accordingly. When the pressure is too high, the tyres will make deeper tracks and if it’s too low, the tyre may come off the rim.

• During the first pass of the year, run the pivot around dry on a day when the soil is fairly moist but does not stick to the tyres or squeeze out. These conditions are optimum for packing the soil in the wheel track. During the second pass, apply 6 - 12mm of water. This will help compact the soil and reduce the depth of the pivot track during the season. 

• Over-watering and keeping the irrigated area too wet often leads to deep tracking problems, so it’s important to maintain a good irrigation schedule. Apply the largest practical irrigation depth, without runoff, and allow the paddock surface to dry more before the next pass. 

In areas where conditions create significant problems, Melvin said growers have additional options, including:

• Adding a three-foot extension in the pivot pipe at the pivot point every other year, which allows the wheels to move out of the old tracks for a year. This gives the soil an opportunity to firm up before moving back the following year.

• Adjusting the sprinkler configuration around each tower to direct water away from pivot tracks or applying water after the pivot has passed.

• Integrating Variable Rate Irrigation technology (VRI) for pinpoint control of irrigation systems. With VRI technology, problem areas can dry out, reducing the depth of the tracks throughout the growing season. For more information visit growsmartprecisionvri.co.nz.

• Increasing tyre footprint by switching to larger tyres, NFTrax or radials to minimise the kg's per square centimetre the wheel puts on the soil.

To access the complete article that Melvin wrote about track management options, visit www.ksre.k-state.edu/irrigate/oow/p16/Melvin16.pdf.

For information about tracking solutions, including NFTrax, talk with your local Zimmatic dealer or visit www.zimmatic.com/tracking-solutions. 

This helpful guide to managing wheel track rutting has been adapted from a recent Zimmatic by Lindsay blog article (Managing Wheel Track Problems) and posted today by Sarah Elliot from Lindsay NZ.

Winter Is Coming! Tips for preparing AquaCheck soil moisture sensors for winter.

Preparation for winter is key when soil moisture is involved. Once soil moisture probes have been removed from the paddock the first thing to do is plan where they will be installed for the coming season. Choice of paddock, crop and location are all important.

 Re-installing the probe in a similar location for the following season will allow for the comparison of moisture management from year to year. It can also provide insights into how soil moisture is used by different crops in a rotation. Re-installing the probe in a different paddock will require some thought as to where the probe should be placed. Ideally a few key things should be considered as to the location:

Plan:

• Choosing a location that is representative of the paddock. If an EM survey has been done then a location can be selected from the results. If no EM survey has been conducted then a location that looks, or has anecdotally been, representative of the paddock should be identified.
• Make sure that the site is located in the middle third of a pivot, isn’t under any towers or under the end gun and that nozzles that pass over the probe aren’t blocked. Generally placing the probe in the middle of a span is optimal.

Prepare:

• Run the pivot or lateral over the paddock if possible so that wheel tracks are easily identifiable.
• Ensure that tramlines can be identified. This is to avoid installing too close to the tramline. 
• Generally installing after the first spray or fertiliser application is ideal.
• Winter provides the best time for soil moisture probes to bed in. Therefore it is important that probes are installed as early as possible. By installing early it allows for the soil profile to have time to rebuild structure around the probe which is key for accurate data capture. On top of this winter time will provide an opportunity to identify the soil moisture field capacity.

A recent install ready for winter. Tramlines are visible in the background.

If the probes are not being re-installed prior to winter then the following will apply:

• Disconnect the probe from the AquaLINK 3G telemetry unit. Store the probe in a safe place. Particularly away from anything that may chew on the cable.
• Place the AquaLINK 3G telemetry unit on a windowsill or in the garden, somewhere it will receive sunlight. This is to ensure that the battery remains charged up over the winter.
• If the probe is not going to be used for a whole calendar month contact Agri Optics to get the connection deactivated and save on the monthly bill.

Remember the 6 Ps. Prior Preparation Prevents Piss-Poor Performance. Ultimately your soil moisture management will be improved due to accurate and timely data from probes that are installed in the right place and as early as possible.

Efficient water management = successful cropping season

The 2015/16 cropping season saw a year that required a large amount of irrigation across most of the country due to the dry weather. If you weren’t using spray irrigation, variable rate irrigation (VRI) or measuring your soil moisture you probably ended up either over or under-doing the irrigation required for your pasture or crops. The more efficient an irrigation system, particularly this season the better off you would have been with maximising your return times and applying the right amount of irrigation for each crop.

Following harvest for the cropping guys we’ve certainly seen that more efficient irrigation methods (pivots and laterals and VRI) coupled with soil moisture monitoring has resulted in both increased crop yields as well as more even crops, even in this tricky dry year that we’ve had.

At Greenvale Pastures this season Craige Mackenzie has seen a massive advantage in his investment in spray irrigation (1 pivot and 1 lateral) both with VRI and his soil moisture probes. Average wheat yields have been up approximately 3.5t/ha this season and ryegrass yields have been up approximately 800kg/ha. These quite large yield increases during a testing dry year show that good yields are highly achievable and in Craige’s case, that Precision Agriculture (PA) and the tools and technologies that are part of PA are helping him achieve this.

Wheat yield map - 2015/16 season

Assuming that 50ha of a farm was in ryegrass and 50ha was in wheat with these yield increases it would give an increased profit of $64,750 (assuming wheat is $370/t) for wheat and $100,000 (assuming ryegrass is $2.50/kg) for ryegrass. This averages an increased profit of $1,647.50/hectare. When put into perspective this increase in yield is enough to almost pay for a pivot a VRI system and EM Surveying in one year.

The other advantage of using VRI on cropping farms is that you typically get a more even crop which makes life far easier when it comes to harvest as the entire crop is mature and ready for harvest at once. This advantage is very hard to tie an actual cost/benefit value to however the feedback from cropping farmers to date is that this is worth a significant value to their enterprises and this differs from crop to crop.

Wheat (Starfire) on 7th January 2016 - Paddock 19 @ Greenvale Pastures

The challenge from here is to see how we can consistently keep these yields up for all crops and across all seasons while maintaining strong on farm profitability. From where we’re placed and with the experiences we’re having across a wide range of farms we see Precision Agriculture as the way to do this. It’s all about knowing your paddocks and your crops and mitigating the weakest limiting factor and working from there. For some it might be fertility, for others it might be variable soil types and irrigation but for all cropping farmers yield mapping should play a key part in this Precision Ag journey.    

Here’s a photo for a bit of yield motivation…what can you achieve in this coming season? 

Great yields in wheat - 2015/16 season @ Greenvale Pastures

You can also see more of what’s happening on farm at Greenvale and keep up with their progress on their Facebook page https://www.facebook.com/Greenvale-Pastures-Ltd-135453169954919/

If you have any questions on how you can get the most out of your yield data or where to start the Precision Ag journey please give us a call at Agri Optics (03 3029227) so we can help you get started in the most efficient way for your farm. Cheers, Jemma