News

Jan 10

Summer moisture preservation is critical

Posted by Kylie Dunstan at Friday, January 10, 2020

The following article appeared in the Summer 2019 edition of the FarmLink quarterly member-exclusive publication The Link (archives appear at http://www.farmlink.com.au/the-link).

While it might be tempting to allow weeds and crops that have been cut for hay or windrowed to regrow as a source of livestock feed, the impact on following crop yields could be significant.
Riverina Independent Agronomy consultant Neil Durning says weedy canola crops are ideally sprayed before windrowing to reduce the addition of ryegrass to the seedbank and a loss of moisture and nutrients from the soil.
“As part of an integrated weed management plan, it is worth applying glyphosate to canola with ryegrass from early senescence at label rates,” he says. “One way or another you want the canola and the ryegrass dead. It doesn’t take much rain for ryegrass to stick a head out and add more seeds to the seedbank.”
Mr Durning says wheat following canola where glyphosate was applied before harvest appears to hang on for longer in dry finishes. Spraying before windrowing also reduces the likelihood of plant regrowth after rain.
3D-Ag consultant Peter McInerney advises his clients against grazing sheep on paddocks that have been cut for hay.
“Do not try to retrieve residual grazing from hay paddocks because there is none to be had,” he says. “All you will do is powder the soil and have it blow away, particularly paddocks that have been cut for hay for two consecutive years.
“A crop that would have produced 2.5t/ha of grain leaves 3 to 3.5t/ha of residue. That same paddock cut for hay will leave behind less than 1t/ha of residue.”
Where hay has been cut for two consecutive seasons, Mr McInerney encourages the application of manure to replace lost organic matter and nutrients.
Effective summer weed management is critical to reap the soil water conservation benefits of retained crop residues (Flower, Dang & Ward 2019).
Zeleke (2017) showed that summer weed control increased residual soil water and soil nitrogen by 64 millimetres and 60 kilograms per hectare respectively.
Lilley and Kirkegaard (2007) used modelling to show that summer weed control could increase subsequent wheat yield by up to 20 per cent.
According to NSW Department of Primary Industries researcher Colin McMaster (https://weedsmart.org.au/how-much-moisture-and-nitrogen-is-wasted-on-weeds-over-summer/) trials in Central New South Wales showed the economic benefit of every dollar per hectare spent on herbicides to control summer weeds was $8/ha.
Mr Durning says mixed farmers must treat weeds as if there are no livestock in the system, particularly if the paddock is earmarked for cropping.
“The minute you compromise on summer weed control by allowing weeds to grow large is when you start to reduce the yield potential of next year’s crop,” he says. “Preserving moisture over summer is the difference between having a crop that can be harvested and salvaging a failed crop in a dry finish.”
John Stevenson allows sheep to lightly graze stubbles on ‘Orange Park’ near Lockhart only after the first summer knockdown has been applied. His actions back research showing grazing sheep on crop residues at low stocking rates has no detrimental impact on following crop yield (Hunt et al. 2016, Allan et al. 2016).
Where paddocks are bare, Mr Durning says a strategic cultivation may be needed to curb erosion and maximise water infiltration, although this depends on slope and implement choice. Cultivation leaves the surface coarse and lumpy to slow run-off and reduce surface wind speed.
Mr Condon says one of his clients with discs on 16.5cm row spacings planted millet over summer as a cover crop.
“It was sprayed out at early tillering and we saw no yield loss in the following crop even in a dry season,” he says. “You have to be disciplined to avoid grazing and spray it out before the roots reach 15 to 20cm deep to prevent stored soil water loss.”
While two to three tonnes of wheat stubble per hectare (Kirkegaard & van Rees 2019) or 70 per cent soil cover are suggested to minimise erosion and maximise water infiltration, Mr Condon suggests keeping 100 per cent of cover if possible.
He and Mr McInerney agree that confinement lots are worthwhile to preserve soil cover. Confinement lots work on the theory that less topsoil is lost by concentrating sheep in a small area rather than a large area.
Mr McInerney suggests positioning a new confinement lot near an existing tree line where there is standing crop and to apply for grants for infrastructure needs.
Mr Condon says confinement lots allow sheep to be efficiently kept at target condition scores using grain and straw, while preserving soil cover.
“My clients with diverse rotations who kept stubble from 2016 have produced reasonable crops during the past two years,” he says. “The retained stubble allowed autumn rain to infiltrate rather than run off and enabled crops to be established on time.”
Mr Durning agrees, adding that he has noticed paddocks with less stubble cover failed two weeks earlier this year than paddocks with a higher percentage of cover.
Acknowledgements: Peter McInerney, Neil Durning, Greg Condon and John Stevenson.

Apr 27

Preparing for planting 2016

Posted by Cindy Cassidy at Wednesday, April 27, 2016

Rain forecast for this weekend means Riverina farmers are in the middle of preparing for, and sowing, the 2016 winter crop, an integral part of Australia’s agricultural output. Riverina farmers produce $2.1 billion worth of total agricultural output annually (ABARES) with grain production alone worth $795 million annually.
As a part of the preparation for this year’s crop, farmers have been using stubble burning as an important tool in the management of their farming systems. But why do farmers burn?
There are lots of reasons why farmers burn crop residue, but the overriding issue is that this stubble residue will adversely affect their cropping program, which can be compromised if the stubble -
• causes blockages to seeding equipment
• causes uneven crop emergence
• perpetuates crop diseases
• provides habitat for crop pests
• affects the efficacy of weed control
• affects the uptake of nutrients by the new crop
Farmers retain their stubble for as long as possible to provide grazing for sheep, to reduce erosion risk and to retain moisture.
Southern NSW produces some of the highest crop yields and best quality grain in Australia. Average wheat yields of 3-4 tonnes/ha are common, and could be double that in a good year. A direct result of that is that there is large amounts of stubble to deal with before the next crop can be sown. Typically stubble residue can be 1.5 x the grain yield. Research has shown that if the amount of stubble exceeds 3 tonne/ha then many seeders will have difficulties in sowing crops evenly and there will be blockages as the stubble tends to clump up. Getting crops sown to emerge within the correct time period for each variety is so important for the end result. Agronomists spend a lot of time planning crop rotations with farmers and selecting varieties suitable for each paddock to avoid frost and heat stress in critical times in spring, and this depends on the sowing operation going smoothly.
Many crop diseases and pests are harboured in the old stubble residue, so depending on the crop rotation the stubble may need to be removed to prevent the problems. Fungal leaf diseases such as Yellow Leaf Spot in cereals and Blackleg in canola are carried over in stubble residue. Stubble burning reduces these risks in the paddock so that crop seedlings are not exposed to the disease at emergence. Pests such as earwigs, millipedes and slugs rely on stubble cover to improve their habitat in cropping paddocks and can damage emerging seedlings, especially fragile canola seedlings. Removing the stubble by burning can help prevent these from causing a problem.
Weed competition is the greatest threat to crop productivity worldwide, so early control is essential for ensuring that crop yields are not compromised, and the emerging crop can become competitive itself. Stubble can interfere with efficient application of herbicides. Soil active pre-emergent herbicides will not be effective if stubble cover absorbs the spray, preventing even application. Post emergent weed control may also be compromised if standing stubble is shading seedling weeds so that spray droplets do not reach the target so burning stubble before herbicide application will give better results.
The technique of windrow burning as a way of destroying resistant weed seeds is also becoming an important part of the integrated weed management package. Instead of spreading harvested weeds seeds across the paddock, stubble residues are simply dropped via a shute at the back of the header so they can be burnt in late summer or early autumn in a hot burn that destroys all the weed seeds. This allows the majority of the stubble to be conserved, but herbicide resistant weed seeds are destroyed.
Stubble residues can also affect the uptake of nutrients to crops in some circumstances. Cereal stubble from high yielding crops can have a carbon : nitrogen ratio of 80 : 1. When this residue is incorporated into soil it will provide a feedstock for soil microbes. Carbon from crop residues is the primary driver of soil microbial activity and this in turn leads to the release of plant nutrients. The problem here is that the microbes (bacteria and fungi) need other nutrients, particularly nitrogen to digest this carbon. Nitrogen is stripped from soil reserves to do this, hence there will be a short term tie-up of nutrients that are not available to the emerging crop. Farmers have the choice of adding more nutrient for the crop, having the stubble residue in contact with soil for a longer fallow period, or removing the stubble by burning to avoid these nutrient problems. Local research showed that grazing stubbles over summer helped to avoid this nutrient tie-up and redistribute the nutrients across the paddock. Care needs to be taken to not over graze the stubble and increase the risk of soil erosion by wind and water.
Farmers do their best to avoid any impact of smoke on nearby communities by observing some basic principles when conducting stubble burning, including -
• checking with the Bureau of Meteorology and local Rural Fire Authorities when weather conditions will be suitable for burning
• avoiding calm weather conditions that are associated with temperature inversions where smoke will hang in the air for long periods and can drift into local towns.
• burning stubble in the heat of the day with a good cross breeze to give a quick, hot burn.
• awareness of when winds will take smoke into neighbouring towns.
Burning stubble can be done at various strategic times for many reasons, but there is a need to be aware of the “big picture” how it fits into the farming system and how it can be done to minimise the effects on the community.
FarmLink is continuing its work in the GRDC Stubble Initiative to ensure farmers have the support of their local communities thanks to improved stewardship of stubble burning and ongoing sustainable farm management practices.

Feb 27

New FarmLink Seasons in Stubble video series

Posted by Cindy Cassidy at Friday, February 27, 2015

The first in what will become a series of videos documenting the GRDC funded Stubble Initiative being conducted by FarmLink has been launched on the FarmLink YouTube Channel.
The first set of videos in the Seasons in Stubble Series is featured below and can be viewed by following the relevant links. This is just another way FarmLink is keeping members informed about the groundbreaking research and projects being conducted throughout the FarmLink region. Further additions to the series will be created and uploaded as the Stubble Initiative research progresses.

FarmLink Research - Stubble Demonstration Day 2014 Intro video can be viewed at http://youtu.be/zpiF3js4U44
The demo day featured a range of equipment trials, with the following videos also available for viewing -
Harper Stubble Cruncher - http://youtu.be/SetVD1OH9Iw
K-Line Speed Tiller - http://youtu.be/t-2R5OexiuI
K-Line Trash Cutter - http://youtu.be/ILhAN8O12tw
Lemken Heliodor - http://youtu.be/3gq2XZ9MfFI

Harvest & Post Harvest
Stubble Management Project

For the past two years FarmLink Research and the GRDC have partnered to conduct a paddock scale experiment comparing plant growth, yield and profitability of different harvest and post harvest stubble management techniques.
The project is part of the GRDC Stubble Initiative and was established in December 2013 on the property of Ben and Lou Beck at Downside.
View the video about the project - http://youtu.be/M6USwWXl-Tk