Light stubble grazing doesn't reduce crop yields
Author: Natalie Lee | Date: 04 Dec 2014
Light sheep grazing of crop residues over summer in no-till systems does not negatively impact on subsequent grain crop yields, soil health or ground cover, Western Australian research has confirmed.
But grazing the same paddock throughout the year – such as in a pasture phase – can significantly reduce residue levels and potentially lead to reduced water infiltration and lower crop yields, especially on heavier soil types.
The research was conducted at Wickepin, Yealering, Cunderdin and Meckering as part of the $12 million national Grain & Graze 2 program, funded by the Grains Research and Development Corporation (GRDC) and the Federal Government's Caring for our Country initiative.
The University of Western Australia (UWA) carried out the research from 2010 to 2013, in conjunction with the WA No-Tillage Farmers Association (WANTFA) and the Facey Group.
UWA agronomy lecturer Ken Flower said it had been suspected that light sheep grazing did not reduce grain yields and soil health in WA’s no-till farming systems, as long as sufficient crop residue was retained to prevent wind erosion and maintain water infiltration.
“The Grain & Graze 2 research in WA has confirmed that this is the case and similar results have been found in trials in other states,” he said.
“Results show that carefully managed grazing in summer can preserve topsoil structure and water infiltration and have no impact on compaction and subsequent crop establishment and yields.”
Dr Flower said the WA results suggested that growers could safely use summer stocking rates of up to about four dry sheep equivalent (DSE) per hectare, or a grazing intensity of about 150-200 DSE days/ha.
“This level of grazing was enough to maintain 50 to 70 per cent of ground cover in the trials, or about 2t/ha of cereal stubble cover,” he said.
“Sheep should be monitored regularly to ensure that residue levels do not fall below 50 per cent.”
There were no significant differences between in-crop weed numbers for the grazed and ungrazed plots.
Dr Flower said Grain & Graze 2 modelling work indicated that the value of grazing crop stubbles was about $6.70 per hectare of crop or $2.40 per tonne of stubble for a typical farm in WA’s central grainbelt that was 80 per cent cropped.
GRDC resource management project manager Tanya Robinson said the four-year Grain & Graze 2 program had overseen some significant changes to farming practices.
“At the program’s completion in 2013, Grain & Graze 2 had delivered an estimated cumulative net profit to Australian growers of $100.2 million through better management of stubbles, increased stocking rates and adoption of novel rotations and fodders,” she said.
Grain & Graze entered a new three-year phase in July, 2014, with a focus on risk management, grazing cropped lands and crop/fodder rotations in southern and western regions of Australia.
More information about Grain & Graze 2 research is contained in a GRDC supplement which was mailed to growers with the November-December edition of the GRDC magazine Ground Cover and is available at www.grdc.com.au/GCS113.
To subscribe to Ground Cover visit www.grdc.com.au/groundcover.
Caption: Sheep grazing summer stubbles in WA. Photo by Sarah Hyde, Facey Group.
Ken Flower, UWA
08 6488 4576, 0417 952 080
Tanya Robinson, GRDC
02 6166 4500
Natalie Lee, Cox Inall Communications
08 9864 2034, 0427 189 827
GRDC Project Code FG100007