- Sow early to maximise the biomass available for livestock.
- Early and lighter grazing will maximise livestock benefit with minimal impact on crop yield.
GroundCover™ Supplement Issue: 129 | 15 Jun 2017 | Author: Philip Barrett-Lennard
Over the past decade, mixed farmers in Western Australia have increasingly embraced crop grazing as a tool to improve livestock productivity and whole-farm profitability. However, with much of the information initially based on research and experience from eastern Australia there were concerns about the impact on crop yields in the WA environment.
In most crop-grazing trials in WA, grazing reduced crop yield. While crop grazing can improve whole-farm profits, in many cases growers simply swapped cropping income for livestock income.
Growers hoping to adopt crop grazing need to look at how the whole farming system needs to be adapted. Without these changes, whole-farm profit is likely to remain unchanged, or even decline, as too much crop income is sacrificed in the pursuit of additional livestock income.
The keys to improving whole-farm profits through crop grazing are to:
Sowing crops destined for grazing early has a huge impact on the amount of biomass available for grazing in late autumn and early winter. In most seasons, mixed farms in WA suffer from a feed shortage in late autumn and early winter. Supplementary feed, such as grain and hay, is typically used to fill this feed shortage. Early-sown crops potentially offer a cost and labour-effective alternative.
In Grain & Graze trials at Wickepin, WA, in 2014 and 2016, crops sown in mid-to-late April produced significantly more early winter biomass than late-May-sown crops (Figure 1). Crops sown in late May produced 50 to 200 kilograms per hectare of edible biomass by early to mid-July, while April-sown crops produced 400 to 2200kg/ha of edible biomass by early to mid-July, with approximately 50 per cent of that biomass available by early June.
Grazing crops lightly (‘clip’ grazing the top of the plant) and early in the growing season results in far smaller yield reductions than heavier and later grazing.
When crop grazing is managed appropriately, yield reductions in the zero to 10 per cent range should be expected.
Western Australia has fewer early-sowing opportunities than eastern Australia, so the vast majority of crop grazing is conducted on standard ‘grain only’, spring-type crop varieties. Wheat, barley, oats and canola are all suitable and used for grazing in WA.
But growers chasing the extra biomass from early sowing will need to plant a winter-type cereal with a vernalisation requirement for flowering. Standard spring varieties will develop prematurely in response to the warmth and photoperiod of autumn.
The most popular choice for early sowing is the barley variety Urambie, a winter feed barley with early vigour and early maturity that is commonly grown in Esperance. Some winter wheat varieties being sown early by WA growers include Currawong and Revenue, both winter feed wheats, and EGA Wedgetail, a winter milling wheat. However, the problem with all the available winter wheats is that their flowering date is too late for the vast majority of the WA grainbelt. A fast-maturing winter wheat variety, which can be sown early but will still flower at a similar time to spring cereal varieties sown in May is needed. The variety RAC2341, soon to be released by Australian Grain Technologies, is expected to fill this gap.
In Victoria, many growers have successfully sown winter-type canola in spring to provide grazing over summer–autumn.
Unfortunately, most of the available winter-type canola varieties are very late flowering and not particularly suitable for WA, although some growers in the Great Southern and South Coast are experimenting with these varieties.
Crop yield loss is largely governed by the timing and intensity of grazing, but also by the interaction between grazing and other environmental stresses, such as heat, moisture stress and waterlogging. Grazing delays flowering, which can push the flowering date away from frost, having a positive effect on yield, but can also push grain fill into a period of hot and dry conditions, and thereby having a negative effect.
Growers are not advised to use grazing as a frost management tool – altering crop type, variety and sowing time are proven and reliable options and do not come with the risk of incurring a yield penalty from overgrazing.
While grazing with a high stocking rate for a short period is preferable to avoid overgrazing and to speed crop recovery, the low stock numbers and large paddock sizes in WA make this less practical. In most situations, a low stocking rate over a longer period will be successful. The only downside of a low stocking rate is that livestock will often graze a crop unevenly. By keeping the grazing period relatively short – two to three weeks, for example – the unevenness rarely causes too many problems.
GRDC Research Code FGI00010
Philip Barrett-Lennard, agVivo
0429 977 042
‘Tips for crop grazing’, western region video
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