Summer rain proves perennial worth By Catriona Nicholls
W
elcome rain across much of southern Australia during spring and summer has showcased the benefit of summeractive perennial pastures. Producers and researchers across the country have been impressed with the ability of various species to respond to out-of-season rainfall and convert water into feed.
Northern exposure Across northern New South Wales, a run of dry autumns and wet November–Decembers has seen repeated failure of annual legumes but a huge response by perennial tropical grasses. Researchers are focussing their efforts on developing drought-tolerant perennial options to use this summer rainfall. Industry & Investment NSW researchers Dr Suzanne Boschma and Carol Harris are investigating a range of grass and legume pasture mixes to address persistence and production challenges in the region as part of the EverGraze® linked Productive Persistent Tropical Grasses CRC Project. “Traditionally native pastures and lucerne provide most of our feed during summer. However, despite lucerne being the most productive and persistent legume in the region, producers are hesitant to establish pure stands of lucerne because of the
i key points • Widespread summer rain across
much of south-eastern Australia has proven the value of summer-active perennial pastures
• In lower-rainfall areas in eastern Australia lucerne remains the standout performer for livestock producers
• Continuing impressive
performance by Tedera in Western Australian trials could see the perennial legume become and addition option for lowrainfall areas in years to come.
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Kondinin Group
associated bloat risk and poor groundcover,” Dr Boschma explained. “We are investigating a range of mixes based on lucerne to overcome these issues along with other annual temperate and perennial tropical pasture legumes in mixes with tropical grasses that will provide better grazing options and respond to summer rainfall.” Performance during the 2009–10 summer has showcased the ability of the perennial tropical grasses to capitalise on rainfall (see Table 1). “After a dry spring and hot, dry November, the region was inundated with about 200 millimetres of rain during the Christmas — New Year period,” Dr Boschma said. “In terms of our sown summer-growing species, everything responded to rainfall really well.”
ABOVE: Late summer rain in Western Australia saw perennial grasses, such as panic (pictured) flourish. The false break also instigated a flush of sub-clover germination, but without follow-up rain most seedlings died. (Photo: Geoff Moore)
above-ground production offered by perennials during the past summer at his trial sites near Tamworth, NSW. “Of the 199 mm of rain we received during late December and early January, the tropical perennial grasses had used most of it by the second week of February (see Table 2),” Dr Murphy said. “I’m constantly surprised at how quickly tropical perennial grass pastures use soil water.” Summer-active perennials tend to take up whatever is available and use it to grow herbage mass according to Dr Murphy.
Looking deeper
“That is why we are targeting the tropical species — they have a tremendous ability to use summer rainfall events and deliver high amounts of herbage.”
Industry & Investment NSW hydrologist Dr Sean Murphy saw more than just the
However, Dr Murphy warns that managing this production is quite challenging.
Table 1 Pre-grazing herbage mass and plant frequency of elite lines and cultivars of Megathyrsus maximus, Panicum coloratum and Chloris gayana sown in the grazing experiments at Tamworth and Bingara, NSW
Species
Tamworth
Bingara
November 2009 (kgDM/ha)
January 2010 (kgDM/ha)
November 2009 (kg DM/ha)
January 20 10 (kg DM/ha)
M. maximus cv. Gatton
534
4226
838
2269
M. maximus cv. Green
792
4179
808
1352
M. maximus (049)
644
4226
829
1858
M. maximus (050)
1029
4488
988
2773
M. maximus (057)
734
4289
942
2494
M. maximus (059)
542
4321
938
2061
M. maximus (062)
1136
4440
896
2451
M. maximus (066)
682
4353
913
2006
1519
4393
1113
2747
P. coloratum cv. Bambatsi P. coloratum (020)
1649
3983
963
1838
C. gayana cv. Katambora
1164
3965
1029
2447
C. gayana (018)
1656
3989
1213
2296
Average
1007
4238
956
2216
i n n o vat i o n
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p r o f i ta b l e
perennial
fa r m i n g
systems
“The perennials respond so vigorously to the moisture that producers may under estimate how much herbage mass will be produced,” Dr Murphy explained.
As a result, farmers are forced to pay a high price for less-than-ideal cultivars or choose to grow something else entirely.” The other impact of the rain was an influx of summer weeds according to Richard.
“It is not uncommon for producers to have insufficient stock to utilise the growth at the time. However, there are strategies to use the dry feed later during autumn even if follow-up rains don’t eventuate, which has been the case during recent years.
“Producers who didn’t have lucerne found themselves battling with an influx of weeds such as witch grass and black grass. “Where there are good stands of lucerne we didn’t see summer weed invasions.”
“We still have some way to go to understanding the best way to match the production capacity of these species with grazing strategies.”
Richard is currently looking at new lines of phalaris, cocksfoot and tall fescue.
Southern summer rains
“Unmanaged vigorous growth can increase the weed risk potential. Producers need to consider this risk in their production systems.”
Summer rains in south west Victoria produced good results in all of the perennials trialled at Hamilton. Department of Primary Industries Victoria researcher Steve Clark is quietly hoping for a hotter drier summer next time around to allow the potential of his new cultivars to show their worth.
Moving south Similarly, wet conditions were experienced across much of southern NSW and after 10 years of dry summers, producers who have stuck by lucerne finally found their persistence paying off according to Industry and Investment NSW research agronomist Richard Hayes.
“Normally, we hope to see big differences between existing cultivars and our new ones, but this summer everything survived,” Steve admitted. “Where we had summer rain, all varieties in our experiments demonstrated the value of perennials as they were able to grow feed over summer and persist.”
“Our experience during the past 10 years is that lucerne is the most drought-tolerant perennial species available for this region and the only practical option farmers perceive they have,” Richard said.
“That’s really what we are after, but the existing cultivars normally get quite stressed and with a couple of hot dry summers in a row you start losing quite a lot of plants.”
“Lucerne proved it’s worth, surviving the drought and summer rain saw survival turn to surplus — local lucerne growers had paddocks that were unable to be fully utilised due to lack of grazing power.”
“I expect the new cultivars to persist better.”
According to Richard, alternative species, such as chicory, are an option that persists only in higher-rainfall areas. Richard suggests producers in the lower-rainfall areas of southern NSW have perennial grass options such as phalaris and cocksfoot, but if these pastures are not yet established the current cost of seed can be prohibitive. Tropical grasses are not an option in the south due to a high risk of poor establishment. “Phalaris seed currently costs up to $24 per kilogram this season, compared with lucerne at less than $10/kg,” Richard said. “In addition, there are some desirable cultivars that are simply unattainable due to the effects of drought on seed production.
Heading west Throughout most of the northern agricultural region of Western Australia, conditions were dry from mid-November through to late March. However during mid-March as storms lashed Perth, the upside was the northern region received between 40–100 mm. According to Department of Agriculture and Food WA (DAFWA) pasture researcher, Geoff Moore, the subtropical grasses are tough and persist even through dry summers when there is no rain for up to seven months. This year the established perennials (a range of panic grasses and Rhodes grass), exhibited minimal growth during the dry, hot summer, but revived more or less overnight with the warm conditions and rain — unfortunately
Table 2 Soil water balance components (stored soil water, SSW) of a range of perennial pasture species for an eight-week period between December 9, 2009 and February 10, 2010 where total rainfall was 199 mm
Premier digit
Premier digit +Venus lucerne
Venus lucerne
Kasbah cocksfoot
Dalkeith subterranean clover
Start SSW (mm)
568
561
565
778
733
Rainfall (mm)
199
199
199
199
199
End SSW (mm)
570
578
596
845
839
2
17
31
67
106
Water use (mm)
197
182
168
132
93
Daily water use (mm/d)
3.1
2.9
2.7
2.1
1.5
Change in SSW (mm)
the story was the same for many of the annual pasture species. “At the same time as the perennial grasses reacted to the summer rain annual pastures germinated on the false break, particularly softened sub-clover seed,” Geoff explained. “There was a large germination of annual pasture and in some areas the pasture has hung on, but most of the germinating annual pasture has died. “Unfortunately for producers, a high proportion of the seedbank will be lost, especially for species like subterranean clover.” The picture for perennials is much brighter as the rain produced good quality feed to carry the animals through the autumn feed gap. “As a rule of thumb, subtropical grasses will produce 20–30 kg/ha per mm of rainfall over the summer-early autumn period (assuming rainfall events of >20 mm over seven days),” Geoff said. “New perennials sown last spring generally looked good prior to the rain in March as they were growing into subsoil moisture and with the rain these pastures have provided valuable grazing in their first autumn.” While lucerne is the main perennial legume, not a lot is grown across WA and the potential of Tedera still has researchers excited. Once again, experimental plantings of Tedera has shown that through a tough dry early summer, where lucerne drops its leaves, Tedera remained green and didn’t wilt,” Geoff said. “After the rain, the perennials legume really jumped away. “A commercial release is still a few years away but a recently formalised agreement with three Spanish research institutions ensure continued access to a broad range of genetic material.” EverGraze — More livestock from perennials is a Future Farm Industries CRC, Meat & Livestock Australia and Australian Wool Innovation research and delivery partnership.
More information Dr Suzanne Boschma, I&I NSW T: (02) 6763 1202 E: suzanne.boschma@industry.nsw.gov.au Dr Sean Murphy, I&I NSW T: (02) 6763 1244 E: sean.murphy@industry.nsw.gov.au Richard Hayes, I&I NSW T: (02) 6938 1615 E: richard.hayes@industry.nsw.gov.au Steve Clark, DPI Victoria T: (03) 5573 0977 E: steve.clark@dpi.vic.gov.au Dr Geoff Moore T: (08) 9368 3293 E: geoff.moore@agric.wa.gov.au
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