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Bringing New Life to Drought-hit Pastures

03 October 2008

AUSTRALIA - Planting a summer forage crop as an immediate feed source to relieve grazing pressure on pasture country subjected to a decade of low seasonal rainfall can give stressed pasture time to reseed and restore productivity.

Department of Primary Industries and Fisheries senior beef extension officer Ken Murphy coordinated a September 25 field day for CQ BEEF Bajool Group members to consider their management options to reinvigorate grazing lands.

Raglan district cattle producer David Parsons, Moncton Hills, and fellow group members have noted a steady degradation of their native and improved pasture species even when stocking rates were significantly reduced.

Mr Parsons said he appreciated there was no quick fix "silver bullet" solution but he said the group was keen to implement recommended best practice combined with favourable wet seasons to get their businesses back on track.

Guest speaker DPI&F principal pasture scientist Bob Clem said that planting a one-off summer forage crop of either lablab (formally Dolichos lablab) legume or forage sorghum to provide short term bulk feed provided a window to spell the balance of the pasture.

Mr Clem said that given a reasonable growing season, landholders could work on a stocking rate of a beast/0.4 ha for 60 days on an average crop (2.5 t/ha dry matter) or 100 days (5 t/ha dry matter) on a good stand.

"As a rule of thumb, lablab should deliver a liveweight gain of 0.7 to 0.8 kg/head/day," Mr Clem said.

"The advantage of using lablab is that, at the completion of its grazing contribution, this leguminous crop delivers a bonus of 30-90 kg/ha of available soil nitrogen.

"This approach sets up the paddock for a follow-up planting of either forage sorghum to utilise the nitrogen and boost the soil organic matter content or to lay the foundations for planting a permanent pasture grass and legume mix."

Mr Clem said he was not a keen advocate for planting a quick-response annual-forage cover crop in combination with a permanent pasture seed mix.

He said the resultant forage crop tended to shade out any emerging pasture seedlings and dominated competition for available soil moisture during the critical establishment phase.

Mr Clem said it was essential to prepare a seedbed for any pasture seed planting as ploughing helped the release of mineralised soil nitrogen, controlled weeds, opened the profile for water infiltration and soil moisture storage and promoted soil-seed contact for germination.

Field day visitors took the opportunity to inspect Cedric Creed's newly sown pasture mix of buffel and Bisset bluegrass combined with a legume mix of siratro, Verano stylo, Wynn cassia with a lablab cover crop.

Mr Creed said he had trialled butterfly pea and burgundy bean legumes on his coastal country but they had not performed to expectations.

Mr Parsons said he planned to prepare and plant 60 ha to forage crop this summer season and was reviewing the subsequent grass and legume planting mix selection for the shallow duplex soil.

Mr Clem advocated the drought tolerant Katambora Rhodes grass to utilise the available nitrogen in combination with Bisset or Hatch creeping bluegrass, that were less nitrogen demanding with good yield potential.

Soil tests undertaken at Moncton Hills showed soil phosphorus content ranged from 21 ppm to 122 ppm - quite adequate for pasture productivity.

Mr Clem said he would recommend Seca and Verano stylo legumes to the mix as they were both proven contributors to the animal's dietary protein requirements in the Central Coast environment.

While the short to medium height American and Gayndah buffel varieties were a drought-tolerant grass option, they tended not to persist because of their high nitrogen demand.

All landholders were avid supporters of pangola grass as it was drought tolerant, withstood heavy grazing and responded well with rainfall. Establishing pangola was the major issue as the need to plant vegetative cuttings on a large scale was labour intensive and time consuming.

There was also consensus that Wynn cassia tended to dominate pasture stands and was unpalatable until frosted in May-June when it was capable of delivering a 35 kg/head/year liveweight gain advantage.

Mr Clem told the group that as a management tool, he was not anti-burning pasture although there was a nitrogen loss. Timely burning of the less palatable, less productive Aristida (white or three-awned spear grass) could promote a resurgence of the desirable black-spear grass.

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