Southern pasture renovation options

Beef Central, 24/08/2011

The Victorian DPI is urging farmers to take full advantage of the short window of opportunity that exists to renovate pastures.With only a short window of opportunity available to farmers to renovate paddocks this year, the Department of Primary Industries in Victoria has issued the following advice on how to make the most of the time available:

Conditions suitable to renovate paddocks might be as short as a fortnight, and the Department of Primary Industries is recommending farmers start planning now to optimise the opportunity.

It is likely pugged paddocks will dry out enough in September for some farmers to consider pasture repairs.

DPI Pasture and Fodder Conservation Specialist, Frank Mickan warned the window of opportunity, where soil conditions are ideal for sowing, might be as little as two weeks.

“Cultivating soils that are too dry can create a paddock of hard sods, while direct drilling when the soil is too wet will cause smearing and compaction,” he said.

“Where rolling is required to smooth paddocks, the best conditions are when the soil can be just moulded.”

He listed the factors farmers need to be considering now.

Is renovation necessary?

“Look closely at the density of the pasture to determine if renovation is necessary,” he said. “It only takes one grass tiller to make a full-sized plant. Given favourable conditions, a tiller can become a full-sized plant over spring and summer.

“One grass tiller in an area the size of a drink coaster can be enough to get back to a productive pasture, however re-seeding a sparse pasture will speed up the recovery process.

“If the damage has only occurred in specific areas of the paddock, consider repairing this area only. Separate the remainder of the paddock using temporary electric fencing, grazing it as normal.

“Alternatively, the undamaged section could be cut for silage or hay while allowing the damaged part to recover.”

How much to renovate?

While it is desirable to have all pastures fully productive as soon as possible, be careful not to have too much area cultivated.

Frank suggested the following rule of thumb: No more than 10 per cent to be cultivated for crop and/or pasture.

“Any remaining area could be considered for oversowing in early spring or resowing in autumn,” he added. “Again, don’t renovate too much area in autumn as it will have implications for both trafficability and autumn/winter feed supply.”

Pasture renovation options

Rolling only: Rolling only will not increase pasture production. Rolling is used to level out rough paddocks.

“If rolled too early, when the soil is still too wet, the tractor wheels will leave ruts and the rolling itself may overly compact the soil. This is especially so in soils of high clay content such as heavy clay loams,” said Frank.

“Rolling too late might have little effect. The heavier the roller, the better the job – assuming it is done at the ideal soil moisture.”

Broadcast seed + harrow or roll: This method has been shown to be a good option in past research, he said.

“Broadcasting allows the seed to be spread evenly over the ground surface and the soil seed contact is ensured by the harrowing or rolling. The preferred sequence for ensuring good seed soil contact is to harrow beforehand then broadcast,

followed by the rolling. Consider increasing the sowing rate, compared to drilled rates.

Drill + harrow: This has been shown to be beneficial as long as the soil is damp and friable and suitable for sowing.

“If it is too wet, the seed chute can smear the soil,” Frank said. “This makes it difficult for the seedling roots to penetrate the smeared walls of the slot, which then holds water if rain occurs, possibly rotting the seed.

“The problem becomes much worse if sowing is followed by hot weather, which hardens the smeared walls even more.”

Power harrow + drop seed + light harrow or light roll: The power harrow can be set for 2-3cm depth and this will ensure a reasonable levelling of the ground surface. This method will open up/aerate the soil to working depth.

“However, don’t use this method if it creates a soil compaction layer,” Frank warned.

Discing + power harrow + drop seed + roll: Discing in too-dry conditions can create a paddock of hard sods, or – if too wet – can cause smearing.

“However, in the correct conditions, this treatment could be beneficial in aerating the soil to a reasonable depth while providing the best seedbed. With deep and severe pugging, a full renovation will probably be needed,” said Frank.

What to sow?

Spring sowing of pasture and other small-seeded species is a viable option provided seedlings are well-established (about eight weeks from sowing) before hot or dry conditions arrive.

Summer cropping followed by autumn pasture sowing can be a good way of filling a feed gap. Consider what area is to be sown, and to which summer crops and when. Select crop species with different maturity dates and stagger sowing

times to provide a continuous supply of crop, avoiding it all being ready at once.

Plus, consider the following:

  • Seed might/will rot if heavy rains fall after sowing
  • Before summer crops are sown, soil temperatures (measured at 9am at 10cm depth) need to be: brassicas, 12oC, millet, 14oC and sorghum, 16 to 18oC
  • Flats will be cooler than the hills
  • North-facing slopes will be warmer than south-facing slopes
  • Regrowth crops (hybrid brassicas) grow fast and provide early feed plus summer regrowth (if moisture permits). They might even provide winter feed if well managed.
  • Watch nutrient balance in diets (lot of brassica and lot of grain could cause acidosis)
  • If sowing a mix (eg with rape), match maturity times and adjust the sowing rates
  • Consider using a short-term perennials to increase summer grazing (eg. chicory) and then oversow next autumn with winter forage cereal or ryegrass
  • Consider compatible mixes such as a millet and a regrowth brassica.
  • Watch all crops very carefully at germination and soon after, especially if seed has not been treated. Red-legged earth mite, lucerne flea, slugs, diamond back moths, etc. can decimate crops as they germinate. Particularly watch for pests in seed furrows; they move and decimate plants unseen along the trench.

DPI Victoria


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