Reap rewards of new growth

Date: 2008-04-01 | Category: Dairy News

Autumn is the key time for renewing pastures on many dairy farms. And for farmers considering the option, the first step is being convinced of the economics.

DairyNZ business developer Adrian van Bysterveldt and Graham Kerr, technical development manager of NZ Agriseeds, both part of the Lincoln University Dairy Farm’s management team, have found the typical rate of pasture renewal on dairy farms is around five percent annually. Renewing this amount means the farmer expects pastures to last 20 years, usually not enough to keep up with natural deterioration from dry conditions, weed invasion, pests and pugging.

Renovating 10 percent of the farm annually may be a better prospect but there are no specific recipes.

“It depends on the individual farm situation,” said van Bysterveldt.

To put the economics into perspective, a conservative example for an average-sized 120ha dairy farm shows the farmer loses 6ha/year by renewing only five percent of the pasture/year instead of 10 percent.
It’s assumed the renewed pasture grows an extra five tonnes of dry matter (DM)/ha than the old pasture – typical on many properties.

A 10 percent rate of pasture renewal over five years gives compounding results, and total increased income over five years would be $117,000.

The investment to renew pastures would have a direct cost of $500-600/ha for herbicide, cultivation, drilling, seed etc plus a larger cost in lost growth while the area is out of grazing.

One of the first comments from farmers showing an interest in renewing pasture is, “How can I do this with my high stocking rate?”
“The answer is: be prepared to feed silage or pay for supplements during the nine-week renewal period when there is potential feed shortfall,” Kerr said.

The following example assumes 2t DM/ha growth is lost during pasture renewal, so this amount of silage needs to be purchased.

So the increased income ($117,000) minus total cost ($42,000) means that the total return on investment is $75,000 over five years.

In the first year around six extra cows, and over the five years 25-30 extra cows, will be needed to utilise the new pasture, meaning extra costs but leaving a good margin for profit.

Van Bysterveldt and Kerr stress that in their experience these figures are realistic if farmers are renewing poorer paddocks and subsequent pasture management retains the new sward. They illustrate just how valuable productive pasture is.

“Farmers need to evaluate their own property and work out how much they grow in each paddock, to get an idea of potential benefit to them,” Kerr said.

“In my experience, a rate of 10 percent pasture renewal, and sometimes more, is about the right target.”

The figures only account for increased DM yield and ignore potential increases in production from using modern cultivars which have a higher metabolisable energy (ME) rate, additional endophyte benefits and increased digestibility.

Published courtesy of Dairy Exporter - April 2008

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