Flood-affected farmers may lose pasture species

Press, 3 February 1984, Page 25

Flood-affected farmers may lose pasture species

Southland farmers hit by floods may lose their main pasture species of ryegrass and white clover, according to a M.A.F. agrononmist at Invermay Agricultural Research Centre, Mr Bruce Smallfield.

Mr Smallfield said prolonged flooding or heavy silt coverage of pastures' was known to destroy ryegrass and white clover.

Although most of the affected farms in Southland were only under water for two days, the flooding has left heavy layers of silt covering pastures on the margins of the Waihopai and Aparima Rivers. Mr Smallfield said research had shown that

layers deeper than scm generally destroyed ryegrass and white clover.

“If, however, grass is poking through the silt, it may survive,” he said.

The plants most likely to survive are weeds such as couch and browntop. Recent survey work on dairy pastures damaged in the 1980 Tairei flood revealed that the best way to rejuvenate pastures is by cultivation or by direct drilling using herbicides. This would give the farmer a good ryegrasswhite clover pasture, said Mr Smallfield, who conducted the survey work.

Quicker, but less effective results can be achieved by

direct drilling without spraying, or by surface cultivation and broadcasting of seed.

“These methods are less effective because they result in more weedy pasture and, in the long term, grass production may be down,” said Mr Smallfield. “However, with the faster methods continuing feed can be provided.”

If a farmer cultivated or direct drilled (using herbicides) his entire property, he would be without grass for a period of from six weeks to three months.

Mr Smallfield suggested that farmers whose farms had suffered widespread flooding would be wise to

use a mixture of the long and short term pasture renovation techniques. “That is, on badly damaged pasture, farmers should cultivate or direct drill using herbicides and on less severely-affected paddocks they should either direct drill without spraying or lightly cultivate and broadcast the seed.” If the short term methods were opted for, paddocks should be given frequent but light grazing, he said. This would restrict competition from surviving weeds.

Mr Smalifield also recommended that farmers consider slug control if they had observed a lot of slugs in their pastures.