Late developer worth the wait

Date: 2009-01-01 | Category: Sheep & Beef News

There is nothing bashful about arrowleaf clover.

It grows tall with big leaves and long stems.  The annual clover, originally from the Mediterranean, is developing a reputation for rocketing growth in late spring and summer.  During November and December it grew 153kg DM/ha/day in a Lincoln University experiment.

But scientists agree that arrowleaf's potential is still to be explored.

"We are still wondering about its niche," says Dick Lucas, Lincoln University legume scientist and enthusiast.

Two sets of demonstration plots were sown in Marlborough for the 2008 Grassland Association Conference fieldays at Bonaveree and Tempello.  Marlborough Monitor Farm owner Chris Dawkins has a ryegrass and arrowleaf clover pasture.  DLF Seeds has trial plots near Christchurch airport.  While DLF Seeds has only been selling Arrotas (variety of arrowleaf clover) since 2008 it has been sown in Hawke's Bay and Southland, as well as Marlborough and Canterbury.

Although early days for the clover, initial signs are positive.  The establishment and growth have pleasantly surprised Lucas.

"I was amazed when I visited the Dawkins' farm mid-November for the Monitor Farm day."

Arrowleaf was a hot topic of conversation among the farmers on the tour.

Despite being waterlogged in winter, which it hates, it survived and clover is now dominating in a ryegrass/clover pasture.  The Grassland field-day single-species demonstration plots should make it to over 12t DM/ha.

Speaking at the 2008 Grassland conference in Blenheim, Pedro Evans, plant breeder with DLF Seeds, says arrowleaf can be used several ways.

Farmers can grow it as single species or mixed with other species.  On its own, it can produce a high-quality crop for silage or for strip grazing.  In Southern United States it is grown together with oats or annual ryegrass crops, to help boost animal performance over summer.

Another option is to add arrowleaf clover to permanent pasture swards, to improve pasture quality.  This is similar to how subterranean clover is used.  When included with perennial ryegrass in an Australian experiment, the utilisation of the low quality grass during early/mid-summer increased by at least 1000kg DM/ha.

In its first year, pasture sown with arrowleaf can be grazed several times, after autumn establishment.  Then it should be shut up by late November/early December.

It provides quality feed in the late spring to summer period, when other annual clovers have finished and grass is going to seed.  It retains high grazing preference during the flowering stage, even though the stem content is high into late January.

"It's good for extending the growing season," says Evans.

"It will grow another four to six weeks longer than the late flowering sub clovers like Leura."

Evans expects that, as the seed is particularly prone to being ‘hard-seed', it is unlikely to germinate in the second year but in the third year.  This means farmers should not expect to see many arrowleaf plants in the second year-but the seed will still be there.

Arrowleaf grows slower than sub clover in winter.  About 60% of its total yield is produced from late October onwards when most other annual clovers are dying back after flowering and producing seed.

Another option is to use it as a soil fertility-building crop.  If sown on its own in autumn in year one it can then be followed by a winter crop in year two.  As it grows it fixes nitrogen (at a rate of 25kg of N/t DM) so it sets up the soil for the next crop or pasture.  A 10t crop pumps around 250kg of N into the soil.

Ten kilograms of seed per hectare at around $7/kg gives a total seed cost of $70/ha.  This includes inoculant.  Spray, direct drilling or cultivation costs are on top of this.

However, if the crop produces 10t it should fix 250kg of N (equivalent to around half a tonne of urea per hectare).  This urea would cost around $450 to give the same result.

Evans says it is possible to have success oversowing arrowleaf seed on to sprayed out hill country pasture.

"One farmer in Hawke's Bay successfully broadcast seed onto sprayed hills that had been ‘tickled' with an implement to roughen the surface."

Another option is to not spray but prepare the ground by hard close grazing by sheep, then oversow arrowleaf seed in autumn.  But there are risks to autumn oversowing for all annual clovers.  Timing sowing with rainfall and removing grass cover (down to at least 700kg DM/ha) are critical.

Arrowleaf establishment, like many seeds, is usually most successful when sown into a worked seed bed.  Conservation tillage (direct drilling into sprayed soil) is also successful.  However, seed must be shallow sown-no more than one centimetre deep.  It needs group c inoculant-the same as that used for sub clover.

Lucas's "best guess" is avoid grass competition in year one and sow alone or with sub clover or Balansa clover.  Let it flower and set a large seed bank.  Then go in with winter crop and possibly summer rape in the wetter districts.  But in drier areas use a summer fallow to conserve moisture before sowing permanent pasture. 

Use a low grass rate (5kg) with 5kg of sub clover and anticipate a good strike of arrowleaf.

Published courtesy of Country-Wide - February 2009

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