It's all coming up clover

It's all coming up clover

By Janette Busch

Recent research by scientists at Lincoln University has shown pasture growth increased when subterranean clover, an annual species of clover, was over-drilled into grass-dominant dryland pastures in drought prone areas.

Over-drilling, is where new seed is put into an existing pasture to revitalise pasture growth instead of replanting the pasture, which is a more expensive option.

Since the 1980s scientists at Lincoln University have undertaken research to investigate new pasture combinations and planting regimes to increase pasture yields for grazing animals during times of drought.

"At important part of farmers' pasture management is to ensure pastures receive adequate supplies of nitrogen," says Professor Moot, programme leader in the Faculty of Agriculture and Life Sciences.

"However, New Zealand's aspect in the southern ocean means that the east coast of both islands experience droughts in summer causing on-going challenges for farmers to provide adequate high quality feed for their stock."

"Scientists from the Faculty of Agriculture and Life Sciences have shown that farmers can increase herbage production by over 40% if they over-drill their struggling pastures with subterranean clover in autumn" says Professor Moot.

A two-year study was carried out at Ashley Dene, Lincoln University's dryland research farm. Groups of sheep were set-stocked (allowed to graze for a set period of time) on five different combinations of pastures in the spring and then rotationally grazed on the different pastures during summer and autumn.

Dry matter production, daily growth rates and botanical composition measurements were taken from the five pastures to allow comparative analyses to be made.

While the value of subterranean clover for permanent pastures was demonstrated at Ashley Dene in the 1940s this study specifically looked at its benefit in maintaining and improving pasture during times of stress, as experienced under drought conditions.

"Using nitrogen provided by legumes such as clover through nitrogen fixation was also a cost effective way to increase soil nutrients rather than by using nitrogen-based fertilisers, which were expensive to apply," says Professor Moot.

Traditionally New Zealand pastures have been a combination of ryegrass and white clover sown together. White clover is a perennial plant with a single tap root that thrives in the wetter areas of New Zealand but struggles to survive in drought prone areas.

"Subterranean clover is an annual clover that is a dense-low-growing crop with shallow roots that allow it to thrive in the 11% of land area in New Zealand that receives less than 800 mm annual rain," says Professor Moot.

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