Increasing fertiliser nitrogen price shows how important it is to go biological with clover says Hamilton-based Soil Scientist Dr Gordon Rajendram (PhD).

Waikato-based Soil Scientist Gordon Rajendram PhD is considered one of New Zealand’s experts in soil fertility. He is committed to helping New Zealand farmers get the most out of their soil so that their farm can work more proficiently, be sustainable while still increasing the farm profitability. Dr Gordon Rajendram worked at AgResearch, Ruakura Research Centre, Hamilton.  He has developed two fields of calibrated soil tests (N & S) which are used for agronomic advice in NZ and his work on leaching has been included in the Overseer nutrient model.

The ever-increasing price of urea has highlighted the value of growing clover to fix nitrogen (N) advises New Zealand’s leading expert in soil fertility, Hamilton-based Soil Scientist Dr Gordon Rajendram (PhD).

“This increase in Urea price (~$850/tonne) and the 190 N rule may be a godsend as farmers reliant on mineral nitrogen will need to utilize more efficient ways/technologies of applying nitrogen fert and now need to grow more clover to fill this gap,” says New Zealand’s leading expert in soil fertility, Hamilton-based Soil Scientist Dr Gordon Rajendram (PhD).

Research shows that above 200 kg of N the fixation of N by clover decreases to where if 400 kg of N/hectare was applied zero fixation of N occurs. 

White, red, and subterranean are predominant clovers growing in NZ with white best or most persistent for NZ temperate climate. 

“The country’s high-quality primary products are internationally competitive due to a predominate ryegrass and white clover pasture mix, which responds favourably to our temperate climate,” comments Gordon.

The annual financial contribution of white clover cannot be overstated. White clover contributes to the economy of New Zealand indirectly through fixed nitrogen, forage yield, seed production and honey production and is estimated to be more than $3 billion.

“White clover benefits pastoral agriculture through its ability to fix nitrogen, its high nutritive value, its seasonal complementarity with grasses, and its ability to improve animal feed intake and utilisation rates,” says Gordon.

The potential N-fixation rates from white clover can be as high as 700 kg N/ha/year, however the presence of fertiliser nitrogen and factors can limit white clover growth. These factors include moisture stress, low soil fertility and pH, grazing and grazing management, temperature and since 1996 the clover root weevil.

As a result of these pressure factors, annual nitrogen fixation levels from white clover in grazed pastures are extremely variable, ranging from 20 kg N/ha/year in infertile, unimproved hill pastures to 400 kg N/ha/year in intensively managed pastures.

It is without a doubt that white clover is the key to the competitiveness of our agricultural products on international markets. White clover is considered the best quality component of grazed pastures because of its high nutritive and feeding value.

After all, nitrogen has been the base of our pastures for more than a century except in our very driest regions, providing a cheaper source of nitrogen than fertiliser nitrogen. Yet nitrogen deficiency still limits agricultural production.

“The challenge over the next decades will be to improve the reliability of white clover to increase annual inputs from N-fixation and effectively integrate the strategic use of fertiliser nitrogen without losing the benefits from white clover,” says Gordon

Live weight gains of animals fed white clover are consistently higher than for those fed perennial ryegrass. Research has shown that gross milk yields are higher from cows fed white clover than ryegrass.

The higher live weight gains and milk yields on white clover are due to the higher voluntary intake rates and by the higher gross efficiency (gain per unit of intake). Metabolizable energy consumed was approximately 40% higher for white clover than perennial ryegrass.

White clover has a lower resistance to chewing than grasses because it has less cell wall and fibres is lower.  The lower resistance to breakdown during eating and ruminating results in 10–35% higher intake rate of white clover than perennial ryegrass.

It was clover and N fixation expert Professor Walker that once said, “Any fool can grow ryegrass, but it takes a real farmer to grow clover”.

About The Soil Scientist

Gordon is dedicated to helping all farmers get the most out of their soil so that their farm can work more efficiently, be sustainable while improving the farm profitability.

Contact Gordon:


Phone: 021 466 077





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