Many in the agricultural industry had forgotten how to grow a clover-based pasture that was once the basis for New Zealand’s pastoral agriculture and were now spending more money to achieve poorer results, he said.
“It costs three to four cents to grow a kilogram of clover drymatter (DM) and it costs 12c to grow a kilogram DM of fert nitrogen.
“A farmer looks at their pasture and they look like they’re running out. And they’re encouraged to use bag nitrogen which works for four to six weeks before the pasture goes back to what it was. If they attended to getting their clover going, they would have 150-200kg nitrogen a hectare from that source.”
He considered it the biggest problem in nitrogen management on dairy farms and widespread, with farmers ending up paying more money for their nitrogen source and achieving poorer-quality pasture than the clover option.
“We’ve forgotten how to grow clover-based pasture and we’re covering that up by using fertiliser nitrogen and using supplements.”
An ideal pasture should have between 30% and 40% clover content, which should fix 200kg N/ha for free, if it’s looked after properly, he said.
“Clover has a high requirement for nutrients and the whole fertiliser programme should be directed to getting the clover up to speed. Clover likes its nutrients and you can only grow clover with all 16 nutrients, so you want to get the balance right. And it can be done readily.”
He said few farmers knew what good pasture really looked like because they had depended on fertiliser nitrogen for so long.
Environmentally, clover nitrogen had the same effect as fertiliser nitrogen applications on the pasture, he said. Both clover nitrogen and fertiliser nitrogen had to pass through an animal and hence the urine patch that was the source of most leached nitrogen. Adding fertiliser nitrogen or increasing clover nitrogen resulted in more animals and hence more urine nitrogen increasing leached nitrogen.
