Soil biology is key to saving fertility
Complacency is costing us some of our best soils, says ecologist and educator Nicole Masters.
New Zealand is losing 11 tonnes of topsoil per hectare a year, more than 10 times the global average, she said during a recent Beef + Lamb New Zealand field day held at Claire Parkes and Simon Vincent's farm near Wakefield in the Nelson region, and attended by about 35 farmers.
"We live in one of the most blessed soil environments in the world.
"We are fertile, we have good carbon and beautiful rainfall, but we are losing all this topsoil and it's not sustainable."
Australia, where she did a lot of work attempting to restore soils depleted by sedimentation, was paying the price for a lack of action.
She wants farmers here to be proactive and take a more holistic approach to managing their properties.
Many already knew through keen observation much of what needed to be done and just required help "putting all the pieces of the puzzle together".
Masters, a director of Integrity Soils and spokeswoman for the Association of Biological Farmers, said focusing on soil health was not only good for the environment, but made economic sense.
"If you are not looking after your underground workforce, it will cost you in fertiliser use and retention, erosion control, sedimentation and water quality."
Many animal health and weed problems could be traced back to the soil, she said.
Farmers often didn't put enough lime on their pastures and got hung up on the pH of the soil when that had little to do with it.
"Calcium is really the foundation of a soil system and of bodies and what goes out the gate, yet it's quite often not looked at."
Nelson was fairly typical in that it had some soils high in magnesium which required more calcium to provide a balance, she said.
Even where soil tests showed there was adequate calcium, it was often not available because the soil lacked fungi.
"Calcium and fungi have a very intimate relationship and fungi is what holds soil together."
Farmers could improve their soil biology by adding humic acid, fish oil or seaweed when applying fertiliser, Ms Masters said.
"It's very simple stuff and it makes a big difference.
"Most farming systems we look at might have the equivalent of one angus steer per hectare in biomass, but if you manage your soil biology you can have five angus bulls per hectare under there."
Better biology also meant soils didn't release as much greenhouse gases.
More attention needed to be paid to pasture and grazing management as a way of improving pasture and controlling weeds, she said.
AgResearch had recently discovered that if thistles were mown in the rain, it allowed a fungi to get in and kill them.
"Farmers have been doing this for more than 20 years. They just didn't know why."
Overseas research showed longer grazing rounds encouraged grasses to grow deeper roots, crowding out weeds and making them easier to pull out.
A similar approach could be tried on Chilean needlegrass, which was a problem in Marlborough and Hawke's Bay, rather than resorting to using a previously banned chemical for control, she said.
Instead of farmers stocking animals in large paddocks for long periods, they should be rotating bigger mobs "harder and faster".
"So you might not be coming back to pastures for 30 to 50 days and those grass roots really get down there and outcompete weeds quite quickly."
Too often pastures were kept too short and therefore didn't develop rooting depth, which made them susceptible to extreme weather and climate change, Masters said. Without adequate biology, soils could not act like a sponge and were more easily washed or blown away.
While adopting better soil health practices was "not sexy", it could bring big lifts in production, although it was better to focus on quality rather than quantity.
"It's like preventive health in humans. Instead of going to the doctor for pills, you go for a run, stop smoking and drinking all that booze and get more sleep.
"It's about applying the same principles to soil.
"For so long we have focused on just one part of the soil - the chemistry - whereas physics and biology have just as much a part to play.
"It's not necessarily what farmers and consultants are talking about, but I think there is a growing awareness about the key role of biology and how to harness it."
Dennis Meade, who farms in Sherry Valley, said the field day reinforced much of what he was already doing, including doing regular worm counts and using more reactive phosphate rock fertiliser rather than superphosphate.
He had also halved his cattle herd and increased his sheep numbers in an effort to reduce winter pugging and soil compaction on his property.
Tadmor farmer Brent Hodgkinson said Masters' visit had been well worthwhile and a refreshing change, which fertiliser co-operatives should take more notice of.
"She made the very valid point about how much was spent on chemistry rather than on biology. It was good because there wasn't a sales pitch where a particular product was pushed."
He was keen to see more of his Beef + Lamb levy spent on soil research.
The soil health field day was one of three run in the South Island this month as a pilot.
Beef + Lamb northern South Island extension manager Ian Knowles said turnout and interest had been so good it was considering holding them around the rest of the country.
- © Fairfax NZ News
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