Methven farmer Hamish Marr, Waikato’s Colin Jackson, Mid Canterbury’s Angus McKenzie and South Canterbury’s Mike Porter were on a farmer panel answering questions at the Foundation for Arable Research (FAR) conference in Lincoln.
Mr Jackson came from a dairy farming background with his family growing maize in the mid-1970s.
"When I describe myself and system I’m putting my hand up and saying I’m the guy you don’t want to be," he said.
He went share milking in 1990 and grew the dairy business, retaining an interest in cropping maize grain.
The system changed to maize silage and annual ryegrass over winter for 900 dairy cows.
The dairy business was sold and the priority now is arable farming on poorly-drained clay soils initially with 9% organic matter.
He said tillage was easy and competition-winning yields were high in the early days.
Then tillage became harder, yields reduced and soil organic matter fell to about 3.5%, he said.
"Over time it didn’t feel right that we were leaving the soil in poorer condition and productivity-wise poorer than it was when we started. So there’s been a shift in our philosophy."
They are trying to restore the soil now with soil mapping and testing grids and zones and treating the soil differently with a move to strip tillage to reduce cultivation. Ryegrass is sown in between permanent rows of maize and clover on the maize rows over the winter.
Winter crops are no longer grazed — even though regenerative agriculture suggest they’re good for the soil — as they were doing too much damage to wet soils.
"It took 30 years to deteriorate the soil, but I’m hoping it’s going to take less to restore it."
Mr McKenzie and his family specialise in forage seed production — mainly grasses, herbs and brassicas with some cereal — at Wairuna Farm on the coast south east of Ashburton. Most of the crops go through combine harvesters, while some land beside the beach is forage cropped.
"We are fairly well invested into our soil health and quality journey. To me crop health is as important and is the best indicator of what our soil health is."
When he was working in the graduate programme at FAR the former chief executive Nick Poole told him that cultivation was just for the seed drill, but there were "horses for courses"and farmers needed every tool in the tool box.
"Much to my father’s disgust that last one really hit home — every tool in the tool box to solve your establishment and [everything else] so on our farm we have four drills and it’s horses for courses on the different crops we grow and to be able to drill a paddock with a system that suits the crop."
Mr Porter has just under 500ha mostly in steep hills in dryland South Canterbury with the steepest paddocks they crop at an angle of 27 degrees.
Concerned about soil erosion they decided to do away with tillage.
"We haven’t cultivated anything since and this is year 25, yet they said it wouldn’t last."
He said they had made more progress in the past five years than the 20 years before because of cover crops.
"That led us down the track that we we now steadfastly follow all five tenets of regen-ag philosophy which is little to no soil disturbance, soil armour, living roots, diversity — we have a 10 crop rotation — and re-integrating livestock into the arable system."
Mr Marr farms at the edge of Mt Hutt on a 500ha traditional mixed Canterbury cropping operation.
The farm is in two separate cropping rotations with 100ha of pasture and about 100ha of cocksfoot.
"We keep those things very separate basically for grass weed control and run a traditional mix of arable crops among all that at the same time as well as grazing lambs and winter grazing cows."
He replied to a question that he would consider removing cattle from grazing winter crops if he was purely looking after soil health.
"In terms of grazing pasture there’s nothing wrong with cattle on grazed pasture."
He said they had grown kale, fodder-beet and other winter crops. High yielding fodder-beet was good for the farm income, but they had stopped growing it because it impacted on soil quality.
"Our wintering of cows is done on rape and greenfeed oats and some grass and also swedes and kale. We specifically grow those things because cows and cattle are over them very quickly."
The break size of greenfeed oat crops was larger than fodder beet so the stock moved through them quickly, he said.
"So it’s about managing what you do in a way that provides you income, but looks after the soil."
Mr Porter said livestock were integral for growing cover crops for regulating the amount of above-ground biomass at drilling time and for preparing a seed bed under no-till.
He said soil compaction was caused by pressure and a nutrient imbalance so they were careful to retain 25% of air in the soil structure by keeping farm machinery on tram lines.
Some crops with large tap roots were good for compacted soils, while others such as oats with a fibrous shallow roots system were good for alleviating soil compaction at the top, he said.
Mr McKenzie said they had not run mixed-age cattle on their farm because they had heavy soils , but they had dairy heifers.
"We view grazing intensity like tillage intensity so the higher-yielding crop and the heavier class of stock more damage to the soil."
Mr Marr said they direct-drilled, minimum-tilled and ploughed some crops such as cocksfoot — as it can come back to "haunt you" later on if direct drilled.
"You’re actually better to ... fix the problem. So it’s about being open to whatever fits the scenario at the time to give you the best result in the end."
Cocksfoot seed was in the ground for five to six years and helped to remove soil compaction, he said.
Mr Jackson said when they moved from 500-600kg cows to grazing rising one-year-olds there was still an issue as they were surface-sealing their clay-type soil and water was sitting on top.
