“Cut, place, press and cover” is the mantra of South Australian farmer Tom Robinson when it comes to successful seed establishment under a no till regime.
“Perfect seed placement for every seed in every row across the whole farm is our goal,” he told a FAR's Growers Leading Change breakfast webinar with New Zealand growers outlining his journey to building healthier soils.
“Every seed costs dollars to put in the ground, so drill set up and placement absolutely matters.”
Watch the full webinar video here.
Tom Robinson farms at Hoyleton, north of Adelaide, with his partner Cassi and Tom’s parents Ashley and Kaylene. They farm 1,540ha of wheat, barley, canola, peas and lentils. Tom is a long time Vic No Till member and leader.
The Robinson family initially adopted no till as a way of managing and retaining as much crop residues on the soil surface as possible for moisture conservation in their hot, dry climate. They later realised the additional soil health gains.
They have been minimum till and then no-till for 25 years. The Robinsons have implemented a number of changes to help improve their soils, use of a Shelbourne stripper header front to help retain stubble, controlled traffic system to help manage soil compaction, summer cover crops, decreasing fertiliser inputs, and more recently, companion cropping and intercropping.
The farm has a 325 to 425mm annual rainfall, which predominantly falls in winter. In summer it bakes, with temperatures above 40degC and annual evapotranspiration of 3000mm. The soil type is red brown earth and some loam over clay, with organic matter between 1 to 2 per cent.
As lack of moisture is their biggest limiting factor, the benefits of moisture conservation mean that district average wheat yields are 4 tonne/ha under no till and full input, double those under full tillage and full input.
No till is the biggest change on the farm for 160 years, Tom says.
A disc seeder was purchased to handle the crop residue. Tom says there are four principles for disc seeding, “cut, place, press and cover”.
- 1. Cut all the crop residue. Sharp discs are needed to cut the residue and soil cleanly.
- 2. Place seed in the bottom of the slot. “We are not going to drop it or throw it. We will place it as gently as possible in the bottom of the slot.”
- 3. Press the seed into the bottom of the slot into firm soil, which is particularly important in marginal moisture conditions.
- 4. Cover the seed with loose soil to stop the capillary action of water moving up the soil profile and evaporating.
The Robinsons’ John Deere 1890 disc seeder is able to sow directly into heavy stubble and is modified with a narrow gauge wheel. As downward pressure is important, 1.5 tonnes of weight has been added. “We aim for two inches (5cm) of spring compression which provides downward pressure on to the discs. Too many people don’t run enough downward pressure to get correct seed placement and correct cut.”
To gain more even crop residue across their paddocks the Robinsons purchased a Shelbourne stripper header, a type of combine harvester which removes the grain from the plant, leaving the stem standing in the field. This has led to a 30 to 50 per cent increase in harvester capacity in cereals and a similar amount in fuel savings, depending on the conditions.
“Not putting the amount of straw through of a conventional draper header is saving a lot of horsepower and diesel.”
The longer straw also reduced hair pinning during seeding.
The Robinsons have also adopted controlled traffic farming, taking six years to change their machinery over to the 30m system. Advantages were improved yields of 10 to 40 per cent and fuel savings as well as improved soil with faster water infiltration.
However, Tom says he probably won’t continue with this, as no till, the stripper header, crop rotation and livestock rank higher, particularly as the farm’s soil structure improves.
Summer cover crops are grown, with each having its own purpose, either for soil health or to feed livestock. The farm had no livestock for 28 years until 2018, when cattle were introduced and these work well with cover crops, which are sown through the standing harvested crop.
“We like sunflowers here. They don’t have much ground coverage, but they have a big taproot and are hardy in our hot summers. Tillage radish is grown for livestock.”
They have no issues with a disc seeder running through a cover crop.
Tom recommends that farmers adopting no till terminate a cover crop three to four weeks before seeding, leaving an unsprayed test strip to see whether this would work in their own situation.
“We find that material breaks down fairly quickly. That’s where trial work is needed on your own farm.”
He is a fan of companion crops, successfully growing peas and canola together, as well as lentils and linseed.
“I love the companion planting and they work well, but it depends on the market for seed. The main challenge is export seed delivery standards. If our region had more of a domestic livestock feed market I could supply this.”
In response to a question about the limited ability to use a brassica as a cover crop, particularly in Canterbury, because of its export brassica seed market, Tom says that companion planting is about adding things that weren’t normally in the rotation.
Soil fertility testing is important and the farm is part of a trial doing monthly deep N testing for two years to track soil N.