A DRAMATIC increase in stubble levels has shown some early signs of reducing the problem of non-wetting soils at Neridup, north east of Esperance.
Colin de Grussa farms 2100 hectares of country, with 1500 hectares cropped on an annual basis, and runs Wiltshire Horn sheep on the remainder of the property.
Mr de Grussa has embraced technology across the operation including autosteer on all the major equipment, allowing for two-centimetre accuracy and he’s also moved to introduce variable fertiliser rates in his cropping program.
One of the major farming challenges Mr de Grussa has encountered is non-wetting soils.
“Some of our sandy soils are non-wetting, so preserving ground cover is a high priority on this property as this minimises wind damage and maximises the establishment of the crop,” Mr de Grussa said.
“We have strategically clayed or spread clay on some of the non-wetting soil in the past.
“It is very expensive but with recent rises in the value of land, it’s probably becoming more economic.”
The other way Mr de Grussa has found to reduce the impact from non-wetting soils is to retain as much crop and biomass residue as possible on the top of the soil.
This has seen a move back to a disc seeder to enable him to seed through very high stubble residue loads.
“The discs allow us to leave heavy stubble on the surface of the soil where it can maintain soil moisture and stability,” Mr de Grussa said.
“We’ve re-introduced discs because we believe it will help improve our non-wetting soils.”
Stubble retention had slipped until recently as about seven years ago he had gone back to a tyned seeder to plant the crop. Previously discs were used and at the time the seeder was replaced the cost of discs was prohibitive.
“The crop residue got buried every year by the tynes and broke down into the soil which meant it wasn’t retained on the surface to the point where we started having a lot less cover on our soils,” Mr de Grussa said.
“We also had a few wind events which did a bit of damage so we went back to discs and this is the first year back with the discs since that transition.
“They are certainly working effectively in terms of protecting soil cover and I’ve got a lot more residue on the surface than what we would normally have.”
It hasn’t all been smooth sailing for the Neridup producer with a frost last year wiping out nearly all the wheat on his property. There was even one paddock which he didn’t harvest as there was no grain in the head.
Not letting a setback stand in the way of the next crop, he seeded straight into that full wheat crop stubble with his new machine and was been able to maintain all the cover on the soil.
“The canola has come up very well through it, even though the paddock is known to have non-wetting issues and I can certainly see the benefit already,” Mr de Grussa said.
“We had some good rainfall in May and that was the first opportunity for that soil to wet up and it did.
“Having that residue on top meant that the moisture was able to penetrate rather than running off the soil and we’re seeing the benefit in the number of plants in the paddock.”
While there has been an improvement in germination due to the disc seeder, some plants have still come up later than others. The crop is staggered but this has occurred where there is less residue and the soil is a bit barer.
Overall though, Mr de Grussa is very happy with the plant population after the first year of using discs again.
He has also been involved in variable rate trials funded by the Grains Research and Development Corporation (GRDC) and conducted by CSIRO and a local agronomist.
“We started out with a guidance system around 2000, which just provided guidance on the sprayer and a boom switching control,” Mr de Grussa said.
“That saved us a lot in terms of overlap and wasted chemical and that sort of thing and missed chemical application as well.
“We could see the benefits from there and then we went to auto steer and now we have two centimetre steering on the seeding tractor and sprayer and that gets used on the header as well at harvest time.
This system has now allowed the Esperance district producer to start controlling the rates on the seeder.
He saw the immediate savings in overlapping, with around a 10 per cent saving in inputs but the trial work has now taken this a step further.
“I’ve gone down the variable rate path in the past couple of years,” Mr de Grussa said.
“Last year we did a bit of trial work and could see there is going to be some benefits, particularly with the input costs so high and they don’t look like coming down.
“We can more accurately target those inputs particularly the starter fertiliser.”
Last year’s yield maps, though in most cases on the lighter side because of the frost, have still been able to be used in conjunction with the previous five years of yield data and specialised software to map out a variable application map.
“We’ve been able to calculate the amount of phosphorus removed from each part of the paddock and I’ve used that to establish the basis of a rate map for this year’s fertiliser,” Mr de Grussa said.
“This meant that we have reduced this year’s fertiliser application quite significantly.
“We don’t use the absolute yield value to determine the fertiliser rate, as we have to account for the losses and tie ups and that sort of thing.”
This saw the development of a rate map across the paddock with trial strips applied around the farm to see the performance and this will be assessed at harvest time.
“It did save us significantly on inputs and I don’t believe it will compromise our crop potentials,” Mr de Grussa said.
“You may see a biomass difference with phosphorus but once you put the header in, if you see it on a yield map then it is a significant effect but if you can’t see it then I don’t believe it is significant enough to worry about.
“This year we have used nutrient removal as a basis but we may not use that every year.
“Most importantly, we’ve tried to keep this as simple as possible and I think that is very important with Precision Ag, as there is so much data available which can bog us down if we’re not careful.”
* For more information, visit www.grdc.com.au