Yields lift rewards soil work
GroundCover™ Issue: 104 | Author: Melissa Williams
A decade of liming and recent mouldboard ploughing efforts on their property in Badgingarra, Western Australia, has helped to double cereal crop yields for Jeff and Wendy Fordham.
These soil renovation techniques have been used in an attempt to address aluminium toxicity issues on yellow sandplain country and overcome problems of non-wetting sands.
Badgingarra is about 180 kilometres north of Perth. Having moved there 11 years ago from further north at Mingenew, the Fordhams – who are members of the local West Midlands Group – were surprised when deep-ripping did not start to improve plant vigour and crop yields.
Soil testing indicated high aluminium toxicity, and this kickstarted a liming program that has become ongoing.
In some paddocks, surface soil pH (calcium chloride) levels have now increased from about 4.8 to 6.7 and subsoil pH has risen from about 4.3 to 4.5.
Jeff says average wheat and barley yields on paddocks that have received up to four tonnes per hectare of lime during the past decade have increased from 1.5 to 2t/ha to 2 to 3t/ha.
This has resulted in a more profitable rotation of wheat/canola/wheat, which has allowed the Fordhams to move away from pasture phases. In addition, Jeff says soil inversion by mouldboard ploughing on 200ha of non-wetting country in 2010 and 2011 has made a big difference to crop performance in areas where germination and plant vigour had been very poor.
He says soil water-holding capacity in this area has improved, seeding rates have been halved to 50 kilograms/ha, germination rates have lifted by about 30 per cent, plant vigour has increased and cereal crop yields have doubled in the past two years to 2t/ha.
“Crop plants are healthier, weeds are not germinating as much and herbicides are working more effectively.”
Owners: Jeff and Wendy Fordham
Location: Badgingarra, Western Australia northern agricultural region
Farm size: 1820 hectares
Enterprises: grain and 2000 head sheep
Average annual rainfall: 450 millimetres
Soil types: yellow sand
Soil pH: (CaCl2) 5 surface average
Ideal crop rotation: canola/wheat/canola/barley
Crops grown 2012: wheat (700ha), canola (500ha), barley (100ha)
Jeff conducts deep and surface soil testing. In a dry growing season, such as 2012, he uses a single nitrogen application of 80kg/ha urea on limed and mouldboard ploughed areas.
Grain reached average protein targets of 10 to 12 per cent, indicating nitrogen uptake is adequate.
Jeff says he became involved in non-wetting soil trials by the GRDC and the Department of Agriculture and Food, WA (DAFWA) on his property due to a lack of locally relevant information about managing fertiliser when using mouldboard ploughing or spading.
“I am hoping the findings about nutrient movement and availability after mouldboard ploughing, in particular, will be another key to explaining what else I need to do on these soils to boost crop production.
“Mouldboard ploughing has had a dramatic effect on our property, but we know treated soils won’t hold much moisture or nutrients at the surface.
“When we have more information about this, we will really be able to refine our fertiliser program.”
Jeff says the trial, which is supported by the West Midlands Group, has already produced surprising information about the depths to which roots travel in mouldboard ploughed areas and how wet and nutrient-rich deeper subsoil layers can be.
He notes mouldboard ploughing does have some downsides – it is difficult to maintain consistent seed depth at sowing, and areas become very soft and prone to erosion until the crop gets established.
Moora-based grower and central wheatbelt agronomist with agVivo Erin Cahill has been involved in paddock-scale mouldboard ploughing and rotary spading trials in the Fordhams’ area and has helped local growers convert whole properties to these systems.
He says growers in eastern parts of the region are reaping up to a 1.2t/ha cereal yield advantage in the first year of using spading and a 0.6 to 0.7t/ha gain yield advantage from deep-ripping compared with nil cultivation.
Mr Cahill says even at a cost of $230 to $250/ha, spreading lime, deep-ripping and using soil inversion tactics pay off in the first year due to these higher grain yields.
Further west, near the Fordhams’ farm, the potential yield loss from water-repellent soils is not as great and therefore yield gains do not tend to be as high.
Mr Cahill says the average long-term yield response for the whole central wheatbelt region in the first year after spading or mouldboard ploughing is about 0.5 to 0.7t/ha.
“We generally see a lot better availability of soil nutrients post-spading or mouldboard ploughing and better plant establishment because the deeper mineralised nutrients are coming up to the surface,” he says.
“Generally we can pull back nitrogen, phosphorus, potassium and sulfur fertiliser inputs in the first two years of cropping after the soil inversion.”
Mr Cahill says in the dry growing seasons of 2012 and 2011, nitrogen inputs on many of these areas had dropped 30 to 40 per cent, which was a significant cost saving.
He explains that growers using these techniques can also be more relaxed about nitrogen management because mineralised nitrogen tends to be available to plants at the soil surface early in the season and deeper in the profile later in the season.
This allows growers to assess how the season is unfolding and better estimate crop yield potential before making fertiliser decisions.
Mr Cahill says there are also positive spin-offs from one-off spading and mouldboard ploughing in achieving up to 70 per cent and 90 per cent weed control respectively in the first year.
He says further research is needed into erosion danger in the first year arising from soil inversion methods, use of controlled traffic to minimise re-compaction and improving the accuracy of sowing depth.
“But, to date, the science behind these techniques is good, the extension is good, and we are seeing a greater uptake of mouldboard ploughing and rotary spading, with some farmers in this area now using it across their whole farms.”
Soil renovation pays off for Fordhams
GRDC Project Code DAW00204, CPS00139
Region North, South, West