Krui Pastoral Co, Condamine, Qld
East-west sowing between shade lines and spot-spraying
Half an hour west of Condamine on the western Darling Downs, Jake and Felicity Hamilton work with Jake’s father to farm 5000 ha of brigalow scrub, which was originally cleared for cattle grazing in the decades since 1975. Although the cattle are all gone now, the Hamiltons have maintained the shade lines of native vegetation, which occupy about 10 per cent of the farm’s area, left when the property was cleared.
Jake says the thick stand of buffel grass in the shade lines prevents other weeds from establishing and the buffel doesn’t move into crop areas. Most of the fencelines are also timbered, with the low soil moisture keeping a lid on weeds.
“When the farm was cleared, the shadelines were left running east-west to maximise the shading effect for the livestock, and now we are cropping east-west in fairly large, square paddocks,” says Jake. “We are now taking advantage of the shading effect on the inter-row to suppress weed germination and growth.”
Crop rows run east-west, parallel with tree lines left when the property was cleared, to provide shade for stock.
Growing wheat / chickpea / wheat, with few opportunities for summer cropping in recent years, Jake has been working hard to keep on top of herbicide resistance in summer growing species including barnyard grass, liverseed grass, button grass and feathertop Rhodes grass.
Not being able to grow summer crops on a regular basis, Jake has implemented a robust fallow management program to keep these weeds under control.
“We try to double knock the glyphosate applications with paraquat, especially if the weed burden is high, there are large weeds present or weeds are not dying like they should,” he says. “And we always use full label rates to avoid herbicide resistance.”
“Spot spraying summer grasses using the ‘Gator was quite time-consuming but incredibly effective and cost-efficient,” he says. “We have recently increased our spray capacity to get across the whole cropping area within seven days using two self-propelled sprayers fitted with John Deere See and Spray Select optical weed detection units. The optical sprayer is treating just 2 to 5 per cent of our area for grasses and up to 10 per cent of the area for fleabane.”
Spot and patch spraying is time-consuming but very worthwhile.
They have noticed feathertop Rhodes grass germinating earlier, particularly on their lighter soil types, so they have introduced imi-tolerant wheat to the rotation so they can apply OnDuty* in winter before canopy closure in spring. *OnDuty is a Group 2 [B] pre-emergent herbicide (imazapic + imazapyr) registered for use in Clearfield canola and wheat production.
The Hamiltons employ an agronomist to visit the farm once a fortnight to assist with monitoring and planning the weed control program.
“We know we are losing Group 9 [M] (glyphosate) and can see resistance to Group 1 [A] (grass selective) chemistry on button grass, which will leave us with very few herbicide options. We rotate crops as best we can so we can use different methods of weed control to try and break the resistance.”
Laser levelling to remove the melon holes that are characteristic of brigalow scrub soils brings about an immediate increase in yield and more even crops. Using a second-hand Caterpillar D11R dozer fitted with TopCon GPS, Jake cuts 10 cm below grade on the first pass, which creates a good blend of topsoil with any exposed subsoil to avoid ‘scalping’ the paddock.
Every four years the Hamiltons also incorporate 10 t/ha of manure to a depth of 15 cm and use variable rate technology to apply manure to ameliorate some areas of soil fertility decline.
“After using a chisel plough for several years to incorporate the manure, we are moving toward a program of deep ripping and deep application of phosphorus fertiliser to a depth of 40 to 50 cm, on 50 cm spacings,” says Jake.
Since 2001 the farming system has been controlled traffic with 12 m bays, to suit 36 m sprayer, 24 m planter and 12 m header. Their new planter is configured for 375 mm (15″) spacings for wheat and barley, 750 mm (30″) for chickpeas, faba beans and mungbeans and 1500 mm (60″) sorghum and cotton. Jake also uses high seeding rates to maximise crop competition, along with their efforts to improve overall soil fertility and boost crop competitiveness.
Although there are some risks associated with the short crop rotation Jake says residuals are doing a good job controlling weeds in-crop, with no late germinations evident.
“We use residuals plus picloram and aminopyralid for fleabane control in wheat,” he says. “In chickpea we apply simazine and Balance and follow with an in-crop application of a Group 1 [A] herbicide.”
“If there are weeds present in-crop they usually don’t seed before harvest,” he says. “Black oats is a potential problem though if there is a spray miss.”
They also apply pre-emergence herbicides Balance + Flame + diuron in some paddocks to keep them clean over summer while leaving their summer cropping options open in other paddocks.
The Hamiltons store planting seed on farm and grade all their seed through a mobile grader on the Easter long weekend, aiming to achieve a good clean sample – 99 per cent purity.
Jake spreads their frost risk by planting 50 per cent of the wheat area to Gregory in early May then sowing the chickpea area the following week. The remaining wheat area is sown later to Suntop or Crusader.
After suffering severe frost damage in late August 2017 the Hamiltons changed their planting schedule to reduce their frost risk. Jake says late frosts can be a problem in the Condamine area and can badly affect chickpea crops if the temperature drops to zero or below during flowering or podding.
“We aim to have all our wheat planted between 7 and 21 May and then plant chickpeas after that,” he says. “Our planting equipment has superior breakout force, compared to our old machine, which allows us to plant chickpeas to a depth of 200 mm (8″). Planting at this depth delays seedling emergence until after the first week of June, pushing the flowering window back a fortnight, closer to the warmer weather of spring.”
“Chickpea makes a huge difference to our farming system with better wheat yields, less fertiliser and softer soil.”
First published in 2018, updated in 2024.
