Soil and yield improvements from controlled traffic farming on a red chromosol were similar to CTF on a swelling black vertosol. Tim Ellis
Soil and yield improvements from Controlled TrafficFarming on a Red Chromosol were similar to CTF on a swelling Black Vertosol. Tim Ellis CSIRO, Brisbane (previously University of Adelaide) Soroush Sedaghatpour, Cliff Hignett, Hugh Cameron, John Thomas, Jeff Tullberg, Terry Riley and 1 x 106 students
Controlled Traffic field research conducted atRoseworthy South Australia, 1989 to 1994Funded by: Key Centre for Dryland Agriculture andLanduse Systems; John Shearer LTD; Grains ResearchCouncil; and Grains Research and DevelopmentCorporationSite - Roseworthy South AustraliaClimate - Mediterranean-type– rainfall 440 mm/yrSoil – generally Red Chromosol – some variation
Aim: shattering of compact layer and exclusion of wheeltraffic(expectation): this should improve soil structure, root growth and crop yieldC – Conventional wheel traffic; tractors and trailedimplementsCR – Conventional wheel traffic, deep RippedCT – Controlled TrafficCTR – Controlled Traffic deep RippedRipping – 300 mm deep, once only at establishment of trialRandomised split-plot design; each plot 0.1 hectares
A “moderate” compact layerbelow tilled depthSome root deflection
Controlled Traffic treatments CT and CTRTillage, seeding (DD) and Harvestingspraying Modified MF585 harvesterExperimental John ShearerGantry
Conventionally wheeled treatments C and CR (just imagine)Tractor(s) and (identical) trailed implements andharvester
NS• 12 to 22% greater yields from CT in 5 out of 6 years.• No significant difference from deep ripping (surprise)
C Wheat CT“Better” soil structure if you don’t drive on it.(seems obvious) Why?
C CTCR CTRWhich structure is “better”? Deep ripping doesn’t necessarily “improve” soilstructure, especially if you don’t stop driving on it. Why?
Conclusions/questions•Simply removing the wheel traffic (CT) improved yields by12 to 22%•Deep ripping did not improve yields•“Better” soil structure from CT – why? What at thephysical and ecological processes?•“Better root growth from CT – but what is “better”?•More stable soil aggregates; better infiltration•Similar results to a swelling Black VertosolBonus conclusions/questions•Twice as many earthworms in CT compared to C•Easier overall field operations and timeliness•Improved efficacy of direct drilling•Need to measure effects at system scale?