A recent rapid change in the cotton harvesting system has increased the risk of soil compaction within the cotton industry with the inception of the John Deere 7760 cotton harvester, a round-bale module builder that weighs >36 Mg. This project involved a novel approach to reducing the risk of soil compaction, whereby cotton defoliation was delayed at times of high field moisture so that the evapotranspiration demands of the crop could be used to dry down the soil profile and consequently reduce the compaction risk at harvest. A field trial at Aubigny, Queensland, was used to evaluate the merit of the proposed management strategy in the 2014–15 growing season, in conjunction with a modelling approach to assess the long-term effectiveness of the strategy in several Australian cotton-growing regions. Although the proposed strategy did reduce the compaction risk, the risk reduction was insufficient for the strategy to be deemed effective. Nonetheless, a strong correlation was found between small changes in soil moisture and changes in observable compaction. An observed 10% increase in soil bulk density after traffic suggested damage to soil pore networks. Furthermore, the depth of compaction was observed well beyond the feasible cultivation depth (to 80 cm).
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13 June 2017
Efficacy of delaying cotton defoliation to mitigate compaction risk at wet harvest
Stirling D. Roberton,
John McL. Bennett
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Crop and Pasture Science
Vol. 68 • No. 5
June 2017
Vol. 68 • No. 5
June 2017
risk management
soil conservation
soil moisture management