Dynamic crop sequencing in Western Australian cropping systems

Authors: MALIK, RAJ - Department Of Food And Agriculture Western Australia; SEYMOUR, MARK - Department Of Food And Agriculture Western Australia; FRENCH, ROBERT - Department Of Food And Agriculture Western Australia; KIRKEGAARD, JOHN - Commonwealth Scientific And Industrial Research Organisation (CSIRO); LAWES, ROGER - Commonwealth Scientific And Industrial Research Organisation (CSIRO); Liebig, Mark

Submitted to: Crop and Pasture Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2015
Publication Date: 5/29/2015
Publication URL: http://handle.nal.usda.gov/10113/61417
Citation: Malik, R.S., Seymour, M., French, R.J., Kirkegaard, J.A., Lawes, R.A., Liebig, M.A. 2015. Dynamic crop sequencing in Western Australian cropping systems. Crop and Pasture Science. 66:594-609.

Interpretive Summary: Increased incidence of diseases and weeds coupled with reduced soil fertility are major consequences of continuous wheat cropping systems. Rotating wheat with a non-cereal crop, however, can neutralize these negative consequences. A multi-year study was conducted to evaluate a suite of 'break crops' that included wheat, barley, oats, oaten hay, canola, lupins, field peas, green manure (oats-vetch) and bare fallow on subsequent wheat yield, where wheat was treated with and without a fungicide seed dressing. Canola, lupins and field pea performed poorly when grown on their own residue, despite no obvious foliar disease issues. Conversely, crop biomass and grain yields were higher when crops were grown on residues other than their own. Lupins were found to increase yield of subsequent crops to a greater extent than canola. Research findings from this study will provide farmers with crop rotation options that fit their individual needs for responding to short-term dynamics in crop prices and growing conditions, as well as help guide management decisions for developing sustainable cropping systems.

Technical Abstract: In the last decade in Western Australia crop sequences have become increasingly dominated by wheat. Wheat may now be grown in sequence with a wide range of crops and pastures that may influence the yield of the subsequent wheat crop by suppressing weeds, disease, or increasing the supply of nitrogen. Here we evaluated the effect a suite of break-crops that included wheat, barley, oats, oaten hay, canola, lupins, field peas, green manure (oats-vetch) and bare fallow on subsequent wheat yield, where wheat was treated with and without the fluquinconazole fungicide Jockey (J). Broadleaf crops such as canola, lupins and field pea performed poorly when grown on their own residue, despite no obvious foliar disease issues. Conversely, crop biomass and grain yields were higher when crops were grown on residues other than their own. Wheat+J consistently out-yielded wheat-J (treated with a conventional seed treatment flutriafol fungicide) in the majority of sequences. In second year of sequence, lupins grown as a break crop increased wheat+J and wheat-J yields significantly above (826 and 589 kg/ha, respectively) when they were grown on their own residues. In third year of sequence, the grain yield of wheat+J grain after lupins was 26 and 28% higher than after wheat+J and wheat-J treatments, respectively. The effect of the lupins break on the yield of the following crop was larger than the effect of the canola break. It is anticipated these research findings will provide farmers with crop choices that fit their individual needs for responding to short-term dynamics in crop prices and growing conditions, as well as guide the development sustainable cropping systems.