Long fallows can maintain whole-farm profit and reduce risk in semi-arid south-eastern Australia

David J. Cann, James R. Hunt and Bill Malcolm

Agricultural Systems, 2020, vol. 178, issue C

Abstract: The practice of leaving a paddock out of production for an entire growing season, known as long fallowing, is used to accumulate soil water and mineral nitrogen (N) and break disease cycles in low-rainfall environments where in-crop rainfall is unreliable. This study used whole-farm economics and rule-based crop simulation at a site in the grain-growing Mallee region (300–350mm annual rainfall) of south-eastern Australia to determine if long fallowing could be used to reduce production risk and maintain profit by reducing input costs. The Agricultural Production Systems sIMulator (APSIM) was used to model crop production on a hypothetical 4000-ha property over 20 years. Three fixed rotations (continuous wheat, wheat-chickpea and wheat-fallow) were managed as whole-farm systems, with unique soil water-based fertiliser rules for each rotation and a sowing window designed to reflect the improved timeliness of operations associated with reducing cropped area. Two flexible rule-based sequences were also created, where long fallow replaced a crop if plant available water and mineral N thresholds were not met at sowing. APSIM outputs were used for whole-farm economic analyses and to assess the returns and risks of each farming system. Converting 50% of a continuously-cropped wheat farm to fallow increased average annual net cash flow by 44% and decreased the variability of inter-annual profit by 49%. A long fallow-wheat rotation was more profitable than a chickpea-wheat rotation when chickpea prices were below $AUD800/t. Wheat production that incorporated long fallowing into the system when there were less than 100 water-nitrogen units at sowing was the most profitable system, increasing average net cash flow by 63% compared to continuous wheat production.

Keywords: Whole-farm economics; Crop simulation; Long fallowing; Farming systems; Wheat (search for similar items in EconPapers)
Date: 2020
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Citations: View citations in EconPapers (6)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:agisys:v:178:y:2020:i:c:s0308521x18307406

DOI: 10.1016/j.agsy.2019.102721

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