Understanding the economics of horticultural management practices and systems for improving water quality runoff in the Great Barrier Reef catchment areas

Abstract

The main objective of this report is to identify available studies and prioritise future economic research on dominant horticultural cropping systems in the Great Barrier Reef (GBR) catchment. Due to the wide array of horticultural crops and production systems, available databases have been utilised to identify the major crops by area that pose the highest potential risk to reef water quality (RWQ)1 impact and decline. However, it is anticipated based on preliminary agronomic research that different horticultural production systems are likely to have different effects on both runoff and sub-surface leachate. Crops are therefore grouped according to common production system attributes. This allows for possible transfer extension of research findings to other horticultural crops within each group.

Of the 150 different horticultural crops grown in the GBR catchment, thirteen major horticultural crops have been identified for this report. Only crops exceeding 1,000 hectares (ha) in total within the catchment are considered (excluding banana plantations and intensive horticulture, sometimes referred to as protected cropping)2 . These include six perennial crops (macadamias, mangoes, avocados, citrus, pineapples and grapes), six vegetable crops (beans, sweetcorn, potatoes, capsicums, tomatoes and pumpkins) and one seasonal fruit crop (melons). A literature review was conducted on each of these crops to identify published studies that evaluated the economic costbenefit of RWQ decline risk reduction practices.

The report and findings align with practices listed in the Horticulture Water Quality Risk Framework (2017-2022) as developed by the Paddock to Reef (P2R) Team and Growcom. Despite a relatively small land use area, horticulture is acknowledged in general to involve some of the most intensive farming practices in agriculture. This has implications for risk of RWQ decline. The Soil Catchment and Riverine Processes Group (2022) has compiled much of the background research investigating horticultural crops in the GBR catchment, and where applicable, their potential impact on the Reef (RP240 ‘Improving knowledge and research for horticulture and cropping activities’). In complement to their body of work this literature review focusses on practices that reduce the risk of excess sediment, nitrogen and chemical residues reaching the GBR and identify any economic related horticulture specific findings.

The findings conclude there is limited publications available that assess RWQ risks from the horticulture industry, and none that thoroughly demonstrate an economically viable improved management practice for the industry. Positively, horticultural practices are generally progressive due to market requirements (e.g., food safety requirements) and constraining production factors (e.g., nutrient and produce quality linkages). Because of these factors, horticulture leads the agricultural industry in several alternative fields in terms of innovation and demonstration of best practice. Strategic investment in research, industry development and extension which utilises such innovation and momentum for practice change may well deliver more rapid outcomes for improved RWQ from the horticultural sector.

Future research priorities incorporating economic analysis include those crops with the highest potential RWQ impact. These may include new macadamia plantations, avocados and pineapples. Others for considerations could be mulched crops (due to environmental management requirements of micro-plastic pollution) and the intensive cycling of continuous supply root crops such as sweetpotatoes which pose persistent risks of RWQ decline regardless of season.