Most cropping and horticulture enterprises are concentrated in the higher rainfall coastal zone, particularly the irrigated floodplains of the Lower Burdekin, Bowen and Rollingstone. Dryland cropping occurs in large areas of the Belyando-Suttor sub-catchment.
The fertile soils of the Burdekin Dry Tropics region support broadacre crops including approximately 1,050 km² of sugarcane and cotton surrounding Ayr and Home Hill; 1,250 km² of dryland crops in the Belyando Suttor areas; and highly-productive horticulture crops of sweetcorn, tomatoes, watermelons, capsicums, squash, pineapples and mangoes (among many others) at Bowen, Gumlu, Giru and Rollingstone.
The warm winters and longer daylight hours enable farmers to double-crop many field crops. During the traditional “dry” period from April to October, farmers can also programme farm management for irrigation and harvesting of many crops. For cane growers these conditions produce the highest yield and sugar content in Australia. The expanding horticultural sector also produces a variety of out-of-season winter vegetables and fruit, and the Bowen Gumlu Agricultural District is Australia’s largest winter vegetable production area.
The focus and investment on agricultural chemicals and sediment loads leaving GBR-connected catchments has led to a better understanding of land management practices, particularly for sugarcane cropping land. Ultimately maintaining good soil health is the key to reducing the runoff of sediment, nitrogen and phosphorous (Dight, 2009) (Queensland Department of Agriculture, Fisheries and Forestry, 2013) ( Australian Bureau of Statistics, 2015).
Continuing soil health issues for the cropping region include reductions in soil carbon, potential accelerated acidity, increased water logging and soil salinisation, as well as runoff of nitrogen and phosphorous into the waterways entering the GBR lagoon (Hook, 2011) (Williams, et al., 2009). The loss of organic material and soil structure, and therefore soil fertility, also inhibits root growth, which leads to productivity losses and increased cultivation and fertiliser application costs (Poggio, et al., 2010). These adverse impacts can be caused by poorly-managed irrigation practices, poor quality irrigation water, and an over-application of nitrogen-based fertilizers.
For cropping lands, best management practices to improve land condition and conserve soil can include: adjusting crop rows, maintaining crop stubble and reducing tilling frequency to increase carbon content, applying fertiliser within the requirements of the soil, improving irrigation efficiency in line with crop needs, and fertigation to prevent a rising water table and salinisation. Additionally, maintaining good riparian vegetation corridors and managing gully erosion in all areas, assists with filtering sediment and nutrients from runoff entering waterways. This leads to overall improved landscape resilience, and benefits may also be present in areas with approved soil carbon sequestration projects.
Adopting new or changed farming systems to improve the rating of land management practice does incur an initial cost, however, an economic analysis of the Burdekin cropping region undertaken by the Queensland Government’s Department of Agriculture and Fisheries, identified that transitioning from land management practice categories ‘D’ through to ‘A’ is worthwhile (Poggio, e al., 2010) (Department of Employment, Economic Development and Innovation, 2010). It is recognised that in any specific year, a higher farm gross margin would be achieved when operating within an improved class of management practices. This suggests that management practices at a higher class are stronger financially, and a positive net present value is indicated when moving up the management practice categories.
The wider impacts of traditional land management practices are well established, and economic data supports the benefits of transitioning to improved methods. Despite this, not enough property owners are currently adopting best practices on their land. The recent Australian Government Reef Report Card identified that for the sugarcane lands in our region, less than a quarter to one fifth of cropping properties are incorporating best management practices for irrigation, pesticides, nutrients and soils (Australian and Queensland Governments, 2015). This highlights the need for a greater coordinated and collaborative effort by industry, government, research organisations and NRM groups to provide landholders with incentives, education and extension to support and enable their transition to more sustainable land management practices.