49 BURDEKIN DRY TROPICS NATURAL RESOURCE MANAGEMENT PLAN 2016-2026
LAND
Areas with high soil carbon are more physically and chemically stable and less prone to soil loss. Rainfall simulation studies in the Lower Burdekin identified that where bare soil is left, the loss of pesticide, nitrogen, phosphorus and sulfate was significantly higher than with a trash blanket soon after application. Land practices that included managing traffic control and subsurface applications of fertilisers had significantly higher water infiltration rates and retention of nutrients.
Cowie, et al.,( 2013).
The SIX EASY STEPS Method, developed by BSES limited, now known as Sugar Research Australia( SRA), manages the input of fertlisers on productive sugarcane land in a way that is economical to the farmer, and maintains soil integrity whilst also being mindful of the quality of runoff. The programme is an integrated nutrient management tool which involves testing soil characteristics to help adopt best practice nutrient management on-farm.
Sugar Research Australia( www. sugarresearch. com. au)
These practices increase pasture coverage, soil carbon content and water infiltration, improving overall soil health and land condition( Meat and Livestock Australia, Department of Primary Industries and Fisheries, CSIRO)( Queensland Department of Agriculture, Fisheries and Forestry, 2013).
Cropping and Horticulture Land Systems
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 subcatchment.
The fertile soils of the Burdekin Dry Tropics region support broadacre crops including approximately 1,050 km ² of sugarcane and cotton surrounding Ayr and Home Hill; 1,250 km ² 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 overapplication 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, et 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