The sophistication of agricultural land management continues to increase. This is seen in ongoing reductions in the intensity of agricultural chemical use in the cotton industry, due largely to the adoption of genetically modified cotton (Acworth et al. 2008); more careful use of fertilisers in sensitive environments (e.g. catchments of the Great Barrier Reef); and more flexible approaches to grazing management to reduce erosion and increase productivity. The stewardship role of farmers and the part that they play in conserving their land are increasingly recognised.
Horticultural production supply, quality and profitability are threatened by introduced and native pests, diseases and weeds. Integrated pest and disease management uses a number of different integrated methods, rather than relying on a single approach. This is advantageous when managing native animals (e.g. parrots, fruit bats) as pests, and for insect pests and diseases (Horticulture Australia 2006).
Integrated pest management practices aim to integrate all available pest control techniques to produce healthy crops with the least possible disruption to the agro-ecosystem, rather than relying on routine applications of pesticides. First proposed in the 1970s, these practices are becoming more widely adopted in the agricultural sector.
Insect-resistant and herbicide-tolerant cotton, and herbicide-tolerant canola are the 3 types of genetically modified crops in Australia. Insecticide use has been reduced by 85 per cent through the use of insect-resistant genetically modified cotton. However, reduced insecticide use against the cotton bollworm caterpillar (Helicoverpa armigera) has allowed other pests to survive and emerge as important pests (Williams et al. 2011). Grain crops (canola and wheat) appear to be able to retain existing yields with reduced insecticide applications, although better forecasting of years with low pest pressure is required to provide growers with opportunities and confidence to reduce insecticide input (Macfadyen et al. 2014).
Native vegetation remnants host a higher density of predatory insects and spiders than crops; crops usually host higher densities of pests (immature and mature) than native vegetation (Parry et al. 2015). Remnant vegetation also provides parasite habitat, which contributes to pest suppression in crops. These biocontrol services reach 125 metres and beyond from native vegetation into crops; however, the spatial pattern of colonisation can be patchy. Reliability of biocontrol increases as the availability of remnant vegetation increases (Bianchi et al. 2015). Management and improvement of remnant vegetation can increase the predator to prey (pest) ratio, which can improve pest control in grain and cotton crops (Bianchi et al. 2013). Retention and management of remnant native vegetation can also maintain populations of native bees (agricultural crop pollinators), which are more abundant and diverse in agricultural landscapes with more remnant native vegetation (especially riparian vegetation) than in those with less native vegetation (Cunningham et al. 2013).
Agricultural practices also aim to protect the soil and prevent sediment movement (see Cultivation). For example, modelled estimates of the nutrient and sediment loads reaching the Great Barrier Reef lagoon suggest that changes to the landscape—grazing, bushfires, and vegetation clearing for agriculture and urban development—will increase deposition to more than 3 times background (pre-European colonisation) levels (McCulloch et al. 2003, Kroon et al. 2012, Waters et al. 2014). Principles and guidelines for managing stocking rates, watering points and groundcover condition aim to improve water quality through best-practice grazing (Bartley et al. 2010, Silburn et al. 2011, Hunt et al. 2014). Significant investment by the Australian Government, state and territory governments, and industry has led to a better understanding of the source and causes of nutrient and sediment increases, and engagement with NRM bodies, industry and farmers is modelled to be potentially achieving significant (10–30 per cent) decreases in sediment loads. A combination of good contextual understanding, participation across the range of stakeholders and adequate funding should thus result in better-quality water reaching the Great Barrier Reef (see Box LAN7). In the Fitzroy Basin in Queensland, adoption of best management practice is high in dryland cropping enterprises as a result of the Reef Water Quality Protection Plan, even though croppers have not received the same resources as graziers and cane growers (Darbas et al. 2013).