The grain producing agricultural zone of Queensland is located largely in the south of the state in a zone 100-400 km west of the coast. Cropping is carried out on the better soils and gentler slopes in the region. Black, grey and brown vertosols (cracking clay) soils are most commonly prized for crop production due to their high plant available water capacity and moderate to high levels of soil fertility.
Climate in the region is largely semiarid and sub-tropical. Annual rainfall is typically between 600-800 mm/yr (increasing from west to east) and is highly variable. On average, the regions annual evaporative demand is at least double the rainfall, resulting in high soil water deficits that can limit planting opportunities. Around two thirds of rainfall typically occurs in the spring and summer periods, although significant falls may also occur over winter, providing the opportunity for both summer and winter cropping. The region is also characterised by high intensity rainfall events, particularly in summer, which can increase the risk of soil erosion.
The most common crops grown are wheat, sorghum, maize and barley, with the proportion of winter crops (wheat, barley) increasing from north to south. Other crops grown include oilseeds (canola, sunflower), pulses (chickpea, faba bean, mung bean, soybean, peanut, navy bean) and cotton. Higher yields are typically observed in more easterly catchments due to higher rainfall, with opportunity cropping often combined with animal production in more marginal areas.
The maintenance of soil fertility in Queensland cropping soils is key to the continued viability of the Queensland agricultural industry. Our objective for soil quality monitoring in Queensland has been to (i) identify factors that limit the capacity of a soil to enhance plant growth for increased production and (ii) ensure through monitoring, that changes to management practices designed to increase production do not cause a longer-term detrimental effect on the soil resource.