Nerada Flashcards
Natural climate variations through cycles (ENSO)
El Nino = warmer temps, lower rainfall in Australia (vice versa for La Nina) e.g. in 2002 (El Nino year and Millennium Drought) average yields were 3t/ha as only 1200mm of rain fell in Malanda, 2006 (La Nina year) yields rose to 4t/ha due to double the average rainfall: 3600mm BUT waterlogging impacted fields (environmental and economic costs), highest yields of 5t/ha in the neutral phase of ENSO
Tropical cyclone
cause defoliation, leaf browning (from waterlogging) and crop death. On average 4-5 tropical cyclines per year affect North Queensland, increasing frequency and intensity with climate change e.g. TC Yasi in 2011 with wind gusts over 115km/h recorded in Nerada –> minor leaf browning but no major damage (Yasi caused over $3.6 billion in damage)
Waterlogging
La Nina years, bi-clonal tea plants used by Nerada are ‘flood tolerant’ – withstand 3 months of waterlogging –> after this period: denitrification and deoxygenation can cause leaf damage and crop death. Response: Nerada monitors water depth through a piezometer. Deep rooted native rainforest vegetation keeps water table lower than 2m,
Response: Nerada has a very high density of tea plants – keeps water table low
Frost
Nerada receives an average of 2 frost events per year e.g. in June 2018 –> Malanda experienced a frost that destroyed 50% of the entire tea estate and 2 weeks later 75%
Soil pH
Nerada regularly tests soil pH with smart soil probes and soil sampling –> too acidic = Nerada adds agricultural lime or dolomite, too alkaline = Nerada adds compost, manures and mulch
Habitat destruction
450 ha was clear-felled for the plantation –> this caused habitat destruction, habitat fragmentation, soil erosion, a loss of biodiversity and the ‘edge effect’ –> danger to the Lumholtz tree kangaroo (near threatened). Aquatic ecosystems were impacted through increased sedimentation, turbidity and chemical pollution (Johnston River Habitat home to the endemic platypus
Synthetic herbicide
runoff of herbicides into waterways introduce toxins in food webs, bioaccumulation
Chemical fertilisers
runoff into aquatic environments and subsequent eutrophication (algal growth, decline in dissolved oxygen and death of aquatic fauna) –> eutrophication risk is highest in the wet season when more fertiliser is added due to nutrient leaching from high rainfall
Habitat conservation and wildlife corridors
tree kangaroos are at risk from animal predation (dogs and cats), habitat destruction and climate change. Nerada has revegetated watercourses and planted umbrella tree and the giant white fig to increase habitat for the tree kangaroo (safety areas) (also stabilises river banks and prevents erosion) – acts as a wildlife corridor
In response to synthetic herbicide use
5m buffer zones between crops and waterway (absorbs toxins), integrated pest management (IPM) to control weeds –> targeted herbicide treatment, manual removal, inter-row mowing and mulching
In response to chemical fertilisers
NIR leaf testing, Smart soil probes –> monitor edaphic conditions 24/7 and send live results and alerts to Tony (25% less nitrogen), pruning mulch and green manure from native perennial grasses to add nutrients to the soil, increase soil moisture and keep soil pH slightly acidic. Organic fertilisers e.g. poultry manure –> add nitrogen, phosphorus and potassium to soil, increase microbial activity and improve soil water holding capacity (cheaper than synthetic fertilisers)
- 11-14 tonnes of sediment to GBR each that smothers coral, maybe be carrying fertiliser and has increased the number of crown of thorns starfish –> Nerada has been very successful at stopping this
