Soil and Land Assessment of the Southern Part of Flying Fox Station for Irrigated Agriculture. Part A: Land Resources and General Land Capability.
Agricultural Land Suitability Series, Report 14A
Andrews, K; Burgess, J; McGrath, N; Wright, A; Walton, S; Northern Territory. Department of Environment, Parks and Water Security
E-Publications; E-Books; PublicationNT; Technical Report No. 3/2021
Flying Fox Station; Roper River Region
This report presents findings from a 52 938 ha soil and land resource mapping investigation of the southern part of Flying Fox Station, in the Roper River Region of the Northern Territory. While the study area was primarily selected because of its diverse geology, terrain and soils, it is also representative of the central Roper River region, and findings from the investigation will underpin and guide future agricultural development in the region.
Made available by via Publications (Legal Deposit) Act 2004 (NT)
Executive Summary; 1. Introduction; 2. Previous land resource investigations; 3. Methodology; 4. Climate; 5. Geology; 6. Landscapes; 7. Land units; 8. Land capability assessment; 9. Land management; 10. References; Appendices.
soil survey; land resource assessment; land units; land capability assessment
Northern Territory Government
Technical Report No. 3/2021
208 pages : colour maps and illustrations ; 30cm
Attribution International 4.0 (CC BY 4.0)
Northern Territory Government
http://www.ntlis.nt.gov.au/metadata/export_data?type=html&metadata_id=6589A5D125EFB385E050CD9B2144202B; https://hdl.handle.net/10070/820014 [Report_print_Soil Land Assessment Flying Fox - Part A Land Resources General Land Capability]; https://hdl.handle.net/10070/820013 [Report_screen_Soil Land Assessment Flying Fox - Part A Land Resources General Land Capability]; https://hdl.handle.net/10070/829192 [Soil and Land Assessment of the Southern Part of Flying Fox Station for Irrigated Agriculture. Part B: Digital Soil Mapping and Crop Specific Land Suitability]
Soil and Land Assessment of the Southern Part of Flying Fox Station for Irrigated Agriculture Part A: Land Resources and General Land Capability 142 adequate soil organic matter (humic and/or chelated compounds) to maintain and improve long-term macropore stability (through water stable linkages); and controlled traffic and surface soil management to limit compaction and structural decline (Jayawardane and Chan 1995). Sodicity and dispersive behaviour in surface soils causes problems with aggregate instability, colloidal sediment loss and structural breakdown (crusting) after rainfall. Management of these effects typically requires gypsum application, reduced tillage and the maintenance of adequate surface cover/mulch to improve surface aggregate stability and limit raindrop impact (Soilpak 1998). Common practices to improve surface cover and organic matter include stubble retention, green manure crops and rotational cropping with deep rooted perennial species (Hall et al. 2021). Subsoil sodicity constraints (caused by in-situ dispersion and reduced macroporosity at depth) are more difficult to manage, but can be improved in the short term through deep ripping and gypsum application. Gains from such treatments are normally short lived however, because of leaching and compaction from agricultural traffic (Jayawardane and Chan 1995). Longer-term improvements to root zone conditions (and crop yields) typically require targeted surface and subsurface drainage, development of permanent beds, deep tillage when soils are at their lower storage limit, and targeted gypsum slotting or trenching (Jayawardane and Chan 1995). The use of strongly rooted rotational crops to promote biological soil loosening and deep soil profile drying is also recommended, particularly in vertic clays (Jayawardane and Chan 1995). Sodicity management for erosion control Effective erosion control in sodic landscapes requires careful land clearing and/or disturbance; strategic placement of surface runoff and drainage controls; and well-maintained ground cover. Sodic landscapes carry an elevated risk of sheet, gully and tunnel erosion, and the timing and staging of works needs to target lower risk periods. The depth and severity of sodic materials needs to be established prior to land disturbance, and surficial exposure avoided to minimise dispersive behaviour, colloidal sediment loss and the initiation of sheet and gully erosion after rainfall. Where sodic materials are inadvertently exposed, they should be treated immediately with gypsum (incorporated through shallow tillage) before a cover of benign topsoil and thick mulch is secured. Wilkinson et al. (2019) recognise the following steps for the successful management of active gully erosion within sodic landscapes: divert or reduce runoff and erosive surface flow away from the gully head through diversion structures and vegetative cover (where practical); reduce, widen and reshape gully batters to limit erosive sideslope gradients to <3%; treat/ameliorate reshaped dispersive batters with gypsum, benign topsoil and mulch; establish/maintain high levels of surface cover (grass sward) both in the gully bed and on gully batters; reinstate woody vegetation to stabilise the system in the longer-term; control drainage from roads and tracks (including cattle tracks) that sit up slope to reduce runoff concentration and erosive flows from entering the system; and