Swan(sea) Song – personal research during my six years at Swansea ... and bey...
Road toward sustainable agricultural prodcution
1. THE ROAD TOWARD SUSTAINABLE PRODUCTION: The Evolution of Soil Structural Repair Under Zero Till, Controlled Traffic, Permanent Bed Farming *A.D. McHugh, # J. N. Tullberg and * D. M. Freebairn *Queensland Department of Natural Resources and Mines # Gatton College, University of Queensland Photo Source: “Storm over Bauhinia” Central Queensland Sustainable Farming Systems Project
2. Objective To assess structural condition of a black cracking clay before and after wheel traffic was isolated to permanent tracks by measuring hydraulic conductivity, bulk density, plant available water capacity and cone penetrometer resistance. Site 1895-1945: Dairy farm. 1945-1996: Conventional cereal & forage production. 1996-2003: Controlled Traffic – Permanent beds N
Objective to quantify the changes in structural form of a Vertosol after replacing the 50 year conventional cropping regime with a controlled traffic zero till farming system. Site Near the Gatton Campus UQ in the Lockyer valley, 1 hours drive west of here Dairy farm 1895 - 1945 Cereal/forage production 45-96 (potatoes on occasion). Furrow irrigation bays constructed early 80s but not used as such Controlled traffic 1996 - onwards
Based on the changes in soil water retention characteristics and bulk density, PAWC improved on conventional conditions by around 5mm per 10cm depth of active root zone. Click This is a comparison of PAWC over the 300mm depth measured between cropping zones and and soil that was wheeled yearly (no difference between soil wheeled twice or six times per year) What is more significant is what happens to the PAWC if the cropping zone having not been traffficked for 5 years is wheeled. Click At 58 months the cropping zone was wheeled once by a tractor weighing 4.2 tonne on the back axle. Consequently PAWC was reduced to near pre CTF conditions. This confirms the susceptibility of soil to compaction and that the 1 st wheeling causes over 85% of the damage.
This sort of intensive tillage and traffic creates profiles like this. Blocky massive structures and plough layers throughout the field. What we are really tying to achieve is soil condition like the 0-250mm section in the photo and extended it to depth. This can be achieved by isolating traffic to fixed lanes and cropping on permanent beds harnessing the unique properties of shrink swell clays and biological activity to ameliorate the soil to depth.
Conventional farming had left the soil profile degraded with plough layers, extreme densification and limited drainage. Soil amelioration is evident after 3 cropping seasons of wheel traffic isolation. Which is demonstrated by pore size redistribution and increased connectivity. Biological drilling and contributions from shrink/swell processes improves hydraulic conductivity by 65% and plant available water by 5mm per 10cm of active root zone.
