Vertical Progressive Tillage to Remove SubsoilCompaction will Improve Subsoil and IncreaseWater Use Efficiency of Field Crops

摘要

Researching long-term conservation tillage between 1978 to 2002, we realised thatpoor water use efficiency in field crops grown in South Australian red-brown earth was mainlyassociated with subsoil problems in particular compaction, and the use of no-till without firstremoving compaction would take more than 15 years to satisfactorily repair compacted subsoil.In 1997 we set up a field experiment to develop a new tillage regime to test the benefits ofvarying tillage depths to ameliorate compaction and increase the depth of soil exploitable byplant roots and improve yield and yield quality. The experiment was fully randomised blockdesign with 4 replicates and included three rotations: continuous cereal with wheat-barleywheat-wheat (WBWWWW); wheat-peas-canola-wheat-peas (WPeCaWPe); wheat-pasturepasture-wheat-peas (WPPWPe). Each rotation had three tillage regimes: conventionalcultivation (CC) - cultivating several times and seeding with 175mm wide shares; no-tillage (NT)- sowing into uncultivated soil with 15mm leading edge points; and tillage rotation (TR) - directdrilled up to 15cm depth of cut but varying from year to year to avoid a consistent uniformdepth of working. TR was sown with points: 8mm leading edge, 50mm wing width and 40mmwing depth and depth of cut alternating between 12cm and 15cm each year. The TR systemtook only 4 years to reduce bulk density in these depths from 1.9t/m 3 to 1.34t/m3. Due to thesedecreases, TR yield and economic returns increased considerably compared with NT and CC.