Stubble retention and tillage in a semi-arid environment: 2. Soil mineral nitrogen accumulation during fallow

Abstract

The accumulation of soil mineral nitrogen (SMN) was studied over 4 years at two sites in north-west Victoria, Australia in response to fallow treatments. The four combinations of stubble management (with and without) and tillage (with and without) in 18-month-long fallows of a fallow-wheat rotation were compared with a tilled summer fallow prior to field pea and wheat crops in rotation. Across both sites, root-zone SMN ranged from 66 to 222 kg N h-1 during the fallows and at sowing time was generally less at Dooen than at Walpeup despite greater total soil N (Dooen O.11%, Walpeup 0.05%). At Dooen, the long fallow with stubble retention and tillage accumulated 46 kg N h-1 more SMN than the sh..