Establishment of wheat in relation to apparent density of the surface soil

Abstract

Measurements were made of wheat establishment and of the apparent density of surface soil on a number of rotation plots at the Waite Agricultural Research Institute. The red-brown earth of the site is common to a large part of the wheat belt of South Australia; this soil shows marked structural deterioration under a variety of cropping systems. Observations made in 1954, 1955, and 1956 provided data on the interaction between the apparent density of the surface soil and the rainfall following seeding, in relation to the establishment of wheat. The apparent density of the surface soil of all rotations varied from season to season and was higher during wetter seasons. Within each season, apparent density was higher on closer rotations and least where wheat was sown direct onto ploughed pasture. Establishment was reduced both by high rainfall and by high apparent density; the latter varied with both rotation pretreatment and current rainfall. It is believed that poor soil aeration resulted either directly or indirectly in reduction in wheat establishment.