Preparation of mixtures of sand and clay-rich subsoil
In Western Australia, crop yield in the sandy soils of the wheatbelt is influenced strongly by the plant-available water and soil strength of subsoils
, and adjacent subsoils
with broadly similar texture (around 20% clay) are known to vary widely in their crop production potential.
Batch equilibrium experiments were used in order to compare metal affinity differences between the subsoil
Given the overall low permeability of the extant subsoils
, all rain gardens were anticipated to produce high amounts of underdrain flow as a response to free drainage of saturated soils (figure 5).
The problem of undisturbed subsoil
in the row middle for double crop, no surface tillage production of winter wheat was successfully addressed with a paratill with shanks set as opposed pairs and spaced 71 cm apart (Frederick and Bauer, 1996).
In the present study, the influence of structure was less pronounced when the entire soils were considered irrespective of sampling depth than when considered separately for the topsoils and subsoils
, despite a reduced number of observations in the latter approach.
2001), but presence of subsoil
constraints (SSC) limits the effective rooting depth and increases crop lower limit (CLL), thereby reducing the amount of water and nutrients that plants can access from soil (Sadras et al.
This experimentation was funded by the Grains Research and Development Corporation and the Victorian Department of Primary Industries through the protect 'Improving the profitability of cropping on hostile subsoils
Many field crops in southern Australia are unable to efficiently extract soil-water and nutrients from depth because physical and chemical constraints prevent root exploration of the subsoil
(1), which contains stored water and some nutrients.
More commonly, transient salinity, associated with poor permeability of subsoils
, may occur in the root-zone unrelated to any groundwater influence (Rengasamy 2002).
The nature of strong subsoils
formed in sedimentary materials will be compared with in situ granitic saprolite that occurs as a subsoil
in many locations.
Differential genotypic responses to subsoil
compaction have been found in essentially all crop species that have been evaluated (Asady et al., 1985; Smucker, 1985; Torbert et al., 1990; Kasperbauer and Busscher, 1991; Yu et al., 1995).