Good no-till starts years earlier with clean and diverse crop rotations. A good crop sequence reduces yield restrictions from pests and diseases and lessens the reliance on pesticides. By controlling weeds, which are hosts to diseases, problems with both weeds and diseases are reduced.
The year before seeding good stubble management is also essential. The need to retain stubble, for soil and soil-life benefits, is shown by the results of a long-term experiment, given in Table I below, conducted at Merredin on a heavy (sandy clay loam) soil.
Knife point establishment (on left) versus disc establishment with press wheels in dry
soil at Muresk.
In order for tyned machines to seed through stubble, the stubble will need managing. Many farmers have opted for wider row spacings to overcome this problem. Cutting the straw short and spreading it evenly improves residue flow. On sandy south coast soils, discs may have to be put in front of tynes to improve flow. For this reason, many farmers have opted for disc only machines in these environments.
When the break to the season occurs, if weeds become well established, much higher rates of knockdown herbicides are needed as no-till does not provide a second knock effect on the weeds as tillage does.
|
Treatments
|
Organic carbon (%)
|
pH CaCl2
|
Water stable
aggregates (%)
|
Bulk density (g/cc)
|
Protein (%)
|
Harvest yield (t/ha)
|
|
Stubble burnt
|
1.01
|
5.5
|
11
|
1.61
|
8.5
|
3.29
|
|
Stubble kept
|
1.11
|
5.6
|
18
|
1.57
|
8.6
|
3.76
|
Table 1. The effect of stubble retention on soil properties and yield of wheat in 1995 on a heavy soil (after nine years of experiment).
|
Row spacing (mm)
|
Stubble burnt
|
Stubble retained
|
Average
|
% of 180mm
|
|
90
|
2.57
|
2.73
|
2.65
|
101.5
|
|
180
|
2.47
|
2.75
|
2.61
|
100.0
|
|
270
|
2.41
|
2.58
|
2.49
|
95.4
|
|
360
|
2.25
|
2.51
|
2.38
|
90.9
|
|
Average
|
2.42
|
2.64
|
2.53
|
|
|
% of Average
|
91.7
|
100
|
|
|
Table 2. Average no-till wheat yield with stubble and row spacing for 1995, 97, 98, 01, 03, 04 (t/ha)
Source: Riethmuller GP, Department of Agriculture, Western Australia, Merredin.
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