|
E. Linacre |
3/'99 |
Table 1 shows that more winter rain tends to lead to higher yields in an otherwise semi-arid climate. The bottom row of figures imply a reduction of yield due to water-logging. The wide ranges of yields for a particular rainfall show the effects of other factors, such as the temperature, changes in farming practices (such as field fertilisation), and the precise time and intensity of the precipitation.
Table 1. Wheat yields for various ranges of rainfall between April and September, i.e. the growth period of winter wheat in Australia. The figures relate to six years’ data (ie 1969-75) from nine districts of New South Wales (1).
|
rainfall: mm |
yields: tonnes/ha |
||
|
range |
median |
||
|
0-100 |
single case |
0.16 |
|
|
100-150 |
0.33-0.99 |
0.86 |
|
|
150-200 |
0.58-1.40 |
0.82 |
|
|
200-250 |
0.86-1.54 |
1.29 |
|
|
250-300 |
0.91-1.45 |
1.31 |
|
|
300-350 |
1.04-1.32 |
1.19 |
|
|
350-400 |
1.40-1.60 |
1.48 |
|
|
400-450 |
1.59-1.74 |
1.71 |
|
|
450-500 |
1.25-1.50 |
1.27 |
|
Reference
(1) Linacre, E.T. & J.E. Hobbs 1977. The Australian Climatic Environment (Jacaranda Wiley) p.223.