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Productive Cropping Systems With High Water Use

P.J. Haines, A. Ellington, and K.F. Wilson

Agriculture Victoria, RMB 1145, Rutherglen,Vic 3685

In many dryland cropping systems in SE Australia, unused rain contributes to the processes of land degradation and to lost crop yield. Cropping systems that use more water are likely to be more productive and sustainable than the present systems and impact less on the environment. While crop management (earlier sowing, later maturing varieties, increased fertiliser use) may increase water use, it seems likely that incorporating a perennial species into the system may be necessary to significantly reduce recharge to groundwater. This experiment is investigating the effect on water use and production of integrating perennial plants into annual cropping systems.

MATERIALS AND METHODS

The experiment which commenced at Rutherglen Research Institute in Northeast Victoria in August 1993 comprises three components. The effect of lucerne (Medicago sativa) on soil water use and productivity in crop rotations is being evaluated in both ley and alley farming systems. Short-term lucerne leys (2-4 years) are being compared against continuous lucerne, crop and annual pasture treatments, while quality of subsequent wheat and canola crops will be measured. Lucerne or trees and shrubs are also grown in alley systems, with the perennial component constituting 10%, 15% or 25% of the crop area, alternating with strips or alleys of crop. Soil water changes are monitored and logged to 3 m continuously using a Sentec enviroscan.

RESULTS AND DISCUSSION

In 1994, the first full year of experimentation, the extremely dry conditions limited the results achieved. The yield of lupin (Lupinus angustifolius) grown in the alleys and the continuous crop treatment yielded 0.3 t/ha, well below the average for the region. In early May 1995, the soil under lucerne in the ley system was about 30 mm drier than in the annual pasture treatment (Fig. 1). As the soil wetted up over winter, the lucerne treatment took about two weeks longer to reach saturation and contained up to 70 mm more water; lucerne had apparently increased the soil water-holding capacity. Both systems remained saturated until August 1995.

Figure 1. Changes in soil water content (mm to 1.4m depth) under lucerne and annual pasture.

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