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Improving fertiliser use efficiency by deep banding

I.T. Mock and A.W. Making

Department of Agriculture, Mallee Research Station, Walpeup VIC 3507
Department of Agriculture, Food Research Institute, Werribee VIC 3030

The viability of cropping the inherently infertile soils of the Mallee would improve if the production achieved from each unit of applied fertiliser (the use efficiency) was increased. Lupin (Lupinus aryistofolius) yields increase as phosphate fertiliser rates are increased but the responses decline and further applications become uneconomic. Deep banding phosphorus fertiliser was evaluated at Walpeup as a means of increasing the efficiency of fertiliser use by avoiding toxic effects to the crop caused by sowing large quantities of fertiliser with the seed.

Methods

An experiment sown on a sandy, low fertility Mallee soil compared lupin production from 4 fertiliser types, (not reported on) and three fertiliser application techniques:

conventionally sown with the seed;

banded 50 mm below the seed using a single tine with fertiliser banding adaptation;

split application (half sown with the seed and the rest top dressed six weeks later).

Results and discussion

Banding fertiliser resulted in significantly greater lupin crop density, dry matter production and grain yield than the conventionally sown or split applications (Table 1).

Table 1. The effect of fertiliser application method on lupin density and dry matter production at anthesis and grain yield.

The results contrast with previous research (1) which has shown that only marginal yield improvements result from increasing lupin density over 35 plants/m2. Two other factors were significantly correlated with the fertiliser application technique used and are likely to have contributed to the increased yield resulting from deep banding fertiliser. These were:

the soil cone penetrometer resistance between 40-90 mm was significantly less for the

banded treatments than for the non-banded treatments;

here was a greater proportion of roots from conventional sowing than banding in the profile between 50-100 mm. At 100-150 mm, however, the reverse occurred.

Cultivation that occurred below the seeding depth when fertiliser was banded reduced soil resistance at this depth and promoted a greater proportion of roots deeper in the profile. It has still to be established if increased production and efficiency of fertiliser can be achieved with sub-seedbed cultivation in the absence of fertiliser banding.

Reference

Dept. Ag. Victoria 1989. The Mallee Legume Book, pp. 4-13.

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