Nutrient status of 1-0 Pinus radiata seedlings grown in 1978 at the Benalla, Rennick, and Trentham nurseries.  J. M. James and D. W. Flinn.  August 1980.  20 pp. (unpubl.)

SUMMARY

Tops of 1-0 Pinus radiata seedlings produced in 1978 at the Benalla, Rennick and Trentham nurseries were analysed for nutrient concentrations. The nutrient status of the seedlings varied considerably between the nurseries, and this was largely attributed to variable fertiliser input.

The nutrient status of seedlings produced at Benalla in 1978 was excellent, with the exception of magnesium, for which levels in seedling tops were often considerably less than desirable. Seedlings from the Rennick nursery had lower than desirable levels of nitrogen, potassium, magnesium and manganese in their tops. At this nursery, additional input of manganese fertiliser may be necessary if soil pH rises to above 7.0; an application of sulphur may be required also to reduce soil pH to around 6.0. A foliar application of zinc sulphate is recommended for this nursery, about one month prior to lifting, especially when seedlings are to be planted out on sites suspected of being zinc deficient.

Trentham nursery produced seedlings with lower than desirable levels of phosphorus, potassium, magnesium and inorganic sulphur in their tops. The seedlings also contained exceptionally high levels of iron and aluminium, and this was attributed to lower soil horizons being mixed with surface horizon during cultivation. Before the next pine crop is sown agricultural gypsum will need to be added to Davies Block at the rate of 1250 kg ha^-1 to reduce levels of iron and aluminium in the surface horizon of the seedling beds. Magnesium input above the current recommended level may be necessary for this Block.

To maintain the production of healthy seedlings in these nurseries, it is essential that a well-balanced fertiliser regime is used. Green cropping is also necessary to maintain soil structure and to improve the nutrient and moisture-holding capacities of the soils. The recommended fertiliser regime for all nurseries is a pre-sowing, broadcast application of Blood and Bone (1 000 kg ha^-1), Pivot 200 (500 kg ha^-1), and magnesium sulphate (200 kg ha^-1), uniformly incorporated into the beds at least four weeks prior to sowing, followed by monthly applications during the growing season of magnesium sulphate (50 kg ha^-1), Aquasol (10 kg ha^-1) and Nitrophoska Blue Special (10 kg ha^-1).