Nutrient status and soil properties in areas of the Benalla, Koetong, Rennick and Trentham Nurseries producing 1-0 Pinus radiata seedlings in 1973.  P. Hopmans and D.W. Flinn.  November 1975.  21 pp. (unpubl.)

SUMMARY

Nutrient status and soil properties in areas of the Benalla, Koetong, Rennick and Trentham nurseries producing 1-0 Pinus radiata seedlings in 1973 have been studied from soil and seedling samples taken at the time of lifting. The objectives were firstly to determine and recommend appropriate fertiliser regimes for future seedling crops in these areas, and secondly to measure soil changes of importance in long-term productivity of the nurseries and to recommend ameliorative treatments where necessary.

At Benalla seedling size was found to be satisfactory and no nutrient deficiencies were evident. However, magnesium concentrations in the seedling tops were less than desirable in all blocks and phosphorus levels were marginal in all blocks except 8C. Consistent evidence was found for a deterioration in soil structure with successive crop rotations, and the continued substantial use of green cropping will be required to arrest this trend. In blocks 3A, 3B and 4A pre-sowing applications of magnesium sulphate (250 kg/ha) and superphosphate (700 kg/ha) are recommended. In block 8C the same rate of magnesium sulphate should be used but super phosphate can be reduced to 400 kg/ha. Aquasol should be applied at 10 kg/ha monthly in the irrigation water until March.

At Koetong the seedlings were small except in block E where an autumn sowing was made. High aluminium concentrations and low magnesium levels in the seedling tops continue to be serious problems. The soil results for this nursery showed that intensive green cropping during fallow rotations is mandatory if long-term productivity is to be maintained. In blocks E, F and G, pre-sowing applications of superphosphate (400 kg/ha), magnesium sulphate (350 kg/ha) and ammonium sulphate (100 kg/ha) are recommended together with aquasol at 10 kg/ha/month in the irrigation water. The practice of applying high rates of gypsum before sowing is valuable and should be continued.

Rennick produced the largest seedlings in 1973. However, in some samples magnesium and zinc concentrations in the seedling tops were quite clearly seriously deficient. The soil results for this nursery were unsatisfactory and green cropping practice must be improved if long-term productivity is to be maintained. In bays 4, 5, 6, 7, and 11, pre- sowing applications of magnesium sulphate (250 kg/ha), blood and bone (100 kg/ha), ammonium sulphate (100 kg/ha) and a 1:11 mixture (by weight) of zinc sulphate and superphosphate (300 kg/ha) are recommended together with aquasol at 10 kg/ha/month in the irrigation water.

Seedlings from the Trentham nursery were of excellent size in 1973 and their overall nutrient status was generally satisfactory, although aluminium levels in the seedling tops were very high and phosphorus, sulphur and magnesium levels lower than desirable in the McGuinness block. The soil results indicate that structure is deteriorating and green cropping must be employed to arrest this trend. In the McGuinness and Davis blocks pre-sowing applications of gypsum (4 tonnes/ha), magnesium sulphate (200 kg/ha), ammonium sulphate (100 and 50 kg/ha respectively) and superphosphate (400 and 200 kg/ha respectively) are recommended. Thrive should also be used at 2 kg/ha/month in the irrigation water.