LUPIN, FERTILISER, AND THINNING EFFECTS ON EARLY PRODUCTIVITY OF PINUS RADIATA GROWING ON DEEP PINAKI SANDS

A balanced application of nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur fertilisers significantly increased height growth of Pinus radiata D. Don on Pinaki sands at Woodhill State Forest, but the presence of Lupinus a r bo reus Sims (yellow tree lupin) did not. Lupin died out of all stands ranging from 741 to 2224 stems/ha by tree age 5 years, but the benefits for basal area and volume increment continued to accumulate up to tree age 11. Stands that have had both lupin and fertiliser can produce 35-40 m 3 annum on 2224 stems/ha, or double the increment of untreated stands at any stocking. The maximum benefits from thinning were obtained only on fertiliser-treated stands, which were three or four times more responsive than untreated controls, particularly at stockings exceeding 1500 stems/ha. It is possible to increase the volume of the dominant trees by 40-50% by pre-competitive thinning in con­ junction with fertiliser application, but there is a commensurate sacrifice of total production.