School of Agriculture, Food and Ecosystem Sciences - Theses

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    The effects of fertilisation and wastewater irrigation on the biomass and nutrient content of Pinus radiata D. Don
    Stewart, Hugh Thomas Lindsay ( 1985)
    Detailed measurements were made of soil and stand characteristics before experimental plots were designed and laid out by collaborators from CSIRO. Fertiliser and irrigation were applied in a 2 x 2 factorial design, giving four treatment combinations. Irrigation commenced when the stand was 15 years old, and continued for 29 months; phosphorus at the rate of 5 g m- 2 was evenly broadcast as superphosphate when the stand was 16 years old. The study of biomass and nutrient uptake was comprehensive. Above-ground biomass was estimated by regression analysis of weights and dimensions of 24 sample trees, six trees being selected from each treatment. Standing litter was sampled, and root biomass estimated from core samples and by excavating the roots of one tree per treatment. Uptake of nine nutrients was estimated after measuring their concentrations in all components of the stand. Fertilisation with phosphorus had no effect on total above-ground biomass over a two-year period. Foliar analysis at the start of the study indicated that the trees were mildly deficient in phosphorus, but there was no increase in foliage biomass after fertilisation, despite substantial uptake of the applied nutrient. The lack of growth response was attributed to limiting soil moisture. This finding reinforces results of studies elsewhere that fertiliser responses are site-specific. (From Summary)