Effects of phosphorus and nitrogen on growth of pasture plants and VAM fungi in SE Australian soils with contrasting fertiliser histories (conventional and biodynamic)
M. Ryan et J. Ash, Effects of phosphorus and nitrogen on growth of pasture plants and VAM fungi in SE Australian soils with contrasting fertiliser histories (conventional and biodynamic), AGR ECO ENV, 73(1), 1999, pp. 51-62
The soil biological community has been reported to differ between conventio
nal and alternative (organic and biodynamic) farming systems. However, few
studies have investigated whether this results in substantial differences i
n the biological pathways controlling major ecosystem processes, such as pl
ant nutrient uptake. This paper describes a glasshouse experiment conducted
using a red-brown earth (Natrixeralf) soil sampled from three conventional
and three biodynamic irrigated dairy pastures located in the Goulburn Rive
r Valley, Victoria, Australia. The biodynamic soils had not had organic or
inorganic fertilisers applied for, on average, 17 years, while the conventi
onal soils had received regular inputs of fertilisers containing soluble ph
osphorus (P) and nitrogen (N). The experiment examined whether the contrast
ing fertiliser histories had resulted in different pathways of plant nutrie
nt uptake through assessing the response of white clover (Trifolium repens
L.), perennial rye grass (Lolium perenne L.) and the indigenous vesicular-a
rbuscular mycorrhizal (VAM) fungi to addition of four levels of soluble P a
nd N. The response to added P and N did not differ between the conventional
and biodynamic soils, although, plants in the biodynamic soils had a slowe
r growth rate and a higher level of colonisation by VAM fungi due to lower
initial soil P and N concentrations. Overall, there was no indication that
the biodynamic and conventional soils had developed substantially different
processes to enhance plant nutrient uptake or that the indigenous VAM fung
i differed in their tolerance to applications of soluble nutrients. (C) 199
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