New Zealand Journal of Agricultural Research abstracts

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Effect of different forage plants on denitrification potential of Horotiu soil

J. R. CRUSH

AgResearch
Ruakura Agricultural Research Centre
Private Bag 3123
Hamilton, New Zealand

Abstract  Denitrification potential (DNP), water-soluble soil carbon, soil nitrate, and plant weights were measured in lysimeters growing cocksfoot, tall fescue, chicory, Yatsyn ryegrass, or Ruanui ryegrass in a New Zealand soil. The soil-related parameters were measured in the topsoil and upper- and lower-subsoil zones of the lysimeters. Significantly lower rates of DNP were measured under Ruanui ryegrass than under the other plants and there was a tendency for higher rates of DNP to be associated with bigger root masses. Water-soluble carbon was higher in the topsoil than in the upper- or lower-subsoil, but soluble carbon did not differ significantly among the cultivars. DNP responded positively to addition of glucose to the soil, demonstrating that soluble carbon rather than the resident populations of denitrifying micro-organisms were limiting DNP. Lysimeters growing cocksfoot had the lowest soil nitrate levels and the largest root systems but only intermediate rates of DNP. The quality of root residues entering the soil under cocksfoot is probably lower than for the other plants.

Keywords  carbon; chicory; cocksfoot; tall fescue; denitrification; nitrate; roots; rooting depth; ryegrass; soil

New Zealand Journal of Agricultural Research, 1998, Vol. 41: 421-426

0028-8233/98/4103-0421 $7.00/0 (c) The Royal Society of New Zealand 1998

PDF file of entire paper: medium quality (528K); (scanned from paper original: notes about this process)

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