New Zealand Journal of Marine and Freshwater Research abstracts
Water quality of a lowland stream in a New Zealand dairy farming
catchment
ROBERT J. WILCOCK
JOHN W. NAGELS
HARVEY J. E. RODDA
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 11 115
Hamilton, New Zealand
email: r.wilcock@niwa.cri.nz
MICHAEL B. O'CONNOR
BRUCE S. THORROLD
New Zealand Pastoral Agriculture
Research Institute Ltd
Private Bag 3123
Hamilton, New Zealand
JAMES W. BARNETT
New Zealand Dairy Research Institute
Private Bag 11 029
Palmerston North, New Zealand
Abstract A small stream in a predominantly dairying catchment
in the Waikato region of New Zealand was monitored for 2 years at three sites.
Total nitrogen (TN) concentrations were up to 7.09 g m
-3 in
winter, with the bulk comprising nitrate nitrogen (NO3
--N). During
summer NO3
--N was near zero and TN mostly comprised organic
nitrogen. Maximum concentrations of total phosphorus (TP) and dissolved
reactive phosphorus (DRP) were 1.64 and 0.555 g m
-3,
respectively, and peaks coincided with spring and autumn applications of
phosphorus fertiliser. Ammoniacal nitrogen concentrations exceeded 1 g
m
-3 on several occasions and mean concentrations at the three sites
were 0.165-0.272 g m
-3. Faecal coliform and enterococci
bacteria concentrations were 64-26000 and 7-23000 cfu per 100 ml, respectively.
Specific yields of TN and NO3
--N (35.3 and 30.7 kg ha
yr
-1, respectively) were much greater than any previously reported
for New Zealand pasture catchments, whereas TP and DRP yields (1.16 and
0.54 kg ha yr
-1, respectively) were more in accord with other
studies. Greater use of land treatment of liquid wastes will reduce stream
inputs of faecal organisms, NH4-N and P.
Keywords suspended solids; nutrients; dissolved oxygen;
faecal bacteria; dairy farming; catchment; New Zealand; lowland stream
M99015
Received 23 March 1999; accepted 23 June 1999
PDF file of entire paper: medium quality (968K); (scanned from paper original: notes about this process)
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