Water quality of a lowland stream in a New Zealand dairy farming catchment |
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| Authors: | Robert J Wilcock John W Nagels Harvey J E Rodda Michael B O'Connor Bruce S Thorrold James W Barnett |
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| Institution: | 1. National Institute of Water &2. Atmospheric Research Ltd , P.O. Box 11 115, Hamilton, New Zealand E-mail: r.wilcock@niwa.cri.nz;3. Atmospheric Research Ltd , P.O. Box 11 115, Hamilton, New Zealand;4. New Zealand Pastoral Agriculture Research Institute Ltd , Private Bag 3123, Hamilton, New Zealand;5. New Zealand Dairy Research Institute , Private Bag 11 029, Palmerston North, New Zealand |
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| 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 (NO‐ 3‐N). During summer NO‐ 3‐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 NO‐ 3‐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. |
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| Keywords: | suspended solids nutrients dissolved oxygen faecal bacteria dairy farming catchment New Zealand lowland stream |
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