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Delayed Sample Filtration and Storage Effects on Dissolved Nutrients Measured in Agricultural Runoff
- Lentz, Rodrick D.
- Communications in soil science and plant analysis 2013 v.44 no.20 pp. 2952
- acid treatment, agricultural management, agricultural runoff, ammonium nitrogen, boric acid, cold storage, edge effects, filtration, furrows, irrigation, nitrate nitrogen, nutrients, phosphorus, pollution load
- Few research studies have examined the influence of delayed filtration on sample stability or runoff nutrient loss assessments. Runoff samples from irrigation furrows were each split into four volumes: two were filtered (45 μm) in the field and two were filtered 10 days later, with or without boric acid treatment, and stored at 4 °C. Sample dissolved reactive P (DRP), nitrate nitrogen (NO ₃-N), and ammonium (NH ₄)-N concentrations were measured in all filtered samples 10 and 107 days after collection. Samples filtered in the field and those with a 10-day delayed filtration had similar dissolved DRP, NO ₃-N, and NH ₄-N concentrations, whether or not boric acid was added. Boric acid stabilized DRP and NH ₄-N sample concentrations, but not NO ₃-N, during the 107 days of storage (relative to field-filtered samples). The effect of treatments on computed furrow stream concentration and runoff mass losses was similar to that for sample concentrations, except that furrow NH ₄-N parameters were unaffected by treatments. The field-filtered or 10-d delayed filtration without boric acid treatments provided the best dissolved nutrient measurements for comparing agricultural management effects at the field edge; however, results suggest that an incubation-type test for field-edge runoff water may provide a more accurate estimate of field management effects on dissolved nutrient loads in downstream aquatic ecosystems.