Transport and transformation of nutrients and sediment in two agricultural watersheds in Northeast Arkansas

摘要: Abstract Understanding pollutant transport at different spatial and temporal scales is crucial to agroecosystems management planning. This study aimed reduce the knowledge gap between edge-of-field larger agricultural watersheds. Nutrients sediment transformation two small watersheds, Little River Ditches Basin (LRDB) Lower St. Francis (LSFB), in Northeast Arkansas, were evaluated. Flow, nutrients, measured 3–5 instream locations these contrasting These watersheds differed primary crop, soil type, size. Differences nutrients loads primarily due differences cropping practices type. LSFB was dominated by rice farms had more load per unit area but lower concentrations for all parameters except nitrate, whereas LRDB cotton less higher concentrations. Turbidity increased considerably LSFB, it did not increase or decrease as water traveled downstream. The median nitrate-N concentration from 1.64 2.34 mg L−1 watershed size increased, contrast no LSFB. Total phosphorus (TP) soluble reactive (SRP) remained constant, ammonium-N decreased downstream both Nitrate-N high spring late fall annual loss of 9.6 8.6 kg ha−1, 1604 1958 kg ha−1, SRP 0.8 0.9 kg ha−1, respectively Source control could be effective reducing pollution.