Role of Rainfall Intensity and Hydrology in Nutrient Transport via Surface Runoff
- 1 July 2006
- journal article
- research article
- Published by Wiley in Journal of Environmental Quality
- Vol. 35 (4), 1248-1259
- https://doi.org/10.2134/jeq2006.0015
Abstract
Loss of soil nutrients in runoff accelerates eutrophication of surface waters. This study evaluated P and N in surface runoff in relation to rainfall intensity and hydrology for two soils along a single hillslope. Experiments were initiated on 1- by 2-m plots at foot-slope (6%) and mid-slope (30%) positions within an alfalfa (Medicago sativa L.)–orchardgrass (Dactylis glomerata L.) field. Rain simulations (2.9 and 7.0 cm h−1) were conducted under wet (spring) and dry (late-summer) conditions. Elevated, antecedent soil moisture at the foot-slope during the spring resulted in less rain required to generate runoff and greater runoff volumes, compared with runoff from the well-drained mid-slope in spring and at both landscape positions in late summer. Phosphorus in runoff was primarily in dissolved reactive form (DRP averaged 71% of total P), with DRP concentrations from the two soils corresponding with soil test P levels. Nitrogen in runoff was mainly nitrate (NO3–N averaged 77% of total N). Site hydrology, not chemistry, was primarily responsible for variations in mass N and P losses with landscape position. Larger runoff volumes from the foot-slope produced higher losses of total P (0.08 kg ha−1) and N (1.35 kg ha−1) than did runoff from the mid-slope (0.05 total P kg ha−1; 0.48 kg N ha−1), particularly under wet, spring-time conditions. Nutrient losses were significantly greater under the high intensity rainfall due to larger runoff volumes. Results affirm the critical source area concept for both N and P: both nutrient availability and hydrology in combination control nutrient loss. Copyright © 2006. American Society of Agronomy, Crop Science Society of America, Soil Science Society . ASA, CSSA, SSSAKeywords
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