Nitrogen and phosphorus discharge from small agricultural catchments predicted from land use and hydroclimate

• Autores: Jaan Pärn, Hocine Henine, Kuno Kasak, Karin Kauer, Kristina Sohar, Julien Tournebize, Evelyn Uuemaa, Kristiina Välik, U. Mander
• Localización: Land use policy: The International Journal Covering All Aspects of Land Use, ISSN 0264-8377, ISSN-e 1873-5754, Nº. 75, 2018, págs. 260-268
• Idioma: inglés
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• Resumen

  • Excess nutrients cause eutrophication of freshwaters all over the world. Decision-support tools are needed to assess nutrient discharges from catchments. This paper used a 28-year nutrient-discharge, hydroclimate and land-use history of small rural catchments to calibrate a simple nitrogen (N) and phosphorus (P) runoff model. The N and P runoffs declined following the post-Soviet collapse of agriculture, and stabilised at low output during the 1990s and early 2000s. Introduction of the European Union Common Agricultural Policy (CAP) re-intensified the agriculture and somewhat rebounded the N and P discharges. Thus, the history of the catchment represents a broad range of land-management systems. Our objective was to explain annual nutrient runoffs from small rural catchments by five factors: hydroclimate, soil type, land-use type, fertilisation and the autumn soil-nutrient stock. Our model independently predicted the eight-year mean N and P losses from a test set of small agricultural catchments in Estonia. This shows the impact of political decisions on agricultural contamination of waters. We can suggest our robust model as a decision-making tool for land-use management in small agricultural catchments.