The degree of phosphorus saturation of agricultural soils in Germany: Current and future risk of diffuse P loss and implications for soil P management in Europe

P Fischer; R Pöthig; M Venohr

doi:10.1016/j.scitotenv.2017.03.143

The degree of phosphorus saturation of agricultural soils in Germany: Current and future risk of diffuse P loss and implications for soil P management in Europe

Sci Total Environ. 2017 Dec 1:599-600:1130-1139. doi: 10.1016/j.scitotenv.2017.03.143. Epub 2017 May 12.

Authors

P Fischer¹, R Pöthig², M Venohr³

Affiliations

¹ Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Ecohydrology, Justus von Liebig Straße 7, 12489 Berlin, Germany; Humboldt-University Berlin, Geography Department, Unter den Linden 6, 10099 Berlin, Germany. Electronic address: peter_fischer@online.de.
² Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Ecohydrology, Justus von Liebig Straße 7, 12489 Berlin, Germany. Electronic address: r.poethig@gmx.net.
³ Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Ecohydrology, Justus von Liebig Straße 7, 12489 Berlin, Germany. Electronic address: m.venohr@igb-berlin.de.

PMID: 28511358
DOI: 10.1016/j.scitotenv.2017.03.143

Abstract

Decades of intensive agricultural production with excessive application of P fertilizer have resulted in the accumulation of P in soils, threatening water bodies in most industrialized countries with eutrophication. In our study, we elucidated the risk of P loss of German agricultural soils by transforming provided monitoring data of plant-available P determined by the calcium-acetate-lactate (PCAL) and double-lactate method (PDL) into the degree of phosphorus saturation (DPS). As water-soluble phosphorus (WSP) is correlated to DPS, we derived a pedotransfer function (PTF) between PCAL and WSP for different soil types. Considering all soils together resulted in WSP=0.1918×PCAL (R²=0.80, n=54). Subsequently, risk parameters DPS and EPC0 were calculated from PCAL and PDL monitoring data (n>337,000) by using the determined PTF and soil type-independent correlations with WSP, as published in an earlier study. Calculated DPS values from monitoring data indicated high risks of dissolved P loss for >76% of German arable soils. Recent suggestions by the Association of German Agricultural Analytical and Research Institutes (VDLUFA) to reduce recommended PCAL levels are crucial for the reduction of P loss risks in the future. The accuracy of predicted DPS and EPC0 values by CAL and other methods used in Europe to estimate plant-available P is limited by the soil type-dependency of these methods. Consequently, we recommend considering WSP as an agri-environmental soil P test across Europe. Our results indicate that a WSP level in soils can be defined that constitutes a reasonable compromise between the securing of agronomic production and the fulfillment of environmental goals.

Keywords: Agri-environmental soil P test; Calcium-acetate-lactate; Equilibrium phosphorus concentration; Plant-available phosphorus; Soil fertility classes; Water-soluble phosphorus.