Regional-scale phosphorus flows and budgets within France: The importance of agricultural production systems

Abstract

Large-scale studies at the regional, national and global scales are increasingly needed to assess nutrient flows in agroecoystems and to identify their drivers. In this study, we aimed to quantify the extent to which regional phosphorus (P) flows and soil P budget depend on agricultural production systems. Phosphorus was taken as a case study due to its sorbing properties in soil and to the many questions concerning its future availability. The issue was studied from two different stages: (1) for the 21 administrative regions of France; and (2) by selecting four contrasting French regions-the Centre region (a crop farming region), Brittany (an animal farming region) and Lorraine and Aquitaine (mixed farming regions). Phosphorus flows and soil P budgets were quantified on a yearly basis for the 21 regions from 1990 to 2006, whereas a 5-year average was calculated for the years 2002-2006 to compare the four selected regions. At the beginning of the study (1990), the calculated P budget was positive for all regions averaging 17.5 kg P ha -1 year -1 which declined over years to 4.4 kg P ha -1 year -1 in 2006, but huge differences between the 21 regions were observed, confirming the heterogeneity of the regional P flows. Agricultural production systems strongly influenced the P flows through feed, fodder and animal excretion, while P fertiliser consumption was only partially influenced. As a consequence, both the regional soil P budgets and the magnitude of soil P inflows and outflows were strongly dependent on the regional agricultural production systems. A balanced soil P budget could be obtained in crop farming regions, but it strongly relied on P fertiliser use. The animal farming regions continued to accumulate P in the soil, and further use of P fertilisers in these regions is questionable. Finally, there was no simple rule between the mixed farming systems and the soil P budget. This study offers some initial elements for understanding the drivers of mineral P fertiliser use, i.e. the factors governing P fertiliser use by the farmers. It may also contribute to the redesign of regional farming systems oriented towards more effective use of nutrients at the global scale.

Global and regional phosphorus budgets in agricultural systems and their implications for phosphorus-use efficiency

“…The negative impacts of this perturbation on the natural environment depend on how much P is lost from regions with intensive fertilizer use (Smil, 2000;Bennett et al, 2001). P application differs significantly between countries and crop types (Grote et al, 2005), and previous researchers have attempted to estimate the P flows in agricultural systems in Europe (Ott & Rechberger, 2012), the United States (Suh & Yee, 2011), China (Ma et al, 2011), France (Senthilkumar et al, 2012), Australia (Cordell et al, 2013), and the world (Smil, 2000;Liu et al, 2008;MacDonald et al, 2011;Schipanski & Bennett, 2012). International trade and regional agricultural policies affect P budgets by increasing or decreasing the gap between P inputs and P outputs in agricultural land (Grote et al, 2005).…”

Spatial variability of soil phosphorus in the Fribourg canton, Switzerland

“…Awareness of the P crisis has been highlighted in the last couple of years by many studies that have investigated P status and its consequences at different spatial and temporal scales. For example, it has been shown that P flux heterogeneity, observed at the national scale (Senthilkumar et al, 2012a) and regional scale (Senthilkumar et al, 2012b), is most often due to industrial and agricultural activities. Moreover, soil P content expresses certain heterogeneity even at the field level (Juang et al, 2002;Umali et al, 2012), leading to site-specific fertilization recommendations.…”

A substance flow analysis of phosphorus in the food production, processing and consumption system of the Netherlands

“…In France the national average balance decreased from 17.5 in 1990 to 4.4 kg P/ha in 2006. However, in 2006 it ranged from 17 kg P/ha in Brittany, a region with a high livestock density, to 0 kg P/ha for the Central region with a low livestock density (Senthilkumar et al 2012).…”

“…Senthilkumar et al 2012). However, when considering the importance of recycling it becomes relevant to include also the food and feed processing and consumption sector.…”