Contribution of anthropogenic phosphorus to agricultural soil fertility and food production

Abstract

Agricultural intensification over the last few decades has been accompanied by the extensive use of anthropogenic phosphorus (P) derived from mined phosphate rock. Given the increasing scarcity of P resources, accurate estimates of the reliance of agriculture on anthropogenic P are required. Here we propose a modeling approach for assessing the contribution of anthropogenic P to agricultural soil fertility and food production. We performed computations at country level, and France was chosen as a typical western European country with intensive agriculture. Four soil P pools were identified based on their bioavailability (labile versus stable) and origin (anthropogenic versus natural). Pool evolution between 1948 and 2009 was estimated by combining international databases and a simple biogeochemical model. An optimization procedure demonstrated the necessity of representing a stable P pool capable of replenishing the labile pool within 14 to 33 years in order to match country-scale observations. Mean simulated P pool sizes for 2009 (0-35 cm soil horizon) were 146, 616, 31, and 156 kgP/ha for natural stable, anthropogenic stable, natural labile, and anthropogenic labile pools, respectively. We found that, on average, 82% (min-max: 68-91%) of soil P (sum of labile and above defined stable) in that year was anthropogenic. The temporal evolution of this contribution is directly related to the integral of chemical fertilizer use over time, starting from 1948. The contribution of anthropogenic P to food production was similar at 84% (min-max: 72-91%), which is greater than budget-based estimates (~50-60%) commonly reported in the literature. By focusing on soil fertility and food production, this study provides a quantitative estimation of human perturbations of the P cycle in agroecosystems.

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

“…A small fraction (8 %) of P from mined phosphate rock is used to produce animal feed additives. Apart from fertilizer and animal feed additives, the rest of the mined P is used to produce detergents and other products directly consumed by humans (Ringeval et al, 2014). Atmospheric Figure 1.…”

“…the budget); P > 0 indicates net P accumulation in the soil, P < 0 indicates a net deficit, and P = 0 represents no net change. P calculated in this manner does not reflect the legacy effects from previous management and fertilization practices (Ringeval et al, 2014), but it is a useful metric to identify regions with a P surplus or deficit at any point in time and to compare countries. Annual soil P values were calculated as the differences between annual inputs and outputs.…”

Integrating legacy soil phosphorus into sustainable nutrient management strategies for future food, bioenergy and water security

“…6 Tg. Ringeval et al (2014) estimated that over 80 % of the total P in French soils is associated with past P inputs (equivalent to ca. 65 Tg).…”

Sustainable food production: constraints, challenges and choices by 2050

“…As is well known, the growing consumption of inorganic phosphorus (P) fertilizers has contributed to major increases in crop yields since the 1950s (MacDonald et al 2011). For example, Ringeval et al (2014) found that the contribution of anthropogenic P to food production in France was as high as 84 %. In the United States, crop production would decline at least around 50 % over time without N, P, and K commercial fertilizer (Ringeval et al 2014).…”

“…For example, Ringeval et al (2014) found that the contribution of anthropogenic P to food production in France was as high as 84 %. In the United States, crop production would decline at least around 50 % over time without N, P, and K commercial fertilizer (Ringeval et al 2014). P mined from phosphate rock is a finite fossil resource with highly concentrated deposits -more so than that for oil reserves (Vaccari 2009).…”