Phosphorus stocks and flows in an intensive livestock dominated food system

Abstract

Current use and management of phosphorus (P) in our food systems is considered unsustainable and considerable improvements in the efficiency of P use are required to mitigate the environmental impact of poor P stewardship. The inherent low P use efficiency of food production from animals means food systems dominated by livestock agriculture can pose unique challenges for improving P management. This paper presents the results of a substance flow analysis for P in the Northern Ireland (NI) food system for the year 2017 as a case study for examining P stewardship in a livestock dominated agricultural system. Imported livestock feed was by far the largest flow of P into the NI food system in 2017 (11,700 t ± 1300 t) and P from livestock excreta the largest internal flow of P (20,400 ± 1900t). The P contained in livestock slurries and manures alone that were returned to agricultural land exceeded total crop and grass P requirement by 20% and were the largest contributor to an annual excess soil P accumulation of 8.5 ± 1.4 kg ha −1 . This current livestock driven P surplus also limits the opportunities for P circularity and reuse from other sectors within the food system, e.g. wastewater biosolids and products from food processing waste. Management of livestock P demand (livestock numbers, feed P content) or technological advancements that facilitate the processing and subsequent export of slurries and manures are therefore needed.

A transition management framework to stimulate a circular phosphorus system

“…As the major consumer of P, the agricultural sector is key to understanding P sustainability, as it often dominates P stocks and flows (Rothwell et al, 2020). In this section, we examine changes in agricultural P use over the past 70 years, driven by increased pressure for efficient crop production, technological advancements, and niche innovations.…”

“…Transition shifts make P use efficiency a tool that requires a long-term perspective and global thinking beyond a one-dimensional assessment (Scholz & Wellmer, 2015). For example, when manure P is considered, it can provide a buffer against conventional P fertilizer shortages and price fluctuations, potentially reducing the vulnerability of livestock intense areas to shocks related to global P availability (Rothwell et al, 2020). Eventually, the P shocks on grain producing areas would be felt by the livestock areas, particularly those heavily reliant on imported feeds that are dependent on conventional P fertilizer (Rothwell et al, 2020).…”

“…For example, when manure P is considered, it can provide a buffer against conventional P fertilizer shortages and price fluctuations, potentially reducing the vulnerability of livestock intense areas to shocks related to global P availability (Rothwell et al, 2020). Eventually, the P shocks on grain producing areas would be felt by the livestock areas, particularly those heavily reliant on imported feeds that are dependent on conventional P fertilizer (Rothwell et al, 2020). To become truly sustainable, research and policy development must be motivated to balance the requirements for both food security and environmental safety, globally.…”

“…Increasing P sustainability and reducing vulnerability to P shocks will require connectivity between sectors, circularization, and minimization of P loss throughout the entire P production system (Rothwell et al, 2020). As a society, we must also focus on reducing the P demand and creating a more balanced distribution of P sources and sinks.…”

Optimizing the P balance: How do modern maize hybrids react to different starter fertilizers?

“…Several studies have shown that P in Europe is sufficiently to abundantly available on agricultural lands [18]. This holds specifically true for agricultural businesses that have a surplus of organic fertilizers available, namely livestock-and biogas-based farms [19,20]. In many cases however, the abundant P is fixed by minerals and therefore not fully available for plants [21].…”