Restoring nutrient circularity in a nutrient-saturated area in Germany requires systemic change

Bernou Zoë van der Wiel,Matthias Kleinke,Florian Wichern,Corina Everarda van Middelaar,Cees Jan Nico Buisman,Jan Weijma

doi:10.1007/s10705-021-10172-3

Abstract

Regions with intensive agriculture often encounter environmental problems caused by nutrient excess of agro-food-waste systems that have become increasingly linear over previous decades. In this study, nitrogen (N), phosphorus (P), potassium (K) and carbon (C) flows in the whole agro-food-waste system of district Cleves in Germany were quantified simultaneously using substance flow analysis. Moreover, nutrient use inefficiency hotspots were identified to establish options to improve nutrient self-sufficiency as a first step towards nutrient circularity. Data on mass flows and nutrient contents was acquired for the year 2016 from stakeholders, statistical databases, literature and modelling. Organic C was included for flows with potential as organic fertilizer. Results show that animal production drives the nutrient flows in the export-oriented district, with feed import, manure application and losses from housing and manure storage accounting for 40, 45 and 60% of all N, P and K flows, respectively. In particular agriculture is responsible for N losses, with 150 kg N lost ha−1 agricultural land. Crop production surplus and with that soil accumulation of P and K are 515 t and 4100 t respectively. Stoichiometry of N:P:K:C in the different organic materials does not allow direct application and meeting crop requirements without exceeding demand of especially P. Processing of biomass is therefore required. Based on mass, especially manure holds potential for processing into bio-based fertilizers. To improve nutrient cycling and soil C conservation, being an important element for a sustainable agricultural sector, local balances between crop and animal production need to be considered.

Highlights

Food production in Europe and other areas of intensive agriculture depends heavily on external inputs of inorganic nitrogen (N), phosphorus (P) and potassium (K) fertilizers (Bellarby et al 2018; Kuokkanen et al 2017)
The systems current nutrient self-sufficiency, calculated as the percentage of all input flows stemming from local sources was, 50, 54 and 61%, respectively flows nutrient load in WwTP effluent and (for N), P and K
This study, may serve as a methodical blueprint for others who aim to analyse local nutrient flows in agro-food-waste systems. This multi-nutrient flow analysis with a local perspective indicates that the primary flows in the agro-foodwaste system in district Cleves are related to agriculture, especially to animal production

Summary

Introduction

Food production in Europe and other areas of intensive agriculture depends heavily on external inputs of inorganic nitrogen (N), phosphorus (P) and potassium (K) fertilizers (Bellarby et al 2018; Kuokkanen et al 2017). Some areas in the world are dependent on diminishing reserves of K (Bellarby et al 2018; Santos et al 2017; Sipert et al 2020) and in light of climatic extremes, Ks role in plant and soil functions, such as for the soil’s water holding capacity and plant drought stress alleviation, might become more important. Other regions of the world have insufficient access to inorganic fertilizers, which limits production of crops and impairs food security (Van Ittersum et al 2016)

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