Academic journal article Sustainability : Science, Practice, & Policy

Closing the Food Loops: Guidelines and Criteria for Improving Nutrient Management

Academic journal article Sustainability : Science, Practice, & Policy

Closing the Food Loops: Guidelines and Criteria for Improving Nutrient Management

Article excerpt

Introduction

The global population has grown sharply over the last century, placing increasing burdens on the natural resources that provide us with food, energy, and shelter. Roughly one third of food internationally produced for human consumption, equivalent to 1.3 billion tons per year, is lost or wasted (Godfray et al. 2010; Gustavsson et al. 2011). Estimates of the volume of food wasted along global supply chains, from agricultural production to final human consumption, range from 25-50%. There are great differences among regions in the amount of food lost and in terms of where the losses are most pronounced (Mena et al. 2011). In all regions, however, there is growing recognition of the need to improve agricultural resource efficiency with respect to both water and nutrients (Foley et al. 2011). Increasing access to fertilizers, particularly locally produced agricultural additives, and improved soil-nutrient management are critical in assuring global food security (Chen et al. 2011).

Increased productivity since World War II has been achieved through application of chemical fertilizers, pesticides, and irrigation, yet the contemporary global environmental situation and growing constraints in resource availability challenge us to take a more sustainable approach. The production of chemical fertilizers relies on limited sources of phosphorus and energy-intensive nitrogen fixation. Both nitrogen and phosphorus cycles have been identified as critical planetary boundaries for maintaining a balance in the Earth's biophysical processes (Rockström et al. 2009). Currently, cycles for these two elements are under threat in many parts of the world where reactive nitrogen from fertilizer production ends up polluting waterways or is released as a greenhouse gas (nitrous oxide), and excessive use of phosphorus not only reduces access to this limited resource, but phosphorus runoff causes eutrophication of lakes and puts oceans at risk for anoxic events. Better management of these macronutrients is needed both from an agricultural perspective in terms of, for example, reducing fertilizer runoff and with respect to the global environment by managing material flows of these elements. At the same time, it is important that we devote more attention to the role of micronutrients and soil organic carbon in enhancing productivity.1 Studies show that an increased soil organic-carbon pool can influence yields (Lal, 2006) and that many micronutrients enhance disease resistance and tolerance (Dordas, 2009). The recycling of organic waste has the potential to return both carbon and nutrients to soils.

The planetary boundary for nitrogen has already been exceeded and that for phosphorus is threatened (Rockström et al. 2009). It is time to radically rethink nutrient management across the entire food chain. Scientists see recycling of nutrients in food waste and excreta, for example, as an important way of limiting the use of mineral nutrients as well as improving national and global food security (Cordell et al. 2009), particularly if such measures can balance local and regional nutrient flows. Improving global nutrient management will require a holistic approach that includes the entire food cycle from production and distribution to consumption and resource recovery. There is a need for guiding principles and actions that reach a broad spectrum of stakeholders in diverse sectors and unite them in a global vision for sustainable nutrient management. Taking this broader approach means linking material flows and management sectors that today are generally managed on a separate basis, such as food-processing plants and wastewater-treatment facilities.

This article aims to influence policy development by presenting a working framework for sustainable nutrient management based on multi-stakeholder collaboration. Current models for sustainable waste and material-flow management highlight the need for waste prevention, recycling, and life-cycle perspectives. …

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