Nitrogen Use Efficiency: A Local and Regional Approach for Brazilian Agriculture

Abstract

The exponential growth of human activities has been significantly altering the global Nitrogen (N) cycling. Due to the scale of these changes, integrated approaches are required to optimize nutrient cycles to meet food and energy demands, while minimizing threats to climate, ecosystem services, and human health. Brazil is now in a leading position on the world stage as one of the great producers and exporters of agricultural products, and must reconcile the expansion of this sector with environmental preservation and promotion of social equity. The Nitrogen Use Efficiency (NUE) is a tool to evaluate the progress of its management, and can be estimated by the ratio between the outflows and N inputs in the agro systems. In this study, NUE was calculated on different scales: regional, covering the entire Brazilian territory, and local, comprising the Vermelho River watershed, an important agricultural area of the Upper Pantanal. The spatialized results indicate great heterogeneity in the NUE, with most of the Brazilian states presenting values outside the desirable range. Low efficiency in nutrient use is identified in several states of Northeast and Southeastern Brazil. On the other hand, regions of great agricultural importance in the Cerrado have high values, suggesting that the N exports by the products outweigh the replacement of this element, which can lead to N mining and degradation of productive land. On a local scale, NUE is very close to the desirable ceiling, with subtle reduction between 2000 and 2015.

Nutrient Balance and Use Efficiency in Agricultural Lands in the Vermelho River Watershed, Upper Pantanal, Brazil

“…Nitrogen Use Efficiency (NUE) and Phosphorus Use Efficiency (PUE) consist of broad information that addresses the basics of crop nutrition and the 4R Nutrient Stewardship Framework, which is a critically important concept to evaluating crop production systems (Zhang et al, 2015). Estimates of NUE and PUE have been widely used as indicators of the progress in nutrient management (Brentrup & Palliere, 2010;Norton et al, 2015;Sutton et al, 2013). The objective of the these indicators is to increase the overall performance of cropping systems by providing economically optimum nourishment to a given crop while both minimizing nutrient losses from the field and contributing to soil fertility or other soil quality components, thus supporting the sustainability of a given agricultural system (Fixen et al, 2015 a,aa,u,v,w,x,z Pasture N retained in animal products ab,r P retained in animal products ab,r…”

“…It has been widely recognized that vast amounts of nutrients are lost annually from croplands throughout the globe (Liu et al, 2010). Additionally, these nutrient losses are expected to increase in the future as a result of increased used of mineral fertilizers (Mogollón et al, 2018;Sutton et al, 2013) and climate change (Bowles et al, 2018). In the VRW, the N losses have increased by an average of ∼5% per area unit annually over 15 years (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015).…”

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The exponential growth of anthropogenic activities over the last century has altered the biogeochemical cycles on a global level (Sutton et al, 2013). The scale of these changes has increased the need to develop joint approaches that both optimize nutrient flows and produce food, fiber, and energy for the growing societal demand.

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“…Nitrous oxide (N 2 O), nitrogen oxide (NO x ) and ammonia (NH 3 ) emissions, and losses of nitrogen (N) and phosphorus (P) compounds to water systems, are some of the direct consequences of changes in the biogeochemical cycles. These emissions and other losses affect the sustainable use of natural resources, human health, resource management, livelihoods, and economies (Abrol et al, 2017;Sutton et al, 2013;van Grinsven et al, 2013).The production of enough food to meet human demand could threaten the environment and human health if nutrients are not adequately used and managed in the process. Disruptions to aquatic systems, such as eutrophication, or impact on the climate, are examples of the result of unbalanced nutrient use (Oenema et al, 2009).…”

“…Nitrous oxide (N 2 O), nitrogen oxide (NO x ) and ammonia (NH 3 ) emissions, and losses of nitrogen (N) and phosphorus (P) compounds to water systems, are some of the direct consequences of changes in the biogeochemical cycles. These emissions and other losses affect the sustainable use of natural resources, human health, resource management, livelihoods, and economies (Abrol et al, 2017;Sutton et al, 2013;van Grinsven et al, 2013).…”