Cascade Effect of Nitrogen on Brazilian Soybean Production Chain

Vanessa Theodoro Rezende,Ricardo Barboza Alves,Rafael Araújo Nacimento,Thierry Bonaudo,Augusto Hauber Gameiro

doi:10.3390/nitrogen2020009

Abstract

Soybean is one of the most traded products. Naturally, soy fixes nitrogen through biological symbiosis. Its cultivation transforms natural inert atomic nitrogen into its reactive forms. The advancement of soybean can have environmental impacts, both locally and globally. This study estimated nitrogen flows and their use efficiency in the Brazilian soybean production chain applying material flow analysis. We innovate proposing a new indicator to estimate the “cascade effect of nitrogen” in a framework of 12 years (2007 to 2019). We hypothesized that it is capable to show accumulated nitrogen emissions through the chain. Besides, the method can show the main sources of nitrogen to the environment. The biological fixation was the largest entry. The efficiency in the use of nitrogen was 81% for grain production, and the nitrogen cascade indicator, which represents the ratio of the nitrogen emission in the environment to the total nitrogen available in the product, was only 5.2% in the soybean meal production chain for the year of 2019, with a clear trend of increasing during the period. Thus, Brazil contributes significantly to global nitrogen emissions in the environment since the country is an important producer and player in the world market.

Highlights

Nitrogen, despite having provided growth in agricultural and livestock production, is responsible for adverse effects on the environment with damage to human health and the biodiversity of aquatic and terrestrial ecosystems [1,2,3]
The greatest nitrogen input into the soybean production system was through biological nitrogen fixation (BNF), with an increase of 39% in the 12 years evaluated
It can be observed that the increase in soybean planted area contributed to the increase in biological nitrogen fixation and that Brazil contributes with a large percentage to the maximum global nitrogen inputs from agriculture and livestock

Summary

Introduction

Despite having provided growth in agricultural and livestock production, is responsible for adverse effects on the environment with damage to human health and the biodiversity of aquatic and terrestrial ecosystems [1,2,3]. The increase in reactive nitrogen causes environmental impacts on various scales, local, regional, and worldwide because the amount of reactive nitrogen produced is greater than the capacity of ecosystems to convert it to a non-reactive form. The “cascade effect” represents a dynamic view of the nitrogen cycle, which demonstrates the existing interactions between the evaluated systems and their impacts on the different ecosystems [10]. An important feature of the cascade is that once it has started, the initial source of reactive nitrogen becomes irrelevant. This is because the forms of reactive nitrogen can convert between them and cause different effects on the atmosphere and terrestrial and aquatic ecosystems [11]

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