This paper outlines the main sustainability challenges linked to nitrogen, including inadequate access to nitrogen fertiliser in some parts of the world and excessive fertiliser application in other areas, leading to water pollution, algal blooms and risks to human health. The paper argues that solving nitrogen problems would have co-benefits for other sustainability issues such as hunger, air, soil and water quality, climate and biodiversity.

Rice cultivation emits methane and nitrous oxide, which are both more potent greenhouse gases than carbon dioxide. Policies to reduce methane emissions from rice farming generally recommend using intermittent (as opposed to continuous) flooding. However, intermittent flooding could produce much higher nitrous oxide emissions than continuous flooding, according to a recent paper.

The planetary boundaries concept provides a theoretical upper limit on human activity which the planet is able to sustain without major perturbation to the current ‘Earth system’. Previously, nine planetary boundaries (PBs) have been proposed and recently Steffen et al. (2015) have updated these boundary definitions and assessed the current state of the position of human activity with respect to each boundary. In this article, researchers from a number of food, climate change, agricultural and environmental research institutions around the world build on this work by assessing the impact of agriculture on each PB status, based on a detailed literature review of the available research.

This paper presents the findings of a food systems model that considers how specific agronomic characteristics of organic agriculture could be harnessed so as to enable it to play a greater role in sustainable food systems.

In this short perspective piece, researchers from the Netherlands, USA and the UK critically assess the COP21 4 per 1000 initiative, which seeks to increase global yearly agricultural soil organic carbon sequestration by 4‰ (= 0.4%, or 1.2 billion tonnes). The authors argue that as soil organic matter (SOM) also contains nitrogen (N), with a C-to-N ratio always approaching 12, this will require the sequestration of an extra 100 million tonnes of N per year, and they question the feasibility of achieving this. 

This paper proposes a solution to the problems associated with the high inefficiencies and indirect detrimental environmental impacts caused by reactive nitrogen use in agriculture.The researchers suggest that land-based agriculture could be bypassed and that Haber Bosch derived nitrogen could be used directly for reactor based microbial protein production. The advantages of microbial protein production are summarised, as are the opportunities and technical challenges for large-scale production. The authors emphasise that, aside from the scientific innovation required, the main challenge to address is obtaining acceptability from regulators and consumers.

This paper examines high-resolution, crop-specific GHG emissions and GHG intensity estimates which are derived using a method that couples biophysical models with novel 5-arc-minute resolution data.

In this paper, the authors present an analysis of the nitrogen cycle in the agricultural production system of 12 world regions. From these results, they go on to suggest improvements in nitrogen use by changing the role of human diet, international trade and local production.

The World Bank has released a short working paper arguing that the expansion of seaweed farming in tropical developing countries could have large positive impacts on local poverty, ecosystem management and climate change mitigation. The report goes through different benefits and uses of seaweed production and briefly discusses current and potential markets for the crop.