Urea is the most widely used nitrogen (N) fertilizer, with a projected increase in annual demand of 1.5% in the coming years. After its application to soil, urea undergoes hydrolysis via the urease enzyme, causing increases in the soil pH in the surrounding area of the granules and resulting in NH3 losses that average 16% of N applied worldwide and can reach 40% or more in hot and humid conditions. The use of urease inhibitors is an effective way to reduce NH3 losses. Several compounds act as urease inhibitors, but only N-(n-butyl) thiophosphoric triamide (NBPT) has been used worldwide, being the most successful in a market that has grown 16% per year in the past 10 years. Only in the past three years other compounds are being commercially launched. In comparison to urea, NBPT-treated urea reduces NH3 loss by around 53%. Yield gain by NBPT usage is of the order of 6.0% and varies from -0.8 to 10.2% depending on crop species. Nitrification inhibitors usually increase NH3 volatilization and mixing them with urease inhibitors partially offsets the benefits of the latter in reducing NH3 loss. The efficacy of NBPT to reduce NH3 loss is well documented, but there is a need for further improvement to increase the period of inhibition and the shelf life of NBPT-treated urea.

Legal restrictions from burning sugarcane prior to harvest are causing a sharp increase in acreage which is harvested as green cane. The presence of a thick sugarcane trash mulch left after harvest makes it difficult to incorporate fertilisers in the soil. Since large losses of ammonia may occur when urea is surface applied to trash, it is important to find ways to improve urea-N use efficiency. The urease inhibitor NBPT slows down urea hydrolysis and thus may help decrease ammonia losses. Ammonia traps were set up in seven sugarcane fields covered with trash and fertilised with ammonium sulfate or ammonium nitrate, urea, and NBPT-treated urea. All N fertilisers were surface-applied at rates of 80 or 100 kg N ha-1. Very little N was lost when ammonium nitrate or ammonium sulfate were used. However, volatilisation losses as ammonia from the urea treatments varied from 1% (rainy days after fertilisation) to 25% of the applied N. The percentage of reduction in volatilisation due to NBPT application ranged from 15% to 78% depending on the weather conditions during the days following application of N. Addition of NBPT to urea helped to control ammonia losses, but the inhibitor was less effective when rain sufficient to incorporate urea into the soil occurred only 10 to 15 days or latter after fertiliser application.

Bioenergy is an important and feasible option for mitigating global warming and climate change. However, large-scale land-use change (LUC) to expand bioenergy crops, such as sugarcane, raises concerns about the potential negative environmental and socioeconomic side effects. Such effects are context-specific, and depending on the LUC scenario and management practices, several co-benefits can be attained. We reviewed the literature and discussed how LUC and best management practices affect key components of sustainability (e.g., soil health, soil carbon (C) sequestration, greenhouse gas emissions (GHG) emissions, nutrient cycling, water quality, among others) of sugarcane-derived bioenergy production in Brazil. Sugarcane expansion has occurred predominantly over pasture areas, although converting croplands could be also an environmentally feasible option. The land transition from low-productivity pastures to sugarcane cultivation seems to be a sustainable pathway to increase bioenergy production. This LUC scenario enhances soil health and soil C sequestration over time, although soil compaction, biodiversity loss, and erosion are still challenging. Besides, adopting best management practices, such as conservation tillage, sustainable crop residue management, rational fertilization, and recycling by-products, has been fundamental to ensuring sustainable bioenergy production. Public policies and well-designed legal frameworks and regulations, such as the Forest Code and the RenovaBio legislations in Brazil, are necessary to make bioenergy production compatible with rational land use and protection. Lastly, our analysis provided insights into sugarcane expansion over a small proportion (1%) of pasture areas in Latin American and Caribbean (LAC) and sub-Saharan African (SSA) countries, which may result in a substantial impact on global bioenergy supply. We concluded that sugarcane-derived bioenergy is a sustainable option to tackle climate change while provisioning other key ecosystem services and promoting socioeconomic development.