Region-specific emission factors for Brazil increase the estimate of nitrous oxide emissions from nitrogen fertiliser application by 21%

Abstract

The use of synthetic nitrogen fertilisers is one of the most important land management practices proposed to improve crop and pasture productivity. The use of such fertilisers in excess can lead to greenhouse gas (GHG) emissions, linked to climate change, as well as ammonia (NH3) emissions, linked to eutrophication and soil acidification.. This context is especially important in Brazil, which is responsible for a significant share of the food produced in the world. To assess the impact of the use of nitrogen fertilisers, we conducted a structured review of Brazilian studies on the emission of nitrous oxide (N2O; 11 studies) and ammonia volatilisation (NH3; 13 studies) from nitrogen fertiliser application. The current emission factors (EF) suggested by the IPCC for N2O and NH3 (1 and 11%, respectively) are lower than the mean values we found in our review (1.12 and 19%, respectively). Our results showed that non-urea fertilisers (ammonium nitrate or ammonium sulphate) had a lower emission factor (EF) for N2O (1.07 and 0.60%, respectively) and NH3 (3.17 and 14%, respectively) in comparison with urea. The use of nitrification and urease inhibitors resulted in a reduction of the EFs of N2O (74% lower) and NH3 (43% lower) when compared with the Urea EF. Urea is the most common fertiliser used in Brazil, and the change for non-urea fertilisers or the use of inhibitors could lead to a reduction of 23% in the total N2O inventory.The use of the new region-specific EFs results in an increase of 21% in the final N2O emission inventory.

Ammonium Fertilizer Reduces Nitrous Oxide Emission Compared to Nitrate Fertilizer While Yielding Equally in a Temperate Grassland

“…The N 2 O-EF for the CN treatment was 1.02% which is very similar to the default value of 1% by IPCC Tier 1 [1]. Globally, the N 2 O-EF for N fertilizers ranged from 0.01% to 6.70%, and 75% of these EFs reported (or calculated) were in the range given by the IPCC for the Tier 1 default EF (0.30-3%, mean 1% [27]). Bouwman [32] analyzed the global values reporting that an average fertilizer-induced N 2 O emission is 1.25% ± 1% of N applied.…”

“…Bouwman [32] analyzed the global values reporting that an average fertilizer-induced N 2 O emission is 1.25% ± 1% of N applied. A recent meta-analysis based on Brazilian cropland done by Mazzetto et al [27] reported the average N 2 O-EF was 1.12%, whereas a lower value was found when using AS (0.60%) fertilizer and a higher value from urea (1.45%) fertilizer. The N 2 O-EF for AS fertilizer presented by Mazzetto et al [27] is 42% higher than that of the present study.…”

“…A recent meta-analysis based on Brazilian cropland done by Mazzetto et al [27] reported the average N 2 O-EF was 1.12%, whereas a lower value was found when using AS (0.60%) fertilizer and a higher value from urea (1.45%) fertilizer. The N 2 O-EF for AS fertilizer presented by Mazzetto et al [27] is 42% higher than that of the present study. The annual N 2 O loss from AS fertilizer in the present study in cool temperate maritime grassland showed 46% lower than the value (0.65%) reported by Bremer [25] in the humid mid-Altantic region in Kansas, USA.…”

“…Bremer [25] mentioned that they irrigated the land after fertilization to incorporate fertilizer into the soil and reduce ammonia volatilization. Several other studies also reported the ammonia volatilization loss especially from urea applications from grass-based pasture [26,27]. There are also volatilization losses reported from fertilizers such as AS but the extend of volatilization loss is much less in AS (8%) in comparison with urea (15%) [27,28], nevertheless the ammonia loss potential should be assessed in any fertilizer strategy.…”

Effects of Urea-Ammonium Nitrate Solution on Yield, N2O Emission, and Nitrogen Efficiency of Summer Maize Under Integration of Water and Fertilizer

“…N 2 O coefficient was used to evaluate the percentage of N 2 O emission in fertilizers (Mazzetto et al, 2020 ):…”