Are CH4, CO2, and N2O Emissions from Soil Affected by the Sources and Doses of N in Warm-Season Pasture?

Abstract

The intensification of pasture production has increased the use of N fertilizers—a practice that can alter soil greenhouse gas (GHG) fluxes. The objective of the present study was to evaluate the fluxes of CH4, CO2, and N2O in the soil of Urochloa brizantha ‘Marandu’ pastures fertilized with different sources and doses of N. Two field experiments were conducted to evaluate GHG fluxes following N fertilization with urea, ammonium nitrate, and ammonium sulfate at doses of 0, 90, 180, and 270 kg N ha−1. GHG fluxes were quantified using the static chamber technique and gas chromatography. In both experiments, the sources and doses of N did not significantly affect cumulative GHG emissions, while N fertilization significantly affected cumulative N2O and CO2 emissions compared to the control treatment. The N2O emission factor following fertilization with urea, ammonium nitrate, and ammonium sulfate was lower than the United Nations’ Intergovernmental Panel on Climate Change standard (0.35%, 0.24%, and 0.21%, respectively, with fractionation fertilization and 1.00%, 0.83%, and 1.03%, respectively, with single fertilization). These findings are important for integrating national inventories and improving GHG estimation in tropical regions.

Land Use, Temperature, and Nitrogen Affect Nitrous Oxide Emissions in Amazonian Soils

“…The interaction of the land-use system and the addition of nitrogen to the soil on the emission of N 2 O observed in the present study (Table 3) confirms its regulatory role in the emission of this gas, being directly related to nitrification and denitrification processes according to the ecosystem [6,12,33]. Further, the crop management adopted in the sampled areas explains the similar and more intense emission of N 2 O from agricultural soils and pastures that is equivalent to 180 and 270 kg of N ha −1 .…”

“…These changes tend to increase up to 2.8 times the emitted N 2 O and pasture soils with more than 10 years of use [32]. In addition to the age of the pasture, the low availability of nutrients in the soil explains the lower emission of N 2 O since the last fertilization was applied in 2016 with reactive natural phosphate and in the absence of nitrogen [12,33].…”

“…Therefore, despite the use of black pepper in the agricultural area, the application of fertilization is more frequent than that of the pastures; that is, the presence of grazing animals promotes the deposition of feces and urine, which in turn are sources of N 2 O [51]. Studies have reported that urine is the main source of N 2 O in pasture areas, and the gas production was boosted by soil moisture, temperature, and available N [12,20,33,52,53]. On the other hand, the characteristic resilience of forest soils under disturbance [8] continues to be considered the main factor responsible for the low emission of N 2 O, even with the addition of nitrogen.…”

How does land use change affect the methane emission of soil in the Eastern Amazon?

“…Nitrogen fertilization contributes greatly to soil quality and increases crop yield and nutritional value (Delevatti et al, 2019;Santos et al, 2020). However, the source, dose, and application form must be considered because inappropriate use increases greenhouse gas emissions (Raposo et al, 2020;Corrêa et al, 2021;Cardoso et al, 2022).…”

“…The presence of nitrogen in the soil has a direct effect on the emission of CH 4 into the atmosphere because it accelerates the process of senescence and death of plant tissues and the tillering rate, thus increasing the litter layer present in the areas and the vegetation cover and accelerating the consumption of methanotrophic microorganisms (Fan et al, 2020;Cui, et al, 2022). However, the source of nitrogen fertilizer can promote high oscillations in the fluxes of CH 4 soon after its application (Raposo et al, 2020), correlating mainly with the content of mineral nitrogen in the soil owing to the inhibitory effect of ammonium in the process of methanotrophy, which is responsible for the oxidation of CH 4 in the soil (Corrêa et al, 2021).…”