Abstract
Grasslands are subject to a wide range of land management practices that influence the exchange of the three main agricultural greenhouse gases (GHGs) that are related to agriculture: carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). Improving nitrogen fertilization management practices through the use of nitrification inhibitors (NIs) can reduce GHGs emissions. We conducted a field experiment at the Colombian Agricultural Research Corporation with four fertilization treatments: urea (typical fertilizer used in this region), ammonium sulfate nitrate (ASN), ASN plus the NI 3,4-dimethylpyrazole phosphate (ASN+DMPP), and an unfertilized control. The highest grassland yields (1956 and 2057 kg DM ha−1, respectively) and apparent fertilizer nitrogen recoveries (34% and 33%, respectively) were generated by the conventional urea fertilizer and ASN+DMPP. Furthermore, the use of ASN+DMPP reduced the N2O emissions that were related to N fertilization to the level of the unfertilized treatment (ca. 1.5 g N2O-N ha−1), with a significant reduction of N-yield-scaled N2O emissions (ca. 20 g N2O-N kg N uptake−1). These results support the application of DMPP as an alternative strategy to increase grassland yield while simultaneously reducing the environmental impact of N fertilization.
Highlights
Agriculture is responsible for just under a quarter (10–12 Gt CO2 -eq year−1 ) of global anthropogenic greenhouse gas (GHG) emissions [1]
The emission factor (EF), which represents the percentage of the applied N-fertilizer that has been lost in the form of nitrous oxide (N2 O), was
Our results show that the N2 O emission factors for the urea and ammonium sulfate nitrate (ASN) treatments were 8.5 and 4.1 times higher, respectively, than the 1% default value that was proposed by the Intergovernmental Panel on Climate Change (IPCC) [34]
Summary
Agriculture is responsible for just under a quarter (10–12 Gt CO2 -eq year−1 ) of global anthropogenic greenhouse gas (GHG) emissions [1]. Among the GHGs that were emitted through human activity, carbon dioxide (CO2 ), methane (CH4 ), and nitrous oxide (N2 O) have the greatest links with intensive agriculture, mainly because of deforestation, livestock emissions, and soil and nutrient management [1,2]. Very few studies have been conducted in Colombia dealing with GHGs emissions from grasslands; GHGs emissions from agriculture are estimated to be 158.6 Gt CO2 -eq year−1 , of which, 10% corresponds to N2 O [4]. The main source of N2 O in agricultural soils comes from microbial activity in processes such as nitrification, denitrification, and nitrifier denitrification [5,6]. The use of nitrification inhibitors (NIs) has become an increasingly important strategy in recent decades to help reduce N2 O emissions [1]
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