Enhanced-Efficiency Fertilizers in Nitrous Oxide Emissions from Urea Applied to Sugarcane

Abstract

The environmental benefits of producing biofuels from sugarcane have been questioned due to greenhouse gas emissions during the biomass production stage, especially nitrous oxide (N 2 O) associated with nitrogen (N) fertilization. The objective of this work was to evaluate the use of nitrification inhibitors (NIs) dicyandiamide (DCD) and 3,4 dimethylpyrazole phosphate (DMPP) and a controlled-release fertilizer (CRF) to reduce N 2 O emissions from urea, applied at a rate of 120 kg ha -1 of N. Two field experiments in ratoon cycle sugarcane were performed in Brazil. The treatments were (i) no N (control), (ii) urea, (iii) urea+DCD, (iv) urea+DMPP, and (v) CRF. Measurements of N 2 O fluxes were performed using static chambers with four replications. The measurements were conducted three times per week during the first 3 mo and biweekly afterward for a total of 217 and 382 d in the first and second seasons, respectively. The cumulative N 2 O-N emissions in the first ratoon cycle were 1098 g ha -1 in the control treatment and 1924 g ha -1 with urea (0.7% of the total N applied). Addition of NIs to urea reduced N 2 O emissions by more than 90%, which did not differ from those of the plots without N. The CRF treatment showed N 2 O emissions no different from those of urea. The results were similar in the second ratoon: the treatment with urea showed N 2 O emissions of 0.75% of N applied N. Application of NIs resulted in a strong reduction in N 2 O emissions, but CRF increased emissions compared with urea. We therefore conclude that both NIs can be options for mitigation of greenhouse gas emission in sugarcane used for bioenergy.

Nitrous oxide emission and fertiliser nitrogen efficiency in a tropical sugarcane cropping system applied with different formulations of urea

“…A field study on a sugarcane farm in Central Queensland, Australia showed that DMPP-coated urea decreased post-fertilisation N 2 O emissions by~44% (Wang et al 2012), while a decrease of~38% in N 2 O emissions from the fertilised area was recorded in another Australian sugarcane cropping system . Studies in a Brazilian sugarcane cropping system found that addition of DMPP to urea reduced N 2 O emissions by 94-100% in two consecutive cropping seasons (Soares et al 2015). These results suggest that the use of DMPP can be an effective N 2 O mitigation technique in many circumstances.…”

“…Extraordinarily high N 2 O emissions (28.2 kg N 2 O-N ha -1 year -1 measured with manual chambers and 45.9 kg N 2 O-N ha -1 year -1 using a micrometeorological method) were observed from a low-lying acid sulfate soil containing 9.8% organic carbon (C) on a sugarcane farm in northern New South Wales, Australia (Denmead et al 2010;. Of the limited number of year-long measurements in sugarcane fields in other countries, 1.9 and 4.5 kg N 2 O-N ha -1 year -1 (EF = 0.69% and 2.03%) were recorded in Brazil where 120 kg N ha -1 was applied as urea and ammonium nitrate, respectively (Carmo et al 2013;Soares et al 2015). The higher N 2 O emissions from Australian sugarcane cropping systems may be attributed to higher fertiliser N application rates (mostly !140 kg N ha -1 ), higher rainfall or retention of crop residues (trash) compared with those in Brazil.…”

The interactive effects of fertiliser nitrogen with dung and urine on nitrous oxide emissions in grassland

“…Furthermore, this experiment focuses on CAN, a NO 3 --N based fertiliser commonly used in Ireland as the N source, whereas grazing systems globally use other N fertiliser sources including urea and ammonium sulphate. In addition, fertiliser formulations including urease and/or nitrification inhibitors such as dicyandiamide and/or 3,4-dimethylpyrazole phosphate (Goos, 2013;Soares et al, 2014;Halvorson et al, 2014) are becoming more widely used in commercial agriculture. These inhibitors result in differential effects on NH 3 volatilisation (Forrestal et al, 2015), thus affecting the ratio of direct to indirect N 2 O emissions from fertiliser N. Whether N 2 O emissions from these other N fertiliser formulations are additive or multiplicative when combined with urine is unknown.…”

More Food, Low Pollution (Mo Fo Lo Po): A Grand Challenge for the 21st Century

“…The lack of response in 2 of the 3 yr complicates the benefits and acceptance of using ESN. Soares et al (2015) found that nitrification inhibitors reduced N 2 O emissions from fertilized sugarcane (Saccharum officinarum L.) fields in Brazil by more than 90%, but a controlled-release fertilizer was ineffective. Reducing N 2 O emissions is an important challenge for the use of sugarcane for producing biofuels because N 2 O emissions negate some of the potential greenhouse gas mitigation resulting from substituting biofuels for fossil fuel combustion.…”