The interactive effects of various nitrogen fertiliser formulations applied to urine patches on nitrous oxide emissions in grassland

Abstract

Pasture-based livestock agriculture is a major source of greenhouse gas (GHG) nitrous oxide (N2O). Although a body of research is available on the effect of urine patch N or fertiliser N on N2O emissions, limited data is available on the effect of fertiliser N applied to patches of urinary N, which can cover up to a fifth of the yearly grazed area. This study investigated whether the sum of N2O emissions from urine and a range of N fertilisers, calcium ammonium nitrate (CAN) or urea ± urease inhibitor ± nitrification inhibitor, applied alone (disaggregated and re-aggregated) approximated the N2O emission of urine and fertiliser N applied together (aggregated). Application of fertiliser to urine patches did not significantly increase either the cumulative yearly N2O emissions or the N2O emission factor in comparison to urine and fertiliser applied separately with the emissions re-aggregated. However, there was a consistent trend for approximately 20% underestimation of N2O loss generated from fertiliser and urine applied separately when compared to figures generated when urine and fertiliser were applied together. N2O emission factors from fertilisers were 0.02%, 0.06%, 0.17% and 0.25% from urea ± dicyandiamide (DCD), urea + N-(n-butyl) thiophosphoric triamide (NBPT) + DCD, urea + NBPT and urea, respectively, while the emission factor for urine alone was 0.33%. Calcium ammonium nitrate and urea did not interact differently with urine even when the urea included DCD. N2O losses could be reduced by switching from CAN to urea-based fertilisers.

Nitrogen fertiliser interactions with urine deposit affect nitrous oxide emissions from grazed grasslands

“…Despite the number of studies investigating N losses from urine patches (Cai and Akiyama, 2016;Chadwick et al, 2018;Li et al, 2012;Selbie et al, 2015;Van Groenigen et al, 2005), the interaction between urine and fertiliser applications to temperate grassland is limited (Buckthought et al, 2015a;Hyde et al, 2016;Krol et al, 2017). This study demonstrates the existence of an interactive effect between urine deposit and N fertiliser application on N O emissions for spring and summer periods which was characterised by low soil moisture content.…”

“…The difference between this study and common practice might have increased the effect of the urine moisture on the dissolution of the fertiliser applied. The study conducted by Krol et al (2017) showed a potential 20 % underestimation of N 2 O emissions from urine and fertiliser applications when the interaction was ignored. This research also agrees with the work of Hyde et al (2016) who showed that the cumulative N 2 O emissions from CAN fertiliser and urine applied together were more than double compared to the emissions from separate applications.…”

“…There have been few studies investigating consequences of the interaction between the excreta deposit and the fertiliser applied on the N 2 O emissions or seasonal variability of the emissions (Anger et al, 2003;Buckthought et al, 2015a;Krol et al, 2017). Krol et al (2016) studied the seasonal differences of EFs of urine and dung deposit applied separately and found that emissions from urine deposit were significantly higher in autumn than in other seasons.…”

Optimising soil P levels reduces N2O emissions in grazing systems under different N fertilisation

“…This flux per chamber area was extrapolated to flux on a Kg −1 N ha −1 d −1 basis. Although, chamber flux methods can be associated with large uncertainties due to artefacts that de‐couple the chamber microclimate from external conditions (Rochette et al, 2008), the chamber technique is still the most commonly used method (accounting for 95% of total field data) to quantify N 2 O emissions and investigate treatment effects on soil N 2 O fluxes at small spatial scales (Chadwick et al, 2014; Clough et al, 2020; Krol et al, 2017).…”

Efficacy of the Nitrification Inhibitor 3,4 Dimethylpyrazol Succinic Acid (DMPSA) when Combined with Calcium Ammonium Nitrate and Ammonium Sulphate—A Soil Incubation Experiment

“…The soils were destructively sampled on day −14 (two weeks before fertiliser application), on 0 (before fertiliser application), and subsequently on day 2, 5, 8, 12, 18, 30, 45, 60, and 80 after fertiliser application. At each sample date, soils of all incubated treatments were analysed for mineral NH 4 + -N and NO 3 --N. Mineral N extraction was using a 2M KCl solution following the standard protocol at Teagasc, JC [34]. Briefly, 20 g of soil sample was mixed with 100 mL of 2 M KCl (1:5 ratio), shaken for 1 h in a reciprocating shaker at 160 rpm, filtered through Whatman ® No.…”