Impact of dicyandiamide application on nitrous oxide emissions from urine patches in northern Victoria, Australia

Abstract

Animal production systems in Australia are a significant contributor to nitrous oxide (N2O) emissions from soil, with the Australian Greenhouse Gas Inventory attributing ~25% of the N2O emissions from agricultural soils to animal production. Recent studies in New Zealand using dicyandiamide (DCD) in association with the application of urine to pastoral soil have reported reductions in N2O emission of up to 78% and reduced nitrate leaching of up to 45%. As such, the application of DCD to grazed pastures offers potential to reduce emissions resulting directly from animal production. This study was conducted on a border-check irrigated perennial pasture used for dairy production in northern Victoria. Automated enclosure chambers were linked to a fourier transformed infrared spectrometer to determine N2O emissions. The three treatments were a control, dairy cow urine (1000 kg N/ha) and dairy cow urine (1000 kg N/ha) with DCD included (10 kg/ha). The treatments were applied in mid-spring (15 September 2005) and again in mid-summer (25 January 2006) to a new area of pasture with N2O emissions measured for 120 and 70 days, respectively. Soil temperature and soil water content were monitored continuously. Soil inorganic-N was measured (0–100 mm) every 7 to 14 days for up to 120 days. Application of DCD reduced N2O emissions from a urine patch by 47% when applied in mid-spring and 27% when applied in mid-summer. The impact of the application of DCD on emissions from single urine patches lasted for ~50 days in mid-spring and 25 days in mid-summer. These reductions are lower than those reported in New Zealand studies and are likely to be related to soil conditions, principally temperature. The surface application of DCD has potential to reduce emissions from urine patches in northern Victoria; however, the effects are likely to be short-lived given the soil temperatures and high clay content typical of many Australian soils. More research is required to examine emission reduction options that are cost effective for animal production systems.

A Fourier transform infrared trace gas and isotope analyser for atmospheric applications

“…A fully automated system has operated continuously since 2004 measuring N 2 O fluxes from irrigated and non-irrigated pasture in Victoria, Australia (Kelly et al, 2008), and another system was deployed over a complete sugar cane growth cycle in northern Australia (Denmead et al, 2010). Both studies were based on earlier FTIR systems but provided continuous measurements over periods of months to years.…”

Livestock production in a changing climate: adaptation and mitigation research in Australia

“…Fertilisers coated with nitrification inhibitor have been shown to be effective in reducing nitrification, and N 2 O emissions by up to~80%, as reviewed by (de Klein et al 2001). Applied as a spray, nitrification inhibitors can also be effective in reducing N 2 O emissions from animal urine by 27-91%, with pasture yield increases of 0-36%, depending on the magnitude of N loss (Di et al 2007;Kelly et al 2008;Smith et al 2008). However, many of these studies have been conducted under optimal conditions for N 2 O production and over short periods, so the potential on-farm abatement is likely to be more conservative than the published data.…”

“…More-recent research has shown that the nitrification inhibitor dicyandiamide (DCD) can be fed to a ruminant and be transferred to the urine, targeting the inhibitor where and when required, thus requiring a fraction of the product compared with spraying an entire paddock (Ledgard et al 2007); this technology therefore has potential to be cost-effective in more extensive grazing systems where an offset income could exceed the cost of feeding the inhibitor. Nitrification inhibitors are also temperature-sensitive, as evidenced by lower efficacy reported on dairy pastures in northern Victoria; Kelly et al (2008) reported a 47% reduction in N 2 O from urine patches for~50 days in midspring and 27% reduction in N 2 O for~25 days when applied in midsummer. Their use has historically been restricted, mainly due to cost, and this is likely to remain the case unless there is an added incentive for their adoption.…”

“…As the annual N fertiliser rate is the key input into national inventory Tier 1 and Tier 2 methods (DCCEE 2010a), offset methods that result in net reductions in annual fertiliser rate would be reasonably simple to implement. Likewise, nitrification inhibitors, used as a coating on fertiliser or as a spray, have been well documented for temperate latitudes in Australia (Kelly et al 2008) and New Zealand (Di et al 2009Qiu et al 2010;de Klein et al 2011).…”

Influence of enhanced efficiency fertilisation techniques on nitrous oxide emissions and productivity response from urea in a temperate Australian ryegrass pasture

“…The nitrification inhibitors DMPP and DCD have been reported to decrease N 2 O emissions in laboratory studies on Australian soils (DMPP) and in field studies in pasture systems (DCD) (Di et al 2007;Kelly et al 2008;Di et al 2010;Gilsanz et al 2016). A recent review found them effective in temperate grassland-based agriculture (Li et al 2013a).…”