A novel and effective technology for mitigating nitrous oxide emissions from land-applied manures

Abstract

Abstract. Land-applied manures produce nitrous oxide (N 2 O), a greenhouse gas (GHG). Land application can also result in ammonia (NH 3 ) volatilisation, leading to indirect N 2 O emissions. Here, we summarise a glasshouse investigation into the potential for vermiculite, a clay with a high cation exchange capacity, to decrease N 2 O emissions from livestock manures (beef, pig, broiler, layer), as well as urea, applied to soils. Our hypothesis is that clays adsorb ammonium, thereby suppressing NH 3 volatilisation and slowing N 2 O emission processes. We previously demonstrated the ability of clays to decrease emissions at the laboratory scale. In this glasshouse work, manure and urea application rates varied between 50 and 150 kg nitrogen (N)/ha. Clay : manure ratios ranged from 1 : 10 to 1 : 1 (dry weight basis). In the 1-year trial, the abovementioned N sources were incorporated with vermiculite in 1 L pots containing Sodosol and Ferrosol growing a model pasture (Pennisetum clandestinum or kikuyu grass). Gas emissions were measured periodically by placing the pots in gastight bags connected to real-time continuous gas analysers. The vermiculite achieved significant (P 0.05) and substantial decreases in N 2 O emissions across all N sources (70% on average). We are currently testing the technology at the field scale; which is showing promising emission decreases (~50%) as well as increases (~20%) in dry matter yields. This technology clearly has merit as an effective GHG mitigation strategy, with potential associated agronomic benefits, although it needs to be verified by a cost-benefit analysis.

Organic Wastes Amended with Sorbents Reduce N2O Emissions from Sugarcane Cropping

“…Biochar and bentonite most strongly reduced the soil concentration of extractable inorganic N. Testing these sorbents in the laboratory, we confirmed that both effectively sorb NH 4 + [30,31]. In the present study, sorbents were mixed with the N source immediately prior to application to the soil, which may explain why our findings differ from previous studies where pre-incubation resulted in over~50% greater NH 4 + sorption (e.g., [46,53]). Because water and solutes diffuse slowly in bentonite [54], and possibly biochar, pre-incubating sorbents with N-rich materials could attenuate the early release of inorganic N. For the development of nextgeneration fertilisers based on organic wastes and sorbents, pre-incubation should therefore be considered.…”

“…Amendments were thoroughly mixed with the manure before being applied to soil. In previous research, manure-sorbent blends were incubated for over a week to maximise the contact of N ions and sorbent [45,46]. Here, treatments were applied within 1 h of mixing so that we could determine if rapidly assembled treatments are effective at the field-scale.…”

Geo-Agriculture: Reviewing Opportunities through Which the Geosphere Can Help Address Emerging Crop Production Challenges

“…The N 2 O emission decrease was attributed to NH 4 + exchange on the negatively-charged zeolite and subsequent nitrification suppression [142]. Hill et al [143] investigated the potential for vermiculite-a high cation exchange capacity clay-to decrease N 2 O emissions from organic and chemical N fertilisers applied to a range of soils in a glasshouse trial. These authors reported an average 70% decrease in N 2 O emissions at a vermiculite application rate of 7 t/ha over a one-year period.…”

Mitigating Methane: Emerging Technologies To Combat Climate Change’s Second Leading Contributor

“…In addition to promoting methanotroph growth and activity via physical processes, as alluded to by Brandt, et al 104 , the expanded vermiculite may have helped maintain sufficient nitrogen concentrations for microbial activity via ammonium sorption. Previous work by Hill, et al 115 and Pratt, et al 116 has shown that vermiculite, which is a high cation-exchange capacity clay, can effectively bind soil and solution ammonium through exchange processes. It might be possible to overcome nutrient deficiency to methanotrophs through other sustainable approaches, such as incorporating nitrogen-fixing bacterial strains into the filter or by trickling nutrient-rich waste streams over the filter in applications relating to agriculture, landfills and wastewater treatment.…”