Timing of Manure Injection and Nitrification Inhibitors Impacts on Nitrous Oxide Emissions and Nitrogen Transformations in a Barley Crop

Abstract

Mitigating the greenhouse gas emissions that arise durin manure is a crucial environmental challenge. We evalu effects of liquid manure timing (fall vs. spring) and nitrifi [2-chloro-6-(trichloromethyl) pyridine (nitrapyrin) vs. 3 phosphate (DMpp)] on n 2 O emissions, soil mineral n ley (Hordeum vulgare L.) productivity, and n uptake. E established in an incomplete split-plot design in Laco AB, Canada. Repeated measurements included n 2 O flu chambers, and soil ammonium (nH 4 -n) and nitrate (nO Relative to the manured soils without nIs, the use of n significantly reduced annual n 2 O emissions by 81% w with nitrapyrin in our Lacombe site; however, this diffe in the comparable spring treatments applied during the These beneficial effects were discernable in Lacombe, wetter than Edmonton, indicating the overriding role o n dynamics and fluxes. Following a 5-mo freezing wi caused at least 64% of annual n 2 O emissions from the f these intense episodic fluxes also revealed that the effic still continued during the early spring. On average, fal the n 2 O direct emission factors by about threefold com sponding spring treatments. Thus implementing liquid m nIs at the right timing has the potential opportunity to crops and simultaneously diminish global warming effect Abbreviations: CT, control treatment where the soil was disturb without soil disturbance); DM, dry matter; DMPP, 3, 4-dimethyl direct emission factors; FMD, fall-manured soil with DMPP, FMN nitrapyrin; FMW, fall-manured soil with no nitrification inhibitors; SMD, spring-manured soil with DMPP; SMN, spring-manured so spring-manured soil with no nitrification inhibitors.

Modelling nitrification inhibitor effects on N<sub>2</sub>O emissions after fall- and spring-applied slurry by reducing nitrifier NH<sub>4</sub><sup>+</sup> oxidation rate

“…These events preceded the start of the automated chamber measurements on DOY 102 and so could not be corroborated by them. However measurements with manual chambers earlier in spring 2015 by Lin et al (2018) indicated that N 2 O emission events occurred from DOY 85 to 100 that were similar in magnitude although not always in timing with those modelled (Fig. 4b).…”

“…Weather data (radiation, air temperature -T a , humidity, wind speed and precipitation) were recorded hourly from 2012 to 2016 at the South Campus Farm. During the first experimental year (16 September 2014 to 15 September 2015) T a remained 1-2 • C higher than historical (1981-2010) averages (Lin et al, 2018; Table 4). Precipitation was slightly higher than historical averages during autumn and winter but Year Date Management Amount was about one-half those during spring and summer.…”

“…Soil NH + 4 concentrations were measured from 0 to 10 cm every 2-3 weeks between spring thaw and autumn freezing in 2014, 2015 and 2016. Further details of this field experiment are given in Lin et al (2018).…”

“…Based on the analytical precision of the gas analyser, the N 2 O flux detection limit was determined to be ±0.03 mg N m −2 h −1 . N 2 O emissions were also measured once or twice per week from spring thaw to autumn freezing during both experimental years with manually operated chambers as described in Lin et al (2018). The time required for installation of the automated chambers after snowmelt limited their ability to measure N 2 O emissions during spring thaw so that measurements from the manually operated chambers were used to evaluate emissions during these periods.…”

“…Akiyama et al, 2010). The effectiveness of NI with fall applications of fertilizer or slurry on cold soils has thus far received very limited attention (Ruser and Schulz, 2015), although in cold climates N 2 O emissions during the spring thaw following fall applications may exceed those during late spring and summer following spring applications (Lin et al, 2018). Emissions during spring thaw were attributed by Wagner-Riddle and Thurtell (1998) to soil NO 3 -N concentrations exceeding 20 mg kg −1 generated by fallapplied slurry that contributed to total N 2 O emissions exceeding 0.2 g N m −2 measured between January and April of the following year.…”