Edaphic and environmental controls of soil respiration and related soil processes under two contrasting manuka and kanuka shrubland stands in North Island, New Zealand

Soil Research ◽  
2013 ◽  
Vol 51 (5) ◽  
pp. 390 ◽  
Author(s):  
C. B. Hedley ◽  
S. M. Lambie ◽  
J. L. Dando
Keyword(s):  
Nitrous Oxide ◽  
New Zealand ◽  
Soil Respiration ◽  
Respiration Rate ◽  
Nitrous Oxide Emissions ◽  
Volcanic Soil ◽  
Mineral N ◽  
Organic C ◽  
Respiration Rates ◽  
Environmental Controls

The conversion of marginal pastoral land in New Zealand to higher biomass shrubland consisting of manuka (Leptospermum scoparium) and kanuka (Kunzea ericoides var. ericoides) offers opportunity for carbon (C) sequestration, with potential co-benefits of soil erosion control. We therefore selected two areas with different soils in different climatic regions to investigate and compare soil respiration rates, methane and nitrous oxide emission profiles, and key carbon exchange processes controlling carbon sequestration. In addition, two shrubland stands of different ages were selected in each area, providing four sites in total. Regular (almost monthly) soil respiration measurements were made over a 2-year period, with less frequent methane and nitrous oxide flux measurements, and soil sampling once at the end of the study. The cooler, wetter volcanic soils had higher total organic C (6.39 ± 0.12% v. 5.51 ± 0.17%), soil C : nitrogen (N) ratios (20.55 ± 0.20 v. 18.45 ± 0.23), and slightly lower mineral N (3.30 ± 0.74 v. 4.89 ± 0.57 mg/kg) and microbial biomass C (1131 ± 108 v. 1502 ± 37 mg/kg) than the more drought-prone, stony, sedimentary soils. Mineral-N contents at all sites indicated N-limited ecosystems for allocation of below- and above-ground C. The estimated mean annual cumulative respiration rate recorded in the volcanic soil was 10.26 ± 7.45 t CO2-C/ha.year compared with 9.85 ± 8.63 t CO2-C/ha.year in the stony sedimentary soil for the 2 years of our study. Older shrubland stands had higher respiration rates than younger stands in both study areas. Methane oxidation was estimated to be higher in the volcanic soil (4.10 ± 2.13 kg CH4-C/ha.year) than the sedimentary soil sites (2.51 ± 2.48 kg CH4-C/ha.year). The measured natural background levels of nitrous oxide emissions from these shrubland soils ranged between negligible and 0.30 ± 0.20 kg N2O-N/ha.year. A strong climatic control (temperature and moisture) on gas fluxes was observed at all sites. Our sampling strategy at each of the four sites was to estimate the mean soil respiration rates (n = 25) from an 8 by 8 m sampling grid positioned into a representative location. Soil respiration rates were also measured (by additional, less frequent sampling) in two adjacent grids (1-m offset and 100-m distant grid) to test the validity of these representative mean values. The 1-m offset grid (n = 25) provided a statistically different soil respiration rate from the main grid (n = 25) in 25% of the 12 sampling events. The 100-m grid (n = 25) provided a statistically different respiration rate to the main grid in 38% of the 26 sampling events. These differences are attributed to the spatially variable and sporadic nature of gaseous emissions from soils. The grid analysis tested the prediction uncertainty and it provides evidence for strong spatial and temporal control by edaphic processes in micro-sites. A partial least-squares regression model was used to relate the 2009 annual cumulative soil respiration to site-specific edaphic characteristics, i.e. biomass, nutrient availability, porosity and bulk density, measured at the end of that year. The model explained ≥80% of the variance at three of the four sites.

Winter wheat yield and nitrous oxide emissions in response to cowpea-based green manure and nitrogen fertilization

2019 ◽  
Vol 56 (2) ◽  
pp. 239-254 ◽  
Author(s):  
Tanka P. Kandel ◽  
Prasanna H. Gowda ◽  
Brian K. Northup ◽  
Alexandre C. Rocateli
Keyword(s):  
Nitrous Oxide ◽  
Winter Wheat ◽  
Green Manure ◽  
Inorganic Nitrogen ◽  
Wheat Yield ◽  
Nitrous Oxide Emissions ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
Winter Wheat Yield

AbstractThe aim of this study was to compare the effects of cowpea green manure and inorganic nitrogen (N) fertilizers on yields of winter wheat and soil emissions of nitrous oxide (N2O). The comparisons included cowpea grown solely as green manure where all biomass was terminated at maturity by tillage, summer fallow treatments with 90 kg N ha−1 as urea (90-N), and no fertilization (control) at planting of winter wheat. Fluxes of N2O were measured by closed chamber methods after soil incorporation of cowpea in autumn (October–November) and harvesting of winter wheat in summer (June–August). Growth and yields of winter wheat and N concentrations in grain and straw were also measured. Cowpea produced 9.5 Mg ha−1 shoot biomass with 253 kg N ha−1 at termination. Although soil moisture was favorable for denitrification after soil incorporation of cowpea biomass, low concentrations of soil mineral N restricted emissions of N2O from cowpea treatment. However, increased concentrations of soil mineral N and large rainfall-induced emissions were recorded from the cowpea treatment during summer. Growth of winter wheat, yield, and grain N concentrations were lowest in response to cowpea treatment and highest in 90-N treatment. In conclusion, late terminated cowpea may reduce yield of winter wheat and increase emissions of N2O outside of wheat growing seasons due to poor synchronization of N mineralization from cowpea biomass with N-demand of winter wheat.

The effectiveness of dicyandiamide in reducing nitrous oxide emissions from a cattle-grazed, winter forage crop in Southland, New Zealand

2008 ◽  
Vol 48 (2) ◽  
pp. 160 ◽  
Author(s):  
L. C. Smith ◽  
C. A. M. de Klein ◽  
R. M. Monaghan ◽  
W. D. Catto
Keyword(s):  
Nitrous Oxide ◽  
New Zealand ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
Research Station ◽  
Forage Crops ◽  
N Losses ◽  
Forage Crop ◽  
Spring Period ◽  
Simulated Grazing

A study was conducted in Southland, New Zealand to: (i) measure nitrous oxide (N2O) emissions and nitrate (NO3–-N) leaching losses from a cattle-grazed, winter forage crop; and (ii) quantify the effect of dicyandiamide (DCD) in reducing these losses. Drainage losses were measured for 12 months (December 2005–November 2006) from a December-sown kale crop using 12 hydrologically isolated drainage plots at the Woodlands Research Station. N2O emissions were measured for 6 months (June–November) following simulated grazing of the crop in mid-June. N2O emissions from the bare ground following grazing of the crop amounted to 3.6 kg nitrogen (N)/ha for the winter–spring period. This figure is higher than that measured for pasture on the same soil type over a similar period. DCD application significantly reduced N2O emissions for the whole crop area by 25% over this period and reduced the N2O emission factor for urine by 54%. DCD application increased the length of time mineral N (0–10 cm soil depth) was maintained in the ammonium form and significantly reduced soil NO3–-N levels for 6 weeks following the simulated grazing. Annual NO3–-N losses in drainage under this winter forage crop were relatively high at 79 kg N/ha.year, with the majority of this (67%) being lost over the wet summer months (December–January rainfall 434 mm or 200% of normal) during crop growth. The application of DCD following the grazing resulted in a 47% decrease in NO3–-N leached over the winter–spring period (26 kg N/ha v. 14 kg N/ha) with this equating to a 29% decrease over the full 12-month measurement period. This study suggested that winter forage crops are major contributors to N losses from livestock farming systems in Southland and that DCD application following the grazing of such crops by cattle can significantly reduce N2O emissions and leaching N losses.

Nitrous oxide emission from Australian agricultural lands and mitigation options: a review

Soil Research ◽  
2003 ◽  
Vol 41 (2) ◽  
pp. 165 ◽  
Author(s):  
Ram C. Dalal ◽  
Weijin Wang ◽  
G. Philip Robertson ◽  
William J. Parton
Keyword(s):  
Nitrous Oxide ◽  
Global Warming ◽  
N2o Emission ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
Tropical Savannas ◽  
Agricultural Lands ◽  
Mineral N ◽  
N2o Production ◽  
Mitigation Options

Increases in the concentrations of greenhouse gases, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and halocarbons in the atmosphere due to human activities are associated with global climate change. The concentration of N2O has increased by 16% since 1750. Although atmospheric concentration of N2O is much smaller (314 ppb in 1998) than of CO2 (365 ppm), its global warming potential (cumulative radiative forcing) is 296 times that of the latter in a 100-year time horizon. Currently, it contributes about 6% of the overall global warming effect but its contribution from the agricultural sector is about 16%. Of that, almost 80% of N2O is emitted from Australian agricultural lands, originating from N fertilisers (32%), soil disturbance (38%), and animal waste (30%). Nitrous oxide is primarily produced in soil by the activities of microorganisms during nitrification, and denitrification processes. The ratio of N2O to N2 production depends on oxygen supply or water-filled pore space, decomposable organic carbon, N substrate supply, temperature, and pH and salinity. N2O production from soil is sporadic both in time and space, and therefore, it is a challenge to scale up the measurements of N2O emission from a given location and time to regional and national levels.Estimates of N2O emissions from various agricultural systems vary widely. For example, in flooded rice in the Riverina Plains, N2O emissions ranged from 0.02% to 1.4% of fertiliser N applied, whereas in irrigated sugarcane crops, 15.4% of fertiliser was lost over a 4-day period. Nitrous oxide emissions from fertilised dairy pasture soils in Victoria range from 6 to 11 kg N2O-N/ha, whereas in arable cereal cropping, N2O emissions range from <0.01% to 9.9% of N fertiliser applications. Nitrous oxide emissions from soil nitrite and nitrates resulting from residual fertiliser and legumes are rarely studied but probably exceed those from fertilisers, due to frequent wetting and drying cycles over a longer period and larger area. In ley cropping systems, significant N2O losses could occur, from the accumulation of mainly nitrate-N, following mineralisation of organic N from legume-based pastures. Extensive grazed pastures and rangelands contribute annually about 0.2 kg N/ha as N2O (93 kg/ha per year CO2-equivalent). Tropical savannas probably contribute an order of magnitude more, including that from frequent fires. Unfertilised forestry systems may emit less but the fertilised plantations emit more N2O than the extensive grazed pastures. However, currently there are limited data to quantify N2O losses in systems under ley cropping, tropical savannas, and forestry in Australia. Overall, there is a need to examine the emission factors used in estimating national N2O emissions; for example, 1.25% of fertiliser or animal-excreted N appearing as N2O (IPCC 1996). The primary consideration for mitigating N2O emissions from agricultural lands is to match the supply of mineral N (from fertiliser applications, legume-fixed N, organic matter, or manures) to its spatial and temporal needs by crops/pastures/trees. Thus, when appropriate, mineral N supply should be regulated through slow-release (urease and/or nitrification inhibitors, physical coatings, or high C/N ratio materials) or split fertiliser application. Also, N use could be maximised by balancing other nutrient supplies to plants. Moreover, non-legume cover crops could be used to take up residual mineral N following N-fertilised main crops or mineral N accumulated following legume leys. For manure management, the most effective practice is the early application and immediate incorporation of manure into soil to reduce direct N2O emissions as well as secondary emissions from deposition of ammonia volatilised from manure and urine.Current models such as DNDC and DAYCENT can be used to simulate N2O production from soil after parameterisation with the local data, and appropriate modification and verification against the measured N2O emissions under different management practices.In summary, improved estimates of N2O emission from agricultural lands and mitigation options can be achieved by a directed national research program that is of considerable duration, covers sampling season and climate, and combines different techniques (chamber and micrometeorological) using high precision analytical instruments and simulation modelling, under a range of strategic activities in the agriculture sector.

scholarly journals The Dynamics of Nitrous Oxide Emission from the Use of Mineral Fertilizers in Russia

2001 ◽  
Vol 1 ◽  
pp. 336-342 ◽  
Author(s):  
A AA. Romanovskaya ◽  
A M.L. Gytarsky ◽  
A R.T. Karaban ◽  
A D.E. Konyushkov ◽  
A I.M. Nazarov
Keyword(s):  
Nitrous Oxide ◽  
Agricultural Development ◽  
Agricultural Practices ◽  
Nitrous Oxide Emission ◽  
Nitrogen Fertilizers ◽  
Nitrous Oxide Emissions ◽  
Mineral Fertilizers ◽  
N2o Emissions ◽  
Mineral N ◽  
Fertilizer Nitrogen

The intensity of nitrous oxide (N2O) emission was considered based on literature data on the single input of mineral N (nitrogen) fertilizers into different agricultural soil types in Russia. Ambient environmental factors exert a combined effect on the process of gaseous nitrogen formation from fertilizers applied. To reduce the uncertainty of estimates as much as possible, only experimental results obtained under conditions similar to natural were selected for the assessments. Mineral nitric fertilizers were applied to soil at a rate of 40 to 75 kg/ha and the N2O emissions were measured for approximately 140 days. Daily average emission values varied from 0.08 to 0.45% of fertilizer nitrogen. Correspondingly, 1.26 and 2.38% of fertilizer nitrogen were emitted as N2O from chernozems and soddy podzols. In 1990, the use of fertilizers in Russian agricultural practices for 53 Gg N2O-N, which equates to approximately 6.1% of global nitrous oxide emissions from nitric fertilizers. Later, the emission dropped because of a decrease in the input of nitric fertilizers to agricultural crops, and in 1998, it constituted just 20.5% of the 1990 level. In the period from 2008 to 2012, the nitrous oxide emission is expected to vary from 0.5 to 65.0 Gg N2O-N due to possible changes in national agricultural development. In the most likely scenario, the use of mineral fertilizers in Russia will account for approximately 34 to 40 Gg N2O-N emissions annually from 2008�2012.

Sign in / Sign up

Export Citation Format

Share Document