Mixed grazing and clipping is beneficial to ecosystem recovery but may increase potential N2O emissions in a semi-arid grassland

In semi-arid vineyard agroecosystems, highly vulnerable in the context of climate change, the soil organic matter (OM) content is crucial to the improvement of soil fertility and grape productivity. The impact of OM, from compost and animal manure, on soil properties (e.g., pH, oxidisable organic C, organic N, NH4+-N and NO3−-N), grape yield and direct greenhouse gas (GHG) emission in vineyards was assessed. For this purpose, two wine grape varieties were chosen and managed differently: with a rain-fed non-trellising vineyard of Monastrell, a drip-irrigated trellising vineyard of Monastrell and a drip-irrigated trellising vineyard of Cabernet Sauvignon. The studied fertiliser treatments were without organic amendments (C), sheep/goat manure (SGM) and distillery organic waste compost (DC). The SGM and DC treatments were applied at a rate of 4600 kg ha−1 (fresh weight, FW) and 5000 kg ha−1 FW, respectively. The use of organic amendments improved soil fertility and grape yield, especially in the drip-irrigated trellising vineyards. Increased CO2 emissions were coincident with higher grape yields and manure application (maximum CO2 emissions = 1518 mg C-CO2 m−2 d−1). In contrast, N2O emissions, mainly produced through nitrification, were decreased in the plots showing higher grape production (minimum N2O emissions = −0.090 mg N2O-N m−2 d−1). In all plots, the CH4 fluxes were negative during most of the experiment (−1.073−0.403 mg CH4-C m−2 d−1), indicating that these ecosystems can represent a significant sink for atmospheric CH4. According to our results, the optimal vineyard management, considering soil properties, yield and GHG mitigation together, was the use of compost in a drip-irrigated trellising vineyard with the grape variety Monastrell.

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Understanding N2O Emissions in African Ecosystems: Assessments from a Semi-Arid Savanna Grassland in Senegal and Sub-Tropical Agricultural Fields in Kenya

Sustainability ◽

10.3390/su12218875 ◽

2020 ◽

Vol 12 (21) ◽

pp. 8875

Author(s):

Laurent Bigaignon ◽

Claire Delon ◽

Ousmane Ndiaye ◽

Corinne Galy-Lacaux ◽

Dominique Serça ◽

...

Keyword(s):

Agricultural Land ◽

Pore Space ◽

Seasonal Pattern ◽

Arid Ecosystems ◽

N2o Emissions ◽

African Continent ◽

1D Model ◽

Dry Seasons ◽

Grassland Site ◽

Semi Arid

This study is based on the analysis of field-measured nitrous oxide (N2O) emissions from a Sahelian semi-arid grassland site in Senegal (Dahra), tropical humid agricultural plots in Kenya (Mbita region) and simulations using a 1D model designed for semi arid ecosystems in Dahra. This study aims at improving present knowledge and inventories of N2O emissions from the African continent. N2O emissions were larger at the agricultural sites in the Mbita region (range: 0.0 ± 0.0 to 42.1 ± 10.7 ngN m−2 s−1) than at the Dahra site (range: 0.3 ± 0 to 7.4 ± 6.5 ngN m−2 s−1). Soil water and nitrate (NO3−) contents appeared to be the most important drivers of N2O emissions in Dahra at the seasonal scale in both regions. The seasonal pattern of modelled N2O emissions is well represented, though the model performed better during the rainy season than between the rainy and dry seasons. This study highlighted that the water-filled pore space threshold recognised as a trigger for N2O emissions should be reconsidered for semi-arid ecosystems. Based on both measurements and simulated results, an annual N2O budget was estimated for African savanna/grassland and agricultural land ranging between 0.17–0.26 and 1.15–1.20 TgN per year, respectively.

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Dynamics of fallow secondary succession pathways and prospects of ecosystem recovery in semi-arid agricultural landscapes

Transactions of the Royal Society of South Africa ◽

10.1080/0035919x.2013.781969 ◽

2013 ◽

Vol 68 (2) ◽

pp. 133-140 ◽

Cited By ~ 1

Author(s):

Edwin Tambara ◽

Tatenda Dalu ◽

Amon Murwira ◽

Shakkie Kativu ◽

Lenin Chari

Keyword(s):

Secondary Succession ◽

Agricultural Landscapes ◽

Ecosystem Recovery ◽

Succession Pathways ◽

Semi Arid

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Emission of nitrous oxide and carbon dioxide from semi-arid tropical soils in Chiapas México

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832010000500015 ◽

2010 ◽

Vol 34 (5) ◽

pp. 1617-1628 ◽

Cited By ~ 2

Author(s):

Alejandro Ponce-Mendoza ◽

Juan Manuel Ceballos-Ramírez ◽

Federico Gutierrez-Micelli ◽

Luc Dendooven

Keyword(s):

Arable Land ◽

Tropical Soils ◽

Co2 Production ◽

Sampling Location ◽

N2o Emissions ◽

Acacia Angustissima ◽

Fertilized Soil ◽

Different Seasons ◽

Semi Arid Region ◽

Semi Arid

The semi-arid region of Chiapas is dominated by N2 -fixing shrubs, e.g., Acacia angustissima. Urea-fertilized soil samples under maize were collected from areas covered and uncovered by A. angustissima in different seasons and N2O and CO2 emissions were monitored. The objective of this study was to determine the effects of urea and of the rainy and dry season on gas emissions from semi-arid soil under laboratory conditions. Urea and soil use had no effect on CO2 production. Nitrons oxide emission from soil was three times higher in the dry than in the rainy season, while urea fertilization doubled emissions. Emissions were twice as high from soil sampled under A. angustissima canopy than from arable land, but 1.2 lower than from soil sampled outside the canopy, and five times higher from soil incubated at 40 % of the water-holding capacity (WHC) than at soil moisture content, but 15 times lower than from soil incubated at 100 WHC. It was found that the soil sampling time and water content had a significant effect on N2O emissions, while N fertilizer and sampling location were less influent.

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Response of soil nitrous oxide flux to nitrogen fertiliser application and legume rotation in a semi-arid climate, identified by smoothing spline models

Soil Research ◽

10.1071/sr12049 ◽

2015 ◽

Vol 53 (3) ◽

pp. 227 ◽

Cited By ~ 18

Author(s):

Sally Jane Officer ◽

Frances Phillips ◽

Gavin Kearney ◽

Roger Armstrong ◽

John Graham ◽

...

Keyword(s):

Nitrous Oxide ◽

Smoothing Splines ◽

Pulse Field ◽

Wheat Crop ◽

N2o Emissions ◽

Barrel Medic ◽

Field Peas ◽

Eastern Australia ◽

Supplementary Irrigation ◽

Semi Arid

Although large areas of semi-arid land are extensively cropped, few studies have investigated the effect of nitrogen (N) fertiliser on nitrous oxide (N2O) emissions in these regions (Galbally et al. 2010). These emissions need to be measured in order to estimate N losses and calculate national greenhouse gas inventories. We examined the effect of different agronomic management practices applied to wheat (Triticum aestivum) grown on an alkaline Vertosol in south-eastern Australia on N2O emissions. In 2007, N2O emissions were measured over 12 months, during which N fertiliser (urea) was applied at sowing or N fertiliser plus supplementary irrigation (50 mm) was applied during the vegetative stage and compared with a treatment of no N fertiliser or irrigation. In a second experiment (2008), the effect of source of N on N2O emissions was examined. Wheat was grown on plots where either a pulse (field peas, Pisum sativum) or pasture legume (barrel medic, Medicago truncatula) crop had been sown in the previous season compared with a non-legume crop (canola, Brassica napus). To account for the N supplied by the legume phase, N fertiliser (50 kg N ha–1 as urea) was applied only to the wheat in the plots previously sown to canola. Fluxes of N2O were measured on a sub-daily basis (up to 16 measurements per chamber) by using automated chamber enclosures and a tuneable diode laser, and treatment differences were evaluated by a linear mixed model including cubic smoothing splines. Fluxes were low and highly variable, ranging from –3 to 28 ng N2O-N m–2 s–1. The application of N fertiliser at sowing increased N2O emissions for ~2 months after the fertiliser was applied. Applying irrigation (50 mm) during the vegetative growth stage produced a temporary (~1-week) but non-significant increase in N2O emissions compared with plots that received N fertiliser at sowing but were not irrigated. Including a legume in the rotation significantly increased soil inorganic N at sowing of the following wheat crop by 38 kg N ha–1 (field peas) or 57 kg ha–1 (barrel medic) compared with a canola crop. However, N2O emissions were greater in wheat plots where N fertiliser was applied than where wheat was sown into legume plots where no N fertiliser was applied. Over the 2 years of the field study, N2O emissions attributed to fertiliser ranged from 41 to 111 g N2O-N ha–1, and averaged of 75 g N2O-N ha–1 or 0.15% of the applied N fertiliser. Our findings confirm that the proportion of N fertiliser emitted as N2O from rainfed grain crops grown in Australian semi-arid regions is less than the international average of 1.0%.

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Fertiliser timing and use of inhibitors to reduce N2O emissions of rainfed wheat in a semi-arid environment

Nutrient Cycling in Agroecosystems ◽

10.1007/s10705-018-9941-7 ◽

2018 ◽

Vol 112 (2) ◽

pp. 231-252 ◽

Cited By ~ 5

Author(s):

Ashley J. Wallace ◽

Roger D. Armstrong ◽

Robert H. Harris ◽

Oxana N. Belyaeva ◽

Peter R. Grace ◽

...

Keyword(s):

Arid Environment ◽

N2o Emissions ◽

Rainfed Wheat ◽

Semi Arid

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Livestock enclosures in drylands of Sub-Saharan Africa are overlooked hotspots of N2O emissions

Nature Communications ◽

10.1038/s41467-020-18359-y ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Klaus Butterbach-Bahl ◽

Gretchen Gettel ◽

Ralf Kiese ◽

Kathrin Fuchs ◽

Christian Werner ◽

...

Keyword(s):

Sub Saharan Africa ◽

N2o Emissions ◽

Arid Environments ◽

Current Estimate ◽

Continental Scale ◽

Livestock Population ◽

Sub Saharan ◽

Semi Arid ◽

Over Time

Abstract Sub-Saharan Africa (SSA) is home to approximately ¼ of the global livestock population, which in the last 60 years has increased by factors of 2.5–4 times for cattle, goats and sheep. An important resource for pastoralists, most livestock live in semi-arid and arid environments, where they roam during the day and are kept in enclosures (or bomas) during the night. Manure, although rich in nitrogen, is rarely used, and therefore accumulates in bomas over time. Here we present in-situ measurements of N2O fluxes from 46 bomas in Kenya and show that even after 40 years following abandonment, fluxes are still ~one magnitude higher than those from adjacent savanna sites. Using maps of livestock distribution, we scaled our finding to SSA and found that abandoned bomas are significant hotspots for atmospheric N2O at the continental scale, contributing ~5% of the current estimate of total anthropogenic N2O emissions for all of Africa.

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