scholarly journals Nitrapyrin decreased nitrification of nitrogen released from soil organic matter but not amoA gene abundance at high soil temperature

2015 ◽  
Vol 88 ◽  
pp. 214-223 ◽  
Author(s):  
L.M. Fisk ◽  
L.D. Maccarone ◽  
L. Barton ◽  
D.V. Murphy
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Temperature ◽  
Amoa Gene ◽  
Gene Abundance ◽  
High Soil ◽  
High Soil Temperature

scholarly journals CO2-C losses and carbon quality of selected Maritime Antarctic soils

2012 ◽  
Vol 25 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Juliana Vanir De Souza Carvalho ◽  
Eduardo De Sá Mendonça ◽  
Newton La Scala ◽  
César Reis ◽  
Efrain Lázaro Reis ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Temperature ◽  
Soil Carbon ◽  
Humic Substances ◽  
Microbial Activity ◽  
Chemical Characteristics ◽  
Maritime Antarctic ◽  
Antarctic Soils ◽  
Humification Degree

AbstractPolar Regions are the most important soil carbon reservoirs on Earth. Monitoring soil carbon storage in a changing global climate context may indicate possible effects of climate change on terrestrial environments. In this regard, we need to understand the dynamics of soil organic matter in relation to its chemical characteristics. We evaluated the influence of chemical characteristics of humic substances on the process of soil organic matter mineralization in selected Maritime Antarctic soils. A laboratory assay was carried out with soils from five locations from King George Island. We determined the contents of total organic carbon, oxidizable carbon fractions of soil organic matter, and humic substances. Two in situ field experiments were carried out during two summers, in order to evaluate the CO2-C emissions in relation to soil temperature variations. The overall low amounts of soil organic matter in Maritime Antarctic soils have a low humification degree and reduced microbial activity. CO2-C emissions showed significant exponential relationship with temperature, suggesting a sharp increase in CO2-C emissions with a warming scenario, and Q10 values (the percentage increase in emission for a 10°C increase in soil temperature) were higher than values reported from elsewhere. The sensitivity of the CO2-C emission in relation to temperature was significantly correlated with the humification degree of soil organic matter and microbial activity for Antarctic soils.

Coping with soil and climatic hazards during crop establishment in the semi-arid tropics

1996 ◽  
Vol 36 (8) ◽  
pp. 971 ◽  
Author(s):  
DG Abrecht ◽  
KL Bristow
Keyword(s):  
Soil Temperature ◽  
Water Deficit ◽  
Weather Data ◽  
Simulation Studies ◽  
Management Options ◽  
Crop Species ◽  
Crop Establishment ◽  
High Soil ◽  
High Soil Temperature ◽  
Semi Arid

Climatic induced hazards (e.g. water deficit, high soil temperature and high soil strength) that adversely affect seedling emergence and establishment of annual crops on red earth soils (Kandsols) at Katherine in the Daly basin of the Northern Territory are reviewed and results of some recent simulation studies and experiments are presented. Simulation studies, using 100 years of historical weather data, have shown that maize and sorghum density at Katherine is rarely reduced by water deficit during crop establishment. However, the median number of days between 1 December and 20 January during which seedlings may be exposed to damagingly high soil temperature (>55�C between 2 and 7 days after sowing) was 5.5, out of an estimated 21 days suitable for sowing. While the exposure of a crop to inclement conditions during establishment may have immediate and dramatic effects on the mortality of pre-emergent and post-emergent seedlings, there may also be longer-term and less evident adverse effects on crop growth and development. The responses of developing seedlings to inclement conditions following sowing are described and management options (eg adjusting planting dates, changing crop species, changing seedbed configurations, using surface mulch) for the amelioration of the seedbed environment are discussed. Of the possible management options for ameliorating adverse seedbed conditions during crop establishment in the semi-arid tropics (SAT), it appears that the best practice is to maintain a soil surface cover (mulch) in close proximity to the emerging seedlings. The presence of surface mulch extends the window of opportunity for establishing crops by slowing soil drying, delaying the onset of high soil temperatures and high soil impedance, and by improving the availability of water to the young seedlings at this critical stage.

scholarly journals Changes in Fatty Acid Composition and Saturation in Leaves and Roots of Creeping Bentgrass Exposed to High Soil Temperature

2004 ◽  
Vol 129 (6) ◽  
pp. 795-801 ◽  
Author(s):  
Xiaozhong Liu ◽  
Bingru Huang
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Soil Temperature ◽  
Acid Composition ◽  
Creeping Bentgrass ◽  
High Soil ◽  
Leaves And Roots ◽  
High Soil Temperature

Previous studies found that high soil temperature is more detrimental than high air temperature for the growth of creeping bentgrass (Agrostis palustris L.). The objective of the study was to investigate changes in fatty acid composition and saturation levels in leaves and roots for creeping bentgrass exposed to high soil temperature. Shoots and roots of `Penncross' plants were subjected to a differential air/soil temperature of 20/35 °C in a growth chamber. Soil temperature was controlled at 35 °C using an immersion circulating heater in water bath. Shoot injury induced by high soil temperature was evaluated by measuring level of lipid peroxidation expressed as malonyldialdehyde (MDA) content, chlorophyll content, and photochemical efficiency (Fv/Fm) of leaves. MDA content increased while chlorophyll content and Fv/Fm decreased at high soil temperature. The content of total fatty acids and different species of fatty acids were analyzed in both leaves and roots. Total fatty acid content in leaves increased initially at 5 days of high soil temperature and then decreased at 15 days, while total fatty acid content in roots decreased, beginning at 5 days. Linolenic acid was the major fatty acid in leaves and linoleic acid and palmitic acid were the major fatty acids in roots of creeping bentgrass. Leaf content of all fatty acid components except oleic acid increased initially and then decreased at high soil temperature. Root content of all fatty acid components except palmitoleic acid and oleic acid decreased, beginning at 5 d of high soil temperature. Oleic acid in leaves and palmitoleic and oleic acid in roots did not change during the entire experimental period. Leaf content of saturated fatty acids and unsaturated fatty acids increased during the first 5 to 10 days of high soil temperature and decreased at 15 and 25 days, respectively. Root content of saturated fatty acids and unsaturated fatty acids decreased beginning at 5 days of high soil temperature. Double bond index decreased in both leaves and roots. High soil temperature induced changes in fatty acid composition and saturation levels in leaves and roots, and this could be associated with physiological damages in leaves even though only roots were exposed to high temperature.

Carbon dioxide efflux from the floor of a boreal aspen forest. I. Relationship to environmental variables and estimates of C respired

1998 ◽  
Vol 78 (2) ◽  
pp. 301-310 ◽  
Author(s):  
C. A. Russell ◽  
R. P. Voroney
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Temperature ◽  
Environmental Variables ◽  
Net Primary Productivity ◽  
Organic Matter Content ◽  
Aboveground Net Primary Productivity ◽  
Closed Chamber ◽  
The Relationship

Soil CO2 efflux (Soil Fc) in a boreal aspen (Populustremuloides) forest was related to environmental variables to estimate the mass of carbon (C) annually respired. Measurements of soil Fc were made between April and September with a dynamic closed chamber via an infra-red gas analyzer.Over the course of the study day-time soil Fc ranged from 0.027 to 0.411 mg CO2 m−1s−1. Summertime estimates of soil Fc were higher than expected, and this was attributed to underestimation by static chamber methods. Strong relationships were found between seasonal patterns of (1) soil Fc and soil temperature (Ts) at various depths (R2 = 0.77 to 0.87, Q10 = 3.9 to 5.1), (2) soil Fc and humus [CO2] and volumetric moisture (θv; R2 = 0.76 to 0.88) and (3) humus [CO2] and humus Ts and θv (R2 = 0.74). On their own, θv, litter and soil organic matter content explained little (<5%) of the variation in soil Fc. Ts was the single most effective variable used to predict soil Fc.Annual masses of soil Fc C were estimated from the relationship between soil Fc and 0.1 m Ts in 1994. Long-term (49-yr) estimates were generated from monthly mean air temperatures (Ta) using the relationship between Ts (0.10 m) and Ta (2 m) at the site throughout 1994–1995. In both years, Ta explained about 70% of the variability in Ts. Estimates of annual soil Fc C were 905 (1994), 870 (1995) and 809 (long-term) g m−2. Growing season soil Fc approximated 75% of the annual C mass respired. These annual C fluxes far exceed current estimates for boreal and most temperate forest ecosystems. 1994 soil Fc C also exceeded the site estimate of aboveground net primary productivity (361 g C m−2yr−1). This extreme shortfall, along with the inability of soil organic matter or litter mass to explain soil Fc, suggests that about 60% of annual soil Fc C is attributable to the presence of roots. If soil Fc in vegetated environments is primarily due to the presence of roots then the significance of soil Fc to global C cycling can only be understood with concurrent estimates of net ecosystem C exchange. Key words: Soil CO2 flux, soil respiration, soil temperature, soil moisture, root respiration, boreal forest

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