Organic-matter source variation and the expression of a late Middle Ordovician carbon isotope excursion

The Permo-Triassic Extinction was the most severe in Earth history. The Siberian Traps eruptions are strongly implicated in the global atmospheric changes that likely drove the extinction. A sharp negative carbon isotope excursion coincides within geochronological uncertainty with the oldest dated rocks from the Norilsk section of the Siberian flood basalts. The source of this light carbon has been debated for decades.We focused on the voluminous volcaniclastic rocks of the Siberian Traps, relatively unstudied as potential carriers of carbon-bearing gases. Over six field seasons we collected rocks from across the Siberian platform and show the first direct evidence that the earliest eruptions particularly in the southern part of the province burned large volumes of a combination of vegetation and coal. Samples from the Maymecha-Kotuy region, from the Nizhnyaya Tunguska, Podkamennaya Tunguska, and Angara Rivers all show evidence of high-temperature organic matter carbonization and combustion.Field evidence indicates a process in which ascending magmas entrain xenoliths of coal and carbonaceous sediments that are carbonized in the subsurface and also combusted either through reduction of magmas or when exposed to the atmosphere. We demonstrate that the volume and composition of organic matter interactions with magmas may explain the global carbon isotope signal, and have significantly driven the extinction.

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Organic matter and soil moisture content and double cropping with organic matter sourceplants

Pelita Perkebunan (a Coffee and Cocoa Research Journal) ◽

10.22302/iccri.jur.pelitaperkebunan.v21i1.124 ◽

2005 ◽

Vol 21 (1) ◽

Author(s):

John Bako Baon ◽

Aris Wibawa

Keyword(s):

Organic Matter ◽

Soil Moisture ◽

Organic Matter Content ◽

Matter Content ◽

Farm Yard Manure ◽

Soil Organic Matter Content ◽

Matter Source ◽

Robusta Coffee ◽

Double Cropping ◽

Organic Matter Source

Double cropping of coffee with organic matter source plants is thought to increase organic matter content of soil. This study examined the effect of double cropping of coffee and organic matter source plants on soil organic matter content and yield of coffee plants. Arabica coffee trees in Andungsari Experimental Station (Bondowoso district), 1400 m asl. and climate type C; and Robusta coffee trees in Sumberasin Experimental Station (Malang district), 550 m asl. and climate type C, were used as experimental sites of this study which lasted for five years. Organic matter source plants consisted of some species that can be routinedly pruned and surface applied to coffee soil, and other creeping species that not being pruned, however the organic matter source derived from their fallen leaves. Application of farm manure and control (neither organic matter source plants nor farm yard manure) were used as comparison treatments. Results indicate that Ramayana (Cassia spectabilis) had vigorus growth resulting in greater biomass production compared to lamtoro (Leucaena leucocephala), mogania (Moghania macrophylla) and even kaliandra (Calyandra calothyrsus) which produced greater biomass among organic matter source plants grown in Arabica coffee farming. Double cropping of coffee with organic matter source plants did not affect soil organic matter content of Arabica and Robusta coffee farmings, though farm yard manure application increased soil organic matter content and soil bulk density, especially of Robusta coffee farm. Soil moisture content examined in dry season was not affected by double cropping. In contrary, Robusta coffee farm applied with farm yard manure had higher soil moisture content. At Arabica coffee farm, double cropping did not influence green coffee yield, on the other hand Ramayana reduced green coffee yield of Robusta coffee while farm yard manure increased the yield.Keywords : Coffeea arabica, Coffeea canephora, organic matter, soil moisture, double cropping, biomass producing plants.

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