Filters: Tags: Fertilizer (X) > Extensions: Citation (X)
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This paper contrasts the natural and anthropogenic controls on the conversion of unreactive N2 to more reactive forms of nitrogen (Nr). A variety of data sets are used to construct global N budgets for 1860 and the early 1990s and to make projections for the global N budget in 2050. Regional N budgets for Asia, North America, and other major regions for the early 1990s, as well as the marine N budget, are presented to Highlight the dominant fluxes of nitrogen in each region. Important findings are that human activities increasingly dominate the N budget at the global and at most regional scales, the terrestrial and open ocean N budgets are essentially disconnected, and the fixed forms of N are accumulating in most...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Biogeochemistry,
Denitrification,
Fertilizer,
Fossil fuel combustion,
Haber-Bosch,
Effects of annual additions of mineral N and P (100 kg ha-1) on plant species composition and annual aboveground net primary production (ANPP) were investigated during the first three years following disturbance in a semi-arid ecosystem. Additions of N reduced richness of perennial plant species during years 2 and 3, while P reduced the number of perennial species only in year 3. From year 1 to year 2, annual and biennial species richness declined in all treatments while ANPP of annual species increased greatly. Added N increased ANPP of annual species while it decreased ANPP of most perennial species relative to the unfertilized control treatment. Community similarities were higher for the control and native vegetation...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Plant and Soil,
Springer Netherlands,
disturbance,
fertilizer,
nitrogen,
In the absence of human activities, biological N fixation is the primary source of reactive N, providing about 90–130 Tg N year−1 (Tg = 1012 g) on the continents. Human activities have resulted in the fixation of an additional 150 Tg N year−1 by energy production, fertilizer production, and cultivation of crops (e.g., legumes, rice). Some sinks of anthropogenic N have been estimated (e.g., N2O accumulation in the atmosphere; loss to coastal oceans), however due to the uncertainty around the magnitude of other sinks (e.g., retention in groundwater, soils, or vegetation or denitrification to N2) a possibly large portion of the N fixed by humans is missing. While we know that N is accumulating in the environment,...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Asia,
Environmental Pollution,
Nitrogen,
fertilizer,
food production,
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