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 In this study an inventory of N2O emissions from agriculture in Belgium was made according to the Intergovernmental Panel on Climate Change (IPCC) guidelines. Three sources of N2O were distinguished between: (1) direct N2O emissions from agricultural soils (N2O-direct), (2) N2O emissions due to animal production systems (N2O-animals), and (3) indirect N2O emissions as a result of N losses from agricultural soils (N2O-indirect). In 1996, the total N2O emission from agriculture in Belgium was 12.8×106 kg N2O-N. N2O-direct, N2O-animals and N2O-indirect contributed 60%, 7% and 33%, respectively, to the total N2O emission. The IPCC methodology tended to give an overestimate of the N2O emission from agriculture by 45% when IPCC default values were used instead of country-specific N-input data. Between 1950 and 1996, the total N2O emission from agriculture in Belgium increased from 8.4×106 kg N2O-N to 12.8×106 kg N2O-N. This was an increase of 53%, or about 0.1×106 kg N2O-N-year–1. Received: 25 May 1999  相似文献   

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Abstract

The objective of this study was to investigate the effects of long-term application of ammoniacal N fertilizer for 43?years on the availability of 10 essential elements (B, N, Mg, K, Ca, Mn, Fe, Ni, Cu, and Zn) and Al in root-zone soils and their supply to ‘Jonathan’ apple trees. To achieve this objective, we used simultaneous multi-element analysis. To estimate the soil depth from which the apple trees took up these elements, we calculated the ratios of their concentrations in the N fertilized plot (N plot) to those in the no N plot (0?N plot) (N/0N ratio). Long-term N fertilization significantly increased the fruit and leaf N/0N ratios of N and Mn and significantly decreased that of K. These ratios in the fruits and leaves were similar to those in the 20–90?cm soil layer. This result suggests that N, K, and Mn in the fruits and leaves were supplied from the 20–90?cm soil layer. The N/0N ratios of all 11 elements in the fruits and leaves were significantly positively correlated with those in the 20–90?cm soil layer, but not in the 0–20?cm soil layer. Our findings indicate that long-term N fertilization altered the tree nutrition of not only N, but also K and Mn. These changes in the tree nutrition were ascribed to the fertilizer-induced changes in the availability of elements in the subsoils.  相似文献   

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Book Review

Book reviews, Hunting the Wild Potato in the South American Andes: Memories of the British Empire Potato Collecting Expedition to South America 1938– 1939. J. [John ‘Jack’] G. [Gregory] Hawkes.Botanical and Experimental Garden, University of Nijmegen, The Netherlands 2004. 224 pp.ISBN 90-9018021-4.  相似文献   

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