Inventory, evaluation and fuzzy classification of the ammonium-lactate extractable phosphate in central West-Flanders, Belgium
1993
Meirvenne, M. van | Smet, J. de | Hofman, G. (Gent Univ. (Belgium). Lab. Agrarische Bodemkunde) | Vanderdeelen, J. | Baert, L.
Due to the combined use of mineral P fertilizers and excessive animal manure in West-Flanders, it can be expected that in some areas the phosphate content of soils will exceed the optimal level for crop production, creating a threat to quality of ground and surface waters. Regularization measures for total P fertilization are currently being taken by the government. This paper describes a methodology to map, evaluate and classify the ammonium-lactate extractable P on a regional scale. In this study 673 top soil samples of arable land were used. The average P content was 44.1 mg per 100 g with an important variation (CV =46 per cent ). The variogram of this variable indicated at least three levels of spatial variation with a range of 4 km for the highest (regional) level. The inventory was obtained by kriging blocks of 0.25 sqare km. A total area of 1,230 square km was inventoried. Based on the standards of the Pedological Service of Belgium, the results were evaluated. A limit of 5O mg P per 100 g was used to identify areas which should receive no additional P. Using the fuzzy set theory we added some asymmetric vagueness to the classification of this limit. It was found that for 41 per cent of the total area the P fertilization should be monitored closely in the near future.
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