Contribution To The Study Of The Belgian Agricultural Production 1846-1913: As early as 1830 agriculture was by far the main activity of the country and its relative perfection made it an example for most of the other european states. In 1846 its production was more than 7/10 of the whole physical output, although the crisis of the linen industry and the potato disease had already endangered the prosperity of the land. Industrial growth overturned technology as well as the markets. One could have expected that industrialization would have given agriculture new opportunities of development by producing new fertilizers or machines, by improving the standard of living and by increasing transport facilities. As a matter of fact these have exerted on agriculture a deep influence, but the delay was important. It was not before 1880-1895 that the use of improved machinery and chemical fertilizers became general. Similarly the increase of the living stock was of some importance only towards the end of the century. If for agriculture the good of industrialization was delayed, its evil however was immediate. The shortening of labour forces and capital was cruelly resented already form 1865 on. The introduction of the treshing machine was the cause of a seasonal desequilibrium in the opportunities of employment, which was a new incitation to the migration of workers to the towns and their factories. Routinism and smallness of their exploitation made it very difficult for the farmers to realize in time the necessary adaptations and, from 1865 to 1880 the average area of the farms diminished gradually. This life-or-death reaction contributed itself to delay the proper adaptations, which were the use of new techniques of cultivation and breeding. During the period 1846-1913 the physical production of agriculture increased slowly, with a rate of 0.59% a year, while in the same time the physical output of industry increased at a rate of 3.1% a year. The result was that in less than a century relative positions were reverted : shortly before the First World War agriculture contributed only for less than one third to the whole physical output of Belgium.