Abstract
On the basis of the experience gained in the long-term field tests at the Experimental Station of Leteensuo, some of the factors have been examined which have to be taken into consideration when tests of this kind are established. It is noted that in the course of time the soil may become increasingly inhomogeneous, e.g. owing to sludge brought in by inundations, and owing to the wear of the peat on cultivated peat land. An initial shaping of the soil surface is essential in the case of cultivated peat lands because non-uniform settling of the soil may occur in the course of time in the test area. The soil surface of the different test members may also settle in different degrees, depending on the treatment involved in the test. Because of soil transportation from one test plot to another, caused by the tilling operations, the location and shape of the test plots are of significance in long-term tests intended to clarify questions associated with soil characteristics.
Highlights
The author (2) has observed that on the Sphagnum peat land at Leteensuo the settling of the soil surface during 35 years was larger by 12.5 cm when claying had been done than on the unclayed test member
On the basis of the experience gained in the long-term field tests at the Experimental Station of Leteensuo, some of the factors have been examined which have to be taken into consideration when tests of this kind are established
An initial shaping of the soil surface is essential in the case of cultivated peat lands because non-uniform settling of the soil may occur in the course of time in the test area
Summary
In the planning and arrangement of field tests the aim is to obtain reliable crop yield results and to carry out the calculations implied by statistical mathematics. On cultivated peat lands depressions can come into being spontaneously in the course of time in case the settling of the peat layer is not quite uniform In such an area the draining of the test field by open ditches may prove superior to drainage by buried drains. The author (2) has observed that on the Sphagnum peat land at Leteensuo the settling of the soil surface during 35 years was larger by 12.5 cm when claying had been done than on the unclayed test member This variation in settling, which becomes evident in the course of time, should be taken into account in the shaping, location and draining of the test plots and, above all, in the shaping of the soil surface prior to the establishment of the test. The zero plot no longer satisfies the requirements that have to be placed on a zero test member
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