Abstract
On the fen area of the Experimental Station of Leteensuo, with a peat layer consisting of forest sedge peat, potassium fertilization produced a considerable increase of the hay crop yield on the clayed as well as the unclayed bog, when phosphate fertilization had been added. However, clay displayed a considerable potassium fertilizing effect and also other effects, which probably cannot be reproduced by fertilization. The effect of potassium fertilization on the summer cereal crop yield was different in different tests. In two of them, potassium fertilization increased the grain yield but not in the third. The results obtained in this latter instance are thought to have been influenced by the addition of mud through the action of floods. Potassium fertilization had remarkably increased the root crop yields. When phosphate fertilization had not been added, the effect of potassium fertilization was small asa rule. There was no marked difference between the effects of potassium salt and potassium sulphate, although it should be noted that the tests did not contain any treatments with potatoes as the experimental crops, which might show up this difference most clearly.
Highlights
Numerous experiments intended to clarify the fertilizing questions of peat land have been established at the Experimental Station of Leteensuo and carried on through fairly long periods without interruption
The location of the test plots can be seen from Fig. 1
On the unclayed test strip, the increase was higher than on the clayed strip in the instance of the first four potassium fertilizer quantities in the series, but the highest potassium fertilizer addition produced about equal crop yield increases on both strips. This serves to show that clay has a considerable potassium fertilizing effect and other effects which cannot be reproduced with potassium fertilization
Summary
Numerous experiments intended to clarify the fertilizing questions of peat land have been established at the Experimental Station of Leteensuo and carried on through fairly long periods without interruption. The results obtained over longer periods have recently been analysed with reference to the Sphagnum bog fertilizing tests, which have thrown light on the effects of nitrogen and phosphorus as well as potassium fertilization (5, 6). Takala (6) has reported on the experiments arranged with a view to clarifying the effects of phosphate fertilization. The significance of potassium fertilization on the fen area of the Experimental Station of Leteensuo will be described on the basis of the results derived from three field tests. With reference to shorter periods, these tests have been analysed by Malm (3) and Hirvensalo (2). The author has previously examined the results of one of these tests over a longer period (5)
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