Mutasuon kalkituskokeiden tuloksia Leteensuolta

Abstract

A detailed description of the plant cover of the bog region in question has been given by LINDBERG (13), while its geological aspects have been treated by RINDELL (6). The peat of the test area is forest sedge peat and the bog type prior to clearing was wooded swamp with herbs and grasses. The chemical qualities of the peat adjacent to the test areas have been illustrated by RINDELL. These results are found in detail in the publication by VESIKIVI (8, p. 32). It may be mentioned in this connection that the CaO of the soil layer 20 cm in height has been 5858 kg per hectare, corresponding thus to the CaO content of nearly 12 tons of ground limestone. The test begun in 1908 was established by A. RINDELL and E. F. SIMOLA, and the test started in 1932 by A. VESIKIVI. The tests have been conducted by E. F. SIMOLA (1908—1917), E. A. MALM (1918—1919), A. VESIKIVI (1920—1943), J. TÖRMÄ (1944), and U. E. HIRVENSALO (1945—1946). The question of liming on fen at the Leteensuo Experimental Station is studied in the following on the basis of two prolonged liming tests. Liming test No. 1. – The test area had been cleared for cultivation and provided with wooden drains of square cross-section in 1904. The phosphate and potassium fertilizing had been annual, the phosphate fertilizing being equivalent to about 200—300 kg superphosphate and the potassium fertilizing to 100—200 kg 50 % potassium salt per hectare. Mineral soil had not been used as a soil improvement material. The limings were performed according to plan four times (0, 1000, 2000, 3000 kg slaked lime per hectare) that is in 1907, 1911, 1920, and 1940. Liming test No 2. – The test area had been cleared for cultivation in 1904. The following year sand had been given in a quantity of 400 m3 per hectare as soil improvement material. Cultivation had begun the same year. The liming test was arranged as late as 1932 when the liming was performed according to plan (0, 1000, 2000, and 3000 kg slaked lime per hectare). The annual fertilizing had been similar to that of the preceding test. TUORILA (7) has studied the changes in soil acidity resulting from the liming in the test begun in 1908. The pH-figure was 4.9 without lime and 5.25, 5.55, and 6.35 with increasing liming. Crop yield results The weather conditions of the test years have been described in a previous publication (PESSI 5). The annual crop yield results of the test can be seen in Tables I and II in the Appendix. Treating the test results in addition to the annual mean values, the significant crop yield differences are counted only if the F-value has at least one asterisk. Grass ley Tables 1 and 2 show the average annual crop yields. The grass crops have been timothy-dominated. The results show that liming has neither increased nor decreased the crop yields. On the sedge peat bog at Ruukki, on the other hand, where the lime content of the soil before the fertilizing and liming test was about 4500 kg CaO per hectare, liming has increased the crop yields (2, p. 14). Cereals Table 3 and Figure 1 show the average annual yield results of oats and barley. It is noticeable that liming has decreased the grain yields of oats in the same way as in the experiment at Ruukki (2, p. 16). On the other hand liming has neither increased nor decreased the grain yield of barley. Root crops Table 4 and Figure 2 show the yields of root crops. It can be seen that lower liming quantities have increased the root yields of sugar beet while the highest liming quantity has decreased it. On the root yields of swede and turnip liming has had no particular effect. Peculiar to the yields of tops of all root crops is that liming has lowered them. Quality of the yield Studies dealing with the quality of yield are scarce. From a space of two years there exist only the analyses of the sugar content of sugar beet. In 1924 the sugar content was 15.6 % in the treatment without lime and 15.6, 15.6, and 14.4 % when the quantity of lime was increased. In 1932 the corresponding numbers were 16.7, 14.0, 14.8, and 16.0 %. Thus liming has not had a significant effect on the sugar content. Conclusions On fen the peat of which is forest sedge peat and where in a soil layer 20 cm in height the CaO has been nearly 6000 kg per hectare, the effect of liming has varied depending on the test plant. The timothy-dominated grass ley, the grain yield of barley, and the root yields of swede and turnip have not been influenced by liming in a high degree. The root yields of sugar beet are increased by liming although the top quantity of lime has a lowering effect. The grain yield of oats is distinctly decreased by liming. The yields of root crop tops decrease with an increase in the liming.