RESULTS FROM A SOIL IMPROVEMENT AND FERTILIZING TEST ON FEN LAND AT LETEENSUO Yrjö Pessi Society of Peat Cultivation, Experimental Station Leteensuo. Received August 22, 1961 At the Experimental Station of Leteensuo several soil improvement and ferti- lizing tests on fen and Sphagnum bog were established already at an early stage of its activity. The results of these tests over prolonged periods have beenreported in a number of papers published in recent years (2, 3,4, 5,6, 8,9). An extensive, combined soil improvement and fertilizing test was established in 1910 by Simola, but its results have so far been reported only with respect to fairly short periods (7, 10, 11). The following is a report of the results obtained in this test during the period 1910—1960. Test area The peat of the test area is forest sedge peat; the bog type prior to the clearing of the area was a grassy spruce and broad-leaved tree swamp rich in herbs. The peat layer has a depth of more than 2 metres. This area has been drained by means of open ditches, dividing it into strips 20 m in width. The quality of the peat is reflected by the results of the analysis stated in Vesikivi’s (10, p. 32) investigation, which also gives an account of the results of the analysis relating to the clay and sand used as soil improving agents (loc.cit., p. 34). Procedure The test area was cleared for cultivation in 1909 and the soil improving agents were spread in the winter of 1909/1910. The quantities of clay or sand were 0, 100, 200, 300 and 400 m 3 per hectare. The claying or sand addition was repeated ac- cording to the same schedule in the early spring of 1928. The soil improving agents were spread uniformly over each strip between the ditches (10 m X 100 m). Various kinds of experimental phosphate and potassium fertilizations were combined with the soil improving treatment. Nitrogen fertilization is redundant https://www.c-info.fi/en/info/?token=waRDZatkCxhWZmhP.z3ZFMzPmh6V0RLsMhdpmAg.Eo_qvOO5GRI6F3KPqx_7vpeuK788mDKxRhjkeLllXFSeOJC_KFZQqnX7gqQjs1wh4GhKPpCSWixr_3NOzhUMnFYUEaWmJU7vyuKxLfSTOVr4Pu8vW_XynB7nD43NqfgQLzqNbOHrJE4BpIUKEX00zeVl_l-DFF9JziijGaA 224 on the bog in question. The annual phosphate fertilizer additions were 50 (P) and 100 (2 P) kg P 20 3 per hectare in the years 1910—1927; from 1928 onwards the quantities of 40 and 80 kg per hectare, respectively, were applied. The fertilizing agent was superphosphate. The potassium fertilization consisted of 100 kg K 2O (K) per hectare, as potassium salt, throughout the test period. In 1917 no fertilizers were given, and in 1918 only the phosphate fertilizer was given at half the above- mentioned dosage. The detailed location of the test plots is shown in Fig. 1. Crop yield results The weather conditions ofalmost the entire test period can be found in another publication (2). The annual test results are shown in tables in the Appendix, which is depos- ited in the Agricultural Library of the University of Helsinki and in the Office of the Peat Cultivation Society, Leteensuo. Meadows. —Tables 1, 2 and 3 give the results of the tests as mean values of the hay crop yield; Table 1 showing the mean crop yield figures referring to the period prior to the repetition of the soil improving treatment (the period 1910—1927), Table 2 those for the period after the second treatment (1928—1960), and Table 3 states the means for the entire test period. Some of the results are further graphically illustrated in Figs. 2 and 3. Fig. 1. The position of plots in the test. 225 The effect of the soil improving treatment on the hay crops can be most conveniently studied with the aid of Fig. 2. It can be seen, for instance, that the soil improving agents had little effect and the crop yields were low whenno fertilizers were applied. When phosphate fertilization was administered, the crops increased in a decisive degree with the increasing quantity of the soil improving agents. In this instance, the beneficial effect of the soil improving agents on the crop yield is largely due to the potassium fertilizing effect of the added mineral soil, a Fig. 2. Average annual hay crop yields (29 years), during the entire test period Fig. 3. Incerases of hay crop yields per year caused by various fertilizing combined with various soil improving, during the entire test period. 226 fact which has also been observed at the Experimental Station of Northern Pohjan- maa (1). Comparison of the effects of sand and clay clearly reveals the higher potas- sium fertilizing effect of clay. That the high increases in crop yield were indeed caused by the potassium fertilizing effect of the added mineral soil is obvious if one compares these results with the crop increase figures found in the test plots with PK fertilization and mineral soil addition. When potassium fertilization was given in addition to phosphates, good hay crops were also obtained on the strip that had not received any mineral soil. How- ever, it can be noted that, even if no potassium fertilization was applied, a certain further increase of the crop yield was produced by the addition of mineral soil, while the type of the mineral soil was by then no longer of importance. It might be conjectured that the crop yield-increasing effect of the mineral soil addition could perhaps be made up for in its entirety by a further increase in the potassium fertilization. But the results from a test with increasing potassium quantities and soil improvement, established adjacent to the test under considera- tion, have shown that the increases in crop yield produced by mineral soil addition did not progress any further with increasing potassium quantities (4, p. 232). The beneficial effect of mineral soil is therefore thought to be due also to other factors besides its fertilizing action, and it seems unlikely that any substitution can be made for these effects. In investigating the significance of fertilization, the observation can be made in the first place that both phosphate and potassium fertilization is indispensable if no soil improving agent has been given. Particularly owing to the high potassium fertilizing effect of mineral soil, especially of clay, fairly good crop yields are already obtained with phosphate fertilization alone if soil improvement has been done. Clay in particular has a surprisingly good potassium fertilizing effect. However, potassium fertilization is also required. Fig. 4. Avergae annual grain yields of oats (11 years) during the entire test period 227 Oats. The mean crop yields of oats per year have been tabulated in Tables 4, 5 and 6 and illustrated in Fig. 4. On the whole, the soil improving agents and fer- tilizers have produced effects similar to the case of hay. Comparison of these results with the results from the other fertilizing and soil improvement tests performed at Leteensuo (4, 6,9) reveals a uniform tendency. Duration of the effect of soil improvement. As has been said in the description of the test, soil improving agents were applied twice in this test, namely, in the years 1910 and 1928. The latest application was thus about 30 years ago. Fig. 5 shows the increases in crop yield produced by clay and sand additions 400 m 3 per hectare at 2 PK fertilization, as means of five-year periods. The fodder unit equivalents are the same as in a previous investigation (2). The graph reveals that the crop yield increases produced by the soil improvement have remained constant during the last decades, and no drop in the crop yield increase can be noted. It is thus evident that the soil improvement has a fairly prolonged effect. This is also borne out by the investigation of Anttinen (1) as well as by several other tests carried out at Leteensuo (2, 6). Conclusions Clay and sand, used as soil improving agents, have increased the hay crops as well as the cereal crops. When the fertilization contained phosphates only, the in- creases in crop yield produced by the soil improvement were quite high. In this case clay developed a higher effect than sand. In connection with phosphate plus po- tassium fertilization both kinds of mineral soil were approximately equal in value, but Fig. 6. The increases of yield caused by the clay and sand addition 400 m 3 per hectare. The increases of yield have been calculated from 5-years periods. 228 their effect fell considerably below that of phosphate fertilization alone. These agents have thus a remarkable potassium fertilizing effect. However, potassium fertiliza- tion was not able to account for the entire crop yield-increasing effect of mineral soil. The highest increases in crop yield per unit of mineral soil addition were obtained with the mineral soil quantity of 100 m 3 per hectare. The addition of mineral soil has a prolonged effect since the effect has not decreased in the 30 years since the latest soil improving treatment in this test. Phosphate and potassium fertilization are both necessary. For spring cereals and for the annual top dress fertilization of hay meadows the superphosphate quan- tity of 200—300 kg per hectare is adequate. The requirement of potassium fertilizer varies according to the quantity of soil improving agents and their quality. In all circumstances 200 kg 50 % potassium salt per hectare seems to be a sufficient po- tassium fertilization for the plants considered in this test. A slightly higher quantity is thought to be necessary for the top dress fertilization of hay meadows without soil improving agents. REFERENCES (1) Anttinen, O. 1957. Saraturvesuon saveus- ja lannoituskokeen tuloksia. Referat; Ergebnisse eines Lehmzufuhr- und Düngungsversuchs auf Seggentorfmoor. Valt. maatal. koetoim. julk. 163: 1-20. (2) Pessi, Y. 1959. Kivennäismaan vaikutuksesta rahkasuon maanparannusaineena Leteensuon koeaseman pitkäaikaisten kenttäkokeiden perusteella. Summary: On the effect of mineral soil as a soil improving agent on Sphagnum bogs on the basis of prolonged field tests at Leteensuo Experimental Station. Acta agr. fenn. 94, 14: 241—268. (3) —1959. Mutasuon kalkituskokeiden tuloksia Leteensuolta. Summary: The results of liming tests on fen at Leteensuo. Maat. tiet. aikak. 31: 285 293. (4) —*— 1960. Fen fertilization with potash in the light of tests at Leteensuo Experimental Station. Selostus; Mutasuon kalilannoituksesta Leteensuon kokeiden perusteella. Ibid. 32; 229 238. (6) —»— 1960.Fertilization of Sphagnumbogs on the basis of certain field experiments at Leteensuo. Selostus; Rahkasuon lannoitus eräiden Leteensuon kokeiden perusteella. Ibid. 32: 144—157. (6) —»— 1960. Kivennäismaan merkityksestä mutasuon maanparannusaineena Leteensuon koe- aseman pitkäaikaisten kenttäkokeiden perusteella. Summary: On the significance of mineral soil as a soil improving agent on fens on the basis of prolonged field tests at Le- teensuo Experimental Station. Acta agr. fenn. 95, 3. (7) Simola, E. F. 1923. Über die Ernteerträge und die Ausdauer von reinem Timothee- und von Mischgras auf einem Niederungsmoor mit und ohne Lehm und Sand bei Benutzung ver- schiedener Düngungen während des Zeitraumes 1916—1922. Suom. suovilj. yhd. tiet. julk. 4: 1-127. (8) Takala, M. 1958. Suoviljelysten fosfaattilannoituksesta. Summary; On phosphate fertilization Peat Soil. Suovilj.yhd. vuosik. 63; 30 38. (9) —»— 1961. Super-, thomas- ja hienofosfaatin vaikutuksesta mutasuolla. Summary: On the effects of superphosphate, basic slag and hyperphosphate on fen soil. Maat. tiet. aikak. 33: 57-64. 229 (10) Vesikivi, A. 1929. Suonsavetuksen ja -hiekoituksen taloudellisesta kannattavaisuudesta. Metodia selvittävä tutkimus. Referat: Über die Rentabilität der Lehm- und Sandmischkultur auf Moorboden. Suom. suovilj.yhd.tiet.julk. 12: 1 131. (11) —1933. Suonsavetuksen ja -hiekoituksen lannoitusvaikutuksesta. Referat: Über die Dünge- wirkung der Lehm- und Sandmischungen auf Moorboden. Ibid. 14: 1 29. SELOSTUS: MUTASUON MAANPARANNUS- JA LANNOITUSKOKEEN TULOKSIA LETEENSUOLTA Yrjö Pessi Suoviljelysyhdistys, Leteensuon koeasema Maanparannusaineena käytetty savi ja hiekka ovat lisänneet sekä heinä- että viljasatoja. Kun lannoituksena on ollut vain fosfaattilannoitus, ovat maanparannuksen aiheuttamat sadonlisäykset olleet suuria. Tällöin saven vaikutus on ollut suurempi kuin hiekan. Fosfaattikalilannoituksen yhtey- dessä molemmat kivennäismaat ovat olleet jokseenkin samanveroisia. Niiden vaikutus ei ole ollut kui- tenkaan läheskään yhtä suuri kuin pelkän fosfaattilannoituksen yhteydessä. Niillä, ja varsinkin savella on siis huomattava kalilannoitusvaikutus. Kalilannoitus ei ole kuitenkaan täysin korvannut kivennäis- maan satoalisäävää vaikutusta. Lisättyä kivennäismaayksikköä kohti on saatu suurimmat sadonlisäykset maanparannusmäärällä 100 ma /ha. Kivennäismaan vaikutusaika on pitkä. Vaikutus ei ole vähentynyt 30 vuoden kuluessa, mikä aika on kulunut viimeisestä maanparannuskäsittelystä. Sekä fosfaatti- että kalilannoitus ovat tarpeellisia. Kevätviljoille ja nurmen vuotuiseen pinta- lannoitukseen on superfosfaattimäärä 200 300 kg/ha riittävä. Kalilannoituksen tarve vaihtelee käyte- tyn maanparannusaineen määrästä ja laadusta johtuen. Kaikissa olosuhteissa lienee mainituille kasveille riittävä kalilannoitus 200 kg/ha 50-prosenttista kalisuolaa. Nurmen pintalannoitukseen ilman maan- parannusainetta tarvittaneen vähän enemmän. Appendix Table 1. Average annual hay crop yields (10 years), kg per hectare, during the period 1910 1927 Mineral soil, ms per hectare 0 P 2P PK 2PK Mean 0 600 800 1 300 5 570 6 310 2 950 Clay 100 1 100 2 850 3 610 6 780 7 730 4 420 » 200 1 220 4 080 4 390 6 580 7 590 4 770 » 300 1280 4 360 5 550 6 160 7 520 4 970 » 400 1 730 4 910 5 770 6 910 7 550 5 370 Sand 100 1 050 1 870 2 740 6 260 6 810 3 750 » 200 1150 2 560 2 810 6 600 6 910 4 010 » 300 1 130 3 290 3 320 6 240 7 140 4 270 »400 1 340 3 760 3 960 6 580 7 510 4 630 Mean 1180 3 160 3 720 6 410 7 230 4 340 Fertilizing 223* 294** 375*** Mineral soil 229» 393** 502*** Table 2. Average annual hay crop yields (19 years), kg per hectare, during the period 1928 1960 Mineral soil, m 3 per hectare 0 P 2P PK LM'K Mean 0 600 870 1180 6 420 6 190 3 060 Clay 100 810 2 750 3 520 6 910 6 940 4 200 »200 1 180 4 720 4 720 6 900 6 850 4 880 » 300 1220 5 780 6 450 7 010 7 300 5 350 »400 1 670 6 190 6 730 7 320 7 540 5 900 Sand 100 770 1610 2 160 6 920 6 740 3 640 » 200 890 2 420 2 720 6 820 6 800 3 930 » 300 980 3 430 3 440 7 120 7 000 4 400 » 400 1 310 4 100 4 120 7 200 7 200 4 780 Mean 1 050 3 440 3 900 6 970 6 970 4 480 Fertilizing 186* 245** 313*** Mineral soil 252» 332** 424*** Table 3. Average annual hay crop yields (29 years), kg per hectare, during the entire test period Mineral soil, ms per hectare 0 P 2P PK 2PK Mean 0 600 850 1 230 6 130 6 270 3 020 Clay 100 910 2 790 3 550 6 880 7 240 4 280 » 200 1190 4 500 4 610 6 810 7 110 4 840 » 300 1 240 5 290 6 140 6 730 7 390 5 360 » 400 1690 5 740 6 410 7 200 7 540 5 720 Sand 100 870 1 700 2 360 6 710 6 760 3 680 » 200 980 2 470 2 750 6 750 6 840 3 960 » 300 1 030 3 390 3 400 6 820 7 050 4 340 » 400 1320 3 980 4 060 6 980 7 310 4 730 Mean 1 090 3 410 3 830 6 780 7 060 4 440 Fertilizing 156» 204** 261**» Mineral soil 208* 273** 349*** 230 -I Table 4. Average annual grain and straw yields of oats (6 years), kg per hectare, during the period 1910-1927. Mineral soil m 3 per hectare 0 P 2P PK 2PK Mean Grain yields 0 790 850 1 000 2 910 2 740 1 660 Clay 100 1140 1830 1920 3 120 3 110 2 220 » 200 1170 2 220 2 310 3 270 3 320 2 450 » 300 1 320 2 550 2 590 3 400 3 560 2 680 » 400 1680 2 680 2 710 3 410 3 560 2 810 Sand 100 850 1310 1710 3 040 3 190 2 020 » 200 940 I 590 1 780 3 040 3 300 2 130 • 300 900 1 880 1 760 3 200 3 520 2 210 • 400 1 130 2 190 2 140 3 310 3 370 2 430 Mean 1100 1900 1990 3 180 3 270 2 l'7o Fertilizing 122» 160" 204»«» Mineral soil 163* 215** 274*** Straw yields 0 1 310 2 130 2 090 3 010 4 790 2 670 Clay 100 1930 3 240 3 640 4 740 5 180 3 740 » 200 I 960 3 410 3 730 4 780 5 130 3 800 » 300 1 990 3 500 3 980 5 120 5 390 3 990 » 400 2 490 3 800 3 820 4 630 5 030 3 950 Sand 100 1 790 2 470 3 370 4 780 5 250 3 520 » 200 1 550 2 700 3 200 4 430 4 840 3 340 » 300 1490 2 710 3 050 4 050 4 740 3 200 » 400 15110 2 930 3 430 4 170 4 870 SSM Mean 1780 2 990 3 360 4 410 5 020 3 510 Table 5. Average annual grain and straw yields of oats, kg per hectare, during the period 1928 1960. Mineral soil, ms/ha 0 P 2P PK 2PK Mean Grain yields (5 years) 0 1 220 1 240 1 330 2 530 2 510 1 760 Clay 100 1 560 2 020 2 340 2 520 2 620 2 210 » 200 1 580 2 330 2 390 2 440 2 490 2 250 » 300 1 540 2 460 2 520 2 540 2 550 2 320 » 400 1 580 2 300 2 470 2 710 2 600 2 330 Sand 100 1 390 1 510 1 650 2 450 2 510 1 900 » 200 1 360 1 730 1 780 2 540 2 430 1 970 » 300 1350 2 040 1960 2 680 2 560 2 120 » 400 1 430 2 100 2 040 2 420 2 280 2 060 Mean 1450 1970 2 050 2 540 2 510 2 100 Fertilizing 66* 87** 111*** Mineral soil 89* 120** 153*** 231 232 Straw yields (4 years) 0 1 910 2 370 2 720 4 270 4 390 3 130 Clay 100 2 580 3 190 4 130 4 500 5 260 39 30 » 200 2 680 3 790 3 800 4 650 4 440 3 870 » 300 2 940 4 120 4 720 5 110 4 910 4 240 » 400 2 760 4 540 4 700 5 160 5 120 4 460 Sand 100 2 150 2 930 3 280 4 630 4 670 3 530 » 200 2 120 2 880 3 080 4 680 4 720 3 500 » 300 2 330 3 120 3 550 4 770 5 010 3 760 » 400 2 550 3 730 4 370 4 940 5 190 4 160 Mean 2 450 3 410 3 820 4 751» 4 860 3 860 Table 6. Average annual grain and straw yields of oats, kg per hectare, during the entire test period Mineral soil, m» per hectare 0 P 2P PK 2PK Mean Grain yields (11 years) 0 990 1 030 1 150 2 730 2 630 1 710 Clay 100 1330 1920 2 110 2 840 2 890 2 220 » 200 1 360 2 270 2 350 2 890 2 940 2 360 » 300 1 420 2 510 2 560 3 010 3 100 2 520 » 400 1 640 2 510 2 600 3 090 3 120 2 590 Sand 100 1 090 1 400 1 680 2 770 2 880 1 960 » 200 1 130 1 650 1 780 2 810 2 910 2 060 » 300 1 100 1 950 1 850 2 960 2 980 2 170 • 400 1 260 2 150 2 090 2 910 2 880 2 260 Mean 1380 1930 2 020 2 890 2 920 2 210 Fertilizing 79* 104** 133*** Mineral soil 104* 137** 175*** Straw yields (10 years) O 1 550 2 230 2 340 3 510 4 630 2 850 Clay 100 2 190 3 220 3 830 4 640 5 220 3 820 » 200 2 240 3 560 3 760 4 730 4 860 3 830 • 300 2 370 3 750 4 270 5 110 5 200 4 140 » 400 2 600 4 100 4 170 4 840 5 070 4 150 Sand 100 1930 2 660 3 330 4 710 5 020 3 530 • 200 1 780 2 770 3 150 4 530 4 790 3 400 » 300 1 830 2 880 3 250 4 330 4 830 3 420 » 400 1 960 3 250 3 800 4 480 4 990 3 700 Mean 2 050 3 160 3 540 4 540 4 960 3 650