Phosphorus in virgin peat soils
In the present paper the total and organic P content of virgin peat soils is studied on the basis of 217 peat samples mostly collected from Northern Finland and consisting of 32 Sp, 34 CSp, 62 SCp, 12 EuSCp, 36 BCp, and 41 Cp samples. The material was found to be satisfactorily typical for a study o...
Published in: | Agricultural and Food Science |
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Main Author: | |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
The Scientific Agricultural Society of Finland
1956
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Subjects: | |
Online Access: | https://journal.fi/afs/article/view/71396 https://doi.org/10.23986/afsci.71396 |
Summary: | In the present paper the total and organic P content of virgin peat soils is studied on the basis of 217 peat samples mostly collected from Northern Finland and consisting of 32 Sp, 34 CSp, 62 SCp, 12 EuSCp, 36 BCp, and 41 Cp samples. The material was found to be satisfactorily typical for a study of Finnish peat soils as to the pH, ash and N contents. Only the BCp samples were, in some respect, of a poorer quality than in general. The total P content of the 217 samples ranged from 190 to 2350 ppm or from 30 to 2440 kg/ha. In the Sp and BCp groups the mean P content was equal, 580 ± 80 ppm and 560 ± 90 ppm resp., and significantly lower than the corresponding value in all the other groups which was 950 ±120 ppm in the Cp-group, 980 ± 290 in the EuSCp-group, 800 ± 60 in the SCp-group, and 800 ± 120 ppm in the CSp-group. A low but significant correlation was found to exist between the degree of land quality estimated on the basis of the surface vegetation and the P content of the surface samples: r = 0.361***. When the BCp samples were excluded an even closer correlation was detected: r = 0.481***. The correlation coefficient between the total P content and the degree of humification was r = 0.317***, that between the total P and the ash contents r = 0.289**, and that between the total P and N contents r = 0.206*. The organic P content of the 217 samples ranged from 130 to 1950 ppm with an average of 600 ± 40 ppm. The Sp and BCp groups showed significantly lower means, 430 ± 60 ppm and 440 ±7O ppm resp., than the other groups with averages of 630 ± 120 ppm in the CSp-group, 620 ± 50 ppm in the SCp-group, 770 ± 100 ppm in the Cp-group and 820 ± 280 in the EuSCp-group. The organic P content was very closely correlated with the total P content; the total correlation coefficient was r = 0.934***. The connection with the degree of humification was not distinct: the total correlation coefficient was r = 0.336***, but the partial correlation coefficient after the elimination of the effects of total P and N contents was only r = 0.136. No significant correlation existed between the organic P content and the N content, r = 0.184. The organic P content of the 217 samples expressed as a percentage of the total P content ranged from 55 to 95 per cent with an average of 78 ± 1 per cent. The proportion of organic P of total P was correlated with the degree of humification, the total correlation coefficient was r = 0.504***, the partial correlation coefficient after the elimination of the effect of the sampling depth was r = 0.427***. No correlation with the sampling depth existed after the elimination of the effect of the degree of humification: the partial correlation coefficient was r = 0.159, whereas the total correlation coefficient was r = 0.334***. A low correlation existed between the percentage of organic P of total P and the pH value even after the elimination of the effect of the degree of humification, r = 0.228*, but the connection with the total P content appeared to be only indirect and arised from the effect of the degree of humification, the total correlation coefficient was r = 0.222*, the partial correlation coefficient r = 0.076. The amount of organic P expressed as a percentage of the organic dry matter ranged from 0.01 to 0.25 per cent with an average of 0.07 ± 0.004. The ratio of N/org.P ranged from 12 to 133 with an average of 45 ± 3. Owing to the low P content of the BCp-group its mean ratio was significantly higher than that of the other groups. The degree of humification did not show any correlation with the ratio of N/org.P. The solubility of inorganic P in 0.5 N acetic acid and in 0.2 N sulphuric acid was highest in the Sp-group. On the average approximately from 15 to 30 per cent of total inorganic P was extracted by the latter solution. The acetic acid extracted only about 2 per cent of the inorganic P in the Cp-group but about 15 per cent in the Sp-group. The phosphorus conditions in virgin peat soils was discussed and it was attempted to explain the results obtained on the basis of the supposition that phosphorus is a minimum factor in the metabolism of peat. Tutkimuksessa on yritetty selvittää luonnontilaisten turvemaitten fosforin määrää ja koostumusta. Tutkimusaineistona oli 217 turvenäytettä, jotka oli kerätty etupäässä maamme pohjoisosista ja jotka edustivat eri turvelajeja ja suotyyppejä. Näytteiden kokonaisfosforin pitoisuus vaihteli 190—2350 mg/kg ja 30—2440 kg/ha. Rahkaturpeitten ja ruskosammalsaraturpeitten ryhmät sisälsivät keskimäärin selvästi vähemmän fosforia kuin muut turvelajit. Pintanäytteiden ja soitten boniteetin välillä oli havaittavissa merkitsevä, joskin heikohko vuorosuhde, korrelaatiokerroin oli r = 0.361***. Tilastollisesti merkitsevä korrelaatiokerroin saatiin myös kokonaisfosforin pitoisuuden sekä maatumisasteen välille, r = 0.317***, samoin kokonaisfosforin pitoisuuden ja tuhkapitoisuuden välille r = 0.289**. Kokonaisfosforin pitoisuuden ja Kjeldahl-typen pitoisuuden välillä oli myös havaittavissa merkitsevä riippuvuus, r = 0.206*. Näytteiden orgaanisen fosforin pitoisuus vaihteli 130—1950 mg/kg, keskiarvo oli 600 ± 40 mg/kg. Erot- eri turvelajien välillä olivat samanlaiset kuin kokonaisfosforin pitoisuuden kohdalla. Orgaanisen fosforin pitoisuuden ja kokonaisfosforin pitoisuuden riippuvuus oli erittäin voimakas; r = 0.934***. Orgaanisen fosforin suhteellinen määrä vaihteli 55—95 % kokonaisfosforista ja oli keskimäärin 78 ± 1 %. Tämä suure ei osoittautunut riippuvaksi kokonaisfosforin pitoisuudesta eikä näytteen ottosyvyydestä. Sen sijaan havaittiin verrattain voimakas korrelaatio orgaanisen fosforin suhteellisen määrän ja maatumisasteen välillä: osittaiskorrelaatiokerroin syvyyden vaikutuksen eliminoinnin jälkeen oli r = 0.427***. Heikko, joskin tilastollisesti merkitsevä korrelaatio voitiin todeta myös orgaanisen fosforin suhteellisen määrän ja pH:n välillä; maatumisasteen vaikutuksen eliminoinnin jälkeen saatu osittaiskorrelaatiokerroin oli r = 0.228*. Orgaanisen fosforin määrä ilmoitettuna prosentteina orgaanisesta kuiva-aineesta oli hyvin alhainen: 0.01-0.25 %, keskimäärin 0.07 ± 0.004 %. Suhde N/org.P vaihteli 12—133 keskiarvon ollessa 45 ± 3. Ruskosammalsaraturveryhmän keskimääräinen N/org.P oli selvästi suurempi kuin muitten ryhmien. Maatumisasteella ei näyttänyt olevan vaikutusta suhteen arvoon. 0.2 n rikkihappo uutti noin 15—30 % turvenäytteiden epäorgaanisen fosforin kokonaismäärästä. 0.5 n etikkahappo uutti vain pari prosenttia saraturpeiden epäorgaanisesta fosforista, mutta noin 15 % rahkaturpeiden epäorgaanisesta fosforista. Saatujen tulosten perusteella oletettiin, että fosfori on eräs nimitekijöistä turvemaitten metabolismissa |
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