Availability for plants of phosphorus in some virgin peat samples

Authors

• Armi Kaila University of Helsinki, Department of Agricultural Chemistry

DOI: https://doi.org/10.23986/afsci.71446

Abstract

The availability to plants of native peat phosphorus was studied by chemical methods and by a pot experiment in which three successive oat crops were grown with peat as the only source of phosphorus. The eight samples were collected from virgin peat lands. They were air-dried and ground. The samples were found to represent three different types of phosphorus condition: the first group contained relatively high amounts of inorganic phosphorus which was fairly easily available; the second group had a very high capacity to fix phosphorus which made its high quantity of inorganic phosphorus difficultly available; the third group was very poor in total and inorganic phosphorus but the latter was easily soluble and available to plants. On the basis of the capacity and intensity factors determined according to the method by Teräsvuori and also on the basis of inorganic phosphorus extractable by water fairly reliable predictions could be made of the mutual order of the samples as phosphorus supplyer to the plants in the pot experiment. In an incubation experiment at 27°C the amounts of organic phosphorus mineralized during the period of four months were in some of the samples quite marked, even 40 mg/l, and in most of the samples they corresponded to 5 to 15 per cent of the organic phosphorus. The amounts of phosphorus taken up by the oat crops under the favourable conditions of the pot experiment varied from 11 to 60 mg/l or from 20 to 120 kg/ha.