Peat nutrient deficiencies

Poor plant growth on raw peats is also frequently due to high acidity and to nutrient deficiencies, discussed in the following section. 

Lime deficiency is characteristic of most sphagnum and woody peats. As already stated, the pH of these peats commonly lies between 3.0 and 5.0, which is in a region too low for the growth of all but the most acid-tolerant plants. Cultivated crops prefer a pH between 5.0 and 7.0. There is some uncertainty as to whether a very low acidity inhibits directly, or whether poor growth results primarily from lack of the proper nutrients, especially calcium (lime). Undoubtedly, both pH and nutrient deficiencies are important, but pH as such seems to play a secondary role. More important is likely to be lack of... 

In studies with insoluble peat humic acids, Szalay and Szilagyi (1968) found that these organic substances retained Cu, Zn, Mn and Mo so tenaciously that the symptoms of deficiency of these nutrients in plants growing on drained moor, or peatland soils, could well be caused by such retention. In addition, Co was also so strongly held that plants grown on such soils supplied inadequate amounts to meet the needs of animals fed on the plant material. 

Peat was often used in earlier years as both a humus source and as a fertilizer, with the expectation that it would give results similar to those obtained with animal manures. Although increased yields were often obtained, and the physical condition of the soil was improved, it did not act like animal manures. This was due in part to deficiencies in mineral nutrients, but to a greater extent to the comparatively inert nature of the material. As already pointed out, manure is an active material and as it decomposes, nutrients are constantly released through biological action. In contrast, peat is so resistant to decomposition that much of the release of nutrients must be through exchange reactions and as chelated elements. 

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