Forest soils, organic matter content

Farmers reported that yields following compost application increased up to 4000 kg ha of maize and more importantly, that crops are less prone to damage from dry spells because of higher soil organic matter content. Some farmers even experiment with the combination of compost and fertiliser. They achieve yields of up to 5000 kg ha One particular farmer planted trees around his 8 hectare farm and allowed 2.8 hectares to develop into forest. The leaves of the fence and the... 

Interaction of forest soil organic matter with abundant mineral content... 

On the basis of this comparison study, at present, it is still difficult to adopt a universal selective sequential dissolution procedure, which may be used everywhere and be suitable for all soils with diversified physical, chemical and mineralogical properties. The application of the SSD procedure must consider individual soil characteristics, such as soil type and properties. The two typical SSD procedures were developed to address soils formed in two climates. The Rehovot procedure was developed to be suitable for the calcareous soils in arid and semi-arid zone soils, whereas the Bonn procedure was created to primarily handle the acid and neutral soils in humid zones. In general, the Bonn procedure appears to be unsuited for calcareous soils in arid and semi-arid zones. The Rehovot procedure has limitations in handling acid and neutral soils, especially forest soils with higher content of organic matter. 

Egli, M., Fitze, P., and Oswald, M., Changes in heavy metal contents in an acidic forest soil affected by depletion of soil organic matter within the time span 1969-93, Environ. Pollut., 105, 367, 1999. 

Potassium is bound rapidly in silicates and adsorbed in day minerals, albeit very loosely in soil organic matter. Most agricultural soils continue to supply potassium for a long time (> 20 years). Potassium appears to be plentiful in most forest soils, but exceptions are add glacial outwash sands, soils vdth a low clay content and skeletal soils, for example, derived from quartzit. Subsoils are almost always low in exchangeable potassium. 

The organic matter content of the lateritic-like tropical soils, especially the forested ones, is low primarily because of the high temperatures and rainfall, abundant plant and animal life in the soil, and the scarcity of inorganic colloids with which the organic matter might combine. Clays of the montmorillonite and illite types that are known to hold much humus are nearly absent from many of these soils. A considerable mat of organic matter does accumulate in time on the soil surface but no great portion of it accumulates in the mineral soil. It disappears quickly from the surface when the trees are removed. 

The content of heavy metals in Steppe soils is tightly connected with their contents in geological rocks. In formation of soil exposure pathways in Desert ecosystems, water-soluble forms of these metals play the most important role. We can see an analogy between the increasing content of elements in soil dead organic matter as a function of decreasing water excess in Forest ecosystems and the increasing content of water-soluble species of chemical elements in the soils of Dry Steppe and Desert ecosystems as a function of enhanced aridity. The accumulation of water-soluble species occurs in the upper horizon for almost all elements, with exception of strontium. The main factor responsible for the accumulation of water-soluble forms is connected with evapotranspiration. 

Urease activity in soils has been found to reflect the bacterial count and content of organic matter. The urease isolated from an Australian forest soil (87) was crystallized and found to have a specific activity of 75 Sumner units (S.U.) per mg. The molecular weight species were estimated (sedimentation velocity) to be 42, 131, and 217 X 103. That urease activity persists in soils is shown by the finding that enzymic activities, including urease, could be demonstrated in soil samples over 8000 years old (88). 

The effects of five phenolic compounds, catechol, protocatechuic, p-coumaric, p-hydroxybenzoic, ferulic acids and their mixture were studied on pH, organic matter, organic-nitrogen, total phenolic content and certain inorganic ions of forest mineral soils (Ae and B horizons). The A- and B-horizon soils, were amended with 104 M concentration of each phenolic compound and their mixture. In general, soil properties were affected by phenolics amendement. However, soils amended with catechol did not influence any of the soil characteristics. Contents of organic matter, nitrogen and phosphate were lower in soils amended with different phenolic compounds compared to the unamended control soil (Inderjit and Mallik, 1997). 

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