Figure 1

samuel tetsopgang

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Rock fines from basalt, trachyte and volcanic pyroclastic materials in addition to limestone and gneiss were applied as fertilizers on tropical soils in several localities in west Cameroon. After harvesting, soil samples from controls and different treatments were collected and analyzed to assess the variation of textures and soil chemical compositions. Cabbage and potatoes as the test crops treated under fines from volcanic pyroclastic materials and basalt yielded the highest and lowest productivities, respectively. The initial loamy sand of the controls moves towards clay textures while initial clay textures remained unchanged, suggesting a loss of sand proportion and an increase in clay particles. For the pH, the slightly, moderately to strongly acidic properties of the local soils (4.8 ≤ pH ≤ 6.5) were shifted upwards in between the slightly acidic and the slightly alkaline soils (6.6 ≤ pH ≤ 7.2). However, a sample treated with fines from pyroclastic materials showed a remarkable pH increase from 5.9 to 6.9. The trends of fluctuation of organic carbon and organic matter are parallel with a general increase of these chemicals in soils. Na and K remains constant with a general increase trend for Mg and Ca in most treatments. The highest available phosphorus content of 96.0 ppm was found on the treatment with trachyte fines; followed by 50.9 and 51.5 ppm encountered on treatments with limestone and basalt fines, respectively. Then, this suggests a significant increase of phosphorus in soil after treatments with some rock fines such as trachyte, limestone, gneiss and basalt.