engleski

The effectiveness of phosphate and liming on acidic soils

In acid soils, availability of certain nutrients like aluminum, iron and manganese increases due to higher dissolution and at times becomes toxic. In strongly acidic conditions, phosphorus reacts with active iron and aluminum forming insoluble phosphates. More than 80 percent of applied phosphate was converted into unavailable forms in acid soils within very short periods. Under such conditions, calcium and magnesium supply is reduced and plant growth suffers. In addition to these, other beneficial nutrients such as nitrogen, phosphorus, and sulfur are also in deficient concentration. To meet the calcium demands, as well as to create favorable conditions for better uptake of other essential nutrients, liming is an important management practice in acid soils. The overall effects of lime on soils include, among others, increased soil pH, Ca and Mg saturation, neutralization of toxic concentrations of aluminum, increase in pH dependent CEC resulting in absorption and hydrolysis of Ca2+ (Mg2+), increase in P availability and improved nutrient uptake by plants. Liming also improves microbiological activities of acid soils, which in turn can increase di-nitrogen fixation and liberate nitrogen (N) from incorporated organic materials. However, over-liming may reduce crop yields, due to lime induced P and micronutrient deficiencies. Therefore, crop yield responses to lime and P are often interdependent. Under these situations, an appropriate combination of lime and P is an important strategy for improving crops growth in highly weathered acid soil.

liming ; phosphorus ; microbiological activity ; MAP

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