Phosphorus fractions in an acid soil continuously fertilized with mineral and organic fertilizers
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- Verma, S., Subehia, S. & Sharma, S. Biol Fertil Soils (2005) 41: 295. doi:10.1007/s00374-004-0810-y
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The effect of different treatments on the fate of applied P was investigated in a long-term field experiment started in 1972–1973 following a maize–wheat sequence. The soil samples were collected after 29 years of continuous addition of mineral fertilizers and amendments such as farmyard manure (FYM) and lime. The total P content of all the treatments increased compared to the original soil; NaOH-inorganic P (Pi) (NaOH-Pi) representing Fe and Al-bound P was the dominant Pi fraction. At the beginning of the experiment (1972–1973), the various P pools could be quantitatively ranked in the following order: residual P>NaOH-organic P (Po)>NaOH-Pi>NaHCO3-Po>NaHCO3-Pi>HCl-P>H2O-P. As a result of continued P fertilization and cropping, the order changed as follows: residual P>NaOH-Pi>NaOH-Po>NaHCO3-Pi>NaHCO3-Po>HCl-P>H2O-P. Compared to the imbalanced mineral fertilizer application, the balanced as well as integrated application of nutrients resulted in significantly lower P adsorption capacity of soils. The Olsen extractable-P fraction (plant-available P) increased from about 12 mg kg−1 soil in 1972 to about 81 mg kg−1 soil in the treatments receiving P for the last 29 years.