Relationship between The Amount of Available P and Manure Application by Calcareous Soils

The objectives of this study were to measure the residual NaHCO3-extractable P resulting from manure applications at high rates and to contrast the NaHCO3exractable P levels for manure vs inorganic P fertilizers.                  When inorganic P was applied annually at a rate of 206 kg/Feddan at the (0 to 30 cm) depth of 2 years, the NaHCO3-extractable P was increased from 17 to 32 ppm  in soil . The application of 42 kg/Feddan annually of P as triple superphosphate  of 2 years  before planting spinach (September-October) was effective for increasing NaHCO3 extractable P during the spinach-growing season (November, 2011) as applying 206 kg/Feddan of P in May or June each of 2 years.  High rates of P (2245 kg/Feddan) applied from manure  resulted in high levels of NaHCO3,-extractable P up to 378 ppm. Total application of more than 152 tons/Feddan of manure (1123 kg P/Feddan) resulted in movement of  P in soil (30 to 60 cm). The increased level of NaHCO3,- Extractable P from a manure application (treatment  152 B) was still evident in the 0 to 30 cm depth , 6 years after manure application had ceased.  The application of 165 kg P/Feddan as triple superphosphate for each of 2 years increased the NaHCO3extractabl P over the control by 12 ppm (November, 2011).In comparing, the application of 141 kg P/Feddan from applied manure each of 2 years increased the NaHCO3-extractable P over the control (after harvest in 2007) by 101 ppm.