Phosphorus Availability in a Calcareous Soil After High Loading Rates of Animal Manure1
- B. D. Meek,
- L. E. Graham,
- T. J. Donovan and
- K. S. Mayberry2
The fixing of phosphorus (P) added to calcareous soils is rapid but can be reduced by applying organic sources. The objectives of this study were to measure in the field the residual NaHCO3-extractable P resulting from manure applications at high rates and to contrast the NaHCO3-extractable P levels for manure vs. inorganic P fertilizers.
When inorganic P was applied at 490 kg/ha for each of 2 years the NaHCO3-extractable P was increased from 16 to 31 ppm at the 0- to 30-cm depth. The application of 98 kg/ha of P as triple superphosphate each of 2 years applied just before planting lettuce (September-October) was as effective for increasing NaHCO3-extractable P during the lettuce-growing season (November 1976) as applying 490 kg/ha of P in May or June each of 2 years.
High rates of P (5,344 kg/ha) applied from manure sources (treatment 720E) resulted in high levels of NaHCO3-extractable P up to 377 ppm. Total application of more than 360 metric tons/ha of manure (2,672 kg P/ha) resulted in movement of P to the 30- to 60-cm depth. The increased level of NaHCO3-extractable P from a manure application (treatment 360B) was still evident in the 0- to 30-cm depth 6 years after manure application had ceased.
The application of 392 kg P/ha as triple superphosphate for each of 2 years increased the NaHCO3-extractable P over the check by 11 ppm (November 1976). In contrast, the application of 334 kg P/ha from applied manure (treatment 180B) each of 2 years increased the NaHCO3-extractable P over the check (after harvest in 1972) by 100 ppm.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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