Phosphorus Supplying Capacities of Previously Heavily Fertilized Soils1
- Roberto Novais and
- E. J. Kamprath2
Four Coastal Plain soils and one Piedmont soil heavily fertilized in the past were intensively cropped in greenhouse pots to determine changes in extractable soil P as measured by North Carolina, Bray I and Olsen extractants. Slopes relating changes in extractable P with P removed by cropping were very similar for the three sandy soils. Changes in extractable P with the North Carolina and Bray I extractants were correlated with P buffer capacity, % clay, and soil surface area. The principal source of P removed by cropping was NH4F-P in sandy Coastal Plain soils; NH4F-P and NaOH-P supplied equal amounts in the clayey Piedmont soil. Sandy Coastal Plain soils which originally contained more than 74 ppm North Carolina extractable P and 71 ppm Bray I extractable P supplied 82 to 108 kg P/ha to nine crops of pearl millet (Pennisetum americanum, cv. Gahi-1).Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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