Premium
Assessing Phosphorus Fertilizer Needs Based on Intensity‐Capacity Relationships
Author(s) -
Lee Yong S.,
Bartlett R. J.
Publication year - 1977
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1977.03615995004100040018x
Subject(s) - fertilizer , phosphorus , soil water , chemistry , soil ph , incubation , intensity (physics) , sorption , zoology , mathematics , agronomy , soil science , environmental science , adsorption , biochemistry , organic chemistry , quantum mechanics , biology , physics
Phosphorus in a pH 4.8 NH 4 OAc soil extract, through crop response correlation work, may indicate the degree to which a level of P in a given soil is optimum. But, being an intensity measurement, this NH 4 OAc‐P value does not indicate the amount of P fertilizer needed to bring a soil, which has a particular P sorption capacity, to its optimum level. The relationship between added P and the square root of the NH 4 OAc‐P, measured after incubation of a given acid or limed soil, was a straight line with a characteristic slope for that soil. The value of this slope, termed the Phosphorus Fertilizer Index (PFI), showed a high correlation with the amount of Al extracted by pH 4.8 NH 4 OAc ( r 2 =0.94). Inclusion of soil chemical characteristics other than Al in the calculation did not improve the P intensity‐capacity relationships significantly. The usefulness of these relationships in determining P fertilizer needs was verified in an incubation study with 50 acid Ap horizon samples of Vermont soils. This study showed excellent correlations ( r 2 =0.90 and 0.92 for unlimed and limed soils, respectively) between NH 4 OAc‐P measured in the soils after fertilizer addition and the NH 4 OAc‐P calculated from the PFI slopes estimated from the Al measured in the same NH 4 OAc extract.