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Fertilizer Evaluation: IV. Use of P32‐Labeled Fertilizers
Author(s) -
Bouldin D. R.,
Black C. A.
Publication year - 1960
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/sssaj1960.03615995002400060022x
Subject(s) - phosphorus , fertilizer , agronomy , human fertilization , yield (engineering) , chemistry , phosphate , crop yield , soil water , environmental science , soil science , biology , materials science , organic chemistry , metallurgy
Two different measures of the yield of fertilizer phosphorus were defined as follows: ( 1 ) The net increase in yield of phosphorus from fertilization is equal to the yield of phosphorus in the phosphate‐fertilized crop minus the yield of phosphorus in the control. ( 2 ) The yield of true fertilizer phosphorus is the yield of the atoms of phosphorus actually applied in the fertilizer and is equal to the product of ( a ) the yield of phosphorus in the phosphate‐fertilized crop and ( b ) the ratio of the specific activity of phosphorus in the crop to that in the fertilizer. Measurements of these two kinds of yields of fertilizer phosphorus were made on a crop grown in greenhouse cultures on 6 soils with 4 particle sizes of P 32 ‐tagged monobasic sodium phosphate applied at 4 rates. The net increases in yield of phosphorus from fertilization exceeded the yields of true fertilizer phosphorus, and the difference between these two values increased with the quantity of labile phosphorus in the soil. These observations can be explained on the basis of ( a ) enhanced growth of roots and absorption of soil phosphorus in the nonfertilizer‐affected soil in the presence of fertilizer, ( b ) enhanced absorption of soil phosphorus in the fertilizer‐affected soil, or ( c ) a combination of ( a ) and ( b ), but no evidence permitting a choice of hypotheses was obtained.