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Yield Response in Experiments With Phosphorus Fertilizers in Relation to: I. Meaningful Differences Among Sources on Acid Soils of the Southeastern States
Author(s) -
Terman G. L.
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/sssaj1960.03615995002400050016x
Subject(s) - phosphorus , limiting , yield (engineering) , agronomy , forage , soil water , mathematics , crop , grain yield , productivity , fertilizer , environmental science , zoology , chemistry , soil science , biology , materials science , mechanical engineering , macroeconomics , organic chemistry , economics , engineering , metallurgy
Yield results from 174 phosphorus rate and source experiments conducted in the Southeast, each including a response curve with CSP (concentrated superphosphate), were examined in relation to the nature of the response and experimental error. In only a few of the tests with various crops showing yield response to P was it possible at the 5% probability level to measure differences among citrate‐ and watersoluble sources which were from one‐half to twice as effective as CSP. Under the conditions where grown, cotton was the poorest crop for this purpose, corn and small grain grown for grain were intermediate, and annual forage was best. The possibility of measuring differences among sources decreased with increase in soil P level and with increase in the rate of application of P at which the comparison was made. Estimated limiting yields of cotton on low‐yielding sites without applied P were lower than most of the check yields at sites of higher productivity. A similar, but less pronounced situation prevailed with corn, but not with small grain. Deficiency of water is thought to be the chief factor limiting yields of summer‐grown cotton and corn at all yield levels, but not of winter‐grown small grain.