Experiment Station Record, Volume 94, January-June, 1946 Page: 24
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24 EXPERIMENT STATION RECORD [Vol. 94
accomplished. The influence of NH, on water penetration in artificially prepared
soil columns varies so greatly among different soils that no generalizations could
Effects of several nitrogenous fertilizers and soil amendments on the physical
and chemical properties of an irrigated soil, D. G. ALDRICH, E. R. PARKER, and
H. D. CHAPMAN. (Calif. Citrus Expt. Sta.). (Soil Sci., 59 (1945), No. 4, pp.
299-312).--Marked physical and chemical changes are shown to have occurred in
an irrigated soil in plots of a long-term fertilizer experiment after 16 yr. of treatment,
the last 4 of which involved the application of much fertilizer. The rate of water
percolation through soil treated with sodium nitrate or with ammonium sulfate was
markedly less than that through soil treated with calcium nitrate. It was found
that if gypsum was applied with the sodium nitrate, and limestone with the ammonium
sulfate, percolation was not so poor as without these, but it was still not
so good as in the calcium nitrate plot. Urea appeared to have decreased permeability
somewhat as compared with that in the calcium nitrate plot, and manure appeared
to have decreased it still more than urea, though the manure plots seemed to be in
excellent physical condition as indicated by aggregate and macropore-space analyses.
Laboratory measurements of structural breakdown by means of macropore-space
analyses produced data from all treatments, with the exception of that of the manure
plots, which were well correlated with percolation data. Chemical data obtained
on the various plots suggested that the poor physical condition of the sodium nitrate
plots is due to an unfavorable calcium-sodium.ratio. The poor physical condition
of the ammonium sulfate plots appeared to be due to the dispersing action of the
ammonium ion, which builds up in the exchange complex as a result of the reduced
ability of soil organisms to nitrify the ammonium at the low pH produced by the
continued application of ammonium sulfate. The addition of gypsum with the
sodium nitrate maintains a calcium-sodium ratio which is conducive to structural
stability. The addition of limestone with the ammonium sulfate neutralizes the
acidity produced by the application of this fertilizer; soil organisms are then able
to nitrify the sorbed ammonium and thus prevent its build-up in the exchange complex
in sufficient quantities to cause structural deterioration.
Greenhouse and field tests comparing colloidal phosphate, phosphate rock,
and superphosphate as sources of phosphorus for various crop plants, B. E.
BROWN and K. D. JAcoB. (U. S. D. A.). (Amer. Fert., 101 (1944), No. 13, pp.
7-10. 22-30, ilhis. 1).-Results of greenhouse and field experiments are presented
on the comparative effectiveness of colloidal phosphate; Tennessee brown-rock phosphate,
and ordinary superphosphate as sources of phosphorus for various crop
plants. On Norfolk loamy fine sand, indicator crops, including German, Hungarian,
and Japanese millets, corn, soybeans, and wheat, responded much better to superphosphate
treatment. Swiss chard responded equally well to the three sources.
When German millet was grown on four widely different soils the yields were
greater in every case with the superphosphate treatment. Potato, sweetpotato, and
tomato yields in Virginia field experiments were greater when superphosphate was
used. While the use of less available raw phosphates may be justified under appropriate
soil conditions, especially in the growing of long-season or perennial crops,
it is considered to be more likely that an available type of phosphate such as superphosphate,
double superphosphate, or ammonium phosphate will provide greater
yields and corresponding profits than the slowly available phosphates, particularly in
the case of short-season crops.
Absorption by plants of phosphorus from a clay-water system: Methods and
ensuing observations, L. A. DEAN and E. J. RUBINS. (U. S. D. A.). (Soil. Sci.,
59 (1945), No. 6, pp. 437-448, illus. 2);-Standard experimental plants, grown under
artificial lighting, were studied to determine their absorption of phosphorus from
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U.S. Department of Agriculture. Agricultural Research Administration. Office of Experiment Stations. Experiment Station Record, Volume 94, January-June, 1946, book, 1947; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5062/m1/35/: accessed July 19, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.