Experiment Station Record, Volume 92, January-June, 1945 Page: 22
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22 EXPERIMENT STATION RECORD [Vol. 92
as fine clays, fixed about one half as much P04. The amount of P04 fixed by clay
was influenced less by the type of clay mineral than by the content and activity of the
free iron and aluminum oxides.
Phosphate studies.-II, Chemical availability of phosphorus in various
organic and inorganic carriers, as indicated by the Neubauer test, V. E.
SPENCER and F. M. WILLHITE. (Nev. Expt. Sta.). (Soil Sci., 58 (1944), No. 2,
pp. 151-161, illus. 1).-"Chemical availability" is adopted as a substitute term for
"availability," to exclude the "positional availability" found by the authors of the
preceding paper (E. S. R., 72, p. 452).
Neubauer tests (E. S. R., 53, p. 319) of one soil treated with 4 organic and 11
inorganic phosphates, and of several soils each treated with 1 inorganic and 1 organic
phosphate, showed the chemical availability of the phosphorus in 9 of the 11 organic
carriers to be quite as high as that in any of the inorganic carriers.
Fused tricalcium phosphate: Relation of degree of defluorination to fertilizer
value of quenched fusions of rock phosphate, W. H. MACINTIRE, S. H. WINTERBERG,
B. W. HATCHER, and G. PALMER. (Tenn. Expt. Sta.). (Soil Sci., 57 (1944),
No. 6, pp. 425-442, illus. 8).--The P205 availability of quenched fusions of brown
rock phosphate was determined as solubility in ammonium citrate and in carbonated
water by Neubauer tests and by crop response and P205 recovery 'in pot cultures.
An 80-percent removal of initial fluorine content appeared necessary to a satisfactory
increase in fertilizer value. X-ray diffraction patterns demonstrated that a
substantially defluorinated and quenched fusion of rock phosphate is composed
chiefly of the readily available alpha form of tricalcium phosphate. The findings
indicated that a quenched rock phosphate fusion carrying not more than 0.4 percent
fluorine and of 100-mesh fineness is satisfactory for incorporation with neutral soils,
those mildly acidic, and those treated with limestone or dolomite sufficient for the
grdwing of red clover. Substantially defluorinated and quenched fusions finer than
50-mesh are believed to be also suitable for such use.
The potassium-supplying powers of 20 New Jersey soils, F. E. BEAR, A. L.
PRINCE, and J. L. MALCOLM. (N. J. Expt. Stas.). (Soil Sci., 58 (1944), No. 2,
pp. 139-149)--The capacity of the A horizons of 20 important New Jersey soils to
yield their reserve K to the alfalfa plant was investigated. The alfalfa was grown
through seven successive crops under greenhouse conditions in which the experimentally
designed limiting factor, in the first series of pots, was a lack of K. This
deficiency was partly or totally eliminated in the second and third series of pots by
applications of KC1 equivalent to 100 and 200 lb. K20, respectively, per acre. The
total and exchange K were determined on the soils as they came from the field and
after the seven crops of alfalfa had been harvested. Potassium was determined in
the crops as harvested and in the roots at the end of the test. The Ca and Mg contents
of the soil exchange-complex and of the harvested crops were also determined.
From these data, calculations of the amounts of K released by the several soils during
the course of the experiment were made.
The data verified the previously known fact that the most reliable index to the
capacity of a soil to supply K to the crop is not its total content of the element,
but the quantity that exists in the exchange form. It was shown, however, that the
soils studied vary greatly in their capacity to renew the exchange supplies from
their reserves of K. Some soils, of which Chester loam was the best example
studied, continued to release much K throughout the period of the test. Other soils,
of which Papakating stony loam was outstanding, were in greater need of fertilizer
K than would have been expected from a knowledge either of their total or of their
exchange supplies of the element. Some factor or factors other than a lack of K
limited the growth of alfalfa on 15 of the 20 soils. The yields of the lowest-producing
soils could not be raised to 50 percent of those harvested from the most productive,
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U.S. Department of Agriculture. Agricultural Research Administration. Office of Experiment Stations. Experiment Station Record, Volume 92, January-June, 1945, book, 1947; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5064/m1/35/: accessed July 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.