Experiment Station Record, Volume 45, July-December, 1921 Page: 25
xxvii, 995 p. ; 24 cm.View a full description of this book.
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26 EXPERIMENT STATION RECORD. [Vol. 45
It was found that soil composts with sulphur added developed much acidity
in 32 weeks, which was greater where sulphur was used alone than where
rock phosphate also was added. Dissociated acid formed but a small portion
of the total acid. Composts of sulphur with horse manure showed appreciable
increases in acidity but no increase in citrate-soluble phosphoric acid after 15
weeks.
Sulphur decreased the loss of organic matter in manure by fermentation.
Increased bacterial counts in these composts were maintained to the conclusion
of 12.5 weeks. Acidity doubled in the rock phosphate and sulphur compost over
this period, but was unchanged after 4.5 weeks. The variations of watersoluble
sulphate were in the same direction as those of acidity, increasing
where sulphur was added and decreasing in the other cases. Citrate-soluble
phosphoric acid approximately doubled where sulphur was added, the percentage
being based upon the common basis of original dry matter of the
composts. In the other cases the percentage of this constituent decreased approximately
one-half.
Yields of oats from soil cultures to which these composts were applied
agreed generally with the results of analysis of the latter, producing the
greatest yields where sulphur had been applied. On sandy loam the yield of
seed where sulphur compost was applied was as great as where the corresponding
treatment included rock phosphate. Increased yields of oats were obtained
also from the application of rock phosphate and sulphur with fermented
manure.
Similar composts which fermented 18.5 weeks showed 60 per cent greater
availability of phosphoric acid (solubility in ammonium-citrate solution) by
the addition of sulphur to rock phosphate. When aerated by weekly mixing
the corresponding increase of available phosphoric acid was 90 per cent,
although the total acidity was decreased thereby. The total acidity developed
in the complete compost was nearly as great as that resulting from an equivalent
addition of acid phosphate to the fermented manure. In this experiment the
use of sulphur alone did not increase the proportion of citrate-soluble phosphoric
acid in the manure. Application of these fermented manures and composts
to sand cultures of barley led to equal yields from the rock phosphate and
sulphur compost and a corresponding portion of fermented manure supplemented
by acid phosphate. These yields were not superior to those from
sulphur compost and manure reinforced by rock phosphate and sulphur.
The process of sulfofication was inactive after 12 weeks, but became very
active after 18 weeks.
In greenhouse trials on silt loam and sandy loam with clover and Cruciferae,
sulphur increased growth on the former soil, 100 lbs. per acre being as effective
as more. Barley on field plats of sandy silt loam apparently in need of lime
produced increased yields of seed by the application of sulphur. Sulphur alone
was as effective as its combinations with marl and rock phosphate, and 100 lbs.
of sulphur per acre was as effective as 50 or 300 lbs. Calcium sulphate produced
better yields of oats upon silt loam than equivalent amounts of sodium
sulphate or sulphur when these supplemented the usual complete fertilizer in
greenhouse cultures. Liming depressed the efficiency of calcium sulphate under
these conditions, and 100 lbs. of elemental sulphur was more effective than
either one-third or three times as much. Benefits from elemental sulphur were
not apparent when it was superimposed upon the sulphates for application.
" It appears probable that sulphur functions as a fertilizer both by oxidation
to the nutrient SOs and by producing, through oxidation, an acid condition
favorable to the production of available P206. These processes occur in composts
of sulphur and rock phosphate. They also, doubtless, continue when the
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United States. Office of Experiment Stations. Experiment Station Record, Volume 45, July-December, 1921, book, 1921; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5009/m1/52/: accessed March 28, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.