Some Effects of
Spray Disposal of Spent Sulphite Liquor
on Soil Mold Populations
WILLIAM BRIDGE COOKE
In Charge Fungus Studies
Robert A. Taft Sanitary Engineering Center
Bureau of State Services
Public Health Service
U. S. Department of Health, Education, and Welfare
Cincinnati, Ohio
INTRODUCTION
The use of additives for improvement of solids is as old-as our knowledge
of agricultural pursuits. Early farmers knew that if crop residues were returned
to the soil the succeeding crop was improved. The deposit of an annual increment of silt on the floodplain of the Nile was welcomed by the early
Egyptian farmer because it gave his next crop a stimulus for growth. The addition of barnyard manure to the soil of a field planted to one crop year after
year helped maintain the yield of that crop. It has been thought that as a
means of disposal a similar use might be made of other wastes, such as waste
sulphite liquor.
Within the last 50 years we have found that the principal reason for the
increased activity in soils following the application of barnyard manures and
the plowing underof last year's stubble or this year's green cover or green manure crop, is related to the activity of countless numbers of microorganisms.
Some bacteria and fungi will attack the sugars which are released by mechanical breakdown of the plant tissues, others will attack the cutin on the leaf or
stem surface, others will attack constituents of protoplasm, others will attack
the cellulose, and finally a few will attack the lignin. The net result of such
attacks will be the reduction of these applied or plowed-in residues, the release of complex carbonaceous, nitrogenous and other compounds, their reduction to simpler compounds, mineralization, and greater availability for
use by the next crop plant to be applied to the particular field.
In a somewhat different way, yet not too dissimilar, the microorganisms
of an area will react on any material applied to a particular soil. Thus, when
spent sulfite liquor is applied to a soil, given optimum conditions of growth
for the population of microorganisms which may be present, those substances
which are present in the liquor and which are available to the organisms will
be attacked, reduced, made usable by other organisms, and a treatment
process will be effected.
AREA OF STUDY AND BACKGROUND OF PROBLEM
At the 13th Purdue Industrial Waste Conference, R. M. Billings (2) described the method of disposal of spent sulphite liquor in excess of that which
can be safely absorbed by the Menominee River at Niagara, Wisconsin. Briefly , the technique is to pipe the spent liquor across the river to the Michigan
side where it is stored in a stainless steel tank until hauled away in a tank
truck to a 40-acre field 1.5 miles distant where thtough a special piece of
equipment it is atomized and sprayed onto the soil at the rate of one lb of
solids per square yard per 24 hr period. Amounts of spent sulphite liquor disposed of in this way have been as follows:
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