Trends in Fertilizers

J. Richard Adams.

Many changes have occurred in the manufacture and use of fertilizers since 1939. The annual use of fertilizers in the United States reached a peak of 23,412,608 tons in 1953, and declined the next 2 years, although more plant nutrients were applied.

Consumption almost tripled in the period 1939-1953, and increases were recorded each year except 1950. A slight decrease then was followed by further decreases in 1954 and 1955. (Unless otherwise noted, the years cited in this chapter are the 12 months ending on June 30.)

About two-thirds of all fertilizers used since 1939 have been mixed fertilizers. This ratio has remained relatively constant. The annual consumption of mixed fertilizers almost tripled between 1939 and 1953 and then declined the next 2 years.

Farmers in New England (Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut), Middle Atlantic States (New York, New Jersey, Pennsylvania, Delaware, District of Columbia, Maryland, and West Virginia), and South Atlantic States (Virginia, North Carolina, South Carolina, Georgia, and Florida) used more than half the mixed fertilizers consumed in 1945 and slightly less than half in 1955. The drop was due to a decrease in New England and to smaller percentage increases in the Atlantic Coast regions than in most of the other regions. Annual consumption in the North Central States (Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South Dakota, Nebraska, and Kansas) increased 156 percent. The combined increase in the Middle Atlantic and South Atlantic States was 40 percent.

The annual consumption of separate materials individual products that contain one or more plant nutrients and are applied directly to the soil reached 7,375,855 tons in 1955. Materials supplying one or more of the primary nutrients nitrogen (N), available phosphoric oxide P₂O₅, and potash (K₂O) accounted for approximately 90 percent of the separate materials. The remaining 1 percent included the secondary and trace nutrient materials. The use of the combined classes of separate materials increased more than 70 percent between 1945 and 1955. The greatest increase occurred in the West North Central and Western States (Montana, Idaho, Wyoming, Colorado, New Mexico, Arizona, Utah, Nevada, Washington, Oregon, and California), while their use in New England and the Middle Atlantic region decreased. Annual consumption in 1954 in the East North Central States (Ohio, Indiana, Illinois, Michigan, and Wisconsin) was more than double the consumption in 1945 and then declined sharply in 1955. Consumption more than doubled in the Pacific region (Washington, Oregon, and California) from 1945 to 1955 and was greater for a number of years than the consumption in any other region.

Use in the United States of separate materials containing primary nutrients increased continuously between 1945 and 1953, after which there was a small drop. Since 1951 the largest tonnage of these materials has been used in the Pacific region. The only other region that used more than a million tons in 1955 was the South Atlantic States. The New England and Middle Atlantic regions were the only ones to show a decrease between 1945 and 1955.

Data on the consumption of secondary nutrient materials are limited to materials supplying sulfur, calcium, or magnesium and refer only to products not containing primary nutrients. The data have been recorded separately only since 1945. (Liming materials, which supply both calcium and magnesium, are not included, as they are considered to be soil amendments rather than fertilizers.) Gypsum was included as a fertilizer material, although most of the tonnage was used to improve alkaline soils, not as a fertilizer. The same was true of sulfur and sulfuric acid.

Between 400,000 and 900,000 tons of gypsum, sulfur, and sulfuric acid are consumed annually. This accounts for almost 100 percent of the tonnage of secondary materials consumed in the United States. The major part of this tonnage is used in the Pacific region. A few thousand tons of magnesium carbonate (mostly in the Pacific region) and smaller amounts of magnesium sulfate (mostly in South Atlantic States) have been used as separate materials. Large additional amounts of these secondary nutrients are supplied in the primary nutrient materials and mixed fertilizers.

The annual consumption of materials supplying manganese, copper, boron, and zinc has never exceeded 25 thousand tons and generally amounts to less than 10 thousand tons. A few thousand tons of borax have been used annually in the United States, mostly in the Coastal States and East North Central States. The major quantities of iron and zinc are used in the Pacific region. The use of manganese is centered in the East North Central States; they and the South Atlantic and Pacific States use most of the copper salts.

THE TOTAL CONSUMPTION of the three primary nutrients almost quadrupled between 1939 and 1955. The increase was continuous for each of the nutrients except in 1954) when there was a slight drop in the consumption of available phosphoric oxide. The rates of increase in use of nitrogen and potash since 1950 were greater than for any previous period since 1939. They exceeded the rate of increase in the consumption of available phosphoric oxide, with a consequent narrowing of the N P₂O₅, K₂O ratio, which was 1.0 1.9 1.1 in 1950 and 1.0-1.2-1.0 in 1954.

Consumption increases of each of the three primary nutrients, in terms of weight, from 1939 to 1955 were surprisingly uniform. The percentage increases in nitrogen and potash were much greater than that of phosphoric oxide. Total consumption of nitrogen increased 410 percent; potash, 370; and phosphoric oxide, 192 percent.

Mixed fertilizers accounted for almost three-fourths of the increased tonnage of nutrients in 1955 relative to 1939. In that period, a drop occurred in the proportion of nitrogen in mixed fertilizers relative to the total consumption in the United States, and the relative proportion of available phosphoric oxide and potash increased.

REGIONAL TRENDS in the use of primary nutrients exhibit interesting variations. The total consumption more than doubled between 1945 and 1955, brought about by increases in the use of each of the three primary nutrients. The rate of increase in consumption of nitrogen was more than triple that of available phosphoric oxide, while potash consumption increased a little more than twice as fast as the use of available phosphoric oxide.

Farmers in the East North Central region accounted for almost a third of the increased consumption of nutrients in the United States. They used more nutrients in 1953, 1954, and 1955 than those in the South Atlantic region, the leaders in previous years.

Mixtures supplied more than three-fourths of the increased nutrient consumption in the East North Central region, and only a little less than 90 percent in the South Atlantic region. Separate materials supplied more than half the increases in the West South Central, Mountain, and Pacific regions. The Middle Atlantic region showed a decrease over the 11-year period in the amount of nutrients distributed as separate materials, but this was more than compensated for by the increased quantity supplied by mixed fertilizers. There was a lower nutrient consumption in New England since the increased consumption of nutrients in mixed fertilizers was not sufficient to offset the decreased consumption of nutrients in the separate materials.

The South Atlantic region used almost 50 percent more nitrogen in 1955 than either the West North Central or East North Central regions. Consumption increased more than 900 percent since 1945 in the North Central States and somewhat more than 70 percent in the South Atlantic region. All other regions used greater amounts of nitrogen in 1955 than in 1945. The consumption in the Territories fell off some after 1951, but increased about 80 percent in the 11 years.

As with nitrogen, the South Atlantic States annually consumed a greater tonnage of available phosphoric oxide than an), other region until 1953, when it was surpassed by the East North Central region. Consumption of available phosphoric oxide has increased more rapidly in the North Central States since 1945 than in any other region. Since 1951, the use of available phosphoric oxide fell off in all regions except the North Central, Mountain, and Pacific. The decrease in New England was sufficient to reduce consumption in 1955 below 1945.

The East North Central and South Atlantic regions consumed almost 60 percent of all the potash used annually in the United States in 1955 and at least two to three times as much as was used in any of the other regions. Annual consumption in the South Atlantic region was greater than in any other region until 1952, when it was surpassed by consumption in the East North Central region. Annual consumption in the East North Central region more than doubled in the 5-year period after 1950.