During the 50s and 60s, the use of commercial fertilizers continued the sharp rise of 4½ per cent per year that began in the 40s before leveling off in the 70s and 80s. Much of the impetus for the rise was that prices declined as producers figured out ways to make anhydrous ammonia fertilizer cheaply from natural gas.
As the chart above shows, between 1950 and 1970s, fertilizer use doubled from less than 20 million tons to 40 million tons. On the price side of the equation, the cost of anhydrous fell by one-half between 1960 and 1970 alone. As a result, yields of most crops shot up. In addition to the impact that fertilizer had on its own, new hybrid varieties were introduced that responded even more to a steady supply of nutrients and irrigation water.
Even by 1959, almost 75 per cent of the farms that reported harvesting crops used some form of fertilizer. That meant that fertilizer was applied to over 133 million acres, or 46.5 per cent of the total cropland.
By 1969, the average farmer was spending $1,131 per farm for fertilizer – at a time when the average value of farm products sold per farm was $16,705. Fertilizer was a significant expense, but studies after the war had shown that every dollar spent on fertilizer or pesticides generated $3 to $5 more in increased crop yields. So most farmers decided the expense was worth the return.
More fertilizer was used on corn than on any other crop. In 1959, more than one-third of all fertilizer was used on corn. Wheat was the second most heavily fertilized crop, at least in terms of the number of acres fertilized – 17.5 million acres. Wheat farmers used less per acre than cotton and hay growers. Those two crops were number three and four in the list of crop land under fertilizers.
In the South, nearly all of the cotton grown was fertilized. Almost all of the tobacco grown was fertilized in 1959, and the same was true for sugar beets. Many beet fields were heavily fertilized, up to a rate of 450 pounds per acre. By contrast, corn at that time was often fertilized at a rate of 150 to 300 pounds per acre.
But there were some farmers who realize now that they and their neighbors were using too much. And what a plant can’t use in its growth cycle will eventually percolate down to the groundwater.
Virgil Obermier (left) admits that he may have used too much fertilizer when it first came out. “We overdone it,” he says. “I had a neighbor that said, ‘Well, 150 pounds at six-cents a pound, why, 300 pounds will do it!'” Virgil notes that the plants will only use about half of that nitrogen. “Eventually, we’re going to have nitrogen in our water.”
Don Reeves (right) says a soil profile study in Hamilton County, Nebraska, showed there was enough nitrogen already in the soil to support corn for eight years – “But it was beyond the reach of the roots, but it hadn’t yet gotten to groundwater. So, we’ve got a 100 year problem in the Platte [River] Valley.”
Yet Paul Underwood remembers how quickly corn yields shot up with fertilizer. Before fertilizers were in general use, a good yield was “30 to 40 bushel [per acre] corn,” he says. “All of a sudden now, we’re
going to get 80 to 90 bushel corn. I mean, that was a great!” That’s one of the reasons that Paul got into the fertilizer business. And it’s been a good business.