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Illinois Fertilizer Conference Proceedings
January 23-24, 1990

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Soil Fertility and Fertilizers -- A 25-Year Perspective

L.F. Welch1
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Solomon must not have been thinking about soil fertility and fertilizer in Illinois during .the last half of the 20th century when he wrote, "There is no new thing under the sun."

Much progress has been made in identifying and correcting nutrient deficiencies in Illinois soils during the hastily-passed, recent 25 years. Technology has allowed the development of relatively inexpensive fertilizer materials. Use of these materials has resulted in Illinois soils being a better nutrient-supplying medium than at any previous time. Increased crop yields bear witness to improvements made from 1964. (Table 1).

Increasing rates of fertilizer per acre added for our crops have allowed higher yields without jeopardizing the future productivity of the soils. (Table 2). The tonnages of nutrients used in Illinois (Table 3) place our state as the greatest user of fertilizer of any state.

CHANGES IN FERTILIZERS
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Although the price of fertilizer has increased from 1964 to 1988 (Table 4), its relative low price has made its use highly profitable for producers. Shifts in the importance of fertilizer materials and grades are illustrated by the data in Tables 5 and 6. Anhydrous ammonia was the largest supplier of nitrogen in 1964 and represented an even larger portion of the total in 1988. Nitrogen solutions and diammonium phosphate provide a considerably larger portion of the total nitrogen used in 1988 compared to 1964. Diammonium phosphate supplied about 68 percent of the total phosphorous used in 1988 versus only 4 percent of the total in 1964.

PEOPLE AND ORGANIZATIONS
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I have been privileged to have been able to spend most of my career in a state where crop production and fertilizer are so important. Working in a state that uses about 10 percent of all the fertilizer in the United States and grows 17 to 18 percent of the nation's corn and soybeans does have advantages. Many challenges and opportunities have come my way simply because I have been located at a premier university in a state where crop production has so much recognition.

I began my tenure in Illinois working alongside Dr. Sam Aldrich, the best known and most capable soil fertility extension specialist in the United States at the time. I finish my career working alongside Dr. Bob Hoeft, the currently acknowledged No. l soil fertility specialist. There are many others in the U of I agronomy department I have learned are "giants" in my professions, and their names are too numerous to mention.

Although Illinois has been blessed with soils and climate highly favorable for crop production, it is the skills and motivation of the people who grow the crops, and those who provide services and products to them, that allow our natural resources to be utilized.

I gave my first talk to this group on Jan. 22, 1965, at the annual meeting held at the Moose Club in Champaign, 111. Five of the 16 speakers on the program that year are still active. The 11 others are retired or deceased. The group was known as the Illinois Fertilizer Industry Association. My last talk to this group is given at the Peoria Convention Center before the Illinois Fertilizer and Chemical Association. Your organization has been outstanding in providing services and information to growers, fertilizer-industry personnel, elected decision-making bodies and the general public. I have been fortunate to have been able to work alongside you as we moved toward many common goals.

A BACKWARD GLIMPSE
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Some of the things I considered important during the past quarter of a century is expressed in the titles of the 29 talks and papers given at the fertilizer conferences. Titles are given in the next section. A few points made in the original talks are summarized below.

The "So What?" title I gave as my first talk in 1965 was not very descriptive. I discussed that the researcher who explains how his findings may be utilized in crop production is appreciated more than just a data presenter.

New research on experimental fields was talked about in 1966. The multi-rates fertilizer studies were aimed chiefly at determining the most profitable rates of fertilizer for corn, soybeans and wheat. Timing of nitrogen application and corn populations were other important variables included in our research. Results of these studies have provided the basis for many of the fertilizer suggestions given in the Agronomy Handbook.

Phosphorus appeared in each of the titles over the four-year span 1966-69. The role of fertility in stalk quality, lodging and corn yield was also a topic in 1969.

Strong environmental concerns began to appear in the late 1960s. The role of fertilizer nitrogen was discussed in two papers given in 1969 and one given in each of 1972 and 1973.

Foliar application of fertilizer was first discussed in 1970. Aerial application of nitrogen was discussed in 1974 after some growers experienced difficulty getting nitrogen applied before the corn was too tall for conventional equipment. Foliar application of fertilizers was researched and presented again in 1977 after agronomists in a neighboring state reported soybean yield increases of about 15 bushels per acre even on soils high in fertility. Neither Illinois nor other states were able to obtain such yield increases.

No-till corn was a continuing hot topic, so I spoke about it in 1970. Society was concerned about lead building up in soils along highways from lead added to gasoline. The effect of excessively high levels of lead added to soil on plant uptake and corn grain yield was discussed in 1971. There was some accumulation of lead in the vegetative part of corn but little appeared in the grain

In 1972, the change in the fertility status of some nutrients was presented. Illinois farmers had changed from mining the soil to building up the fertility status, as indicated by the addition of more nutrients than was being removed in the harvested crop.

The gasoline shortages, escalating prices and our recognized dependency on foreign countries made all of us more energy conscious in the late 1970s. I spoke in 1980 about the large amount of energy in the unharvested crop residues each year in Illinois. Because of the large amounts of natural gas used to make nitrogen fertilizers, I addressed the potential for Illinois farmers to produce "home-grown nitrogen" without giving up grain crop acreage in 1981.

The department had indicated for several years that fertilizer P and K should be categorized as buildup and maintenance. I discussed in 1983 why buildup fertilizer should be thought of as a capital cost and only maintenance as an operation cost.

Increasing crop yield per acre has allowed reductions in unit costs of production for several years in the U.S. In an effort to continue utilizing the advantages that high crop yields provide, four papers on the topic were given during 1984-86. Despite increases in our crop yields, my talk in 1987 pointed out that other countries are increasing yields relatively faster than the U.S.

Crop production is a risky endeavor. I spoke in 1988 how proper fertilizer management can help a producer reduce risk.

TITLES OF TALKS AND PAPERS PRESENTED BY WELCH AT ILLINOIS FERTILIZER CONFERENCES
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TABLES
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Table 1. Grain yields of four Illinois crops in 1964 and 1988 and percent change.

Table 2. Nitrogen, phosphorous, and potassium added to corn, soybeans and wheat in Illinois in 1964 and 1988.

Table 3. Nitrogen, phosphorus and potassium added in fertilizers in Illinois in 1964 and 1988 and percent change

Table 4. Fall prices of fertilizers and limestone in the United States in 1964 and 1988

Table 5. Nitrogen fertilizers used in Illinois in 1964 and 1988

Table 6. The five phosphorus fertilizers that supplied the highest percent of the total phosphorus used in Illinois in 1964 and 1988.

FOOTNOTES
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1L F. Welch is Professor of Soil Fertility, Department of Agronomy, University of Illinois at Urbana-Champaign.

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*Department of Crop Sciences
*University of Illinois Extension
*College of Agricultural, Consumer, and Environmental Sciences
*University of Illinois at Urbana-Champaign
*Illinois Fertilizer & Chemical Association
*Illinois Department of Agriculture
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