Agricultural Biotechnology: Benefits of Transgenic Soybeans
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AGRICULTURAL BIOTECHNOLOGY: BENEFITS OF TRANSGENIC SOYBEANS Leonard P. Gianessi Janet E. Carpenter April 2000 National Center for Food and Agricultural Policy 1616 P Street, NW, First Floor Washington, DC 20036 Tel: 202-328-5048 Fax: 202-328-5133 [email protected] Preparation of this report was supported financially with a grant from the Rockefeller Foundation TABLE OF CONTENTS 1. Introduction 2. U.S. Soybean Production 3. Soybean Products 4. Soybean Physiology 5. Soybeans – Agronomic Factors 6. Soybean Genetic Improvements A. Introduction B. Reproductive Process C. Artificial Cross Breeding D. Mutation Breeding E. Transgenic Plants 7. Weed Competition – Soybeans 8. Weed Control in Soybeans: 1940’s – 1950’s 9. Herbicides – An Overview 10. Herbicide Use in Soybeans: 1960’s – 1995 A. Introduction B. Historical Overview 1. The Early 1960’s 2. Soil Applied Herbicides 3. Postemergence Herbicides 4. Sulfonylurea/Imidazolinone Herbicides 5. Burndown Herbicides C. Summary of Usage: 1995 11. Transgenic Herbicide Tolerant Soybeans A. Glyphosate – An Overview B. Performance of Roundup Ready Soybeans C. Herbicide Ratings D. Adoption Impacts: 1995 – 1998 1. Herbicide Costs 2. Soybean Yields 3. Returns 4. Other Aggregate Studies 5. Herbicide Treatments 6. Herbicide Use Amounts 7. Other Impacts 12. Summary and Conclusions 13. References Appendix 1: Soybean Processing – A Description 1. Introduction Soybeans and other crops have been improved genetically for many decades through traditional crop breeding – a technique that requires that species be sexually compatible. With the development of biotechnology methods, scientists have the ability to transfer single genes from one living organism into another, regardless of species or sexual compatibility. Varieties that are developed through the transfer of genes between species that are not sexually compatible are referred to as “transgenic.” Transgenic soybean plants have been developed with a gene from a soil bacteria that allows the use of an herbicide that would normally kill soybeans. Transgenic soybean varieties have been adopted rapidly by U.S. growers (Table 1). Transgenic soybean acreage represents approximately 60 % of the total acreage planted to transgenic crops grown in the U.S. (Corn and cotton are the other major crops with transgenic variety plantings in the U.S.) Farmers are planting transgenic soybeans in the U.S. because of the weed control benefits that result from the use of an herbicide that damages conventional varieties. This herbicide, glyphosate (trade name “Roundup”) is a cost effective solution to many of the weed problems that U.S. soybean growers must overcome every year. The herbicide tolerant transgenic soybean is referred to as “Roundup Ready.” The purpose of this report is to describe and quantify the weed control benefits provided on soybean acreage planted with the transgenic varieties in 1998. TABLE 1: Herbicide Tolerant Transgenic Soybean Acreage: U.S. Year # of Acres (Millions) % of U.S. Acreage 1996 1 2 1997 9 13 1998 27 37 1999 35 47 Source: Monsanto 1 2. U.S. Soybean Production Soybean is one of the three largest crops grown in the U.S., grown on approximately 70 million acres in 1999 an area smaller than corn and comparable to wheat. Thirty states have significant soybean acreage. Soybean production is centered in the Midwest where ten states account for 73% of U.S. acreage and production. The states of Illinois and Iowa each account for more than 10 million acres of soybeans [58]. The Delta states of Mississippi, Arkansas and Louisiana together account for 10% of U.S. acreage of soybeans. Soybeans were grown primarily as forage crops in the U.S. through the 1930’s. The production of soybeans increased in 1934 in response to the severe drought of that year in the upper Midwest. The performance of soybeans under drought conditions was better than corn, thereby enticing farmers to try this relatively new crop [100]. Soybean harvested for seed represented 40% of the planted acreage in 1939, indicating expanding acreage for processing. Prior to World War II, the U.S. imported 40% of its edible fats and oils. At the advent of the War, this supply was cut, and processors turned to domestically produced soybean oil [1]. By 1944, 72% of the planted soybean acreage was harvested for seed [100]. World demand for cooking oil, salad oil and red meat increased substantially immediately after World War II. These demands stimulated the rapid expansion of soybean production in the U.S. [2]. In the 1950’s, soybean meal became available as a low-cost, high-protein feed ingredient, triggering explosive growth in U.S. livestock and poultry production. U.S. soybean acreage increased from less than 20 million acres in the early 1950’s to over 50 million acres in the 1970’s and a record 72 million acres in 1998, 2 representing 27% of the acreage planted to all crops in the U.S. Figure 1 charts the increase in U.S. soybean acreage from 1944 to 1999. Total annual U.S. soybean production increased from about 500 million bushels in the 1950’s to over 2.5 billion bushels (150 billion pounds) in 1997. Figure 2 charts U.S. soybean production 1944-1999. The increase in annual total U.S. production resulted not only from the expansion of acreage (Figure 1) but also from a steady rise in average U.S. soybean yield per acre. Figure 3 charts the increase in average U.S. soybean yields 1944- 1999. Two-thirds of the increase in soybean yields in the U.S. from 1943 to 1960 is attributed to the planting of improved varieties, with increased fertilizer use accounting for the remaining one-third of the increase [90]. A statistical analysis of the change in soybean yields from 1965 to 1979 concluded that weed control provided by the use of herbicides accounted for 62 percent of the yield increase while further variety improvements accounted for 13 percent of the increase [73]. In the 1990’s, U.S. soybean farmers received an average of $6 per bushel. However, prices dropped to $5/bushel in 1998 [1]. The total value of the soybean crop was $14 billion in 1998, representing approximately 15% of the value of all crops grown in the U.S. The U.S. produces nearly half of the total world soybean crop. Other major producing countries include Brazil, China and Argentina. Competition in export markets comes from Brazil and Argentina as China is a net importer of soybeans. The U.S. accounted for 60% of world exports of soybeans in 1997/98. 3 About 28% of U.S. soybeans (valued at $4.8 billion) were exported in 1998 [1]. The U.S. exported soybean meal and soybean oil valued at $1.6 billion and $0.9 billion, respectively, in 1998. 4 FIGURE 1 U.S. SOYBEAN AREA 1944-1999 80 70 60 50 ACRES 40 (MILLIONS) 30 20 10 0 44 48 52 56 60 64 68 72 76 80 84 88 92 96 SOURCE: [58] FIGURE 2 U.S. SOYBEAN PRODUCTION 1944-1999 3.0 2.5 BUSHELS 2.0 (BILLIONS) 1.5 1.0 0.5 0.0 44 47 50 53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 SOURCE: [58] 5 FIGURE 3 U.S. SOYBEAN YIELD 1944-1999 45 40 35 30 BUSHELS/ 25 ACRE 20 15 10 5 0 44 47 50 53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 SOURCE: [58] 6 3. Soybean Products Approximately 74 billion pounds of soybean meal and 18 billion pounds of soybean oil were produced by U.S. processors in 1998 [1]. (See Appendix 1 for a description of soybean processing.) Ninety-six percent of the soy meal produced in the U.S. is used as an animal feed [74]. Three percent of the soybean meal is used in human food, and approximately 1% is used in industrial uses. Soybean oil makes up about 75% of the oil used in U.S. shortening (baking and frying fats), margarine and salad/cooking oil. Table 2 shows the use of soybean oil in fats and oil products in 1998. The large volume of soybean oil use has been attributed to at least three factors: 1) a plentiful and dependable supply; 2) competitive price; and 3) the improvements made in the flavor and oxidative stability of the oil [74]. Until 1980, cottonseed oil was the preferred oil for mayonnaise products. However, the cottonseed oil emulsion in mayonnaise is rather weak and sometimes breaks down at refrigerator temperatures. With improved flavor stability and stronger emulsion of soy oil, all mayonnaises produced commercially in the U.S. are now prepared exclusively with soybean oil as the key component. Similarly, soybean oil is now used almost exclusively in all prepared salad dressings and imitation mayonnaises sold in the U.S. [74]. Lecithin is a co-product of degumming soybean oil, that, after processing, has significant commercial value as an emulsifier in foods. Soy lecithin is normally added to such food products as shortening, margarines, baked goods, chocolate confectionery coatings, peanut butter, powdered mixes and dietary food. Lecithin increases the stability of these products. 7 When added to margarine, lecithin prevents “bleeding” of the moisture present and reduces spattering during frying. In baked goods, lecithin functions as a useful emulsifier. It helps bring about rapid and intimate mixing of the shortening in the dough. In making chocolate, about 0.25-0.35% lecithin is added. It reduces viscosity of chocolate markedly, enables the manufacturer to apply a uniform coating, decreases the time for grinding and mixing the various ingredients and produces a more stable chocolate. Lecithin is used to keep the chocolate and cocoa butter in a candy bar from separating.