AY-218
High-management soybean production requires close attention to proper seeding rates and plant populations. The seed requirement table below is intended as a general guide to assure establishment of acceptable soybean populations. An example showing how to use the table is given on the other side. (See Extension publication AY-217, "Plant Populations and Seeding Rates for Soybeans," for a more thorough discussion.)
AY-217
To `read' Table 1, you must know three things:
1. Seed germination. This percentage value is given on the tags of all seed which has been commercially processed. If using seed from your own bin, have it germination-tested.
2. Seed per pound. Determine by weighing out 1 ounce of seed, counting the number of seeds in that ounce, and multiplying by 16. This must be done for every variety each year, since seed size will change with variety and growing conditions.
3. Desired population. Table 2 on the back gives Purdue plants-per-acre recommendations for public soybean varieties planted at various row widths. Consult your seed dealer regarding recommended populations for private varieties.
In addition, knowledge of percent expected field emergence under your conditions permits a more accurate seed requirement estimate.
No. seeds Seed requirement when plant population (x 1000)** is -
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per pound 100 110 120 130 140 150 160 170 180
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lbs. seed per acre
90% TAG GERMINATION
2000 56 61 67 72 78 83 89 94 100
2200 50 56 61 66 71 76 81 86 91
2400 46 51 56 60 65 69 74 79 83
2600 43 47 51 56 60 64 69 73 77
2800 40 44 48 52 56 60 63 67 71
3000 37 41 44 48 52 56 59 63 67
85% TAG GERMINATION
2000 59 65 71 76 82 88 94 100 106
2200 53 59 64 70 75 80 86 91 96
2400 49 54 59 64 69 74 78 83 88
2600 45 50 54 59 63 68 72 77 81
2800 42 46 50 55 59 63 67 71 76
3000 39 43 47 51 55 59 63 67 71
80% TAG GERMINATION
2000 63 69 75 81 88 94 100 106 113
2200 57 63 68 74 80 85 91 97 102
2400 53 57 63 68 73 78 83 89 94
2600 48 53 58 63 67 72 77 82 87
2800 45 49 54 58 63 67 71 76 80
3000 42 46 50 54 58 63 67 71 75
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* Assumes percent final emergence will be equal to percent tag
germination. If emergence problems are anticipated, overplant an
additional 5 percent or as experience shows necessary.
** Recommended plant populations for various row widths are given in
Table 2 on reverse side.
A farmer plants his soybean crop in 30-inch rows. He has purchased seed tagged at 85% germination. What would be his per-acre seed requirement (and planter sprocket setting) to obtain optimum plant population and yield?
1.Weighing out an ounce of seed on a postage scale, the farmer counts 150 seeds in that sample, which means about 2400 seeds per pound (150 x 16).
2.From Table 2, he finds that, for 30-inch rows, he should have six plants per foot of row, or a total population of about 104,544 plants per acre.
3.Going to the 85% Tag Germination section of Table 1, he locates his seeds-per-pound figure (2400) in the far left column and 'reads' right to the column closest to his desired plant population. Since 104,544 falls approximately halfway between 100,000 and 110,000. his seed requirement is likewise halfway between 49 and 54 pounds - i.e., 51% pounds of seed per acre.
4.The farmer then refers to the planter manual for the sprocket settings that come closest to this seeding rate. If his planter's sprocket settings were in seeds per foot, he would only need to consult Table 2.
Past experience on various fields may indicate possible soybean emergence problems due to crusting or difficulty in controlling planting depth. If so, consider overplanting by about 5 percent the rates shown in Table 1.
Remember, the recommended planting depth for soybeans is 1 to 1 1/2 inches; and full-season varieties should be planted first. For seeding rate and plant population recommendations for double-cropped soybeans, see Extension publication ID-96, "Double Cropping Wheat and Soybeans in Indiana."
ID-96
Row Plants per Plants
width foot of row* per acre
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36" 7 101,640
30" 6 104,544
20" 5 130,680
18" 4.5 130,680
16" 4 130,680
14" 3.5 130,680
12" 3 130,680
10" 2.75 143,748
8" 2.5 163,350
7" 2.25 168,016
6" 2 174,240
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* If growing determinate or semi-determinate varieties, consider
increasing the populations, consult your county Extension agent,
seedsman or AY-217 for recommendations.
New 1/79
Cooperative Extension work in Agriculture and Home Economics, state of Indiana, Purdue University, and U.S. Department of Agriculture cooperating; H. A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the acts of May 8 and June 30, 1914. Purdue University Cooperative Extension Service is an equal opportunity/equal access institution.