Seeding Practices for Michigan Crops (E2107)
Seed is one of the most important inputs purchased for crop production system. Choosing the variety, using high quality seed and planting your crops at the time, rate and depth, you can have a major impact on the productivity and profitability of your crop
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Seed is one of the most important inputs you purchase for any crop production system. By choosing the proper variety, by using high quality seed and by planting your crops at the proper time, rate and depth, you can have a major impact on the productivity and profitability of your crop enterprise. This bulletin describes seed quality characteristics and presents information you can use when deciding on seeding practices for Michigan crops. Information on selecting varieties and overall crop management can be found in greater detail in other Cooperative Extension Service publications. Contact your local county Extension Service office for additional information.
High quality seed is important to obtain the desired plant population, high yield and high quality in the harvested crop. High quality seed means high germination (usually above 90 percent); absence of noxious weed seeds; and relative freedom from other crop seeds, diseased seeds, weed seeds should be of uniform size for accurate planting, especially with standard planter plates. CERTIFIED SEED is the most reliable source of high quality seed.
Planting information presented here is based on the use of high quality seed. Never plant seed of unknown variety or doubtful quality. If you must plant substandard seed in emergency situations, increase your seeding rate by the difference between the actual germination and 85-90 percent represented by acceptable quality seed.
An optimum plant populations essential for high yields and net return. A very high population can result in excessive plant competition for water and nutrients, sterility in corn, lodging in soybeans and excessive seed cost. A below-optimum population can result in inefficient use of water, nutrients and light, and thus lower yields and lower net return.
Plant population or seeding rate is influenced by row width, crop species, soil and climatic variables, and crop use. (See Tables 1-6 to determine optimum planting rates for various crops grown in Michigan.)
Seeding Rates for Row Crops
Seeding rates for field crops are generally expressed in pounds or bushels per acre. Because of the large number of varieties and hybrids available and the great variation in seed size, other methods of expressing seeding rates are usually more appropriate. Seeds per foot of row is a better designation for soybeans (see Table 1) and field beans (see Table 2). “Inches between seeds” (Table 3) can be used to determine proper plant populations for hybrid corn.
Using these designations allows the same seeding rate to be used for each variety, regardless of seed size or grade. To calculate total seed requirements, you must know the number of seeds per pound.
Seeding Rates for Solid Seeded Crops
Seeding rates for forages and small grains (Table 6) are given in pounds or bushels per acre. The ranges listed account for variable planting conditions and seed size. There are fewer large-sized seeds than small-sized seeds in a bushel or pound. Therefore, it takes a greater weight or volume of large-seeded varieties per acre than of small-seeded varieties to achieve similar populations.
If climatic, soil and fertility conditions are optimal and you are using high quality seed (high germination and purity), you can use the lower seeding rates listed in Table 6. Less than optimal conditions often require the higher rates
Seeding methods also affect seeding rate. Band seedings with fertilization and use of press wheels give best results when establishing forages. When planting a grass with a legume, you can vary the seeding rate of the grass to obtain more or less grass in the stand.
Small grains intended for use as silage or green chop should be seeded at 1.5 times the recommended rates for grain. If you are using small grains as companion (nurse) crops with forages, reduce the recommended seeding rate for the small grains by one-fourth to one-third.
Depending on your tillage system, your planter or grain drill should be equipped with the proper combination of weight (down pressure), coulters, furrow openers, closing device, pesticide applicators (for insecticide and /or herbicides) and fertilizer applicators. Replace all worn parts and align all planting units and accessories properly. Then calibrate the planting unit for the desired seeding rate and seeding depth. Seeding rate will vary, depending on the size and shape of the seed planted. Do not rely on the charts provided with the planter or drill—they serve only as a guide.
A drill can be calibrated by the following method:
1. Open seed tubes from four units of the drill and attach plastic bags or tubes to catch the seed. Each drill unit will vary, so sampling from a number of them and averaging will give a better estimate of the seeding rate than sampling from a single unit.
2. Set the gear drives and settings to those recommended by the manufacturer for the crop to be planted. Be sure the correct seed cups are in place for the desired crop.
3. Drive the planter or drill a known distance (e.g., 100 feet).
4. Measure the weight of the collected seed. Use the following equation to calculate the seeding rate.
5. Record the drill settings and the seeding rates calculated from the sample. If the seeding rate was lower than desired, move to the next higher seeding rate calibration falls between two settings on the drill, use the higher setting to avoid under-seeding and be sure to record the settings.
The planter or drill should also be adjusted for seeding depth. Penetration into the soil will be quite different under no-till conditions than for a tilled field. It will also vary by soil type and soil moisture. Each drill varies in how depth settings are determined. Through trial and error, determine settings for proper seed placement for residue, tillage and soil moisture conditions in your field.
Calculating Seed Requirements for Desired Stands
Row crops, especially corn, are typically overplanted to compensate for seed and seedling morality. Under average conditions of moisture and temperature, 10 to 15 percent seed and seedling mortality may be expected even with high quality seed. On organic soils, or with very early planting on mineral soils, or with very early planting on mineral soils, seedling losses may reach or exceed 20 percent. These principles can also be applied to other row crops.
For hybrid corn, a grower may want a final population of 20,000 plants per acre in 30-inch rows. Allowing about 15 percent extra seed to account for seed and seeding mortality makes the seed requirement 23,000 seeds per acre (1.15 times 20,000). In Table 1, under the 30-inch row spacing, the closest number of kernels to 23,000 is 23,100. This occurs when seed is spaced 9 inches apart in 30-inch rows. One bag with 80,000 kernels will plant 3.5 acres.
Another method of calculating seed requirements, without the use of Table 1, is as follows: Assume you wish to plant 50 acres of a large-seeded soybean variety in 30-inch rows at the rate of 10 seeds per foot of row. Imagine, then, that you have a “long acre,” that is, one row 30 inches wide. Such arrow would need to be 17,424 feet long (43,560 square feet per acre divided by 2.5 feet). With 10 beans per foot in this “long row,” you would need 174,240 seeds per acre. According to Table 5, the number of seeds per pound of a large-seeded variety is 2,200. For 50 acres, multiply 174,240 times 50 and divide by 2,200. Seed required = 3,960 pounds or 66 bushels.
Planting Speed May Affect Plant Stand
Seed spacing in row crops is affected by planting speed. For many corn planters, a speed of 3 to 4 miles per hour is optimum. At higher speeds, spacing of seeds is less uniform and there is a tendency for skipping and bunching. Newer planters are more accurate at higher speeds. Use of planter plates with more cells per plate will improve planting accuracy at higher speeds. Plateless planters may also allow higher speed without sacrificing plating accuracy. Under any condition, check spacing and number of seeds per acre or foot of row, as well as planting depth and fertilizer placement.
Planting speed does not affect the rate of small-seeded legumes or grasses in modern drills with fluted seed delivery units, which deliver accurately measured seed amounts regardless of speed of travel.
Recommended planting depths for various crops are listed in Table 6. Planting depth is affected by seed size, soil texture, moisture and temperature. Crops planted in dry, coarse-textured (sandy) soils may require deeper planting. Soils that are cold, fine textured (clay) and /or wet may require shallower planting. Seeds of forage crops are typically very small and can emerge only from a shallow depth, generally less than ½ inch. Therefore, take extreme care with planting depth. Culti-packer seeders and band seeders followed by press wheels or a culti-packer help ensure shallow seed placement. Check sod seeder drills carefully for seed depth.
Dates of planting for various crops are given in Table 6. Planting dates vary each year because of weather differences. Farther north, the calendar date of planting is normally later with spring-seeded crops and earlier with fall-seeded crops. Proximity to the Great Lakes also affects temperatures and planting dates.