During this time, the cotyledons lose 70 percent of their dry weight. Loss of one cotyledon has little effect on the young plant's growth rate, but loss of both cotyledons at or soon after VE will reduce yields 8 to 9 percent. After V1, photosynthesis by the developing leaves is adequate for the plant to sustain itself. New V stages will appear about every 5 days from VC through V5, and every 3 days from V5 to shortly after R5 when the maximum number of nodes is developed. The ability of the germinating soybean seedling to push through a crusted soil decreases with deeper planting.
Some varieties are especially sensitive to deep planting.
In addition, the cooler soil temperatures at greater depths cause slower growth and decreased nutrient availability. Roots are not attracted to this fertilizer band, so the fertilizer must be placed where the roots will be. Fertilizer placement too near or with the seed can injure the young plant. Weeds compete with soybeans for moisture, nutrients, and sunlight. Tillage operations, herbicides, uniform stands, and crop rotations are useful methods for controlling weeds.