Start soybeans in March or April, when all danger of frost has passed. Choose a site that gets full sun and good drainage, and has enough space for your soybean crop, which will require 2 to 3 feet between rows.
Amend your soil to give soybeans the rich, loose foundation they need. Mix 1/3 compost, 1/3 quick-draining soil and 1/3 well-aged horse or cow manure together, and till the mixture into the top 1 foot of your soil. Make sure you're using aged manure, as fresh manure will burn the seeds. Add 10-10-10 fertilizer to the top inch of the soil, per manufacturer directions.
Plant soybeans at a depth of 1 1/2 inches in the amended soil, spaced 2 inches apart. Space your rows 25 to 30 inches apart to give the soybeans room to grow. Sprinkle 2 inches of water over the plot immediately after planting.
Put soybeans on a regular watering schedule of 2 inches of water every three days. Look for germination in the first week, and flowering and harvest in July and August.