Soybean germination failing in dry spells, when is it safe to sow.
4 Answers
Do not sow soybean on the first shower; wait until you have received about 75 to 100 mm of well distributed rain so the soil is moist deep enough to carry the crop through a possible dry spell after germination. Sowing on insufficient moisture is the biggest cause of germination failure and forced re-sowing. The usual sowing window in central India is mid June to early July. Test seed germination before sowing and reject lots below 70 percent, adjust seed rate for bold seed, treat with fungicide and Rhizobium, and sow at the correct depth of about 3 to 4 cm, not too deep. A broad bed and furrow or ridge layout helps drain heavy rain and conserve moisture in dry spells.
I learned to be patient after losing a whole sowing to a dry spell in Nagpur. The first big rain looked enough but the deeper soil was still dry and the seedlings died when it did not rain for ten days. Now I dig and check moisture at sowing depth before I start, not just the wet surface.
Sowing depth is as important as the rain for me. Soybean sown too deep in my heavy soil could not push out and rotted. About 3 to 4 cm with the seed in moist soil gave even emergence. Set the planter properly and do not bury bold seed deep.
The broad bed and furrow layout has been worth the effort here. In the year of heavy June rain the furrows drained the excess and my soybean did not drown, while flat sown fields nearby had yellow waterlogged patches. The same beds also held moisture better in a later dry spell.