Effects of sowing depth on field emergence of soybeans

Abstract

The effect of sowing depth on the field emergence of soybeans was studied at Trangie, New South Wales, in a grey self-mulching clay soil. Eight varieties were used in 1976 and six varieties (including 3 near-isogenic lines differing only in seed size) were used in 1977. Seeds were sown at 2, 4, 6, 8, 10 and 12 cm depths and the number emerged was recorded daily. Field germination percentages and hypocotyl length were recorded 10 and 14 days after sowing. The results suggest that 4 to 6 cm is the most reliable sowing depth. Emergence was reduced and delayed by deeper sowings, and insufficient soil moisture reduced germination percentage at shallow sowings in 1976. Mean hypocotyl length increased with sowing depth, but only exceeded sowing depth at the shallowest sowings (2 and 4 cm). The varieties differed in emergence percentages, with Ruse being lowest and Forrest highest. Also, Ruse had shorter hypocotyls than the other varieties. Seed size did not influence emergence or hypocotyl length.