Wednesday, November 15, 2006

Effects of Fall- and Spring-seeded Cover Crops with Conservation Tillage on Weed Suppression and Soybean Growth.

Jong-Ho Seo1, Sok-Dong Kim1, Jin-Chel Shin1, and Tony J. Vyn2. (1) National Institute of Crop Science, RDA. Korea, 209 Seodun-Dong, Geonsun-Gu, Suwon, South Korea, (2) Agronomy Dept, Purdue Univ, 915 W State St, West Lafayette, IN 47907-2054

   Fall-seeded winter cover crop or spring-seeded living mulch with conservation tillage system could be suitable at the small farm as Korea rather than large farm. Effects of fall- and spring-seeded cover crops with conservation tillage on soybean production were investigated in 2005 and 2006, respectively at the field of central district of Korea. Soybean was planted into fall-seeded rye cover crop and spring-seeded rye + hairy vetch mixture living mulch with minimum tillage (inter-row spacing 70cm, tillage width for planting 10cm) in early June by domestically made row-spotting planter in 2005 and 2006, respectively. Amounts of weeds germinated after soybean planting such as Echinochloa crus-galli, Portulaca oleracea and Digitaria sanguinalis were reduced at the no-tilled soil surface during early soybean growth in 2005 at the conditions without as well as with rye residue as soil-cover regardless of herbicide spraying at soybean planting. Soybean growth and yield were reduced much by rye cover crop because of poor soybean seedling stand by heavy rye residue on soil surface. Hairy vetch + rye mixture seeded early in the early spring, 2006 suppressed weeds, particularly perennial weed as Calystegia japonica, which has high spreading before and after soybean planting at the condition of no cover crops. Allelopathic or smothering effect of hairy vetch living mulch on early soybean growth was weakened at the simultaneous seeding of row-spotted hairy vetch + rye in contrast to succesive seeding of broadcast hairy vetch and row-spotted rye.