Abstract
Use of conservation tillage and cover crop in crop production systems have been increased in recent years due to regulatory mandates concerning environmental issues and the need of labor-saving in weed management. Changes of weed occurrence at 40 days after soybean planting, soybean seedling stand, yield by reduced tillage and rye cover crop were investigated. Weed occurrence was more affected by soil-disturbing according to tillage rather than soil covering of rye residue showing the lowest weed amount at the plot of 10cm narrow-row tillage. Fig-leaved goosefoot (Chenopodium ficifolium Smith) which was germinated in early spring before soybean planting, increased at the plots of rye cover crop. On the contrary, common purslane (Portulaca oleracea L), henry crabgrass (Digitaria ciliaris Koel), which were germinated in late spring after soybean planting, increased at the plot of no cover crop with glyphosate ammonium SL spraying for killing weeds at 10 days before soybean planting. Soybean stand and yield were reduced much by rye cover crop which had much rye residue on soil, but soybean stand and yield at plots of rye cover crop treatments were more improved by late variety rye rather than early variety rye, particularly in the plot of late rye with partial tillage in which rye residue incorporated at 10 days before soybean planting. More techniques for advancing soybean stand is needed in conservation tillage system with low weed occurrence.
콩재배 시 토양보전 및 잡초억제를 위해 조생호밀피복, 만생호밀피복 및 무피복에 각각 좁은골경운(10cm) 및 부분경운(30cm)으로 콩을 파종하여 콩파종 후 40일에 제초제시용 및 무시용에 따른 잡초발생, 콩 입모율 및 수량을 살펴 본 결과 첫째, 잡초의 발생개체수 및 잡초건물중은 피복작물보다 경운에 크게 영향을 받아 경운면적비율이 가장 적었던 좁은 골경운에서 가장 적었으며, 호밀피복작물에 의한 잡초의 억제효과는 보이지 않았다. 둘째, 파종 10일전 비선택성 제초제로 좀명아주를 고사시킨 무피복구에서는 피, 쇠비름 및 바랭이 등 콩파종 후 발아하는 잡초가 많았던 반면 살초제를 사용하지 않았던 호밀피복구는 좀명아주가 호밀 토양피복 후 많이 생육하여 잡초발생량이 증가하였다. 셋째, 잡초조사 후 잡초를 제거한 상태에서 콩의 수량은 주로 콩 입모율에 의해 영향을 받아 콩입모율이 낮은 조생호밀피복구에서 수량이 현저히 감소하였는데, 호밀피복구에서는 만생호밀-부분경운구에서 입모율이 증가하여 콩수량이 다소 회복되었다.