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Title: DENSITIES AND HERBICIDE RATES FOR NO-TILL DRILLED SOYBEANS

Author
item EBELHAR, STEPHEN - UNIV OF ILLINOIS
item ADEE, ERIC - UNIV OF ILLINOIS
item BARBER, KEVIN - UNIV OF ILLINOIS
item HART, STEPHEN - UNIV OF ILLINOIS
item HINES, RON - UNIV OF ILLINOIS
item PAUL, LYLE - UNIV OF ILLINOIS
item PEDERSEN, WAYNE - UNIV OF ILLINOIS
item RAINES, GLENN - UNIV OF ILLINOIS
item ROSKAMP, GORDON - WESTERN ILLINOIS UNIV
item WAX, LOYD

Submitted to: Annual Southern Conservation Tillage Conference for Sustainable Agriculture
Publication Type: Proceedings
Publication Acceptance Date: 9/15/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: A long-term field study is being conducted at six locations in Illinois to compare soybean management systems that would optimize variety, plant population or density of stand, and herbicide inputs required, when soybeans are close-drilled in under no-tillage conditions. The locations covered a wide range of geographical and weather conditions in Illinois. The research has been conducted for three years to date. Our goals are to determine the days to canopy closure, level of weed control achieved, and eventual grain yields and net returns to the producer. This report summarizes the results from the first two years regarding canopy closure, weed control, and grain yields. In our study, density effects on canopy closure helped in weed control, but differences in canopy closure of 3 to 7 days sooner for the high plant densities were small compared to the effects of PRE and POST herbicides. At most locations, PRE and POST herbicide applications, even at reduced rates, provided significantly better weed control than where no herbicides were applied. This accounted for a 10 bushel per acre increase in soybean yields when averaged across the locations. For most of the weed species involved, the 1/2 rate of POST herbicide was as effective as was the full POST rate. However, with the PRE treatments, sometimes the 1/2 rate was less effective than the full PRE rate, and the 3/4 rate was most always equal to the full PRE rate. These results indicate that, with close-drilled soybeans under no-till, and proper scouting to identify weed species, PRE and POST herbicide inputs may be reduced by 25 to 50%, mainly to the combination of tillage system, herbicide effectiveness, and utilization of the soybean canopy for competition to late-emerging weeds.