Weed Seed Decline and Buildup in Soils Under Various Corn Management Systems Across Nebraska 1

The weed seedbank in the soil makes weed control necessary every year in crop production. Research was initiated to determine if a farmer could reduce weed control practices after several years of excellent weed control. Experiments were conducted at five locations across Nebraska to determine the demise of weed seed in continuous corn ( Zea mays L.) where weed seed production had been eliminated for 3 yr (1975–1977) and then four weed management levels were superimposed for another 3 yr (1978–1980). Soils were Cumulic Haplaquolls, Typic Argiudolls, Udic Agriustolls, Typic Haplustolls, and Aridic Haplustolls. Within 1 yr (1978) after weed eradication had stopped, the average number of weed seeds that germinated increased over the four weed management levels; and weed competition to corn was evident within 2 yr (1979). Weeds have the potential to rapidly increase and reinfest a field once there is a lack of vigilance in the weed control program. Thus, the weed seedbank assures a continuity to the weed problem that will require more than eliminating weed seed production for several years. If a farmer has achieved 3 yr of perfect weed control on a given field, he still must expect weed problems in subsequent crops because of seed longevity in soil.