Dominant weeds in maize (Zea mays L.) cultivation and their competitiveness under conditions of various methods of weed control

A field experiment was conducted in the years 2008-2010 at the Research Station of the Faculty of Agricultural Sciences, University of Life Sciences in Lublin, on brown soil with a slightly acidic pH, a high content of available phosphorus and potassium as well as an average magnesium content. The experiment was set up in a random split-plot design with four replications, with two methods for controlling weed infestation: I. mechanical - weeding of inter-rows twice; II. chemical - the herbicide Afalon Dyspersyjny 450 SC (a.i. linuron, 900 g × ha-1). Next, potassium, calcium and magnesium contents were determined in maize and in the dominant weed species. Based on the dry weight yield of maize and the biomass of particular weed species, nutrient uptake per hectare area was calculated. The chemical method of weed control reduced both the number and dry weight of weeds more than the mechanical method. The dominant species in the maize crop were Echinochloa crus-galli (L.) P. Beauv., Chenopodium album L., Galinsoga parviflora Cav., and Cirsium arvense L. All the weed species examined were more competitive than maize in accumulating potassium, calcium and magnesium. Galinsoga parviflora Cav. was the most competitive species with maize for potassium, Cirsium arvense L. for calcium, and Chenopodium album L. and Polygonum lapathifolium L. subsp. lapathifolium for magnesium. Weeds are serious competitors in taking up nutrients relative to crop plants; their share in the total uptake of macroelements from the soil by the maize crop and weeds together was considerable and it averaged as follows: for K - 35%, Ca - 27.3%, Mg - 27.4%