Weediness of maize in different crop rotation

Abstract

Weed seeds in and on the soil are the primary cause of weed infestations in maize. Cropping system diversification through the use of longer rotations of dissimilar species can increase the range of stress and mortality factors that regulate weed population dynamics, and thus can be useful for maintaining effective weed control while reducing the burden of crop protection placed on herbicides. This paper deals with effect of continuous cropping, two-, three- and six crop rotation on the weediness of maize. A trial was settled on the experimental field of the Faculty of Agriculture, in 1992. The following cultivation systems have been observed: maize continuous cropping, maize-winter wheat rotation (two-), maize-soybean-winter wheat rotation (three-) and winter wheat-maize-soybean-spring barley+red clover-red clover-sunflower (sixcrop rotation). The common conventional cropping practices specific for maize were applied in systems. Crops are grown in non-irrigation regime, on leached chernozem. Long-term effects of various cropping systems on weed infestation were observed by the one square meter area method in 2015. The 23-year continuous cropping was obviously a respectable period for making unambiguous and precise conclusions. Namely, the number of weed species, and especially the number of plants per weed species, has been increasing in maize continuous cropping over years, but the increasing tendency certainly depended on meteorological conditions in particular years. Maize continuous cropping was characterised by the highest number of weed species and plants per weed species with the dominance of perennial species, due to, first of all, great abundance of plants per species Sorghum halepense (L.) Pers and Convolvulus arvensis L. The highest number of plants per annual weed species in maize continuous cropping was recorded in species Solanum nigrum L., Chenopodium album L. and Amaranthus retroflexus L. Dominant species in crop rotations were the same as in maize continuous cropping, only the increased distribution of perennial species Cirsium arvense (L.) Scop. and Agropyrum repens (L.) Beauv. was observed in the six-crop rotation. Crop rotations, especially the three crop rotation, are more effective in suppressing the number of plants per weed species and decreasing fresh biomass of weeds than continuous cropping and the two and six crop rotation are.