The interaction between maize and weeds under the conditions of long-term reduced tillage

Abstract

© Lithuanian Research Centre for Agriculture and Forestry, 2015. One of the most common problems in long-term reduced or no-tillage practices is increased weed infestation. In this study, as no clear conclusions for Southern Baltic Region transitional maritime-continental climate and soil conditions have been reached to date, we investigated the interactions between maize and weeds in such technologies with low herbicide application levels. Toward this aim, a long-term field experiment was initiated at the Experimental Station of Aleksandras Stulginskis University, Kaunas district, Lithuania (54º52′ N, 23º49′ E) in 1988. The soil was ploughed to a depth of 22-25 cm (control) and 12-15 cm, cultivated to a depth of 25-30 and 10-12 cm or no-tilled. In deep-cultivated, shallow-cultivated and no-tilled plots, the residues covered 5.9, 5.7 and 13.2 times higher area of the soil surface than that in the control. The reduced primary and no-tillage conditions typically showed irradiance increases at the ¼, ½ and ¾ altitudes of maize crop. Besides, more weed seeds were found in the upper 0-15 cm layer (60%) than in the deeper (15-25 cm) layer (40%). In the deep and shallow-cultivated plots, there were 2 and 3 times more perennial weeds than in the conventionally ploughed. At the end of the maize (Zea mays L.) vegetation, in the shallow-ploughed, deep and shallow-cultivated or no-tilled plots, there was 46, 40, 30 and 16% greater weed stand density, whereas the dry mass of weeds decreased by 30, 22, 36 and 17%, respectively. Weed infestation in the short season maize primarily depended on the soil coverage with pre-crop residues, the maize stand density, the maize canopy height and the solar radiation level over the soil surface.