Effects of tillage systems and crop rotation on weed density, weed species composition and weed biomass in maize

E. Demjanová¹, M. Macák¹, I. Dalovic,² F Majerník¹, Š. Týr¹, J. Smatana¹

¹Department of Sustainable Agriculture and Herbology, Faculty of Agrobiology and Food
Resources, Slovak Agricultural University in Nitra, Tr. A.Hlinku 2, 949 76 Nitra,
Slovak Republic, milan.macak@uniag.sk 2Institute of Field and Vegetable Crops, Novi Sad, Serbia, maizescience@yahoo.com Department of Sustainable Agriculture and Herbology, Faculty of Agrobiology and Food
Resources, Slovak Agricultural University in Nitra, Tr. A.Hlinku 2, 949 76 Nitra,
Slovak Republic, milan.macak@uniag.sk
²Institute of Field and Vegetable Crops, Novi Sad, Serbia, maizescience@yahoo.com

Abstract:

The field study was conducted over seven years in south-western Slovakia to investigate the effects of different soil tillage intensities and crop rotation on weed density, weed diversity and weed dry biomass in maize. Three basic tillage treatments were the following: mouldboard ploughing to a depth of 0.30 m (conventional tillage); offset disc ploughing to a depth of 0.15 m followed by combined cultivator; twice shallow loosening to a depth of 0.10 m (both reduced tillage). Annual broadleaf weeds (17 species) were clearly the dominant weed group under all soil tillage treatments, compared to perennial weeds (6 species) and annual grassy weeds (4 species). Dominant weed species were Amaranthus retroflexus and A. powelli, Chenopodium album, Echinochloa crus–galli, Convolvulus arvensis and Cirsium arvense. The number of species of the annual broadleaf and grassy weeds group was insignificant in conventional tillage and reduced tillage systems. Total weed density was significantly lower under the conventional tillage than the other reduced tillage systems. The main benefit of conventional tillage is a highly significant decline of perennial weeds. Only 2.6 perennial weed plants per quadrant in conventional tillage as compared to 7.5–9.0 in reduced tillage treatments were noted. Significantly less weed dry biomass was found in conventional treatment under mouldboard ploughing as compared to reduced tillage. Crop rotation did not have a significant influence on variability of species richness expressed according to Margalef’s index in maize. Tillage system was more influential than crop rotations on the weed density and diversity and weed biomass.

Key words:

crop rotation, diversity, tillage, weed density, weed dry biomass

The influence of short crop rotations on weed community composition

V. Seibutis and I. Deveikyte

Lithuanian Institute of Agriculture, Instituto aleja 1, Akademija, Kedainiai distr., LT-58344,Lithuania; e-mail: vytautas@lzi.lt, irenad@lzi.lt

Abstract:

Field experiments were designed to evaluate the effect of crop rotations on weed density and species composition. An 8-year study was initiated in Dotnuva (Lithuania) in 1997 on an Endocalcari-Endohypogleyic Cambisol. Ten crop rotations: peas–winter wheat–sugar beet–spring barley, peas–winter wheat–spring barley, peas–winter wheat-winter wheat, sugar beet-spring barley-winter wheat, sugar beet-peas-winter wheat, sugar beet-spring barley-peas, sugar beet-spring barley-spring rape, peas-winter wheat, sprig barley-sugar beet, winter rape-winter wheat and spring barley monocrops were investigated. It was revealed that weed densities varied between rotations. In winter wheat crops in all crop rotations the density of Fallopia convolvulus was high but there was less Lamium purpureum, Myosotis arvensis and Stellaria media at the end than at the beginning of crop rotations. The density of Elytrigia repens was high in most crop rotations investigated. The exception was crop rotations where sugar beet was involved, compared to a four-course rotation. The largest total of annual and perennial weeds was recorded in winter wheat, when the crop was grown after peas and winter rape. In all crop rotations, in the stands of spring barley the amount of Lamium purpureum, Tripleurospermum perforatum and Taraxacum officinale was 13–18% lower compared with the spring barley monocrop. Annual broad-leafed weeds in the spring barley monocrop were more numerous than in a four-course rotation but less numerous than in the other crop rotations.

Key words: