Influence of long-term application of different methods of cultivation and fertilization on the dynamics of species composition of weeds in short-term crop rotations of the Left-Bank Forest-Steppe

Abstract

Goal. To study the impact of long-term use of various methods of soil cultivation and fertilizer systems on the change in species composition and the number of weeds in short-term crop rotations under the current climatic conditions of the Left-Bank Forest-Steppe. Methods. Field — to study the interaction of research objects with biotic and abiotic factors; laboratory — to account for weeds with the subsequent determination of their species and quantitative composition. The correlation coefficient (r) was used to determine the relationship between weediness and agroclimatic conditions. Results. Field studies were conducted during 2021–2025 in the Cherkasy State Agricultural Experimental Station of the NSC “Institute of Agriculture of NAAS” within 2 stationary experiments on the study of the influence of predecessors, soil cultivation, and doses of fertilizers on the weediness of crops. The soil was a typical low-humus middle-carbonaceous chornozem. In 5-field crop rotations of grain-foraging type for ploughing, the level of weediness of crops was on average 1.7 times lower than for surface tillage, and 1.8 times lower than for flat-cut. The exceptions were sunflower crops, where the number of weeds for surface tillage was 1.25 times less than for plowing, and 1.8 times less than for flat-cut cultivation. In the early spring crops, the pigeon grass (Setaria glauca L.) prevailed, up to 53–84.7%; the share of dicotyledonous (goosefoot (Chenopodium album) and black nightshade (Solanum nigrum)) was 14.8–18%. On average, the weediness of 1 field under control without fertilizers for plowing in the grain crop rotation was 96.9 pcs./m2, in the row crop rotation — 68.5 pcs./m2, and for the introduction of intensive technologies with fertilizers — 103.0 and 84.1 pcs./m2, respectively. For surface tillage, the number of weeds without fertilizers in grain crop rotation was at the level of 189.8 pcs./m2, in row crop rotation — 143.4 pcs./m2, and with intensive technologies — 193.7 and 118.1 pcs./m2, respectively. In the control version without fertilizers and no-till cultivation in grain-grass crop rotation, the number of pigeon grass increased, which influenced the increase in the total number of weeds. With the increase in norms of fertilizers, the share of dicotyledonous weeds — goosefoot and black nightshade — increased. Weed cenosis in 5 field crop rotations was formed in general in the presence of spring weeds, in particular: pigeon grass — 42.3–84.7%, black nightshade — 0.6–12.9, goosefoot — 5.7–30.3, water pepper (Persicaria hydropiper) — 2.2–12.2, and other weeds — up to 3.2%. In spring crops, pigeon grass prevailed — 59.3–84.7%, the share of dicotyledonous (goosefoot, black nightshade, water pepper) was 13.7–38.5%. Conclusions. In general, in the experiment, crops in the grain-forage rotation were more weedy than in the grain-rowed one. During the intensification of soil tillage, a tendency to reduce the weediness of crops by 1.7–1.8 times was revealed.