Weediness of agrophytocenoses of specialized rotation in various systems of basic tillage and fertilization in the right-bank forest-steppe of Ukraine
In pea agrophytocenosis, the highest actual and potential weediness is observed in no tillage in rotation (by 66.7 and 15.6 % respectively compared to the control options). In differentiated and shallow disk tillage the potential weed infestation of arable soil layer was at the same level and amounted 67.2 million/ha of seeds that is by 3.3 million/ha less than in the control. The segetal weed number per 1 m2 of pea agrophytocenosis ranged from 27 to 29 pieces, and their raw weight was from 35 to 37 g in surface, shallow and differentiated tillage in the rotation compared to 45 pieces and 72 g respectively in subsurface loosening. In winter wheat agrophytocenosis, the highest indicators of weediness were obtained in subsurface loosening. As for the other tillage techniques, the results were almost at the same level. In buckwheat agrophytocenosis, the indicators of potential weediness did not significantly differ in allopelagic plowing and differentiated tillage in rotation (65-66 million/ha). In no tillage loosening, they were by 18 % higher and in disk tillage by 6 % lower than in the control. In maize agrophytocenosis, in arable soil layer the average number of physically normal weed seeds was 114.8 per ha in subsurface tillage that was by 10.7 million or 10.3 % more than in the control. In differentiated and shallow disk tillage, this figure was 100.2-100.3 million, almost by 3.5-3.6 % less than in allopelagic plowing in the rotation. In agrophytocenoses of spring barley the highest weediness was also recorded in subsurface tillage for cultures of rotation. The segetal weed number in spring barley agrophytocenosis was identical (51 piece per 1 m2) in surface, differentiated and shallow tillage in crop rotation and in soil loosening by subsurface cultivator it was by 33.3 % higher and amounted 68 plants per 1 m2. In general, in the rotation the weed seed infestation rate, the number and weed raw weight, the raw weight of one segetal plant were higher respectively by 13.6; 45.7; 77.1; 20.5 % in subsurface tillage than in control. Potential weediness and the number of segetal component did not significantly differ in surface, differentiated and shallow tillage in crop rotation. In general, in the rotation with increase of fertilization the growth of potential weediness and number of segetal weeds as well as the reduction of their weight are observed. The most effective system of basic mechanical tillage in controlling the potential weed infestation of crop rotation was shallow disk tillage, and the least efficient one was no tillage. In allopelagic surface tillage the weed seeds are distributed evenly throughout the whole arable soil layer, and in no tillage they are localized at the top (0-10 cm) of it. The highest efficiency of segetal weed control in the agrophytocenoses of crop rotation is achieved in differentiated and shallow disk tillage of typical black soil, the lowest one is observed in loosening the soil by subsurface cultivator. In subsurface tillage, the proportion of monoecious weeds increases. The crop yield, collection of dry matter and feed units as well as the digestible protein yield of the main crops and by-products per hectare of arable crop rotation did not significantly differ from differentiated and shallow tillage. In subsurface loosening these figures are significantly reduced.