Efecto residual de distintos cultivos de servicio sobre el enmalezamiento invernal

In 2023 an experiment was conducted in the Experimental Station “Dr. Mario A. Cassinoni” (E.E.M.A.C) of the Faculty of Agronomy in Paysandú (Uruguay) in order to evaluate the residual effects of different cover crops (CC) on winter weed infestation the following year. The experimental design was a randomized complete block design (RCBD) with 3 replications. The treatments evaluated were Persian clover (Trifolium resupinatum), hairy vetch (Vicia villosa), black oats (Avena strigosa), a mixture of black oats and hairy vetch, yellow oats (Avena byzantina) and a control without plant cover During the fall and winter of 2023, the weeding was evaluated in three stages: fallow prior to barley sowing, crop establishment and pre-harvest. The assessment included identifying and quantifying present weed species, their phenological stage, total weed coverage, residue cover from the previous crop, bare soil coverage, and barley crop coverage. To complement the analysis, data collected at the end of the CCs cycle in 2022 was used. The results were analyzed with ANOVA using the statistical software InfoStat, applying Tukey's test at a 5% significance level for mean separation. The CCs that at the end of the cycle achieved greater and faster soil cover —black oats, hairy vetch, black oat-hairy vetch mixture and yellow oats— showed fewer weeds in the reproductive stage. This effect continued until fallow period, prior to barley planting, except for hairy vetch, resulting in less weeding. Black oats and the black oat-hairy vetch mixture maintained their suppressive effect at planting, while Persian clover was the least effective, performing even worse than the control. In barley preharvest, 100% cover was achieved, with no significant differences in the total or spectrum of weeding. These results demonstrate that the residual effects of CCs on winter weeding the following year varied according to the CC and weeds present in the field, being more evident during the fallow period prior to barley sowing than during the crop cycle.