Effects of Fertilizer Sources and Tillage Regimes on Weed Species Composition and Functional Diversity in the 4‐Year of Durum Wheat–Potato Rotation

Designing environmental-friendly approaches to mitigate weed pressure in agroecosystems is an urgent priority. A field experiment was conducted in 2014/2015 and 2015/2016 to evaluate fertilizer source and soil tillage on weed community composition in durum wheat–potato rotation. Experimental treatments included: (i) two fertilizer sources (mineral and organic fertilizers [MF and OF]) and (ii) three tillage regimes (plowing [CT], spading [RT1] and subsoiling [RT2]). A randomized complete block design with three replications was adopted. Weed characteristics were measured at the wheat tillering and potato flowering stage. In durum wheat, weed biomass ranged from 73.6 g m−2 (MF-CT) to 131.4 g m−2 (OF-RT2). In potato, weed biomass was the highest in OF-RT2 (156.3 g m−2 of DM), while weed density ranged from 29.0 n m−2 (MF-CT) to 46.5 n m−2 (OF-RT2). Overall, annual weeds were more abundant under OF compared to MF (75.3 vs. 64.5 n m−2), regardless of tillage treatments. Within MF treatments, annual weed density was higher under RT2 than RT1 and CT (71.3 vs. 61.1 n m−2). Relative frequency of perennial broadleaf species was highest in OF-RT2, with perennial weeds generally increasing under RT2 and RT1, regardless of the fertilization source. Across both crops, biomass production was higher under MF than OF. A negative relationship was observed between crop biomass and the density of broadleaf weeds (R2 = 0.3894, p < 0.001) and perennial weeds (R2 = 0.2156, p < 0.01). Further studies are required to investigate the long-term implications of these practices and refine weed management approaches across different cropping systems.