Soil nutrition management may preserve non-detrimental weed communities in rainfed winter wheat (T. aestivum)

Abstract

Overuse of fertilizers has been associated with the selection of competitive and dominant weed communities and biodiversity loss. Considering that crop nutrient management is going through a continuous revisitation process to improve nutrient use efficiency and energy savings, we addressed the consequences of different nutritional levels (low, optimal, and surplus) on weed community composition and wheat growth, yield, and kernel quality. Weed density and biomass were evaluated on sampling areas at the heading stage, and the data obtained were subjected to a cluster analysis for the identification of different weed communities throughout the experimental plots. At harvest, plant growth, yield and quality traits of wheat and wheat kernels were evaluated and correlated with the presence of different weed communities. Out of the four weed communities identified under optimal and low nutrition, two communities did not significantly reduce wheat yield. Under surplus nutrition only one weed community was identified, which resulted to be detrimental for wheat production in terms of yield quantity and quality. The non-detrimental communities were characterized by a high presence of corn chamomile (Anthemis arvensis L.), birdeye speedwell (Veronica persica Poir.), and common chickweed (Stellaria media (L.) Vill). On the contrary, the detrimental communities, were characterized by a high density and aboveground biomass of burr medic (Medicago polymorpha L.). Finally, under surplus nutrition, species richness declined, and the density and aboveground biomass of annual ryegrass (Lolium rigidum Gaud.) increased compared to optimal and low nutrition. Our results showed that soil fertilization plays a crucial role in differentiating detrimental vs. non-detrimental weed communities, with excess fertilization reducing species richness and selecting for competitive and specialized weed species. Overall, an efficient management of soil nutrients may promote non-detrimental weed communities while reducing weed management intensity and thereby improving biodiversity and sustainability. Assessing the efficiency of soil fertilization management and understanding how different fertilization rates and forms may affect weed communities is crucial to advancing sustainable weed management.