Wheat–clover temporary intercropping under Mediterranean conditions affects wheat biomass, plant nitrogen dynamics and grain quality

Abstract

Intercropping is often proposed as a valid agroecological tool for low-input arable farming, but few studies assess it at the farm level. We set up a farm experiment to test a wheat-Persian clover temporary intercropping system (Pcw, unfertilized wheat sown at 330 seeds m−2, and clover sown in paired rows; Pcwbc, unfertilized wheat sown at 330 seeds m−2, and clover broadcast sown) against a farm system control treatment (Ctrl, fertilized wheat as a sole crop sown in single rows at 440 seeds m−2) and a factorial control treatment (Ctrlpr, unfertilized wheat as a sole crop, sown in paired rows at 330 seeds m−2). Persian clover in Pcw/Pcwbc was incorporated into the soil at the wheat stem elongation phase. At early stages, wheat biomass and nitrogen accumulation in Pcw/Pcwbc was significantly lower than in Ctrl; the same parameters were lower in Pcw/Pcwbc compared to Ctrlpr, but not significantly different. At harvest, wheat grain yield in Pcw was not significantly reduced compared to Ctrlpr, but it was around 20% lower than in Ctrl. Grain yield and N accumulation in Pcwbc at harvest were lower than Ctrl and Ctrlpr. Wheat grain protein content was 16% and 24% higher in Pcw and Pcwbc, respectively, than in Ctrlpr, and 15% and 28% compared to Ctrl. None of the treatments was economically viable from a farming perspective, although Pcw showed less economic losses, as the higher protein level raises the grain prices. Overall, the insertion of Persian clover in a temporary intercropping system reduces grain yield compared to wheat customarily sown, while simultaneously improving wheat grain protein content. No clear indication on the effect of intercropping on weed dynamics can be given.