Effect of soil-N and urine-N on nitrate leaching under pure grass, pure clover and mixed grass/clover swards

We hypothesized that short duration plant interference aiming to change mainly light intensity and red:far red ratio during crop establishment in Italian ryegrass-infested winter wheat fields, could hinder the development of Italian ryegrass and thus reduce its effect on wheat yield. To test this hypothesis, wheat was planted between previously established live (low red:far red ratio) or dead (high red:far red ratio), barnyardgrass or maize, plant hedges. Experimental results demonstrated that the presence of live or dead plant hedges during the first 30 days of crop establishment and also hedge orientation were important factors regulating weed and crop biomass production and competitive relationships. In barnyardgrass hedge treatments wheat yield was improved up to 67% and Italian ryegrass production was reduced by more than 20%. In plots with maize live hedges oriented N¯S the biomass production of wheat was independent of production of Italian ryegrass. Data presented here suggests that there is room for developing weed control technologies on the basis of understanding photosensory processes of weed and crop species.