Effect of Crop Rotation and Tillage System on the Weed Infestation and Yield of Spring Wheat and on Soil Properties

A field experiment was conducted to evaluate the effect of crop rotation and tillage system on the yield and weed infestation of spring wheat as well as on the chemical properties of soil and number of earthworms. The first experimental factor was the cropping system: 1) crop rotation A: peaspring wheatdurum wheat, 2) crop rotation B: peaspring barleyspring wheat, 3) cereal monoculture: spring barleyspring wheatdurum wheat, whereas the second one was the tillage system: a) conventional (CT), b) reduced (RT), and c) no-tillage (NT). Spring wheat produced a higher grain yield in crop rotation A than in crop rotation B and cereal monoculture. Its higher yield was also achieved in the CT system than in the NT and RT systems. A higher number and weight of weeds was noted in the cereal monoculture compared to crop rotations A and B. Greater weed infestation occurred also in RT and NT systems than in the CT system. In soil samples from crop rotations A and B, analyses demonstrated higher contents of organic C and total N and a lower C/N ratio than in the cereal monoculture. The increased contents of organic C and total N in the soil were also affected by NT and RT systems, then by the CT system. Also the number of earthworms in soil m -2 was significantly higher in RT and NT than in CT system.