Long-term experiments with reduced tillage in spring cereals.: I.: Effects on weed flora, weed seedbank and grain yield

In four field experiments lasting from autumn 1993 to 2000, perennial weeds and overwintering weed species increased with reduced tillage compared to ploughing in autumn or spring. Abundant species were Cirsium arvense, Elymus repens, Matricaria perforata, Poa annua and Stellaria media. With no-tillage, grassland perennials were detected. Volunteer oats increased in plots without ploughing. A combination of glyphosate and post-emergence herbicide was necessary to control different biological groups of weeds in a reduced tillage system. If harvest was late, the effect on E. repens was better when glyphosate was applied in ripe barley or in spring than in late autumn. With reduced tillage more weed seeds were found in 0-10 cm soil depth than in 10-20 cm soil depth. Different tillage treatments produced smaller differences in the weed seedbank in 1999 than in 1996. (C) 2002 Elsevier Science Ltd. All rights reserved.