Einfluss von Mischanbau mit Hafer, flacher Bodenbearbeitung und Biofumigationsbrassicaceen auf Beikrautbesatz, Erbsenkrankheiten und Erträge in der Fruchtfolge mit Winterweizen

Summary

Experiments were conducted to determine how tillage intensity, the use of biofumigation brassica cover crops and mixed cropping with oats affect the performance of organic peas with respect to weed pressure, diseases, and yield. Fields were either ploughed to a depth of about 15-20 cm or only to about 8 cm in late summer followed by either Sinapis alba (low glucosinolate (GSC) content), Raphanus sativus (medium GSC) or Brassica juncea (high GSC). Brassicas were mulched in fall right before flowering and incorporated in the top soil. In mixtures with oats seed rate for peas was as in pure stands, for oats it was 20 %. There was a dramatic spring drought in 2011 resulting in severe water stress for the peas in 2011. Weeds were significantly reduced by about 45 % by oats in both years. Neither tillage nor any of the brassica cover crops or mixing with oats had a significant effect on root disease severity of peas or the pathogen composition. In both years pea lower stems and roots were mostly infected by Phoma medicaginis. In 2011, about half of the infected plants were also infected by Mycosphaerella pinodes and up to 20 % with Ascochyta pisi. Pea yields were 2.2 t ha-1 and 2.1 t ha-1 in 2010 and 2011, respectively. Oat yields were 3.0 and 4.9 t ha-1, respectively. Mixing with oats reduced pea yields by 32 and 63 % in 2010 and 2011, respectively while the oats yielded about 45 % of the pure stands. Tillage did not affect yields, however, pea yields in plots that had been planted to R. sativus as cover crop were significantly reduced. Subsequent wheat yields in the rotation were significantly higher after peas and the pea-oat mixture than after oats alone.