Influence of Reduced Tillage and Green Manures on Weeds in Organic Farming

Abstract

Reduced tillage and green manures may be capable to further improve organic crop production systems, if they are adapted to the specific needs of organic farming. One goal of the European research project TILMAN ORG (www.tilman-org.net) is to develop a more efficient weed management with at the same time increased biodiversity through improved use of green manures in different systems of reduced tillage. The results of a repeated one year trial on “Domaene Frankenhausen”, the research farm of University of Kassel, regarding the effect of both leguminous and non-leguminous green manures on weeds in four different tillage systems is the main topic of this paper. After the green manure species Sinapis alba, Trifolium resupinatum and Vicia sativa and a bare fallow as a control the main crop oat was sown in four different tillage systems: plough, chisel (2012) respectively disc harrow (2013), mulching + drilling and direct drilling. 2012 weed cover was generally low in the plough system compared to the other tillage systems. In the mulching + drilling- and direct drilling- systems the plots after the green manure species S. alba and T. resupinatum and the bare fallow had to be given up because weed pressure was too high. Compared to that V. sativa was able to suppress weeds considerably better and resulted in similar yields to the plough and chisel treatments 2012 on a level from 55.3 dt ha-1 to 59.1 dt ha-1. 201all mulching + drilling- and direct drillingplots had to be given up because of too high weed pressure. The weed pressure in the disc harrow – system differed not significantly from the plough system, but only green manure species Vicia sativa resulted in similar oat yields compared to the plough treatments (V. sativa x disc harrow 56.2 dt ha-1, V. sativa x plough 53.9 dt ha-1). In the plough – treatments there was an overall low weed pressure. Concerning yield there were no significant differences regarding green manure treatment.

Keywords

• Avena sativa
• chisel
• direct drilling
• disc harrow
• mulching + drilling
• Vicia sativa