Blade Roller–Green Manure Interactions on Nitrogen Dynamics, Weeds, and Organic Wheat

Abstract

The blade roller offers new opportunities to reduce tillage, especially in organic farming. The objective of the study was to reduce tillage in the green manure phase of a green manure–wheat (Triticum aestivum L.) rotation by substituting tillage with blade rolling. A pea (Pisum sativum L.) and oat (Avena sativa L.) green manure was used for two site‐years at Carman, MB, while a pea monocrop was used for one site‐year at Oxbow, SK. At pea flowering, the green manure was terminated by rolling, tilling, or a combination of the two. Ammonia emissions were greater in the no‐till compared with the tilled green manure system, though total ammonia losses were low (<13 kg ha−1). Replacing tillage with rolling reduced soil nitrate N in autumn after green manure by 56 to 88 kg ha−1 in the 0‐ to 60‐cm soil depth. Reduced green manure tillage did not affect wheat establishment but delayed plant development in some instances. Fewer weeds were often observed in wheat in the no‐till compared with tilled plots. Total N supply in the green manure–wheat system was reduced in the no‐till system compared to the tilled only system at two out of three site‐years by an average of 44%. While reduced N supply in the reduced tillage system coincided with reduced wheat yield and protein, it was concluded that factors other than N also were involved. Using the blade roller instead of tillage in the green manure year provides soil conservation benefits and facilitates wheat production the following year.