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The green manure residual effect on soil health 2 years later in crop rotation is understudied. Little is known about weed biomass impact on soil microbial communities or their interactions. A Colchester County, NS, Canada, organic grain research trial during 2016-2017 comprised 2 or 3-year rotations with or without green manure crop prior to wheat, and then soybeans. Fall soil sampling was conducted both years. The soybean phase of the crop rotation was managed as weedy or non-weedy. Weedy soil showed significantly increased soil respiratory activity and fungal microbial biomass. Green manure treatments did not significantly influence soil health indicators. [ABSTRACT FROM AUTHOR]

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There is continued interest in adopting no-till practices in organic agriculture. One way to decrease tillage is to implement no-till termination of green manures. Studies on this novel approach have focused primarily on cash crop performance and weed control. The objective of this study was to examine soil organic C distribution and dynamics as influenced by different methods of green manure termination of a spring-planted green manure. In this green manure-wheat (Triticum aestivum L.)-fall rye (Secale cereal L.)-soybean [Glycine max (L.) Merr.] rotation three green manure termination methods were compared (no-till crop roller, spring tillage, and fall tillage). A mixture of hairy vetch (Vicia villosa Roth)-oat (Avena sativa L.) was seeded in late May in two trials, the first commencing in 2013 and the second in 2014. Soil organic C was monitored for 3 yr after green manure termination. In Trial 2, total organic C was greater under no-till green manure termination compared to fall and spring-till termination (by 2.4 ± 1.2 Mg C ha-1 and 2.3 ± 1.3 Mg C ha-1, respectively) and the effect remained significant in all 3 yr. In Trial 1, particulate organic matter C was stratified in no-till and concentrated at the soil surface (0-5cm) and higher overall in no-till in Trial 2. Overall soil organic C was higher under no-till green manure termination and the more labile pool of POXc appeared less responsive to termination treatments. [ABSTRACT FROM AUTHOR]