Soybean is a challenging crop in organic systems due to its low ability to compete with weeds during growth. 2 to 4 hoeing passages with camera-controlled steering systems are an option, but they significantly increase production costs. Moreover, in the traditional Italian growing areas, irrigation is becoming a necessity to ensure good yields. However, not all areas can be irrigated at a reasonable cost.
As a solution, soybeans may be sown into mulched cover crop in a no-till system. The mulch cover suppresses the weeds during initial growth of the crop and reduces the amount of water lost by evaporation.
Several methods of sowing into mulch were tested:
A) No-till sowing into a standing cover crop, then rolling the cover crop with a roller crimper;
B) No-till sowing into a standing cover crop, then creating mulch by passing over it with a flail shredder;
C) No-till sowing into a standing cover crop, and no follow-up procedures;
D) Mulch obtained with a flail shredder, then no-till sowing with a tine air seeder; and
E) Roller crimper followed by no-till sowing with a tine air seeder.
All of these methods, except method B, have shown good results in terms of weed control, and preser-vation of soil water (even during the dry summer in 2016). Yields were comparable with those of the tilled fields, except for method C.
• The cover crop needs to be sown as accurately as the main crop. Poor cover crop stands do not result in good mulches.
• The effectiveness of the mulch depends on the amount of mulch biomass. However, more biomass also means more difficulty for the planter.