Interseeding cover crops in sugarbeet

This field experiment was conducted at Ada and Sabin, MN. Field experiment was laid out in a randomized complete block design with a split-plot arrangement with five cover crop treatments, (i) check (no cover crop), (ii) winter rye, (iii) winter camelina, (iv) winter Austrian pea, (v) brown mustard (Brasica juncea L.) cv. Kodiak, as main plot and two cover crop planting times (end of July and end of Aug.) as sub plot with four replicates. Cover crops were interseeded between sugarbeet rows using a hoe to mimic the large-scale interseeder developed by Amity Technology for this CAP project. Just before beet harvest, cover crop biomass was measured.

Interseeded cover crops in June or July did not reduce sugarbeet yield or recoverable sugar (Table 3, Fig. 9). Interestingly, sugar content (kg ha^-1) was significantly higher than sugarbeet in the no cover crop treatment compared with winter rye, winter camelina, and brown mustard interseeded in June and winter rye interseeded in July in Downer, MN. In Ada, MN, sugar content was significantly higher for all cover crops except for winter camelina and winter pea interseeded in July.  When sugarbeet roots hit a deep soil layer high in available nitrate at the end of the season, the late N will typically decrease sugar content.  We assume the interseeded cover crops acted as scavengers of residual nitrate increasing root sugar content.  Rye was the only crop that was still alive after sugarbeet lifting and harvest. This would allow a cover to protect soil from erosion following harvest. Sugarbeet fields are the most prone to soil erosion in late fall and spring. This research will be repeated in 2019.