Strip-till Sugar Beet Yield Affected By Rotation Diversity and Cereal Crop Residue Management.

Strip tillage (ST) has been shown to be viable for small seeded crops like sugar beet (Beta vulgaris L.). A 7-yr field study was conducted in Sidney, MT to evaluate the performance of ST sugar beet grown in 2-yr (sugar beet/barley [Hordeum vulgare L.]) or 3-yr rotations (sugar beet/barley/soybean [Glycine max L.] or sugar beet/corn [Zea mays L.]/soybean) and with two different residue removal rates (full removal or no removal) for the cereal grain component of the 3-yr rotations. Treatments were randomly assigned to 15 m × 30 m sprinkler-irrigated plots. Strip tillage formed 30-cm-wide tilled strips spaced 60 cm apart alternating with 30-cm-wide untilled strips. Tillage was performed in the fall into small grain (2-yr rotation) or soybean (3-yr rotation) crop residues using a modified parabolic shank strip tiller. Dry urea and monoammonium phosphate were banded about 8 cm below the seed row. Where soybean preceded sugar beet, N rate was reduced by 45 kg N ha^-1. More diverse rotations typically yielded as well as or better than the 2-yr rotation. Removal of cereal crop residue two years prior to the sugar beet phase had little effect on sugar beet yield. Growing sugar beet following soybean allowed the reduction of N application rate by 45 kg ha^-1 without negatively affecting yield but caution must be exercised with this crop sequence due to an increased risk of Rhizoctonia root and crown rot.